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Synthesis and characterization of Carbon Nano FiberLiFePO4 composites for Li-ion batteries

Available online at Journal of Power Sources180(2008)553–560Synthesis and characterization of Carbon Nano Fiber/LiFePO4composites for Li-ion batteriesM.S.Bhuvaneswari a,∗,N.N.Bramnik a,D.Ensling a,H.Ehrenberg a,b,W.Jaegermann aa Darmstadt University of Technology,Institute of Materials Science,Petersenstrasse23,64287Darmstadt,Germanyb IFW Dresden,Institute for Complex Materials,Helmholtzstr,20,01069Dresden,GermanyReceived22September2007;received in revised form17January2008;accepted26January2008Available online16February2008AbstractCarbon Nano Fibers(CNFs)coated with LiFePO4particles have been prepared by a non-aqueous sol–gel technique.The functionalization of the CNFs by HNO3acid treatment has been conﬁrmed by Raman and XPS analyses.The samples pure LiFePO4and LiFePO4–CNF have been characterized by XRD,SEM,RAMAN,XPS and electrochemical analysis.The LiFePO4–CNF sample shows better electrochemical performance compared to as-prepared LiFePO4.LiFePO4–CNF(10wt.%)delivers a higher speciﬁc capacity(∼140mAh g−1)than LiFePO4with carbon black (25wt.%)added after synthesis(∼120mAh g−1)at0.1C.©2008Elsevier B.V.All rights reserved.Keywords:Carbon Nano Fiber;LiFePO4;Raman analysis;X-ray photo electron spectroscopy;Electrochemical analysis1.IntroductionThe commercially used cathode material LiCoO2in lithium-ion batteries is associated with problems such as high cost, toxicity,and safety risks in large scale applications which cre-ated a paramount need for an alternative cathode candidate[1]. Recently lithium3d-metal orthophosphates have gained a sub-stantial interest as positive cathode materials[2–5].Among the orthophosphates LiFePO4exhibits several properties such as environmental friendliness,low price,non-toxicity,and excep-tional stability,which perfectly matches with the needs to replace LiCoO2[6,7].However,a major limitation of this material is its poor rate performance,because of its low electronic con-ductivity[8–11].Current research on LiFePO4-based materials aims towards improving the rate performance by reducing its particle size and by effective carbon coating[8–11].Various synthesis methods such as sol–gel,co-precipitation,carbother-mal reduction,etc.have been utilized to optimize the particle size of LiFePO4,and positive results have been reported[8–13].∗Corresponding author.Tel.:+496151166353;fax:+496151166308.E-mail address:bhuvana.siva@(M.S.Bhuvaneswari).Different organic additives for carbon coating around LiFePO4 particles and cation doping into the olivine structure have also been tried to enhance the intrinsic electronic conductiv-ity of LiFePO4[14,15].Hu et al.reported that the structure of the residual carbon on the LiFePO4particles is important for the electrochemical performance[14].Zaghib et al.reported that a critical factor towards improving the performance is the carbon content in the electrode,which is related to elec-trical conductivity and networking between particles[16].A new approach to enhance the effects of carbon content and coating of LiFePO4particles is reported here,based on the addi-tion of functionalized Carbon Nano Fibers(CNFs)during the sol–gel synthesis of LiFePO4.It has been reported in litera-ture[17]that carbon is found efﬁcient to reduce the resistivity of LiFePO4if sp3bonding in carbon is very small hence in the present study Carbon Nano Fiber has been used instead of amorphous carbon.It has been found that the functional-ized CNFs can be coated with LiFePO4.For comparison,pure LiFePO4has also been prepared by a non-aqueous sol–gel method.LiFePO4-coated CNF electrodes without additional carbon black show excellent electrochemical performance and are compared to electrodes,prepared from pure LiFePO4with additional carbon black.The samples have been characterized0378-7753/$–see front matter©2008Elsevier B.V.All rights reserved. doi:10.1016/j.jpowsour.2008.01.090554M.S.Bhuvaneswari et al./Journal of Power Sources180(2008)553–560by thermogravimetric–differential thermal analysis(TG–DTA), XRD,SEM,Raman spectroscopy,XPS and electrochemical analyses.2.ExperimentalLiFePO4has been prepared from a mixture of Li(CH3 COO)·2H2O(lithium acetate),Fe(CH3COO)2(iron acetate), H3PO4(phosphoric acid)and ethylene glycol.The synthesis conditions reported by Yang et al.with slight modiﬁcations have been adopted[13].The precursors were dissolved in ethy-lene glycol at a molar ratio of1:1:1.After rigorous stirring the resulting gel has been heat treated at700◦C with a heating rate of10◦C min−1in argon atmosphere for12h(here after to be named as pure LiFePO4).The functionalization of pyrolytically stripped Carbon Nano Fibers(commercial grade from Electrovac AG,Austria,with a diameter and length of100–200nm and>20␮m,respec-tively)was achieved by treating the Carbon Nano Fiber with conc.HNO3at70◦C for24h.After treatment the suspension of C-Fibers in HNO3was diluted with deionized water,ﬁltered, washed with water and dried at110◦C in open air atmosphere (here after the acid treated Carbon Nano Fiber to be named simply as CNF).10wt.%of CNF has been added with the same precursors used for preparing pure LiFePO4during sol–gel preparation, and the sol–gel has been stirred for one week in order to get better contact of LiFePO4particles with CNF.The gel has been heat treated at600◦C with a heating rate of10◦C min−1 in argon atmosphere for12h(here after will be named as LiFePO4–CNF).TG–DTA measurements have been performed(TGA92-Setaram)from0to1000◦C at a heating rate of10◦C min−1 under argon atmosphere.The samples were tested by X-ray powder diffraction using a STOE STADI/P powder diffrac-tometer(Mo K␣1radiation).A scanning electron microscope Philips XL30FEG has been used to observe the parti-cles morphology.To determine the carbon content elemental analysis has been performed using VarioEL III CHN elemen-tal analyzer.Raman measurements have been carried out by Labram800HR open microscope from Horiba Jobin Yvon with a laser wavelength of488nm.The XPS studies have been performed using an Escalab250Spectrometer with a monochro-matized Al anode.Electrochemical studies were carried out with a multichannel potentiostatic–galvanostatic system VMP (PerkinElmer Instruments,USA).Swagelok-type cells were assembled in an argon-ﬁlled dry box with water and oxygen contents less than1ppm.A pure LiFePO4cathode compos-ite has been fabricated as follows:60%active material,25% acetylene carbon black and15%PTFE as binder were inti-mately mixed,ground in an agate mortar and pressed onto an Al-mesh(resulting electrodes contain about3mg of active com-pound).The LiFePO4–CNF cathode consists of90%LiFePO4 (10wt.%CNF)and10%PTFE.2.31wt.%and12.29wt.%car-bon(calculated from elemental analysis)contents for the pure LiFePO4and the LiFePO4–CNF samples,respectively,have been included for the cathode active mass calculation,lithium metal was used as anode and the electrolyte was1M LiPF6in2:1EC/DMC.3.Results and discussion3.1.Functionalization of CNFsCarbon Nano Fibers have been functionalized by concen-trated HNO3before they were added to the gel,to get betteradhesion to the LiFePO4particles by introducing compatiblefunctional groups on the Carbon Nano Fiber surface[18].Thistreatment with acid leads to a partial oxidation of the surfaceand the formation of oxidized groups like C OH–or C O.The functionalization has been conﬁrmed by Raman and XPSanalyses.3.1.1.Raman analysisThe Raman spectra of pristine CNF and HNO3treated CNFare shown in Fig.1.The band in the region of2500–2900cm−1is the second order D-band(D*-band),which depends on the3-dimensional packing scheme.The group of peaks observed in therange of1550–1660cm−1is called the graphite band(G-band),which is most pronounced for a high degree of symmetry andordered structure in a carbon material.The bands observed from1250to1450cm−1corresponds to a disorder-induced phononmode(D-band)with a high intensity for disordered carbon mate-rials.The relative intensities I D/I G and I D∗/I G can be used qualitatively to characterize the order of carbon materials and arealso a measure for the amount of carbon defects in the nanoﬁbersdue to the presence of functional groups[19,20].Higher ratiosof I D/I G or I D∗/I G correspond to a lower degree of order in the CNFs[19].The characteristic Raman bands observed for pris-tine and HNO3treated CNF are tabulated in Table1.The I D/I G ratio for HNO3treated CNFs is high compared to the pristine CNFs which conﬁrms the functionalization of the Carbon Nano Fibers,an important factor for networking LiFePO4particles with the surface of Carbon NanoFibers.Fig.1.Raman spectra for pristine and functionalized CNFs.M.S.Bhuvaneswari et al./Journal of Power Sources180(2008)553–560555 Table1Raman wave numbers and corresponding band assignments for pristine and functionalized CNFsSample D line(cm−1)G peak(cm−1)D*peak(cm−1)D/G value(cm−1)D*/G value(cm−1) Pristine CNF1349.21570.32698.90.3940.116 Functionalized CNF1358.11575.02703.90.4900.179LiFePO4–CNF1336.41578.82651.90.4000.1463.1.2.XPS analysisThe XPS survey spectra of pristine CNF and functional-ized CNF(not shown)indicates that carbon and oxygen are the dominant species comprising the carbonﬁber surfaces. The corresponding high resolution carbon C1s and oxygen O1s XPS spectra are shown in Fig.2a and b,respectively. The C1s spectrum of pristine CNFs shows the graphitic car-bon peak at284.6eV.The C1s spectrum of pristine CNF is asymmetric in nature and the O1s peak has been decon-voluted into two main peaks,corresponding to C O groups (∼531.1eV)and C OH groups(∼532.7eV)[21].This indi-cates that the pristine CNFs have already been oxidized to an appreciable extent,a normal behavior of Carbon Nano Fibers[21].The HNO3treated CNFs indicate a signiﬁcant change in the XPS spectra of carbon C1s and oxygen O1s compared to pristine CNFs.Considering the C1s proﬁle,the main emission(284.6eV)broadens towards higher binding energy(B.E.)and there is clearly enhanced emission of a fea-ture near288eV.The former observation is consistent with an increased presence of hydroxyl groups,whereas the latter trend is consistent with an increase in the relative amount of car-boxyl functional groups[21].The O1s spectra become more asymmetric and broader towards lower binding energy,consis-tent with an increase in the relative proportion of C O and C OH groups[21].The O/C atomic ratio of pristine CNFs and HNO3treated CNFs are∼0.02and∼0.234,respectively. The increase in the O/C atomic ratio conﬁrms the function-alization of Carbon Nano Fibers by HNO3acid treatment [22].3.2.Synthesis and characterization of pure LiFePO4and LiFePO4–CNF3.2.1.TG–DTA analysisFig.3shows the thermogravimetric–differential thermal analysis curves for the sol–gel precursors of pure LiFePO4. The TG curves indicate one sharp mass-loss peak between 129and245◦C( m/m=83.18wt.%).This mass-loss process is related to exothermic and endothermic peaks in the DTA curve.The exothermic peaks at96.6,218.6,330.4and422.3◦C are due to the thermal decomposition of ethylene glycol and acetate precursors.The endothermic peaks observed at325.9and 368.5◦C correspond to the elemental carbon formation[23–25]. An endothermic peak has been observed at422.3◦C for pure LiFePO4,but no appreciable weight loss is observed in the TG curve above245◦C,suggesting that the crystallization of LiFePO4takes place at this temperature.A single phase with an ordered olivine structure will be realized even at550◦C,but the effective amorphous carbon coating from the precursors(with-out the addition of CNF)will be obtained when the samples were heat treated at700◦C,hence the synthesis temperature for pure LiFePO4has been chosen as700◦C[4,13].The synthesistem-Fig.2.XPS spectra(a)in the region of C1s for pristine and HNO3treated CNF;(b)in the region of O1s for pristine and HNO3treated CNF.556M.S.Bhuvaneswari et al./Journal of Power Sources180(2008)553–560Fig.3.TG/DTA curves of LiFePO4obtained under argon atmosphere at a heating rate of10◦C min−1.perature for LiFePO4–CNF has been chosen as600◦C as we are not interested in amorphous carbon coating for LiFePO4–CNF samples.3.2.2.XRD analysisThe XRD patterns for pure LiFePO4(Fig.4a)and LiFePO4–CNF(Fig.4b)indicate the good crystalinity of samples.All reﬂections can be indexed based on the orthorhom-bic LiFePO4crystallizing in the space group Pnma.A slight contribution from the amorphous part can be identi-ﬁed in the diffraction pattern of LiFePO4–CNF composite, which can be attributed to the presence of amorphous C-Fibers in the sample.The olivine-like structure was conﬁrmed by Rietveld analysis performed with the structural model taken from Ref.[26].The unit cell parameters obtained for LiFePO4(a=10.3281(3)˚A,b=6.0080(2)˚A,c=4.6947(1)˚A) and for LiFePO4–CNF(a=10.3314(7)˚A,b=6.0064(4)˚A, c=4.6996(4)˚A)are in a good agreement with the ones reported in literature[26].3.2.3.SEMThe scanning electron micrographs of pure LiFePO4are shown in Fig.5a and b.The SEM pictures indicate the agglom-eration of particles and grain dimensions of about500nm Fig.4.Rietveld reﬁnement of(a)LiFePO4and(b)LiFePO4–CNF samples prepared by a non-aqueous sol–gel method.to1␮m.The SEM pictures of LiFePO4–CNF are shown in Fig.6a and b,which indicate a non-homogeneous coating of LiFePO4particles smaller than200nm over Carbon Nano Fibers.The reduction in particle size in comparison withpure Fig.5.(a and b)SEM images of CNF free LiFePO4.M.S.Bhuvaneswari et al./Journal of Power Sources 180(2008)553–560557Fig.6.(a and b)SEM images of CNF added LiFePO 4.LiFePO 4is mainly due to the lower synthesis temperature for LiFePO 4–CNF.3.2.4.Raman analysisThe Raman spectra of LiFePO 4and LiFePO 4–CNF are shown in Fig.7.The carbon lines at 1339.3and at 1579.7cm −1are signiﬁcantly screened by the characteristic Raman lines for both the pure LiFePO 4and the LiFePO 4–CNF samples.The weak carbon lines,which appear for “pure”LiFePO 4are due to the presence of residual carbon from the organic precursors.The intramolecular stretching modes of PO 43−are recorded at 581,987.5and 1051cm −1.Only a slight difference in the characteris-tic Raman wave numbers (shifted by 4–6cm −1)of LiFePO 4has been observed between pure LiFePO 4and LiFePO 4–CNF sam-ples due to interactions with the CNFs.LiFePO 4–CNF shows a second order D-band (D *).The intensity ratios D/G and D */G have been calculated and are also tabulated in Table 1.The D/G and D */G values of LiFePO 4with 10wt.%CNF are higher when compared to pristine CNFs but lower than for the HNO 3treated CNFs.An intermediate value for LiFePO 4–CNF is expected,because in addition to the 10wt.%CNFs amorphous carbon is also present from the organic precursors.These intensity ratios are not reliable to evaluate the sp 3and sp 2content in samples with amorphous carbon in it [17].Fig.7.Raman spectra of pure LiFePO 4and LiFePO 4–CNF samples. 3.2.5.XPS analysisThe XPS spectra of pure LiFePO 4and LiFePO 4–CNF sam-ples in the binding energy range of O1s,C1s and P2p are shown in Figs.8and 9respectively.Their corresponding binding ener-gies are tabulated in Table 2.The LiFePO 4–CNF sample shows the appearance of a shoulder at higher binding energies of O1s spectra which is absent for the pure sample.We therefore assign this emission to the oxidation modiﬁed CNT containing C O and C OH surface moieties [22].The main emission represents the LiFePO 4oxide ions in LiFePO 4.The carbon C1s line is deconvoluted into three contributions for both the CNFfreeFig.8.XPS spectrum in the region of P2p,C1s,O1s for pure LiFePO 4.558M.S.Bhuvaneswari et al./Journal of Power Sources180(2008)553–560Fig.9.XPS spectrum in the region of P2p,C1s,O1s for LiFePO4–CNF. and CNF added samples.The graphitic carbon emission for LiFePO4–CNF sample is observed at284.7eV.The asymmetric behavior of the C1s line for pure LiFePO4is due to the pres-ence of amorphous carbon,as observed in Raman analysis.The P2p emission corresponds to the PO43−group and the Fe/P ratio (1.06)is consistent with the compound stoichiometry for both pure LiFePO4and LiFePO4–CNF samples[27].The XPS spectra in the region of Fe2p for pure LiFePO4 and LiFePO4–CNF samples are shown in Fig.10.Thebinding Fig.10.XPS spectrum in the region of Fe2p for pure LiFePO4and LiFePO4–CNF.energy scale is presented as measured.A single low intensity peak on the low binding energy side of the envelope is due to the formation of Fe ions with a lower than normal oxidation state by the production of defects in neighboring sites[28].For transition metal ions with partiallyﬁlled d-states the appearance of satellite peaks(mentioned as shoulder peaks in literature)is a character-istic feature,and for our samples we observe this satellite peaks along with the main Fe2p peaks at higher binding energies of Fe2p(Table2).The Fe2p emission is consistent to previously published spectra of LiFePO4.The main and the satellite binding energy positions of the Fe2p peaks perfectly match with the B.E. positions reported in literature and are characteristic for Fe2+ cations.Normally the B.E.separation between the Fe2p main peak and satellite peak indicates the Fe2+and Fe3+contribution in the sample.In comparison to spectra obtained for oxides the feature of the2p3/2emission can be assigned to a dominant con-tribution of Fe in its normal2+oxidation state[29–31].For our samples the B.E.separation between the Fe2p main peak and the satellite peak for pure LiFePO4and LiFePO4–CNF samples is nearly6eV,which conﬁrms that only Fe2+contributions are present in the sample.For Fe3+contributions the energy sep-aration between main and satellite peaks would be8eV[31]. We were not able to deconvolute the main emission line as reported in[30]further due to limited resolution of the spec-Table2XPS binding energies of various atoms for pure LiFePO4and LiFePO4–CNFElements Pure LiFePO4(eV)LiFePO4–CNF(eV)AssignmentsOxygen (O1s)531.3531.5LiFePO4533.0CNT(C OH,C O)Carbon (C1s)284.2284.2CNT 286.1285.6CNT–OH 288.2289.3CNT–COPhosphorus(P2p)133.4133.5PO4 Iron(Fe2p)709.6707.6Defects Fe2p3/2712.6710.5Fe2+718.3716.7Satellite Fe2p1/2726.0724.1Fe2+732.7730.2SatelliteM.S.Bhuvaneswari et al./Journal of Power Sources 180(2008)553–560559tra;despite the principle resolution power of our setup is below 0.4eV .This is probably due to some inhomogeneity effects in slight charging and/or crystalline quality of our samples.A more detailed analysis of the photoemission feature will be performed in future experiments also considering the charges in oxidation states during charging (Li deintercalation).3.2.6.Electrochemical measurementsElectrochemical measurements have been performed for pure LiFePO 4and LiFePO 4–CNF samples.The elemental anal-ysis for pure LiFePO 4indicates the presence of 2.3wt.%of carbon content in the sample and has been included in the calculation of the active mass.12.3wt.%of carbon con-tent for the LiFePO 4–CNF sample has two origins,10wt.%from the functionalized CNFs (known amount)and around 2.3wt.%from amorphous carbon,as calculated from elemen-tal analysis.Hence 12.3wt.%carbon has been included for active mass calculation for the LiFePO 4–CNF cathode sample.Fig.11a and b shows the potential versus composition curves of LiFePO 4and LiFePO 4–CNF electrode at 0.5C rate respectively.Fig.12represents the cycling performance of pure LiFePO 4and LiFePO 4–CNF samples.The results indicate that thehighlyFig.11.Potential–composition curves of (a)LiFePO 4at 0.5C and (b)LiFePO 4–CNF at0.5C.Fig.12.Cycling performance of pure LiFePO 4and LiFePO 4–CNF.ordered pyrolytically stripped Carbon Nano Fibers improve the electrochemical performance of LiFePO 4–CNF cathodes with low carbon content (∼10wt.%)in comparison with amorphous carbon black (∼25wt.%)added to pure LiFePO 4.The speciﬁc structure of the carbon additives plays a dominant role for the resulting electrochemical performance [14].Currently interface studies on the electrochemical behavior of LiFePO 4–CNF by in situ XPS and investigations of the rate capability are in progress.4.ConclusionLiFePO 4particles coated over CNF ﬁbers have been synthe-sized by a sol–gel method.An oxidative wet functionalization of Carbon Nano Fibers by concentrated HNO 3gives bet-ter adhesion of LiFePO 4particles on the CNF surfaces.The functionalized Carbon Nano Fiber added LiFePO 4shows bet-ter electrochemical performance compared to acetylene black added LiFePO 4even though the coating is not homogeneous.The results indicate that the speciﬁc structure of the compos-ite electrode induced by the CNT plays a signiﬁcant role in enhancing the electrochemical performance of LiFePO 4–CNF with simultaneously reduced carbon content,which is important for their practical use.The improved performance is probably due to the high electronic conductivity of the cathode material due to the CNF addition and the efﬁcient contact between elec-trochemical active particles and the electronic conducting CNFs.The nanosized composite shortens the diffusion paths for lithium ions,increases the diffusion rate and results in better kinetic conditions in the electrode material.A more uniform coating of LiFePO 4over the CNF layers is the next step to approach the theoretical capacity over large cycle numbers at high charging rates and with low carbon content.AcknowledgementFinancial support from the Deutsche Forschungsgemein-schaft under grant nos.DFG JA859/14and EH183/3within the Priority Programme SPP 1181“Nanoscaled Inorganic Materials by Molecular Design:New Materials for Advanced Technolo-gies”is gratefully acknowledged.560M.S.Bhuvaneswari et al./Journal of Power 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关于磷酸铁锂的英文文献(含中文翻译)

Preparation and characterization of carbon-coated LiFePO 4cathode materials for lithium-ion batteries with resorcinol –formaldehyde polymer as carbon precursorYachao Lan,Xiaodong Wang ⁎,Jingwei Zhang,Jiwei Zhang,Zhishen Wu,Zhijun Zhang ⁎Key Laboratory for Special Functional Materials,Henan University,Kaifeng 475004,Chinaa b s t r a c ta r t i c l e i n f o Article history:Received 8February 2011Received in revised form 26May 2011Accepted 3June 2011Available online 12June 2011Keywords:Lithium iron phosphateResorcinol –formaldehyde polymer Lithium-ion batteryLiFePO 4/C composites were synthesized by two methods using home-made amorphous nano-FePO 4as the iron precursor and soluble starch,sucrose,citric acid,and resorcinol –formaldehyde (RF)polymer as four carbon precursors,respectively.The crystalline structures,morphologies,compositions,electrochemical performances of the prepared powders were investigated with XRD,TEM,Raman,and cyclic voltammogram method.The results showed that employing soluble starch and sucrose as the carbon precursors resulted in a de ﬁcient carbon coating on the surface of LiFePO 4particle,but employing citric acid and RF polymer as the carbon precursors realized a uniform carbon coating on the surface of LiFePO 4particle,and the corresponding thicknesses of the uniform carbon ﬁlms are 2.5nm and 4.5nm,respectively.When RF polymer was used as the carbon precursor,the material showed the highest initial discharge capacity (138.4mAh g −1at 0.2C at room temperature)and the best rate performance among the four materials.©2011Elsevier B.V.All rights reserved.1.IntroductionLiFePO 4is an attractive cathode material for lithium-ion batteries because of its high theoretical capacity of 170mAh g −1,environ-mental benign,and high thermal stability.However,its poor electric conductivity of less than 10−13S cm −1limits its battery performance [1],such as the dramatic decrease in power at a high current density,which is the main drawback to commercial use.To overcome the low electric conductivity of LiFePO 4,many effective approaches have been introduced,including metal substitution [2–5],metal powder com-pounding [6],and conductive carbon coating [7–15].Among them,the preparation of LiFePO 4/carbon composite (LiFePO 4/C)is one of the attractive ways to improve the electric conductivity of the ﬁnal product by forming a good conduction path.Furthermore,carbon can be also used as a reductant,which can reduce Fe 3+ions to Fe 2+ions.It should be noted that many studies involving the synthesis of nano-sized LiFePO 4employ Fe 2+salts as precursors [3,16–20],such as FeC 2O 4·2H 2O and (CH 3COO)2Fe,which are expensive.Therefore,it is necessary to use cheap materials and a convenient method.Here,we report the synthesis,characterization and electrochemical test of LiFePO 4/C composites prepared by two methods using home-made amorphous nano-FePO 4as the iron precursor and various organics as carbon precursors.The two methods using FePO 4as starting material are cheap and environmentally benign for the production of LiFePO 4material.Particularly,we present a novel method to synthesize a uniformcarbon ﬁlm coated LiFePO 4cathode materials.This method involved an in situ reaction of resorcinol and formaldehyde on the surface of amorphous FePO 4.At room temperature,electrochemical tests showed that this material exhibited an initial discharge capacity of 138.4mAh g −1at 0.2C and a good cycling property at 0.5and 1.0C rate,respectively.2.Experimental2.1.Preparation of amorphous nano-FePO 4Amorphous nano-FePO 4was prepared by spontaneous precipita-tion from aqueous solutions.An equimolar solution of H 3PO 4was added to a solution of Fe(NO 3)3·9H 2O at 60°C under stirring and given amounts of PEG-400as surfactant.Then ammonia water (NH 3·H 2O)was slowly added to the mixed solution under vigorous stirring and a milk-white precipitate formed immediately.The pH of the solution was kept at 2.0.The precipitate was ﬁltered and washed several times with distilled water.After drying in vacuum oven at 120°C for 12h,yellowish-white amorphous FePO 4was obtained.2.2.Preparation of LiFePO 4/CTwo methods were used to prepare the LiFePO 4/C composites in this study.2.2.1.Method oneA rheological phase method [21]was employed to synthesize LiFePO 4/C composite.Stoichiometric amount of amorphous FePO 4,LiOH·H 2O were used as the starting materials.The carbon precursorsPowder Technology 212(2011)327–331⁎Corresponding authors.Tel./fax:+863783881358.E-mail address:donguser@ (X.Wang).0032-5910/$–see front matter ©2011Elsevier B.V.All rights reserved.doi:10.1016/j.powtec.2011.06.005Contents lists available at ScienceDirectPowder Technologyj o u r n a l h o me p a g e :w w w.e l sev i e r.c o m /l oc a t e /pow t e care soluble starch(50.0g/1mol LiOH·H2O),sucrose(35.0g/1mol LiOH·H2O),citric acid monohydrate(21.0g/1mol LiOH·H2O),respec-tively.These carbon precursors were respectively solved in an appropri-ate amount of distilled water under stirring and heating.Then the amorphous FePO4and LiOH·H2O were added under vigorous stirring. Subsequently,the mixtures were respectively dried in an oven at120°C for6h,heated at350°C for1h in argonﬂow,treated at750°C for12h in argonﬂow,and ground.Finally,the LiFePO4/C composites were obtained and were denoted as sample A,sample B and sample C,respectively. 2.2.2.Method twoIn a typical synthesis,0.10g of CTAB was solved in30ml of distilled water solution under continuous stirring.Subsequently,1.52g FePO4·3H2O,0.055g resorcinol(R)and0.10ml formaldehyde(F)were successively added.When the temperature of water bath was up to85°C,LiOH·H2O was added.The mixture was kept stirred up in the dark for2h,dried in an oven at120°C for6h,heated at 350°C for1h in argonﬂow,treated at750°C for12h in argonﬂow, andﬁnally ground to obtain the LiFePO4/C composites(denoted as sample D).These four samples and their corresponding parameters are listed in Table1.The carbon contents of the samples were calculated by the loss on ignition of the four LiFePO4/C composites in air.2.3.CharacterizationThermogravimetric(TG)and differential thermal analysis(DTA) analyses were conducted with an EXSTAR6000thermal analysis system at a heating rate of10°C min−1.The powder X-ray diffraction (XRD,X'Pert Pro MPD,Philips)using Cu Ka radiation was employed to identify the crystalline phase of the prepared materials.Raman spectrum was recorded on a Renishaw RM-1000Microscopic Raman spectrometer with457.5nm excitation requiring a10mW power at room temperature.Low-magniﬁcation and high-magniﬁcation TEM images were taken on a JEM-2010transmission electron microscope (using an accelerating voltage of200kV).Electrodes were fabricated from a mixture of prepared carbon-coated LiFePO4powders(80wt.%),carbon black(12wt.%),and polyvinylideneﬂuoride in N-methylpyrrolidinon(8wt.%).The slurry was spread onto Al foil and dried in vacuum at120°C for12h.The carbon-coated LiFePO4loading was2mg cm−2in the experimental cells.The cells were assembled in an argon-atmosphere-ﬁlled glove box.The electrolyte was1M LiPF6in a mixture of ethylene carbonate (EC)and dimethyl carbonate(DMC)(1:1volume).The cells were galvanostatically charged and discharged at a voltage range of2.5–4.2V with LAND battery testing system at room temperature.Cyclic voltammograms were run on an IM6impedance and electrochemicalmeasurement system(Zahner,Germany)at a scan rate of0.1mV s−1 between2.5and4.0V.3.Results and discussionThe TEM images of the amorphous nano-FePO4were shown in Fig.1.The morphology of the as-prepared FePO4is an irregular particle with an average diameter of30nm.Most of the particles connected to each other because of their high surface energy which results from their small sizes.Fig.2a shows the TG/DTA curves of the FePO4·3H2O powder with a heating rate of10°C/min from room temperature to850°C in air.On the DTA curve near150°C,there is a very strong endothermic peak, associating with the sharp weight loss on the TG curve,which is related to the quick dehydration of FePO4·3H2O.During150–550°C, 26.3%weight loss on the TG curve indicates the slow elimination of residual H2O in FePO4·3H2O,exactly corresponding to the loss of crystalline water of FePO4·3H2O.And one exothermic peak is displayed at a higher temperature of590°C,which is not accompa-nied by appreciable weight loss in the TG curve,indicating the transformation of the amorphous FePO4to hexagonal FePO4crystal. The XRD patterns of FePO4·3H2O before and after calcination have been investigated in Fig.2b.As illustrated in pattern A,it can be seen that there is no evidence of diffraction peaks before calcination, indicating the synthesized FePO4·3H2O is just amorphous.While for the calcinated FePO4·3H2O at600°C for6h in air,it exhibits strong and narrow peaks revealing a well-crystallized material in pattern B. All of the diffraction peaks of the prepared FePO4are indexed to a single-phase hexagonal structure with a P3121space group and without any impurities,which is in good agreement with the standard card(JCPDS card no:72–2124).Table1Carbon precursors and residual carbon content of samples A,B,C and D.Samples A B C DCarbon precursor Starch Sucrose Citric acid RF polymer Final carbon content(wt.%) 5.48.5 4.35.1Fig.1.TEM images of the prepared amorphous nano-FePO4.n et al./Powder Technology212(2011)327–331The XRD diffraction patterns of LiFePO 4/C powders prepared with different carbon precursors were shown in Fig.3.All peaks can be indexed as a single phase with an ordered olivine structure indexed to the orthorhombic space group,Pnmb (JCPDS card no.83–2092).The obtained lattice parameters are sample A:a=10.2956Å,b=6.0367Å,and c =4.7001Å,sample B:a =10.1992Å,b =6.0483Å,andc=4.6971Å,sample C:a=10.2472Å,b=6.0208Å,and c=4.6882Åand sample D:a=10.3372Å,b=5.9993Å,and c=4.6932Å,respec-tively.There is no evidence of diffraction peaks for carbon,though some amorphous masses and ﬁlms attached to the LiFePO 4particles were observed from TEM images (see Fig.4).This indicates the carbon contents are very low.Morphologies of these LiFePO 4/C composites were shown in Fig.4.It is obvious that the samples show different carbon distribution on LiFePO 4particle surface.From Fig.4a,c,e and g,we observed that the samples were composed of agglomerated particles whose sizes range from 50to 300nm.From Fig.4b and d,there is not enough carbon coating to spread throughout the substrate particles.In contrast to sample A and sample B,there are uniform carbon thin ﬁlms on the grain surfaces of sample C and sample D,and the thickness of the carbon ﬁlms are about 2.5nm (Fig.4f)and 4.5nm (Fig.4h),respectively.The reason may lie in that different carbon precursors have different adsorbabilities on the surface of FePO 4·3H 2O particles,resulting in different carbon distribution on the surface of LiFePO 4particle after the post treatment.Soluble starch and sucrose possess plentiful hydroxyl groups,by which soluble starch and sucrose molecules could probably weakly adsorb on the surface of FePO 4·3-H 2O particles in the hydrogen bonding.In the post treatment process,part of soluble starch and sucrose molecules desorbed from the surface of FePO 4·3H 2O particles,resulting in the de ﬁcient carbon coating.But citric acid possesses carboxyl groups,which may be partially esteri ﬁed by hydroxyl groups on the FePO 4·3H 2O particles,forming a tight connection.This results in more complete carbon coating after the post treatment.For sample D,we suppose that,in the present synthetic system,the surfactant CTAB may con ﬁne the resorcinol –formaldehyde (RF)polymer molecules and FePO 4·3H 2O particles in plenty of tiny spaces,so the RF polymer molecules were tightly attached to FePO 4·3H 2O particles.After the post treatment,the RF polymer was transformed into the carbon ﬁlm which tightly stuck on the surface of LiFePO 4particle.In addition,from the HRTEM image of sample D (shown in Fig.4h),the d-spacing of 0.294nm corresponds to the (211)plane of LiFePO 4.As an important aid investigating the structure of the carbon,the Raman measurement was adopted,and the results were shown in Fig.5.Every Raman spectrum consists of a small band at 940cm −1,which corresponds to the symmetric PO 4stretching vibration in LiFePO 4.The intense broad bands at 1350and 1590cm −1can be attributed to the characteristic Raman spectra of carbon.The bands at 1590cm −1mainly correspond to graphitized structured carbon of G band,while that at 1350cm −1corresponds to disordered structured carbon of D band [22,23].The graphitized carbon contains sp 2hybrid bonding,which is positively correlated with the electronic conduc-tivity of carbon,and the disordered carbon mainly corresponds to sp 3hybrid bonding.As shown in Fig.5,the integrated intensity ratios of sp 2/sp 3of the LiFePO 4/C composites synthesized with different carbon precursors are 0.865(curve A),0.857(curve B),0.856(curve C)and 0.860(curve D),respectively.So the similar sp 2/sp 3ratios of the four samples give us few clues to explain the difference in their electrochemical performances.Fig.6shows the cycling performance curves of all the samples at different rates.As shown in Fig.6,the initial discharge capacities of sample A,sample B,sample C and sample D at room temperature at 0.2C rate are 110.4,118.8,137.7and 138.4mAh g −1,respectively.The capacity of sample D gradually increases in the initial cycles.This may be due to the incomplete dispersion of the electrolyte into the electrode material at the beginning.Moreover,the capacity of sample D is highest among the four samples at 0.5C and 1.0C,indicating that method two is better than method one.The lower capacities of sample A and sample B must be due to the incomplete carbon coating on the LiFePO 4particles.The higher capacity of sample D than that of sample C may be attributed to the thicker carbon ﬁlm of sample D keeping the crystal structure of LiFePO 4morestable.Fig.2.(a)TG/DTA curves of the FePO 4·3H 2O.(b)XRD patterns of the FePO 4samples before (A)and after (B)calcination inair.Fig. 3.XRD patterns of LiFePO 4/C composites synthesized with different carbon precursors.329n et al./Powder Technology 212(2011)327–331In order to further understand the electrochemical properties of the four samples,the cyclic voltammogram (CV)curves were performed at a scan rate of 0.1mV s −1at room temperature (as shown in Fig.7).Each of the CV curves consists of an oxidation peak and a reduction peak,corresponding to the charge reaction and discharge reaction of the Fe 2+/Fe 3+redox couple.In the CV pro ﬁles of the LiFePO 4cathode material,the smaller voltage difference between the charge and discharge plateaus and the higher peak current means better electrode reaction kinetics,and consequently better rate performance.Sample A and sample B electrodes have broad peaks in CV curves.In contrast,sample C and sample D electrodes demonstrate sharp redox peaks,which indicate an improvement in the kinetics of the lithium intercalation/de-intercalation at the electrode/electrolyte interface.The voltage difference of sample D is smaller than that of sample C,so sample D demonstrates a better rate performance.4.ConclusionsLiFePO 4/C composites were synthesized by two methods using home-made amorphous nano-FePO 4as the iron precursor and various organics as carbon precursors.It was found that employing soluble starch and sucrose as the carbon precursors resulted in a de ﬁcient carbon coating on the surface of LiFePO 4particle,but employing citric acid and RF polymer as the carbon precursors realized a uniform carbon coating on the surface of LiFePO 4particle.Particularly,when RF polymer was used as the carbon precursor,the carbon ﬁlm is thicker,and the material showed the highest initial discharge capacity (138.4mAh g −1at 0.2C at room temperature)and the best rate performance among the four materials.The intensities of redox peak and the voltage differences in the CV curves of the four samples are consistent with their rateperformance.Fig.4.TEM images of synthesized LiFePO 4/C composite synthesized with different carbon precursors.(a)and (b)sample A,(c)and (d)sample B,(e)and (f)sample C,(g)and (h)sampleD.Fig. 5.Raman shift of LiFePO 4/C composites synthesized with different carbonprecursors.Fig.6.The cycling performance curves of the samples with different carbon precursors at various discharge rates.n et al./Powder Technology 212(2011)327–331References[1] A.K.Padhi,K.S.Nanjundaswamy,J.B.Goodenough,Phospho-olivines as positive-electrode materials for rechargeable lithium batteries,J.Electrochem.Soc.144(1997)1188–1194.[2]T.Nakamura,Y.Miwa,M.Tabuchi,Y.Yamada,Structural and surfacemodi ﬁcations of LiFePO 4olivine particles and their electrochemical 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磷酸铁锂电池中文介绍

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Ｐｏｗｅｒｇｒｅｅｎｖｉｓｉｏｎ驱动绿色未来磷酸铁锂电池产品介绍ＴｈｅＰｒｅｓｅｎｔａｔｉｏｎｏｆＶＩＳＩＯＮＬＦＰＢａｔｔｅｒｙ深圳市雄韬电源科技有限公司ＳＨＥＮＺＨＥＮＣＥＮＴＥＲＰＯＷＥＲＴＥＣＨ．ＣＯ．，ＬＴＤｗｗｗ．ｖｉｓｉｏｎ－ｂａｔｔ．ｃｏｍＰｏｗｅｒＧｒｅｅｎＶｉｓｉｏｎ目录概述？产品系列？安全认证？ＶＩＳＩＯＮ铁锂电池优势？电池研制环境？客户案例ＰｏｗｅｒＧｒｅｅｎＶｉｓｉｏｎ一概述雄韬电源是全球最大的蓄电池生产企业之一，产品涵盖铅酸、锂电两大品类，是一个以中国深圳为管理中心，在中国大陆、欧洲、香港、东南亚拥有制造基地或营销中心、分销网络遍布全球１００多个国家和地区的企业集团。

ＶＩＳＩＯＮ磷酸铁锂电池由雄韬电源集团与香港理工大学、清华大学、湖南大学合作开发，是国家火炬计划重点项目和深圳市科技资助项目。

ＶＩＳＩＯＮ铁锂电池着眼环保与高效的绿色未来，项目自２００６年启动，成立之初即定位实用性能最好的锂离子电池；经集团研发中心与各科研院所的艰苦攻关，目前已开发出圆柱、软包、钢壳、ＰＰ四大产品系列，针对不同电流、不同容量、不同尺寸等复杂要求，满足电动汽车、电动自行车、电动工具以及其它大电流启动或高能备用市场。

我集团研发中心现有磷酸铁锂专职科研人员近５０名，并已形成从磷酸铁锂正极材料生产到成品铁锂电池制造、检测的批量供应能力。

“一站式”产品资源保证、稳定的供货能力，加上遍布全球的销售服务网络，ＶＩＳＩＯＮ磷酸铁锂电池以最佳供应成本控制模式服务全球客户。

ＰｏｗｅｒＧｒｅｅｎＶｉｓｉｏｎ磷酸铁锂电池工作原理ＬｉＦｅＰＯ４－ｘＬｉ＋－ｘｅＦｅＰＯ４＋ｘＬｉ＋＋ｘｅ－（１－ｘ）ＬｉＦｅＰＯ４＋ｘＦｅＰＯ４ｘＬｉＦｅＰＯ４＋（１－ｘ）ＦｅＰＯ４ＰｏｗｅｒＧｒｅｅｎＶｉｓｉｏｎ磷酸铁锂材料与传统电池材料的差异ＬｉＣｏＯ２ＳｔｒｕｃｔｕｒｅＯｐｅｒａｔｉｎｇｖｏｌｔａｇｅＴｈｅｏｒｅｔｉｃａｌｃａｐａｃｉｔｙＰｒａｃｔｉｃａｌｃａｐａｃｉｔｙＥｌｅｃｔｒｉｃａｌｃｏｎｄｕｃｔｉｖｉｔｙＤｉｆｆｕｓｉｖｉｔｙＴｈｅｒｍａｌｓｔａｂｉｌｉｔｙＴｏｘｉｃｉｔｙＰｒｉｃｅＬａｙｅｒｅｄ４Ｖ２７３ｍＡｈ／ｇ１６０ｍＡｈ／ｇ￣１０－３Ｓ／ｃｍ￣１０－９ｃｍ２／ｓＵｎｓｔａｂｌｅＨｉｇｈＥｘｐｅｎｓｉｖｅＬｉＭｎ２Ｏ４Ｓｐｉｎｅｌ４Ｖ１４８ｍＡｈ／ｇ１２０ｍＡｈ／ｇ￣１０－４Ｓ／ｃｍ￣１０－７ｃｍ２／ｓＵｎｓｔａｂｌｅＬｏｗＣｈｅａｐＬｉＦｅＰＯ４Ｏｌｉｖｉｎｅ３．５Ｖ１７０ｍＡｈ／ｇ１５０ｍＡｈ／ｇ￣１０－７Ｓ／ｃｍ￣１０－１６ｃｍ２／ｓＳｔａｂｌｅＬｏｗＣｈｅａｐＰｏｗｅｒＧｒｅｅｎＶｉｓｉｏｎＨｅｔｅｒｏｓｉｔｅＳｔｒｕｃｔｕｒｅ钴酸锂充放体积变化率＋３～４％锰酸锂－１～３％ＯｌｉｖｉｎｅＳｔｒｕｃｔｕｒｅ石墨＋６～７％磷酸铁锂－６～７％ＰｏｗｅｒＧｒｅｅｎＶｉｓｉｏｎｌＦｅＰＯ４分子中含有强化学键，Ｐ－Ｏ（键长Ｐ－Ｏ／Ｃｏ－Ｏ：０．１５３ｎｍ／０．１９１ｎｍ）在高于５００ｏＣ的高温下也不会释放出活性Ｏ２。

磷酸铁锂缩写

磷酸铁锂，缩写为LFP（Lithium Iron Phosphate），是一种广泛应用于锂离子电池的正极材料。

因其高安全性、长循环寿命和相对较低的成本，LFP电池在电动汽车、储能系统以及众多便携式电子设备中得到了广泛应用。

### 一、磷酸铁锂简介磷酸铁锂（LiFePO₄）是一种无机化合物，属于正交晶系。

其结构中，磷酸根离子（PO₄³⁻）与铁离子（Fe²⁺）和锂离子（Li⁺）相互作用，形成稳定的三维网络。

这种结构使得LFP具有较高的热稳定性和结构稳定性，从而在高温甚至600°C下仍能保持稳定，大大提高了电池的安全性。

### 二、性能特点1. **高安全性**：LFP电池在高温甚至600°C下仍能保持稳定，且不易燃、不爆炸，相比于其他类型的锂离子电池具有更高的安全性。

2. **长循环寿命**：由于LFP材料的结构稳定性，其电池具有非常长的循环寿命，通常可达到2000次以上充放电循环。

3. **环保**：磷酸铁锂材料中不含对人体有害的重金属元素，对环境友好。

4. **良好的电化学性能**：LFP电池具有平坦的放电平台和较高的能量密度。

### 三、应用领域1. **电动汽车**：随着电动汽车市场的快速发展，LFP电池因其高安全性和长寿命成为电动汽车动力电池的理想选择。

特别是在公交车、出租车等高频使用场景中，LFP电池的高安全性和低成本优势尤为突出。

2. **储能系统**：在可再生能源发电系统（如太阳能、风能）中，储能系统对于平衡电网负荷至关重要。

LFP电池因其长寿命、高安全性和相对较低的成本成为大规模储能系统的优选方案。

3. **便携式电子设备**：从手机、笔记本电脑到电动工具等便携式电子设备，LFP电池也因其安全性和稳定性得到了广泛应用。

4. **其他领域**：除了上述领域外，LFP电池还可应用于无人机、航空航天、军事等领域。

### 四、发展前景随着科技的不断进步和环保意识的日益增强，对电池的性能要求也越来越高。

关于磷酸铁锂的英文文献翻译

锂离子电池正极材料覆碳LiFePO4的制备和表征摘要：用两种方法合成纳米LiFePO4/C复合材料，用国产的非晶体纳米FePO4作离子前驱体，可溶性淀粉、蔗糖、柠檬酸和间苯二酚甲醛聚合物四种物质分别作碳的前驱体。

其中可溶性淀粉、蔗糖、柠檬酸作碳前驱体时用第一种方法合成，间苯二酚甲醛聚合物作碳前驱体时用第二种方法合成。

得到样品后用XRD,TEM ,拉曼波谱和循环伏安法对制得样品的晶体结构，形貌，相成分以及电化学特性进行测试研究。

研究结果显示用可溶性淀粉和蔗糖作碳的前驱体制得的LiFePO4颗粒表面的碳的包覆层不充分,而用柠檬酸和间苯二酚甲醛聚合物作前驱体所得的样品实现了在LiFePO4颗粒表面得到均匀一致的碳包覆层的目的，并且相应的碳包覆层的厚度分别为2.5 nm和4.5 nm。

在制得的四种样品中，使用间二苯酚甲醛聚合物作碳的前驱体时，样品的首次放电比容量最高（室温下0.2 C 时放电比容量为138.4 mAh/ g）,倍率性能最好。

第一章引言LiFePO4作为锂离子电池正极材料由于其理论比容量高（170mAh/g），环保，热稳定性好而受到广泛关注。

然而其低于10−13Scm−1的电导率限制了其电池性能【1】，例如在高电流密度下功率的显著减小是其商业化发展的主要障碍。

目前人们已经引进了很多有效的方法克服LiFePO4电导率低的缺点，诸如金属替换法【2-5】，金属粉末混合法【6】，以及传导性碳包覆法【7-15】，通过形成良好的导电通路来提高最终产物的电导率。

在这些方法中，制备LiFePO4/C 复合材料是最受关注的。

此外，碳还可以用作还原剂使Fe3+降价为Fe2+。

值得提及的是包括纳米尺寸的磷酸铁锂的合成在内的很多研究用昂贵的Fe2+盐作前驱体【3.16-20】，例如FeC2O4·2H2O 和(CH 3COO)2Fe。

因此，研究新的制备方法和应用廉价的材料对磷酸铁锂作为锂离子电池正极材料的产业发展至关重要。

磷酸铁锂磷酸铁锂

磷酸铁锂磷酸铁锂全文共四篇示例，供读者参考第一篇示例：磷酸铁锂（Lithium Iron Phosphate，简称为LiFePO4）是一种新型的锂离子电池正极材料，具有理论容量高、循环寿命长、安全性高等优点，被广泛应用于电动汽车、电动自行车、储能系统等领域。

磷酸铁锂电池的发展历程可以追溯到上世纪90年代初，当时由美国的约翰·戴巴特（John Goodenough）和其团队发明了这种材料。

磷酸铁锂之所以备受关注和广泛应用，主要还是因为它的优点远远超过其他传统的锂电池材料。

磷酸铁锂的理论容量相对较高，可以达到170mAh/g左右。

这意味着相同体积下，能够存储更多的电荷，使得电池具有更高的能量密度。

电动汽车和储能系统所使用的磷酸铁锂电池，可以实现更长的续航里程和更持久的储能效果。

磷酸铁锂电池的循环寿命也非常长，可以达到2000次以上，比传统的锂电池材料要高出许多。

这意味着使用磷酸铁锂电池的设备可以更加稳定和持久地工作，减少更换电池的频率，降低维护成本。

磷酸铁锂电池具有较高的安全性。

由于其结构稳定，即使在高温、短路等极端条件下，也不容易发生热失控、爆炸等危险情况。

这使得磷酸铁锂电池成为电动汽车等领域的首选材料，因为安全性对于这些设备来说至关重要。

除了上述优点之外，磷酸铁锂电池还具有低自放电率、较低的成本等特点。

低自放电率意味着即使长时间不使用，电池也不会快速失去电荷，保持较长的续航时间。

而相对于其他高容量材料如钴酸锂等，磷酸铁锂的成本较低，使得其在大规模应用中具有一定的优势。

第二篇示例：磷酸铁锂（LiFePO4）是一种新型的锂离子电池正极材料，具有高容量、高循环寿命、高安全性等优点，在锂离子电池领域有着广泛的应用。

磷酸铁锂作为目前电动车、储能设备等领域中最为热门的正极材料之一，被誉为“锂电池之王”。

磷酸铁锂电池具有许多优点。

磷酸铁锂电池的循环寿命长，可以循环充放电数千次而不损坏电池性能，通常寿命可以达到2000次以上，远高于其他类型的锂离子电池。

锂电池外文资料译文

The design of the lithium battery charger IntroductionLi-Ion rechargeable batteries are finding their way into many applications due to their size, weight and energy storage advantages.These batteries are already considered the preferred battery in portable computer applications, displacing NiMH and NiCad batteries, and cellular phones are quickly becoming the second major marketplace for Li-Ion. The reason is clear. Li-Ion batteries offer many advantages to the end consumer. In portable computers,Li-Ion battery packs offer longer run times over NiCad and NiMH packs for the same form factor and size, while reducing weight. The same advantages are true for cellular phones. A phone can be made smaller and lighter using Li-Ion batteries without sacrificing run time. As Li-Ion battery costs come down, even more applications will switch to this lighter and smaller technology. Market trends show a continual growth in all rechargeable battery types as consumers continue to demand the convenience of portability. Market data for 1997 shows that approximately 200 million cells of Li-Ion will be shipped, compared to 600 million cells of NiMH. However, it is important to note that three cells of NiMH are equivalent to one Li-Ion cell when packaged into a battery pack. Thus, the actual volume is very close to the same for both. 1997 also marked the first year Li-Ion was the battery type used in the majority of portable computers, displacing NiMH for the top spot. Data for the cellular market showed a shift to Li-Ion in the majority of phones sold in 1997 in Europe and Japan.Li-Ion batteries are an exciting battery technology that must be watched. To make sense of these new batteries, this design guide explains the fundamentals, the charging requirements andthe circuits to meet these requirements.Along with more and more the emergence of the handheld electric appliances, to the high performance, baby size, weight need of the light battery charger also more Come more big.The battery is technical to progress to also request continuously to refresh the calculate way more complicatedly is fast with the realization, safety of refresh.Therefore need Want to carry on the more accurate supervision towards refreshing the process, to shorten to refresh time and attain the biggest battery capacity, and prevent°from the batteryBad.The AVR has already led the one step in the competition, is prove is perfect control chip of the next generation charger. The microprocessor of Atmel AVR is current and can provide Flash, EEPROM and 10 ADCses by single slice on the market Of 8 RISC microprocessors of the tallest effect.Because the saving machine of procedure is a Flash, therefore can need not elephant MASK ROM Similar, have a few software editions a few model numbers of stock.The Flash can carry on again to weave the distance before deliver goods, or in the PCB Stick after pack carry on weaving the distance throughan ISP again, thus allow to carry on the software renewal in the last one minute.The EEPROM can used for conservancy mark certainly coefficient and the battery characteristic parameter, such as the conservancy refreshes record with the battery that raise the actual usage Capacity.10 A/ Ds conversion machine can provide the enough diagraph accuracy, making the capacity of the good empress even near to its biggest capacity. And other project for attaining this purpose, possible demand the ADC of the exterior, not only take up the space of PCB, but also raised the system Cost.The AVR is thus deluxe language but 8 microprocessors of the designs of unique needle object" C" currently.The AT90S4433 reference The design is with" C" to write, the elucidation carries on the software design's is what and simple with the deluxe language.Code of C this design is very Carry on adjust easily to suit current and future battery.But the ATtiny15 reference design then use edit collected materials the language to write of, with Acquire the biggest code density.An electric appliances of the modern consumption mainly uses as follows four kinds of batteries:1.Seal completely the sour battery of lead( SLA)2.The battery of NiCd3.The NiMHhydrogen battery( NiMH)4.Lithium battery( Li- Ion)At right choice battery and refresh the calculate way need to understand the background knowledge of these batteries. Seal completely the sour battery( SLA) of lead seals completely the sour battery of lead to mainly used for the more important situation of the cost ratio space and weights, such as the UPS and report to the police the backup battery of the system. The battery of SLA settles the electric voltage to carry on , assist limits to avoid with the electric current at refresh the process of early battery lead the heat.Want ～only the electricity .The pond unit electric voltage does not exceed the provision( the typical model is worth for the 2.2 Vs) of produce the company, the battery of SLA can refresh without limit. The battery of NiCd battery of NiCd use very widespread currently.Its advantage is an opposite cheapness, being easy to the usage;Weakness is from turn on electricity the rate higher.The battery of NiCd of the typical model can refresh 1,000 times.The expired mechanism mainly is a pole to turn over.The first in the battery pack drive over.The unit that all turn on electricity will take place the reversal.For prevent°froming damage the battery wrap, needing to supervise and control the electric voltage without a break.Once unit electric voltage Descend the 1.0 Vs must shut down.The battery of NiCd carries on refresh in settling the electric current by forever . The NiMH hydrogen battery( NiMH) holds to shoot the elephant machine such as the cellular phone, hand in the hand that the importance measure hold equipments, the etc. NiMHhydrogen battery is anusage the most wide.This kind of battery permit.The quantity is bigger than NiCd's.Because lead to refresh and will result in battery of NiMH lose efficacy, carry on measuring by the square in refresh process with.Stop is count for much in fit time.Similar to battery of NiCd, the pole turn over the battery also will damage.Battery of NiMH of from turn on electricity the rate and is probably 20%/ month.Similar to battery of NiCd, the battery of NiMH also settles the electric current to refresh .Other batteries says compare in lithium battery( Li- Ion) and this texts, the lithium battery has the tallest energy/ weight to compare to compare with energy/ physical volume.Lithium batterySettle the electric voltage to carry on refresh with , want to have the electric current restrict to lead the heat in the early battery of refresh the process by avoid at the same time.When refresh the electric current Descend to produce the minimum electric current of the enactment of company will stop refresh.Leading to refresh will result in battery damage, even exploding.The safety of the battery refreshes the fast charge machine( namely battery can at small be filled with the electricity in 3 hours, is usually a hour) demand of the modern.Can to the unit electric voltage, refresh the electric current and the battery temperatures to carry on to measure by the square, avoid at the time of being filled with the electricity because of leading to refresh.Result in of damage.Refresh the method SLA battery and lithium batteries refreshes the method to settle the electric voltage method to want to limit to flow for the ever ; The battery of NiCd and battery of NiMHs refresh the method.Settle the electric current method for the ever , and have severals to stop the judgment method for refresh differently. Biggest refresh the electric current biggest refresh the electric current to have relation with battery capacity( C).Biggest usually refresh the electric current to mean with the number of the battery capacity.For example,The capacity of the battery for 750 mAhs, refresh the electric current as 750 mAs, then refresh the electric current as 1 C(1 times battery capacity).IfThe electric current to flow refresh is a C/40, then refreshing the electric current for the battery capacity in addition to with 40.Lead the hot battery refresh is the process that the electric power delivers the battery.Energy by chemical reaction conservancy come down.But is not all.The electric powers all convert for the sake of the chemistry in the battery ability.Some electric power conversions became the thermal energy, having the function of the heating to the battery.When electricity.After pond be filled with, if continue to refresh, then all electric powers conversion is the thermal energy of the battery.At fast charge this will make the battery.Heat quickly, if the hour of can not compare with stop refresh and then willresult in battery damage.Therefore, while design the battery charger, to the temperature.It is count for much that carry on the supervision combine to stop refresh in time.The discretion method battery stopped refresh of different and applied situation and work environment limitted to the choice of the method that the judgment stop refresh.The sometimes temperature allow of no.Measure easily, but can measure electric voltage, or is other circumstances.This text takes the electric voltage variety rate(- dV/ dt) as the basic judgment to stopThe method for refresh, but with the temperature and absolute electric voltage be worth for assistance and backup.But the hardware support that this text describe speaks as follows.The method of the havings of say. Time of t – this method that is the decision when stop refresh most in ually used for spare project of the hour of fast charge.Sometimes also be .Refresh(14- 16 Hour) basic project of the method.Be applicable to various battery.Stop refresh when the electric voltage of V – be the electric voltage to outrun the upper ually with the forever settle the electric current refreshes the match usage.The biggest electric current is decide by the battery, usually For the 1 C.For prevent°froming refresh the electric current leads to causes battery lead greatly hot, the restrict of the electric current at this time very key.This method Is a lithium battery basic to refresh and stop project. The actual lithium battery charger usually still continues into after attain biggest electric voltage Go the second stage refresh, to attain 100% battery capacity. For battery of NiCd and battery of NiMHs are originally method can Be the spare judgment stops refreshing the project. - The method exploitation that this judgment of the dV/ dt – electric voltage variety rate stops refresh negative electric voltage variety rate.For the battery of some types, be the battery to be filled with the subsequence Refreshing continuously will cause electric voltage descend. At this time this project was very fit.This method usually useds for the ever to settle the electric current to refresh, Be applicable to to the fast charge of the battery of NiCd and battery of NiMH. The electric current of I –is to refresh the electric current small in a certain the number that set in advance stop refresh. Usually used for the ever to settle the electric voltage to refresh the method.Be applicable to the SLA Battery and lithium battery.The T – temperature absolute zero can be the basis that battery of NiCd and battery of NiMHs stop refresh, but even suited for to be the backup project.Any battery for temperature to outrun initial value have to stop refresh.The basis that the dT/ dt –temperature rising velocity fast charge variety rate of the temperature of hour can be to stop refresh.Please consult the norm that the battery produces the company( battery of NiCdOf typical model be worth for the 1 oC/ min) the –be applicable to the battery of NiCd and battery of NiMHs.Need to stop refresh when the DT – outrun the temperature value of theenvironment temperature to be the bad battery temperature and the environment temperature to exceed the certain threshold.This method can be the battery of NiCd and The project that battery of SLA stops refresh.While refreshing in the cold environment this method compares the absolute zero to judge the method better.Because bigMost systems usually only have a temperature to stretch forward, have to will refresh the previous temperature to be the environment temperature. DV/ dt=0 –s zero electric voltages differ this method with- the method of dV/ dt is very and similar, and more accurate under the condition that electric voltage will not go up again. Be applicable to the NiCd Battery and battery of NiMH.This reference design completely carried out the battery charger design of latest technique, can carry on to various popular battery type quicklyRefresh but need not to modify the hardware soon, a hardware terrace carries out a charger product line of integrity.Need only Want to will refresh the calculate way to pass lately the ISP downloads the processor of FLASH saving machine can get the new model number.Show very muchHowever, this kind of method can shorten time that new product appear on market consumedly, and need a kind of hardware of stock only.This design provide The in keeping with SLA, NiCd, NiMH of the integrity and the database function of the battery of Li- Ion.锂电池充电器的设计介绍根据其尺寸，重量和能量储存优点，锂- 离子可再充电电池正在被用于许多的应用领域。

电动汽车用磷酸铁锂动力电池的制作及性能测试_英文_概要

ISSN 1674-8484CN 11-5904/U 汽车安全与节能学报, 2011年, 第2卷第1期J Automotive Safety and Energy, 2011, Vol. 2 No. 1Manufacture and Performance Tests of Lithium Iron PhosphateBatteries Used as Electric Vehicle PowerZHANG Guoqing, ZHANG Lei, RAO Zhonghao, LI Yong(Faculty of Materials and Energy, Guangdong University of Technology, Guangzhou 510006, ChinaAbstract: Owing to the outstanding electrochemical performance, the LiFePO 4 power batteries could be used on electric vehicles and hybrid electric vehicles. A kind of LiFePO 4 power batteries, Cylindrical 26650, was manufactured fromcommercialized LiFePO 4, graphite and electrolyte. To get batteries with good high-current performance, the optimal content of conductive agent was studied and determined at 8% of mass fraction. The electrochemical properties of the batteries were investigated. The batteries had high discharging voltage platform and capacity even at high discharge current. When discharged at 30 C current, they could give out 91.1% of rated capacity. Moreover, they could be fast charged to 80% of rated capacity in ten minutes. The capacity retention rate after 2 000 cycles at 1 C current was 79.9%. Discharge tests at -20 ℃ and 45 ℃ also showed impressive performance. The battery voltage, resistance and capaci ty varied little after vibration test. Through the safety tests of nail, no in ﬂ ammation or explosion occurred.Key words: hybrid and electric vehicles; power batteries; lithium iron phosphate; lithium ion batteries;电动汽车用磷酸铁锂动力电池的制作及性能测试张国庆、张磊、饶忠浩、李雍( 广东工业大学材料与能源学院,广州 510006, 中国摘要: 磷酸铁锂电池的优异性能使其可以应用在电动汽车和混合动力汽车上。

锂离子电池磷酸铁锂 LiFeP04

电压平台(V)
3.6
3.5
3.7
3.2
循环性能
≥300次
≥800次
≥500次
≥2000次
过渡金属
贫乏
贫乏
丰富
非常丰富
原料成本
很高
高
低廉
低廉
环保
含钴
含镍、钴
无毒
无毒
安全性能
差
较好
良好
优秀
适用领域
小电池
小电池/小型动力电池
动力电池
动力电池/超大容量电源
据专家预测，2－3年内磷酸铁锂电池必将成为动力电池的主流。而纵观全球，磷酸铁锂电池目前发展的瓶颈是其正极活性材料磷酸铁锂材料本身的产业化。因此世界各界的研究院及高校对磷酸铁锂材料的关注异常火热，但真正实现批量化生产企业却为数不多。
再说磷酸铁锂的寿命。我感受到磷酸铁锂正极的长寿命，经历1200次1C充放循环的磷酸铁锂电池的正极无任何变化，由于负极锂枝晶的大量聚集导致了电池的失效。我只能把这个失效原因归结于电解液体系与负极体系的匹配性问题。做了很多种电池，包括铅酸、镉镍、燃料电池、超级电容器等，能够在这么多次循环后保持稳定的电极材料我还是前所未见的。因此我认为，当克服了磷酸铁锂电池的其他弱点后，趋于理性的市场最终会选择寿命长久的电源品种的。
3．太阳能、风能的储能电源？这几年太阳能这个火啊，造就了多少个亿万富翁。我们不能不感受**的政策导向影响之深。锂电算贵了，比起太阳能那算便宜的了。锂电的电动自行车大家消费不起，太阳能就更属于高端的高端了。这东西类似于贵妇人的护肤霜，只要脸好看，多贵都要买。问题是买了发现不好用，摆在冰箱里面也会发臭的。送朋友吧，我看非洲沙漠多，风也大，最需要这个。买不起就送嘛。
2．电动汽车？无论是什么样的理由，国家发展电动汽车的理由都是充分的。问题是，发展EV、HEV、PHEV等，都需要类似加电站、换电站等这样庞大的基础设施的配合。如果这条路走开来，将是能源产业化的一次革命，如果所有的建设在50年内完成，将使GDP五年翻一番。这是个庞大的工程，在开展这个工程之前，论证也要搞个10年吧。想在这方面做大的老板，歇会儿吧。当然，想从国家骗钱的那类老板除外（说到底，也不是骗钱，这叫周瑜打黄盖）。

磷酸铁锂

磷酸铁锂磷酸铁锂（分子式：LiMPO4，英文：Lithium iron phosphate，又称磷酸铁锂、锂铁磷，简称LFP），是一种锂离子电池（可另外参见锂电池）的正极材料，也称为锂铁磷电池，特色是不含钴等贵重元素，原料价格低且磷、锂、铁存在于地球的资源含量丰富，不会有供料问题。

其工作电压适中（3.2V）、电容量大（170mAh/g）、高放电功率、可快速充电且循环寿命长，在高温与高热环境下的稳定性高。

这个看似不起眼却引发锂电池革命的新材料，为橄榄石结构分类中的一种，矿物学中的学名称为triphyllite，是从希腊字的tri-以及fylon两个字根而来，在矿石中的颜色可为灰色，红麻灰色，棕色或黑色。

化学式LiFePO4正确的化学式应该是LiMPO4，物理结构则为橄榄石结构，而其中的M 可以是任何金属，包括Fe、Co、Mn、Ti等等，由于最早将LiMPO4商业化的公司所制造的材料是C/LiFePO4，因此大家就这么习惯地把Lithium iron phosphate其中的一种材料LiFePO4当成是磷酸铁锂。

然而从橄榄石结构的化合物而言，可以用在锂离子电池的正极材料并非只有LiMPO4一种，据目前所知，与LiMPO4相同皆为橄榄石结构的Lithium iron phosphate 正极材料还有A y MPO4、Li1-x MFePO4、LiFePO4･MO 等三种与LiMPO4不同的橄榄石化合物（均可简称为LFP）。

发现自1996年日本的NTT首次揭露A y MPO4（A为碱金属，M 为Co Fe 两者之组合：LiFeCoPO4）的橄榄石结构的锂电池正极材料之后，1997年美国得克萨斯州立大学John. B. Goodenough 等研究群，也接着报道了LiFePO4的可逆性地迁入脱出锂的特性[1]，美国与日本不约而同地发表橄榄石结构（LiMPO4），使得该材料受到了极大的重视，并引起广泛的研究和迅速的发展。

磷酸铁锂中的磷酸锂

磷酸铁锂中的磷酸锂-概述说明以及解释1.引言1.1 概述磷酸铁锂（Lithium Iron Phosphate，简称LFP）是一种重要的锂离子电池正极材料，具有高能量密度、长循环寿命、良好的安全性等诸多优势。

它由铁离子、磷酸根离子和锂离子组成，具有潜在的广泛应用前景。

磷酸铁锂的制备方法较为成熟，可以通过固相合成、溶胶-凝胶法和水热法等多种途径得到高纯度的磷酸铁锂材料。

在电池领域，磷酸铁锂作为一种高性能的正极材料被广泛应用于电动汽车、无人机和储能设备等领域。

它能够提供稳定的电容量，具有优异的充放电性能，适用于高功率和高温环境下的应用。

然而，磷酸铁锂也存在一些缺点。

首先，其比能量相对较低，限制了其在电动汽车等领域的应用。

此外，磷酸铁锂的制备工艺相对复杂，成本较高。

随着科技的不断进步，人们对磷酸铁锂材料的研究也日益深入，相信未来能够克服这些问题，进一步提高磷酸铁锂的性能。

综上所述，磷酸铁锂作为一种重要的锂离子电池正极材料，具有许多优点和应用前景。

在未来的发展中，磷酸铁锂有望在电动汽车、储能设备等领域发挥更大的作用。

不过，我们也要认识到磷酸铁锂存在的问题，并加强研究以改进其性能和制备工艺。

只有不断探索和创新，才能推动磷酸铁锂技术的进一步发展。

1.2文章结构文章结构部分的内容可以如下所示：1.2 文章结构本文将按照以下结构进行论述磷酸铁锂中的磷酸锂。

第二部分将介绍磷酸铁锂的基本特性。

我们将详细讨论磷酸铁锂的化学结构、晶体结构以及其它相关的物理性质。

通过对这些基本特性的了解，我们可以更好地理解磷酸铁锂中磷酸锂的作用机制。

第三部分将探讨磷酸铁锂的制备方法。

我们将介绍传统的制备方法以及目前的研究热点。

不同的制备方法对磷酸锂含量和电化学性能的影响也将进行详细的分析。

在第四部分，磷酸铁锂在电池领域的应用将受到重点关注。

我们将探讨磷酸铁锂作为正极材料的特点和应用情况。

同时，磷酸铁锂与其它主流电池材料的对比也将进行评估，以展示其优势和潜力。

磷酸铁锂英文综述

磷酸铁锂英文综述Lithium iron phosphate, also known as lithium ferrophosphate, is a type of rechargeable battery cathode material that has gained significant attention in recent years due to its potential applications in electric vehicles and energy storage systems.The chemical formula of lithium iron phosphate is LiFePO4. It is a crystalline material that belongs to the olivine group of minerals. The structure of lithium iron phosphate consists of interconnected tetrahedra of phosphate (PO4) and iron (Fe) atoms, with lithium (Li) ions occupying the gaps between the tetrahedra.One of the key advantages of lithium iron phosphate batteries is their high thermal and chemical stability, which makes them safer than other lithium-ion battery chemistries. They also have a longer cycle life and higher power density, making them suitable for high-demand applications.In terms of performance, lithium iron phosphate batteries exhibit a flat discharge curve, which means that they can deliver a nearly constant voltage throughout the discharge cycle. This characteristic makes it easier to monitor the state of charge of the battery. Additionally, lithium iron phosphate batteries have a lower self-discharge rate compared to other lithium-ion chemistries, which contributes to their overall efficiency.From a commercial perspective, lithium iron phosphate batteries are increasingly being used in electric vehicles, grid energy storage, and portable electronic devices. Their safety and long cycle life make them an attractive option for these applications, especially in situations where reliability and stability are paramount.In conclusion, lithium iron phosphate, or LiFePO4, is a promising cathode material for rechargeable batteries, offering a combination of safety, long cycle life, and high power density. Its potential for use in electric vehiclesand energy storage systems makes it an important area of research and development in the field of battery technology.。

磷酸铁锂的理论研究(外文版)

A theoretical study of olivine LiMPO 4cathodesJ.M.Osorio-Guille´n a,*,B.Holm a,b ,R.Ahuja a ,B.Johansson a,c aCondensed Matter Theory Group,Department of Physics,Uppsala University,Box 530,S-75121Uppsala,SwedenbInstitute For Solid State Physics,University of Tokyo,5-1-5Kashiwanoha Kashiwa,Chiba,277-8581,JapancApplied Materials Physics,Department of Materials Science and Engineering,Royal Institute of Technology,SE-10044,Stockholm,SwedenReceived 9July 2003;received in revised form 21August 2003;accepted 23September 2003AbstractWe report on a density functional theory (DFT)calculation of the properties of LiMPO 4,where M is either Fe,Mn or Co.The mixing between Fe and Mn in these structures is also examined.We have derived three relevant battery properties,namely average voltage,energy density and specific energy,as well as the lattice constants and ionic coordinates for each case examined.Our calculated values for these properties are in good agreement with recent experimental values,when available.Further insight is gained from the electronic density of states of the phases,through which conclusions about the physical properties of the various phases are made.D 2003Elsevier B.V .All rights reserved.Keywords:Olivine LiMPO 4;Cathodes;Lithium;Batteries1.IntroductionThe use of portable electronic devices for purposes of communication,data processing and transmission,entertain-ment,etc.is rapidly increasing.Furthermore,the vision of massive commercial use of electrically powered vehicles is becoming more and more realistic.This development has led to a demand for continued pursue of more efficient batteries with a number of crucial properties.These include a relatively flat open-circuit voltage (OCV),low cost,environmental benefit,easy to fabricate and safety in handling and operation.Rechargeable lithium batteries have proven to be one of the most successful solutions to achieve these goals for low load applications.A crucial key towards a good battery design is concerned with the choice of cathode material.The cathode should be both an ionic and electronic conductor in order to allow for the insertion/deinsertion of lithium and electronic conduction during the discharge/charge of the battery.Further,it is desirable that the volume change of the cathode during its operation is as small as possible,as this ensures good reversibility and cycle life.Intensive research on transition metal oxides has lead to the utilization of the layered rock salt systems [1,2]and themanganese-spinel framework system [3–5].These systems operate in a voltage regime between 3and 4V .However,the applications of these materials in the cases of electric vehicles or load-levelling systems demand large batteries.Hence,the cost of transition metals,the low voltage and environmental problems make the materials mentioned unfavorable for these purposes.Systems based upon iron oxides have a potential of being used as cathode materials.They are comparatively cheap,environmentally favorable and,should they exhibit the desired properties,would be an ideal solution to overcome the present problems with the other transition metal oxides.Some experimental investigations in this direction have been undertaken.The layered compound LiFeO 2has been synthesized,although attempts to delithiate this phase have not yet been successful [6,7].Other compounds,such as FePS 3[8],FeOCl [9]and FeOOH [10],have a relatively poor rechargeability and/or low discharge voltage.Another line of research has been devoted to compounds containing polyanions,(XO 4)À3where X =S,P or As,mainly Li 3Fe 2(PO 4)3[11]and Li x Fe 2(SO 4)3[12]and the olivine structure LiFePO 4[13–15],all within the NASI-COM framework.The LiFePO 4compound in principle satisfies the main requirements for a cathode material,but,as we will discuss below in this article,it displays an electronic conduction problem when lithium is completely deintercalated caused by a metal-insulator transition.This in0167-2738/$-see front matter D 2003Elsevier B.V .All rights reserved.doi:10.1016/j.ssi.2003.09.015*Corresponding author.Tel.:+46-18-471-5865;fax:+46-18-471-3524.E-mail address:Jorge.Osorio@fysik.uu.se (J.M.Osorio-Guille ´n)/locate/ssiSolid State Ionics 167(2004)221–227turn could give rise to a poor performance on the discharge cycle of the battery.As a remedy,the doping of the material with manganese has been investigated[13,16,17]in order to obtain an optimal performance for this cathode candidate. We here pursue this line of investigation through our theoretical approach.The structures LiMPO4(M=Mn,Fe,Co and Ni)are orthorhombic(space group Pnma)and have an ordered olivine structure in which the M atoms occupy half of the octahedral sites and the phosphorus atoms occupy one-eighth of the tetrahedral sites in a hexagonal close-packed array of oxygen atoms.Because of the traditional use of transition metals in cathodes,we will look at the case M=Fe as a point of reference,and then bring our attention to the substitution of Fe by Mn/Co,and the consequences thus implied.First-principles calculations have by now become a useful tool for battery design[19,20],since they can be used to calculate their most important properties without any re-quirement of experimentally measured input data.Typical properties of interest include(a)the OCV,(b)the energy density(E V)and(c)the specific energy(E m).As an experiment always needs a large amount of time and is often costly,first-principles calculations can be used for a system-atic study of the parameters mentioned above and other factors,such as the determination of the structures of the phases,instabilities,conductivities,etc.,of novel materials. Thereby the experimental investigations can be focused on those materials,which appear to be the most promising. 2.MethodIn this work,we have made a first-principles investigation using density functional theory(DFT)within the full-poten-tial linear-muffin-tin-orbital(FPLMTO)method,in order to calculate the characteristics of the phases of interest.In order to study the charge/discharge process,it is vital to examine both the lithiated and delithiated phases of the compounds.The OCV between two electrodes depends on the differ-ence between the chemical potential of Li at the anode and that of the cathode.As lithium ions are inserted into the cathode,the chemical potential increases,leading to a decrease in the OCV.It is possible to obtain the OCV, V(x),as a function of x in Li x MPO4as followsVðxÞ¼À1Fy D GðxÞy xT;P;ð1Þwhere F is the Faraday constant and D G(x)is the change in Gibb’s free energy for the reactiony x LiþLi x MPO4!Li xþy x MPO4:ð2ÞIt is difficult to compute the change in the Gibb’s free energy as a function of x,due to the limited knowledge about the nature of the local ordering of lithium ions in Li x MPO4for0<x<1.However,we can compute the average OCV,V¯,for perfectly ordered structures,i.e.for x=0,1.Nevertheless,we have done calculations for inter-mediate Li concentrations,x=0.75,0.5.Other Li concen-trations require supercells,which is a prohibitive time-consuming calculation.In an ideal cathode material,the volume and entropy effects are minimal in the intercalation reaction described in Eq.(2),so that D G can be approxi-mated by the change in the internal energy D E at0K,i.e.,¯V¼À1FD Ex2Àx1:ð3ÞThe energy density E V and specific energy E m of the battery reaction are given byE V¼ÀD EX;ð4ÞE m¼ÀD Em;ð5Þwhere X denotes the average volume of one formula unit of the reactant and one formula unit of the product of the reaction in Eq.(2).The quantity m denotes the mass of one molecular formula unit of either the reactant or the product of the reaction in Eq.(2).The internal energy E has been computed by solving the Kohn–Sham equations of DFT,using the FPLMTO method [21].The calculations were based on the local-density approximation(LDA)with the Hedin–Lundqvist[22]pa-rameterization for the exchange and correlation potential. The spin-orbit coupling was included explicitly.Basis functions,electron densities and potentials were calculated without any geometrical approximation.These quantities were expanded in combinations of spherical harmonic functions(with a cut-off S max=6)inside non-overlapping spheres surrounding the atomic sites(muffin-tin spheres) and in a Fourier series in the interstitial region.The muffin-tin spheres occupied approximately24%of the unit cell. The radial basis functions within the muffin-tin spheres are linear combinations of radial wave functions and their energy derivatives,computed at energies appropriate to their site and principal as well as orbital atomic quantum numb-ers,whereas outside the muffin-tin spheres the basis func-tions are combinations of Neuman or Hankel functions [23,24].In the calculations reported here,we used the so called virtual crystal approximation(VCA)in order to cope with fractional occupation of the manganese and iron atoms.The more straight forward way,by introducing a supercell containing multiple unit cells of a compound and then substituting the metal atoms in parts of them,would render the calculations prohibitively time consuming.We have applied the calculations to the pseudo-atoms Fe0.9Mn0.1,J.M.Osorio-Guille´n et al./Solid State Ionics167(2004)221–227 222Fe0.8Mn0.2,Fe0.7Mn0.3and Fe0.5Mn0.5,whose atomic numb-ers are25.9,25.8,25.7and25.5,respectively.Nevertheless, for half concentration of iron and half concentration of manganese,we have done a non-VCA calculation in order to check the validity of the VCA results.We made use of the pseudo-core3p states for Fe1Ày Mn y and Co,and valence band2s,2p and3s basis functions for Li,valence band3d, 4s,4p and4d basis functions for Fe1Ày Mn y and Co,valence band3s,3p,4s and3d basis functions for P and valence band2s,2p and3s basis functions for O with two corresponding sets of energy parameters,one appropriatefor the semi-core3d states and the other appropriate for the valence states.The resulting basis formed a single,fully hybridizing basis set.This approach has previously been proven to give a well converged basis[21].For the sampling of the irreducible wedge of the Brillouin zone,we used the special k-point method[25].In order to speed up the convergence,we have associated a Gaussian broadening of a width of20mRy to each calculated eigenvalue.The average OCV and the lattice constants calculations of the compounds involved in reaction Eq.(2)are performed by varying the energy with respect to the unit cell volume and then choosing the most stable structure for each of the three compounds in the reaction.For each compound at the equilibrium volume,a full relaxation of the ionic coordi-nates has been done as well.3.Results and discussionThe properties V¯,E V and E m for the cathode compounds investigated,as well as the lattice parameters and the ionic coordinates,both in their lithiated and delithiated states,are shown in Tables1–7.The agreement between the computed unit cell volumes and the experimentally measured ones [13–19]is good.We observe that,for Fe1Ày Mn y PO4,the volume decreases by1%for y=0.1as compared to FePO4,and the volumes for y=0.2,0.3and0.5are about1.3%,1.4%and 1.7%less,respectively.As far as the LiFe1Ày Mn y PO4 volumes and lattice constants are concerned,they appear to follow Vegard’s law,i.e.they increase linearly with Mn paring the MnPO4/LiMnPO4various composi-tions of LiFe1Ày Mn y PO4with LiFePO4,they increase by 0.2%,0.4%,0.7%and1.1%for y=0.1,0.2,0.3and0.5, respectively.Furthermore,the computed volume changes for Fe1Ày Mn y PO4/LiFe1Ày Mn y PO4are2.4%,3.5%,4.0%, 4.4%and5.0%for y=0,0.1,0.2,0.3and0.5,respectively, whereas the volume changes for MnPO4/LiMnPO4is2.2% and2.6%for CoPO4/LiCoPO4.These relatively small vol-ume changes ensure good reversibility and cycle life time of the cathodes,theoretically being best without Mn doping. Among the delithiated and lithiated phases,we can observe an increase of the a and b axes and a decrease of the c axis. This behavior agrees with previous experimental results.The computed average voltage of the systems Li/Li x Fe1Ày Mn y PO4are4.2V in the system without manganese doping and3.4V in the systems with manganese.The non-VCA computed average voltage for the system Li/Li x Fe0.50Mn0.50PO4is3.6V,which is close to the VCA result. When iron is completely replaced for manganese,the computed average voltage is4.0V.However,we have to keep in mind that we only determine the average voltage through knowledge about the fully lithiated/delithiated phases,without taking the intermediate configurations into account.When intermediate Li concentrations for the sys-tem Li/Li x FePO4,with x=0.75,0.5are taking in account, the computed OCV is3.8V for both Li concentrations.ThisTable1Calculated average intercalation voltage,energy density,specific energy and capacity for the battery systems Li/Li x MPO4(M=Mn,Fe and Co)Average voltage (V)E V(W h lÀ1)E m(W h kgÀ1)Capacity(mA h gÀ1)Li/LiMnPO4 4.0(4.1)a2344.9683.5170.9 Li/LiFePO4 4.2(3.5)b2539.8713.5169.9 Li/Li0.75FePO4 3.8(3.5)bLi/Li0.50FePO4 3.8(3.5)bLi/LiCoPO4 4.9(4.8)c3016.3816.4166.6 Experimental values are in parentheses.a Reference[18].b Reference[13].c Reference[15,19].Table2Calculated average intercalation voltage,energy density,specific energy and capacity for the battery systems Li/LiFe1Ày Mn y PO4Averagevoltage(V)E V(W h lÀ1)E m(W h kgÀ1)Capacity(mA h gÀ1)Li/LiFe50Mn50PO4 3.42061.3579.3170.4Li/LiFe70Mn30PO4 3.42063.5578.6170.2Li/LiFe80Mn20PO4 3.42064.3578.3170.1Li/LiFe90Mn10PO4 3.42063.2577.9170.0 Refs.[16,17].Table3Calculated lattice constants for the olivine compounds Li x MnPO4, Li x FePO4and Li x CoPO4(space group Pnma)with x=0and1a(A˚)b(A˚)c(A˚)V(A˚3) LiMnPO410.8616(10.4520)a6.2815(6.1060)a4.8550(4.7460)a297.1246(302.8893)a MnPO410.0982 6.2048 5.0557290.8265 LiFePO410.2941(10.3290)b5.9862(6.0065)b4.6752(4.6908)b288.0792(291.0226)b FePO49.9284(9.8142)b5.8567(5.7893)b4.8376(4.7820)b281.2943(271.7006)b LiCoPO410.1932(10.2020)c5.9169(5.9220)c4.6949(4.6990)c283.1595(283.8960)c CoPO410.0547(10.0890)c5.8331(5.8530)c4.7029(4.7190)c275.8254(278.6610)c Experimental values are in parentheses.a Reference[18].b Reference[14].c Reference[19].J.M.Osorio-Guille´n et al./Solid State Ionics167(2004)221–227223result shows the plateau structure of the OCV over this particular concentration,which compares good with the experiments.On the other hand,the computed average voltage of the system Li/LiCoPO4is4.9V,suggesting ahigh-voltage application for this system.The analysis of the electronic structure shows the char-acteristic features of the cathode materials in the discharge/ charge phases.Looking at the electronic densities of states (DOS)in Fig.1,we first observe that pure FePO4has a band gap of0.18eV around the Fermi level.This makes the material a semiconductor,which infers problems with the electronic conductivity during the battery discharge.How-ever,this could be overcome with a temperature rise.The upper valence band lies in the rangeÀ7.2to0.0eV.Our calculations reveal that it is formed by hybridized iron d-states,phosphorus p-states and oxygen p-states.The con-duction bands are mainly made up from iron d-states and the two bands are separated by a band gap around the Fermi level.As the compound is doped with Mn,we find that the upper valence band becomes a conduction band and we get the desired metallic character for the cathode in the battery discharge cycle.If the content of Mn is further increased,the valence band is shifted to the left,while the conduction bands are shifted to the right with respect to the Fermi level. In, e.g.,F0.8Mn0.2PO4,the Fermi level lies in a corresponding band,which is formed by the hybridization between the metallic d-states,phosphorus p-states and oxygen p-states.The combined metallic d-states in this band are more extensively spread out in energy than the iron d-states of FePO4.Also,the phosphorus p-states and oxygen p-states are more spread out in energy compared to the compound without manganese.We observe the same be-havior for the other Mn concentrations studied here.We note that pure MnPO4appears to be a semimetal, exhibiting a parabolic DOS curve around the Fermi level.On the other hand,we observe in Fig.2the DOS of CoPO4,it shows a metallic character of this compound.The Fermi level lies in a band,which is formed by hybridization of cobalt d-states,phosphorus p-states and oxygen p-states. We now shift our attention to the lithiated phases.For LiFe1Ày Mn y PO4,the calculated total DOS curves(Fig.1) are very similar for all concentrations,with the Fermi level being placed within the conduction band within an energy range of0.7eV.The valence bands are shifted to the left, while the conduction bands are shifted to the right with respect to the Fermi level when the Mn content is increased, although this effect is larger on the valence bands.Our numerical analysis reveals that the behavior of the conduction bands is almost completely dominated by the Fe1Ày Mn y d-states.Further,the band gap in the valence band originating from the hybridization of the lithium s-and p-states and oxygen p-states and the Fe1Ày Mn y d-states increases with the Mn content.This implies that the screen-ing between the pseudo-atoms Fe1Ày Mn y and the oxygen atoms becomes stronger when we add manganese to FePO4.For pure LiFePO4,the DOS is very similar to the compounds with manganese doping calculated by meansTable4Calculated lattice constants for the olivine compounds Li x Fe1Ày Mn y PO4 (space group Pnma)with x=0and1a(A˚)b(A˚)c(A˚)V(A˚3) LiFe50Mn50PO410.3309 6.0076 4.6919291.2311 Fe50Mn50PO410.1558 5.9058 4.6124276.6293 LiFe70Mn30PO410.3160 5.9989 4.6851289.9703 Fe70Mn30PO410.1635 5.9103 4.6159277.2596 LiFe80Mn20PO410.3085 5.9946 4.6817289.3389 Fe80Mn20PO410.1685 5.9132 4.6182277.6649 LiFe90Mn10PO410.3010 5.9902 4.6783288.7096 Fe90Mn10PO410.1802 5.9200 4.6235278.6291 Refs.[13,16,17].Table5Calculated ionic coordinates for Li x MnPO4(space group Pnma)with x=0 and1LiMnPO4MnPO4x y z x y zLi(4a)000Mn(4c)0.281781/40.979610.290131/40.92949 P(4c)0.091241/40.415470.103811/40.42600 O(4c)0.093651/40.739240.125331/40.73506 O(4c)0.456771/40.216220.450641/40.13504 O(8d)0.161350.048180.284750.173770.050140.28537Table6Calculated ionic coordinates for Li x FePO4(space group Pnma)with x=0 and1LiFePO4FePO4x y z x y zLi(4a)0(0)0(0)0(0)Fe(4c)0.27825(0.2822)1/4(1/4)0.97516(0.9716)0.27940(0.2753)1/4(1/4)0.96063(0.9504) P(4c)0.08979(0.0954)1/4(1/4)0.41630(0.4179)0.09447(0.0930)1/4(1/4)0.40796(0.3989) O(4c)0.09012(0.0946)1/4(1/4)0.74619(0.7403)0.11743(0.1153)1/4(1/4)0.73412(0.7107) O(4c)0.45112(0.4538)1/4(1/4)0.22126(0.2056)0.44784(0.4450)1/4(1/4)0.16331(0.1511) O(8d)0.16246(0.1615)0.04188(0.0521)0.28168(0.2861)0.16944(0.1649)0.04626(0.0465)0.26008(0.2520) Experimental values are in parentheses.Ref.[14].Table7Calculated ionic coordinates for Li x CoPO4(space group Pnma)with x=0 and1LiCoPO4CoPO4x y z x y zLi(4a)000Co(4c)0.277971/40.978470.275171/40.97005 P(4c)0.092091/40.419330.09501/40.41027 O(4c)0.090951/40.746730.117771/40.73455 O(4c)0.452791/40.218140.447091/40.16171 O(8d)0.167260.041550.283410.169770.043850.26194J.M.Osorio-Guille´n et al./Solid State Ionics167(2004)221–227 224of VCA here.The same features can be observed in Fig.2 for LiCoPO4.The characteristics of the DOS of LiMnPO4 reveal that this compound is an insulator,with a band gap of 1.8eV.The two upper valence bands and the two lower conduction bands are mainly made up from man-ganese d-states.In Fig.3,we compare the validity of VCA describing the electronic properties with a non-VCA calculation for Fe0.5Mn0.5PO4and LiFe0.5Mn0.5PO4.Both total DOS show approximately well the same main features of the cathode materials.We can see that the higher valence band and the conduction bands of Fe0.5Mn0.5PO4are very similar forthe Fig.1.Total DOS for LiFe1Ày Mn y PO4and Fe1Ày Mn y PO4for y=1,0.5,0.2and0.The Fermi level is indicated by a vertical dotedline.Fig.2.Total DOS for LiCoPO4and CoPO4.The Fermi level is indicated by a vertical doted line.J.M.Osorio-Guille´n et al./Solid State Ionics167(2004)221–227225two calculation methods.For LiFe 0.5Mn 0.5PO 4,the non-VCA DOS shows more structure than the VCA DOS.The valence bands are very similar in both calculations.How-ever,there are more features shown in the conduction bands for the non-VCA DOS.This new features reveal the behaviour of the Fe and Mn d -states,where the metal character of LiFe 0.5Mn 0.5PO 4is due completely to the Fe d -states,which have a band localized between the band gap formed by the Mn d -states located below and above of the Fermi level.By comparing the DOS of the delithiated/lithiated phases,we are able to study the effects on the nature of bonding when lithium is intercalated into the host structures.For Fe 1Ày Mn y PO 4,there is a strong bonding between the Fe 1Ày Mn y d -states,the phosphorus s -and p -states and the oxygen p -states.When lithium is intercalated,the oxygen p -states are shifted to the left with respect to the Fermi level and pushed up,giving rise to a hybridization among the lithium s -and p -states and the oxygen and phosphorus p -states.The Fe 1Ày Mn y d -states are shifted to the leftwithFig.3.Total and partial DOS for LiFe 0.50Mn 0.50PO 4(solid line)and Fe 0.50Mn 0.50PO 4(dashed line).The Fermi level is indicated by a vertical doted line.(a)Total DOS calculated with VCA.(b)Total DOS for the non-VCA calculation.(c)Fe 0.50Mn 0.50pseudo-atom d -states calculated with VCA.(d and e)Fe and Mn d -states for the non-VCA calculation,respectively.J.M.Osorio-Guille´n et al./Solid State Ionics 167(2004)221–227226respect to the Fermi level and become very localized.A final observed effect of lithium intercalation is that it is responsi-ble for the semiconductor–metal transition on FePO4,and a transition from semimetallic to insulating in MnPO4.4.ConclusionsIn conclusion,by means of first-principles theory,we have reproduced most of the observed aspects of Li Fe1Ày Mn y PO4systems.Our calculated volume,average voltage,energy density and specific energy are in good agreement with experiment,and thus gives confidence to the predictive power of the method.We can notice that the main effect of Mn is to broaden the upper valence band of FePO4 and,through the alternation of the position relative to the Fermi level,makes the cathode material metallic.On the other hand,the effect of Fe doping on the insulator LiMnPO4is to transform it to a metal material by the filling of the band gap with Fe d-states.AcknowledgementsWe are grateful to the Swedish Natural Science Foundation(VR),the Foundation for Strategic Research (SSF)and the Japan Society for the Promotion of Science (JSPS)for financial support.Valuable discussions with O. Eriksson and B.Sanyal are acknowledged.We are grateful to J.M.Wills for letting us use his FPLMTO code. References[1]K.Mizushima,P.C.Jones,P.J.Wiseman,J.B.Goodenough,Mater.Res.Bull.15(1980)783.[2]M.G.S.R.Thomas,W.I.F.David,J.B.Goodenough,Mater.Res.Bull.20(1985)1137.[3]M.M.Thackeray,P.J.Johnson,L.A.De Picciotto,P.G.Bruce,J.B.Goodenough,Mater.Res.Bull.19(1984)179.[4]T.Ohzuku,M.Kitagawa,T.Hirai,J.Electrochem.Soc.137(1990)769.[5]J.M.Tarascon,D.Guyomard,Electrochem.Acta.38(1993)1221.[6] B.Fuchs,S.Kemmler-Sack,Solid State Ion.68(1994)279.[7]R.Kanno,T.Shirane,Y.Inaba,Y.Kawamoto,J.Power Sources68(1997)145.[8] A.Le Mehaute,G.Ouvrard,R.Brec,J.Rouxel,Mater.Res.Bull.12(1977)1191.[9]M.S.Whittingham,Prog.Solid State Chem.12(1978)41.[10]R.Brec,A.Dugast,Mater.Res.Bull.15(1980)619.[11] C.Masquelier,A.K.Padhi,K.S.Nanjundaswamy,J.B.Goodenough,J.Solid State Chem.135(1998)228.[12]S.Okada,K.S.Nanjundaswamy,A.Manthiram,J.B.Goodenough,H.Ohtsuka,H.Arai,J.Yamaki,Proceedings of36th International Power Sources Symposium,IEEE,Cherry Hill,NJ,1994,pp.110. [13] A.K.Padhi,K.S.Nanjundaswamy,J.B.Goodenough,J.Electrochem.Soc.144(1997)1188.[14] A.S.Andersson,B.Kalska,L.Haggstro¨m,J.O.Thomas,Solid StateIon.130(2000)41.[15]S.Okada,S.Sawa,M.Egashira,J.Yamaki,M.Tabuchi,H.Kageyama,T.Konishi,A.Yoshino,J.Power Sources97–98(2001)430.[16] A.Yamada,Y.Kudo,K.Liu,J.Electrochem.Soc.148(2001)A1153.[17]G.Li,H.Azuma,M.Tohda,J.Electrochem.Soc.149(2002)A743.[18]G.Li,H.Azuma,M.Tohda,Electrochem.Solid-State Lett.5(2002)A135.[19]K.Amine,H.Yasuda,M.Yamachi,Electrochem.Solid-State Lett.3(2000)178.[20]M.K.Aydinol,A.F.Kohan,G.Ceder,K.Cho,J.Joannopoulo,Phys.Rev.,B56(1997)1354.[21]J.M.Wills,B.R.Cooper,Phys.Rev.,B36(1987)389J.M.Wills,(unpublished);D.L.Price,B.R.Cooper,Phys.Rev.,B39(1989)4945;R.Ahuja,O.Eriksson,J.M.Wills,B.Johansson,Phys.Rev.Lett.75 (1995)3473.[22]L.Hedin,B.I.Lundqvist,J.Phys.C4(1971)2064.[23]O.K.Andersen,Phys.Rev.,B12(1975)3060.[24]H.L.Skriver,The LMTO Method,Springer,Berlin,1984.[25] D.J.Chadi,M.L.Cohen,Phys.Rev.,B8(1973)i5747;S.Froyen,Phys.Rev.,B39(1989)3168.J.M.Osorio-Guille´n et al./Solid State Ionics167(2004)221–227227。

磷酸铁锂蓄电池充电原理及特性研究

10.16638/ki.1671-7988.2018.21.006磷酸铁锂蓄电池充电原理及特性研究宋真玉（陕西工业职业技术学院汽车工程学院，陕西咸阳712000）摘要：汽车工业的快速发展使得环境和能源纷纷出现危机，纯电动汽车的快速推广，也使得对性能优良的动力电池要求越来越高。

文章通过对磷酸铁锂蓄电池结构和工作原理的研究，揭示其极化现象和充放电特性，为磷酸铁锂动力电池的深入研究做了铺垫，使开发性能更优良动力电池打下基础。

关键词：磷酸铁锂；动力电池；原理；放电特性中图分类号：U469 文献标识码：A 文章编号：1671-7988(2018)21-16-04Study on Charging Principle and Characteristics of Lithium Iron Phosphate BatterySong Zhenyu( College of automotive engineering, Shaanxi vocational technical college, Shaanxi Xianyang 712000 )Abstract:The rapid development of the automobile industry has led to environmental and energy crises. The rapid promotion of pure electric vehicles has also led to higher requirements for power batteries with good performance. Through the study of the structure and working principle of the lithium iron phosphate battery, the polarization phenomenon and charge-discharge characteristics of the lithium iron phosphate battery are revealed, which lays a foundation for the in-depth study of the lithium iron phosphate battery and lays a foundation for the development of the battery with better performance. Keywords: lithium iron phosphate; Power battery; The principle; Discharge characteristicCLC NO.: U469 Document Code: A Article ID: 1671-7988(2018)21-16-04引言随着我过汽车工业的飞速发展，随之而来的能源和环境问题也凸显开来。

磷酸铁锂电芯专业英语单词铜排螺母

磷酸铁锂电芯专业英语单词铜排螺母Lithium iron phosphate (LFP) batteries have become increasingly popular in the realm of rechargeable batteries due to their numerous advantages, including high energy density, long cycle life, and excellent safety characteristics. Central to the construction of these batteries are several key components, among which copper bars and nuts play a crucial role.Copper bars, also known as copper straps or copper busbars, are essential for connecting various cell components within the battery pack. They act as high-conductivity pathways, allowing the smooth flow of current between the positive and negative terminals of the cells. The copper's conductivity ensures efficient energy transfer, minimizing power losses and ensuring optimal performance.The selection of copper for these bars is not arbitrary; copper is a highly conductive metal, making it ideal foruse in electrical components. Additionally, it isrelatively inexpensive and easy to work with, further adding to its appeal in battery construction. The bars are typically machined or stamped to the required shape and size, ensuring a secure and reliable connection.Nuts, on the other hand, are vital for maintaining the structural integrity of the battery pack. They are used to secure the copper bars in place, preventing them from loosening or coming apart during operation. This is crucial as any disruption in the flow of current can lead to performance issues or even complete battery failure.The nuts are typically made from corrosion-resistant materials like stainless steel or brass, ensuringdurability even in harsh environments. They are carefully threaded to mate with the holes in the copper bars, ensuring a secure fit. The use of high-quality nuts is paramount to ensuring the long-term stability andreliability of the battery pack.In summary, copper bars and nuts are integral components in the construction of lithium iron phosphate batteries. Their combined use ensures efficient energy transfer, structural integrity, and overall batteryperformance. As the demand for these batteries continues to grow, so too does the importance of these often-overlooked yet crucial components.**铜排和螺母在磷酸铁锂电池技术中的作用**磷酸铁锂（LFP）电池因其高能量密度、长循环寿命和卓越的安全特性，在可充电电池领域越来越受到欢迎。

矿用磷酸铁锂离子蓄电池

矿用磷酸铁锂离子蓄电池英文回答：Introduction.Lithium iron phosphate (LFP) batteries are a type of rechargeable battery that uses lithium iron phosphate as the cathode material and graphite as the anode material. They are known for their long cycle life, high safety, and low cost.Applications of LFP Batteries in Mining.LFP batteries are well-suited for use in mining applications due to their ability to withstand harsh conditions and provide reliable power. They are commonly used in underground mining equipment, such as:Load-haul-dump (LHD) vehicles.Underground coal miners.Roof bolters.Conveyors.Benefits of LFP Batteries for Mining.There are several key benefits of using LFP batteries in mining applications:Long cycle life: LFP batteries can withstand up to 2,000 charge-discharge cycles, which is significantly higher than other types of batteries.High safety: LFP batteries are inherently safe due to their thermal stability and resistance to overcharging. They do not contain any toxic or hazardous materials.Low cost: LFP batteries are relatively inexpensive compared to other types of batteries, making them a cost-effective solution.Reduced maintenance: LFP batteries require minimal maintenance compared to other types of batteries, as they do not need to be watered or serviced regularly.Environmental friendliness: LFP batteries are environmentally friendly, as they do not contain any toxic or hazardous materials.Challenges of Using LFP Batteries in Mining.While LFP batteries offer several benefits for mining applications, there are also some challenges associated with their use:Lower energy density: LFP batteries have a lower energy density than other types of batteries, such as lithium-ion batteries. This means that they may not be suitable for applications where weight and space are critical.Higher self-discharge rate: LFP batteries have ahigher self-discharge rate than other types of batteries. This means that they can lose a significant amount of charge when not in use.Temperature limitations: LFP batteries are sensitive to extreme temperatures. They should be operated within a specified temperature range to ensure optimal performance.Conclusion.LFP batteries are a promising technology for use in mining applications due to their long cycle life, high safety, and low cost. However, it is important to be aware of the challenges associated with their use, such as their lower energy density and higher self-discharge rate. With careful consideration of these factors, LFP batteries can provide a reliable and cost-effective solution for powering mining equipment.中文回答：Introduction.磷酸铁锂电池是一种使用磷酸铁锂作正极材料、石墨作负极材料的可充电电池。

磷酸铁锂正极材料市场深度分析：趋势、竞争、前景全面解读

磷酸铁锂正极材料市场深度分析：趋势、竞争、前景全面解读Title: In-depth Analysis of Lithium Iron Phosphate Cathode Material Market: Comprehensive Interpretation of Trends, Competition, and ProspectsLithium iron phosphate (LiFePO4) has gained significant attention as a cathode material for lithium-ion batteries due to its high thermal stability, safety, and long cycle life. The LiFePO4 market has witnessed substantial growth in recent years, driven by the increasing demand for electric vehicles, energy storage systems, and portable electronic devices. This article aims to provide a comprehensive analysis of the current state of the LiFePO4 cathode material market, including trends, competition, and future prospects.Trends:1. Electrification of Automotive Industry: The global shift towards electric vehicles (EVs) has propelled the demand for LiFePO4 cathode materials. As automakers focus on developing electric and hybrid vehicles, the need for high-performance,cost-effective, and safe battery materials has intensified.2. Energy Storage Systems: With the growing emphasis on renewable energy sources, the deployment of energy storage systems for grid stabilization and off-grid applications has increased. LiFePO4 batteries are preferred for their longer cycle life and enhanced safety, driving the demand for cathode materials.3. Technological Advancements: Ongoing research and development efforts have led to the enhancement of LiFePO4 cathode materials in terms of energy density, charging rates, and manufacturing processes. These advancements are expected to further drive market growth.Competition:The LiFePO4 cathode material market is characterized by intense competition among key players. Major companies are focused on expanding their production capacities, improving material performance, and developing sustainable supply chains. Additionally, partnerships and collaborations between battery manufacturers, material suppliers, and research institutions aredriving innovation and market penetration.Prospects:The future of the LiFePO4 cathode material market appears promising, driven by factors such as:1. Sustainability: Growing emphasis on sustainability and environmental consciousness is expected to drive the adoption of LiFePO4 cathode materials, given their non-toxic and eco-friendly nature.2. Cost-Effectiveness: LiFePO4 batteries are becoming increasingly cost-competitive compared to other lithium-ion chemistries, making them an attractive choice for various applications.3. Regulatory Support: Government initiatives and policies aimed at reducing carbon emissions and promoting clean energy solutions are likely to boost the demand for LiFePO4 cathode materials.In conclusion, the LiFePO4 cathode material market is poised for significant growth, driven by the increasing adoption of electric vehicles, energy storage systems, and technological advancements in battery materials. The market landscape is dynamic, with intense competition and a strong focus on sustainability and innovation.磷酸铁锂（LiFePO4）由于其高热稳定性、安全性和长循环寿命而成为锂离子电池的正极材料备受关注。

Hydrothermal synthesis of high surface LiFePO4 powders

Journal of Power Sources160(2006)516–522Hydrothermal synthesis of high surface LiFePO4powdersas cathode for Li-ion cellsG.Meligrana a,C.Gerbaldi a,∗,A.Tuel b,S.Bodoardo a,N.Penazzi aa Department of Materials Science and Chemical Engineering,Politecnico di Torino,C.so Duca degli Abruzzi24,10129Turin,Italyb Institut de Recherches sur la Catalyse,CNRS(UPR5401),2avenue Albert Einstein,69626Villeurbanne Cedex,FranceReceived13June2005;received in revised form19December2005;accepted21December2005Available online10February2006AbstractAn easy,quick and low cost hydrothermal synthesis was developed to prepare high surface area phospho-olivine LiFePO4powders to be used as cathode material for Li-ion batteries.The samples were prepared in double distilled water starting from commercial LiOH,FeSO4,H3PO4and using solutions with different concentrations of a surfactant compound(CTAB),in order to increase the speciﬁc surface areas,obtaining powders with very small grain size.The structural,morphological and electrochemical properties were investigated by means of X-ray powder diffraction(XRPD), ICP-AES,BET method,scanning electron microscopy(SEM)and constant current charge–discharge cycling.The electrochemical performances of LiFePO4prepared in this manner showed to be positively affected by the presence of CTAB during synthesis,showing capacities near the theoretical value,only slightly affected by the discharge regime(from C/20to10C).©2006Elsevier B.V.All rights reserved.Keywords:Lithium-ion cell;Lithium iron phosphate;Cathode material;Hydrothermal synthesis;Surfactant;Galvanostatic cycling test1.IntroductionIt is well known that the main efforts in the development of Li-ion systems regard the portable electronic devices,like portable phones,camcorders and lap-top computers,trying to increase the battery power density,and the huge market of elec-tric vehicles(EVs)and hybrid-electric vehicles(HEVs)where low cost,low pollution but high speciﬁc performance batter-ies are needed[1,2].In particular,the investigation into new materials for the positive electrode is one of the basic lines of research.Since the pioneering works of Padhi et al.[3],mixed orthophosphates LiMPO4(where M=Mn,Fe,Co,Ni)isostruc-tural to olivine have been intensively studied as lithium insertion cathode materials for the next generation of Li-ion secondary batteries[4].Among these compounds,the mineral triphylite, having the formula LiFePO4and showing an ordered olivine structure,has proved to be one of the most promising among the polyanionic compounds tested over recent years[3,5].∗Corresponding author.Tel.:+390115644638;fax:+390115644699.E-mail address:claudio.gerbaldi@polito.it(C.Gerbaldi).This compound shows several advantages compared with conventional cathode materials such as LiCoO2,LiNiO2and LiMnO2,namely it is lower in toxicity and relatively inexpen-sive.In addition,LiFePO4has an interesting theoretical speciﬁc capacity of about170mAh g−1,a good cycle stability and a technically attractiveﬂat voltage versus current proﬁle of3.45V versus Li+/Li,due to the two-phase extraction/insertion mecha-nism.A further advantage of this material,thanks to its stability, is the improved safety at high temperatures compared to the transition-metal oxides that lose oxygen on overcharging,which increases the probability of electrolyte decomposition at higher temperatures.Lithium iron phosphate,at theﬁrst charge,can de-intercalate 1Li+ion per formula unit,corresponding to the oxidation of Fe2+to Fe3+.The extraction of Li+ions gives rise to a new phase, FePO4(heterosite),which maintains nearly the same structure:a and b lattice constants decrease slightly while c increases[2,3]. This feature assures that the process is highly reversible and repeatable.Theﬁrst investigations on LiFePO4as electrode material have put in evidence that the capacity reached at room temper-ature is far below the theoretical one.Moreover,a reversible capacity loss is present throughout the charge–discharge cycles,0378-7753/$–see front matter©2006Elsevier B.V.All rights reserved. doi:10.1016/j.jpowsour.2005.12.067G.Meligrana et al./Journal of Power Sources160(2006)516–522517increasing with the current density[3,5].This capacity loss seems to be related to the limited area of the interface between the LiFePO4/FePO4phases where the Li+extraction/insertion takes place.According to Andersson and Thomas,the factor limiting the full conversion of LiFePO4to FePO4is based on the combination of low lithium ion diffusion rate and poor electronic conductivity[6].It has been readily recognized that the grain size is a critical issue to minimize high current capacity loss;e.g.Yamada et al. obtained95%of theoretical capacity at room temperature and at current density higher than0.1mA cm−2using samples having 20␮m particle size[5].Apart from increasing temperature,which can have a posi-tive inﬂuence but is impractical for Li-ion batteries directed to a wide market,another possible way of improving LiFePO4per-formance has been followed by Ravet et al.[7,8],who succeeded in coating the grains with carbon,so improving the capacity through an increase of conductivity.The same method was undertaken by many researchers using organic materials,like sucrose,added during preparation[9,10].Our research group, in particular,carried out investigations on phospho-olivine com-pounds using ascorbic acid and citric acid as carbonaceous additives[2,11].Prosini et al.obtained interesting results by addingﬁne particles of carbon black during the synthesis[12]. Croce et al.improved the kinetic properties of LiFePO4by dis-persing copper or silver into the solution during synthesis[13]. Theﬁnely dispersed metal powder promoted a reduction of par-ticle size and an increase in the material conductivity.It was also claimed that the electronic conductivity of LiFePO4could be increased by doping with metals supervalent to Li+(i.e.Mg2+, Al3+)[14].The next logical step was to try to get an efﬁcient charge trans-port preparing a homogeneous active material with reﬁned grains size and intimate carbon contact.Huang et al.[15]obtained higher current density capacities from a LiFePO4/C composite containing15%of carbon and a100–200nm particle size.In a review article,illustrating the progress in the design of olivine-type cathodes at Sony,Yamada et al.[16]showed a cathode material preparation involving an addition of a“disordered con-ductive carbon”added to the precursor of the material,being3% the minimum amount,and a subsequent stage of high energy ball milling to get nano-scale homogenized particles.Experience in thisﬁeld has clearly shown that carbonaceous materials added to the precursors during synthesis have a fun-damental importance in increasing the LiFePO4performance. They can act as reducing agents to avoid the formation of triva-lent Fe ions duringﬁring,maintain the particles isolated from each other preventing their coalescence and enhance intra and inter particle conductivity.The choice of the additive is,there-fore,of marked importance:it will exert the deep inﬂuence previously described only if it can take part in the process itself,like in the synthetic routes followed by Huang et al.[15].In this context,the kind of synthesis used becomes important too.Initially,the most common way of synthesizing LiFePO4 was the solid-state route[5,17],that we also followed in our ﬁrst investigations[2,11].Nevertheless,we obtained higher per-forming LiMPO4(where M=Fe,Mn)materials via a sol–gelsynthetic route[18].The amorphous precursors used allowedthe production of sub-micrometric agglomerates smaller thanthose prepared via solid-state route and produced a very homoge-neous carbon dispersion in the phosphate phase.More recently,hydrothermal preparation has been preferentially chosen for itsadvantages:quick,easy to perform,low cost in energy and eas-ily scalable.Yang et al.[10]obtained3␮m LiFePO4particles,smaller than the20␮m LiFePO4grains obtained by Yamada etal.[5]with a solid-state reaction.Our recent investigations,of which theﬁrst results arereported in the present paper,concern the hydrothermal synthe-sis of LiFePO4powders using an organic surfactant compound(hexadecyltrimethylammonium bromide,hereafter reported asCTAB),which is added during synthesis.Our aim was to inves-tigate the inﬂuence of this additive on the preparation of thematerials.As a dispersing agent it probably modiﬁes the struc-ture of the crystallites more deeply than just decrease theirgrain size.Moreover,with theﬁring of the synthesized sam-ples in inert atmosphere,the CTAB remaining after theﬁlteringstage gives rise to a carbon coating that increases the con-ductivity of the materials and enhances their electrochemicalperformance.2.Experimental2.1.SynthesisThe lithium iron phosphate samples were prepared bydirect mild hydrothermal synthesis.Starting materials wereFeSO4·7H2O(Aldrich,purity99%),H3PO4(Aldrich,purity >85%),LiOH(Aldrich,purity>98%)in the stoichiometric ratio1:1:3and hexadecyltrimethylammonium bromide(Aldrich,C19H42BrN,CTAB).First of all,a CTAB water solution wasprepared,stirring the white powder in distilled water at35◦C forapproximately30min in order to completely dissolve it.FeSO4and H3PO4water solutions were prepared and mixed together.The resulting solution was then added to the surfactant solutionunder constant stirring and only in the end,so avoiding the for-mation of Fe(OH)2which can be easily oxidized to Fe3+,LiOHwas added.The mixture,whose pH ranged between7.2and7.5,was vigorously stirred for1min and then quickly transferredin a Teﬂon-lined stainless steel autoclave and heated at120◦Cfor5h.The autoclave was then cooled to room temperature andthe resulting green precipitate washed,via a standard procedureto ensure complete elimination of the excess of surfactant,ﬁl-tered and dried at40◦C overnight.The heating treatment wascarried out in inert atmosphere to avoid the oxidation of Fe2+to Fe3+:the powders were pre-treated at200◦C(heating rate of5.0◦C min−1)and thenﬁred at600◦C(2.0◦C min−1)in pure N2for12h in order to obtain the crystalline phase and to carbonisethe surfactant,so obtaining a carbonﬁlm that homogeneouslycovers the grains.The four samples obtained in this manner are hereafternamed LF1(sample obtained without CTAB addition duringsynthesis),LF2(4.11mmol CTAB added during synthesis),LF3(6.87mmol CTAB)and LF4(13.70mmol CTAB).518G.Meligrana et al./Journal of Power Sources160(2006)516–5222.2.Chemical,structural analysis and surface area determinationQuantitative elemental analysis was carried out by induc-tively coupled plasma-atomic emission spectroscopy(ICP-AES)with a Varian Liberty100instrument.The samples were digested in hot concentrated HCl:HNO3=3:1mixture.The weight percentage of carbon in the samples was determined by a C,H,N Analyzer model1106Carlo Erba Strumentazione.The X-ray diffraction proﬁles of the samples were obtained using a Philips Xpert MPD powder diffractometer,equipped with Cu K␣radiation(V=40kV,i=30mA)and a curved graphite secondary monochromator.The diffraction data were collected in the2θ-range between15and80◦,with an acquisition step of0.02◦and a time per step of10s.The samples were also submitted to a scanning electron microscope(SEM)investigation for morphological character-ization,using a Hitachi S800microscope(INSA,Lyon)with a magniﬁcation of6×104.Speciﬁc surface areas(SSA)were determined using the Brunauer,Emmet,Teller(BET)method on an ASAP2010 Micromeritics instrument.Prior to adsorption,approximately 50.0mg of solid was placed in the cell and evacuated at350◦C for5h.2.3.Cathode and cell preparation,electrochemical testsThe electrodes for the evaluation of the electrochemical properties were prepared spreading on an aluminum current-collector,by the so-called“doctor blade”technique,a slurry of the LiFePO4active material(70wt%)with carbon black as elec-tronic conductor(Super P,MMM Carbon Belgium)(20wt%) and poly(vinylideneﬂuoride)as binder(PVdF,Solvay Solef 6020)(10wt%)in N-methyl-2-pyrrolidone(NMP,Aldrich). After the evaporation of the solvent by a mild heating,disks of0.785cm2were punched out of the foil and dried by heat-ing them at about130◦C under high vacuum for5h.After their transfer in an Ar-ﬁlled dry glove box,the disks were weighed before their use in the test cells and,by subtraction of the average weight of the Al disks,the weight of the coating mixture was cal-culated.The composite electrodes were used in three electrode T-cells with lithium metal as anode and a glass-wool(Whatman GF/A)disc as the separator.The liquid electrolyte used was1M LiPF6in a1:1mixture of ethylene carbonate(EC)and diethyl carbonate(DEC)(Merck).The galvanostatic cycling tests were carried out at room temperature with an Arbin Instrument Testing System model BT-2000,setting the cut off voltages to2.50–4.00V versus Li+/Li. The charge–discharge cycles were set at the same rate ranging from C/20to10C.3.Results and discussion3.1.Chemical and structural characterizationElemental analysis results gave the basic characterization of the synthesized materials.The results,reported in Table1,show Table1Elemental composition of the materials(expressed in wt%of total weight) Sample CTAB(mmol)Li(wt%)Fe(wt%)P(wt%)C(wt%) LF10.0 3.535.414.6–LF2 4.11 3.733.515.6 1.11LF3 6.87 3.833.115.8 1.52LF413.70 4.133.917.8 4.80 that for all the samples prepared using CTAB during synthesis,the expected LiFePO4stoichiometry was obtained.The molarratio for Li:Fe:P is almost1:1:1for the three samples preparedin the presence of CTAB;major divergences are observed in thecase of sample LF1.As for carbon,it is interesting to observe thatthe content is,for LF4,markedly superior to the other samples.Fig.1shows the X-ray powder diffraction patterns of the sam-ples synthesized in the presence of the surfactant.The puritydegree is high:the main diffraction peaks can be attributedto the orthorhombic LiFePO4olivine-type phase.Some minorpeaks are due to impurities,which can be mainly attributedto Li3Fe2(PO4)3,␣-Fe and hematite Fe2O3.The sample LF4,in particular,looks very pure and its narrow diffraction peaksindicate a good crystallinity degree.The sample LF1,preparedwithout CTAB addition,is not reported in theﬁgure as theX-ray powder diffraction data put in evidence a material consti-tuted by a mixture of various ferrous and ferric phosphates,likeFe3(PO4)3·8H2O,Li3Fe2(PO4)3,Fe2O3and only a little amount of LiFePO4,a result somehow expected from the divergencesin the molar ratio.Therefore,this sample cannot be comparedwith the others,which are prepared in presence of CTAB.As all the samples prepared in the presence of the surfac-tant were submitted to aﬁring stage at600◦C(2.0◦C min−1)in pure N2,the presence of a carbonaceous phase,due to thedecomposition of the organic species,still present after washingandﬁltering,has to be expected.Nevertheless,there is no evi-dence of such phase in the diffraction patterns,probablybecauseFig.1.X-ray powder diffraction patterns of the LiFePO4samples,synthesized under hydrothermal conditions using different concentrations of the organic sur-factant(CTAB)and calcined underﬂowing N2at600◦C for12h.(a)Theoretical LiFePO4,(b)LF2,(c)LF3and(d)LF4.The asterisks indicate the reﬂection peaks of the impurity phases.G.Meligrana et al./Journal of Power Sources160(2006)516–522519Fig.2.Scanning electron micrographs of the LF2(A)and LF4(B)samples,both annealed at600◦C in inert atmosphere.it is present in a low content and/or it is amorphous,causing only a little increase of the background in the low-angle region.The SEM microphotographs,reported in Fig.2A and B,put in evidence the strong grain-reﬁning effect of CTAB,which is directly related to its amount.The sample LF2shows grain dimensions of about90–100nm(Fig.2A),while the size of the LF4grains is estimated around50nm,see Fig.2B.In the same ﬁgure,the particles seem also more homogeneous in size with less signs of coalescence between the grains to form boulders like in Fig.2A.This effect of reﬁning and homogenizing the size of the grains induced by the presence of an organic species has been already reported[5,15,16].Our experience states that, in this respect,CTAB appears one of the most effective additive tested[2,11,18].A conﬁrmation,quite valuable being quantitative,of the posi-tive inﬂuence of the surfactant on the grain characteristics comes from speciﬁc surface area measurements with the BET method. The data reported in Table2show that CTAB markedly enhances the speciﬁc surface area of the powders.The sample LF2shows a speciﬁc surface area almost three times more extended than the sample prepared without CTAB.Also important is the fact that this increase is dependent on the amount of CTAB;in fact, the data indicate an almost linear dependence of SSA versus mmol of CTAB in the synthesis solution.Unfortunately,due to Table2Speciﬁc surface area(SSA,m2g−1)related to the molar amount of CTAB (mmol)used in the synthesis of the different samplesSample SSA(m2g−1)CTAB(mmol) LF1 4.270LF211.60 4.11LF326.80 6.87LF444.7013.70solubility limitations,it is difﬁcult to investigate the effect of the presence of CTAB in higher amounts.3.2.Electrochemical measurementsThe electrochemical performance of the materials,tested in a laboratory cell versus a lithium metal anode,are shown in Figs.3and4.Theﬁgures report the galvanostatic discharge pro-ﬁles of the samples at C/20(Fig.3)and C/5(Fig.4)extracted from cycling tests carried out at increasing C-rates.The results for the sample LF1are not reported in theseﬁgures as they can-not be compared to the others,being LF1constituted by different phases.The curves put in evidence the superior performance of LF4sample,which,in addition,shows a more deﬁnitedischarge Fig.3.Discharge proﬁles vs.lithium at C/20for the LiFePO4samples(3rd cycle of the cycling test,3rd cycle at C/20).Current density=8.5mAh g−1.520G.Meligrana et al./Journal of Power Sources160(2006)516–522Fig.4.Discharge proﬁles vs.lithium at C/5for the LiFePO4samples(18th cycle of the cycling test,3rd cycle at C/5).Current density=34mAh g−1.step with a steep potential decay at its end.A second point of interest is the similar speciﬁc capacity value shown by the sam-ple LF4at the two discharge regimes chosen,suggesting the apparent independence from the discharge rate.Unfortunately, this is not completely true:this feature depends from the par-ticular ongoing of theﬁrst cycles of sample LF4,as it will be discussed in the followingﬁgures.The speciﬁc capacity of the samples at higher current regimes and their cyclability are interesting too.Fig.5shows the cycling behaviour of the samples LF2,LF3and LF4at room tempera-ture,at charge–discharge regimes ranging from C/20to1C.In general,all the curves show a good cycling stability at a cer-tain regime,the charge coefﬁcient(charge capacity/following discharge capacity)being very near to one.The results of the most recent durability tests with hundreds of cycles,conﬁrm this statement.A feature peculiar only to sample LF4is the pro-gressive lowering of the charge capacity at the initial cycles, while the discharge capacity correspondingly increases.Thislow performance at the beginning explains the similar valueofFig.5.Cycling performance of LF2,LF3and LF4samples at C-rates from C/20 to1C.speciﬁc capacity detected in Fig.4with respect to Fig.3.Such unbalanced situation soon stabilizes giving values of the charge coefﬁcient near1.This initial behaviour,not so evident in the other samples,seems to be tied to the initial cycling phase;it has the appearance of an“induction”period during which the material stabilizes its behaviour.The progressive increase of the discharge capacity is not a new feature.Similar phenomena have been reported by several authors[4,12,15,22,23],some of which did not try an explana-tion whatsoever.Zhang et al.[23],considered LiFePO4samples prepared with a carbon content of3–10wt%,all showing this increase in capacity during initial cycling.Such initial irre-versibility,has been related,at least partially,to a“self doping of Li+ions into Fe sites”.At the moment,lacking any clarify-ing experimentalﬁnding,we can only relate the phenomenon to the high amount of carbon present in the sample LF4.We suppose that the extended carbon layer which covers the grains allows the complete migration of Li+ions outside the mate-rial causing structural modiﬁcations inside the grains and at the interface between LiFePO4and carbon layer.The situation is progressively restored during what have been called the induc-tion cycles.A deeper insight of this topic can be achieved by getting additional structure information(e.g.from Raman spec-tra and Rietveld reﬁning of X-ray powder diffraction patterns).The plot of Fig.6reports the results of another cycling test on sample LF4,at room temperature,extended to10C.Apart from the conﬁrmation of the very good performance,the plot puts in evidence the good cycling stability of this sample,which shows a high rate capability and even a slight progressive improve-ment of the charge coefﬁcient at higher discharge regimes.The performance is at the level of the best results of the literature [4,15,17,19–21]and ours[2,11,18],particularly at higher dis-charge regimes,which is very important.The plot of Fig.7summarizes the performance of the studied materials with respect to the discharge rate until10C,at which regime the sample LF4still maintains the65%of the theoretical capacity.The initial upward going of the LF4curve for C/20and C/10cycling rates is a consequence of the anomalous behaviour of theﬁrst cycles for this samples(see Fig.5).So C/20and Fig.6.Charge–discharge cycling test of LF4at different C-rate(from C/20to 10C).G.Meligrana et al./Journal of Power Sources160(2006)516–522521Fig.7.Speciﬁc capacity of the samples at different C-rate(from C/20to10C). Each value is the average among the capacity values of the cycles at the corre-sponding rate.C/10,whose data come actually from the curve of Fig.6,show, in Fig.7,a value of the speciﬁc capacity lower than C/5.Another speciﬁc feature of the sample LF4is that the capacity loss with the increasing of the current is quite limited.From C/10to10C the capacity of LF4shows a lowering of about15%,while for LF2and LF3the value is doubled.The experimental results presented allow to state that CTAB inﬂuences the electrochemical properties of LiFePO4in several ways.Its action is exerted both during the very preparation of the material and in the followingﬁring stage.During synthesis,the CTAB micelles limit the growth of large crystallites,possibly by segregating the crystalline seeds,favouring their dispersion and homogenizing their size.This leads to an increase of the SSA and it makes the electrolyte accessible to a more extended region of the active material.Then,during theﬁring stage at 600◦C in inert atmosphere,the surfactant exerts,as a carbona-ceous material,a reducing action preventing Fe2+from being oxidized to Fe3+,so ensuring the purity of the samples.More important,the carbon layer produced as a consequence of the ﬁring of the organic species,deposits on the grains surface and it acts as an electronic conductor enhancing at a nanoscopic level the transfer of electrons.Moreover,as the volume occupied by the organic surfactant is lowered when carbon is obtained,voids could be formed between the particles,favouring the access of the electrolyte and the passing of Li+ions to and from the material.The sum of these phenomena allow to realize the optimum conditions for LiFePO4action as cathode material for lithium ion batteries.The role played by carbon is still to be put in evidence experimentally:ourﬁrst HR-TEM observations of the samples(not reported here)seem to conﬁrm our point of view.4.ConclusionsAn easy,quick and low cost hydrothermal synthesis in the presence of an organic surfactant compound(CTAB)allowed to prepare LiFePO4powders with outstanding features as cathode material for Li-ion cells.The results obtained in this work have shown that the presence of CTAB is essential to obtain the desired material;moreover, when it is added in high amounts,the cycling performance and the discharge capacity of the samples are markedly enhanced and present typical features.CTAB leads to the preparation of powders withﬁnely dis-persed nanocrystalline grains of pure material,also acting on the degree of agglomeration of the grains and hence on the extent of the speciﬁc surface area.The pyrolysis of CTAB dur-ing theﬁring step produces a strongly reductive atmosphere that prevents the oxidation of Fe2+to Fe3+ensuring the purity of the synthesis product,and improves the conductivity of the material with the in situ coated carbonﬁlm on the LiFePO4 particles.The results presented in this paper have shown that the LF4 sample,prepared in presence of the highest amount of CTAB, shows an electrochemical performance comparable to the best literature results.AcknowledgementsThe Italian Government(PRIN2002032512006funding) contributed inﬁnancing the present research.The help of Prof.B. Scrosati of the University of Rome“La Sapienza”in forwarding technical instrumentation is gratefully acknowledged.Thanks are also due to Dr.M.Malandrino of the University of Turin for the ICP-AES analysis.References[1]B.Scrosati,Nature373(1995)557.[2]M.Piana,M.Arrabito,S.Bodoardo,A.D’Epifanio,D.Satolli,F.Croce,B.Scrosati,Ionics8(2002)17.[3]A.K.Padhi,K.S.Nanjundaswamy,J.B.Goodenough,J.Electrochem.Soc.144(1997)1188.[4]S.Franger,F.Le Cras,C.Bourbon,H.Rouault,J.Power Sources119–121(2003)252.[5]A.Yamada,S.C.Chung,K.Hinokuma,J.Electrochem.Soc.148(2001)A224.[6]A.S.Andersson,J.O.Thomas,J.Power Sources97–98(2001)498.[7]N.Ravet,J.B.Goodenough,S.Besner,M.Simoneau,P.Hovington,M.Armand,in:Proceedings of the ECS Meeting,Abstracts99-2(1999)127.[8]N.Ravet,Y.Chouinard,J.F.Magnan,S.Besner,M.Gauthier,M.Armand,Abstract of IMLB-10(2000)166.[9]N.Ravet,Y.Chouinard,J.F.Magnan,S.Besner,M.Gauthier,M.Armand,J.Power Sources97–98(2001)503.[10]S.Yang,P.Y.Zavalij,M.S.Whittingham,mun.3(2001)505.[11]N.Penazzi,M.Arrabito,M.Piana,S.Bodoardo,S.Panero,I.Amadei,J.Eur.Ceram.Soc.24(2004)1381.[12]P.P.Prosini, D.Zane,M.Pasquali,Electrochim.Acta46(2001)3517.[13]F.Croce,A.D’Epifanio,J.Hassoun,A.Deptula,T.Olczac,B.Scrosati,Electrochem.Solid State Lett.5(3)(2002)A47.[14]S.Chung,J.T.Bloking,Y.Chiang,Nat.Mater.1(2002)123.[15]H.Huang,S.-C.Yin,L.F.Nazar,Electrochem.Solid State Lett.4(10)(2001)A170.[16]A.Yamada,M.Hosoya,S.-C.Chung,Y.Kudo,K.Hinokuma,K.-Y.Liu,Y.Nishi,J.Power Sources119–121(2003)232.[17]A.S.Andersson,J.O.Thomas,B.Kalska,L.H¨a ggstr¨o m,Electrochem.Solid State Lett.3(2)(2000)66.522G.Meligrana et al./Journal of Power Sources160(2006)516–522[18]M.Piana,B.L.Cushing,J.B.Goodenough,N.Penazzi,Solid State Ionics175(2004)233.[19]S.Yang,Y.Song,P.Y.Zavalij,M.S.Whittingham,mun.4(2002)239.[20]Z.Chen,J.R.Dahn,J.Electrochem.Soc.149(9)(2002)A1184.[21]P.Reale,S.Panero,B.Scrosati,J.Garche,M.Wohlfahrt-Mehrens,M.Wachtler,J.Electrochem.Soc.151(12)(2004)A2138.[22]T.-H.Cho,H.-T.Chung,J.Power Sources133(2004)272.[23]S.S.Zhang,J.L.Allen,K.Xu,T.R.Jow,J.Power Sources147(2005)234.。

毕业设计--锂电池的发展过程简介相关文献翻译(中文+英文)

锂电池发展简介锂离子电池是一种充电电池，它主要依靠锂离子在正极和负极之间移动来工作。

在充放电过程中，Li+ 在两个电极之间往返嵌入和脱嵌：充电池时，Li+从正极脱嵌，经过电解质嵌入负极，负极处于富锂状态；放电时则相反。

一般采用含有锂元素的材料作为电极的电池，是现代高性能电池的代表。

发展历史早期锂电池锂离子电池(Li-ion Batteries)是锂电池发展而来。

所以在介绍Li-ion之前，先介绍锂电池。

举例来讲，以前照相机里用的扣式电池就属于锂电池。

锂电池的正极材料是二氧化锰或亚硫酰氯，负极是锂。

电池组装完成后电池即有电压不需充电。

这种电池也可以充电，但循环性能不好，在充放电循环过程中容易形成锂结晶，造成电池内部短路，所以一般情况下这种电池是禁止充电的。

[2] 炭材料锂电池后来，日本索尼公司发明了以炭材料为负极，以含锂的化合物作正极的锂电池，在充放电过程中，没有金属锂存在，只有锂离子，这就是锂离子电池。

摇椅式电池我们通常所说的电池容量指的就是放电容量。

在Li-ion的充放电过程中，锂离子处于从正极→负极→正极的运动状态。

Li-ion Batteries就像一把摇椅，摇椅的两端为电池的两极，而锂离子就象运动员一样在摇椅来回奔跑。

所以Li-ion Batteries又叫摇椅式电池。

发展时间点1970年代埃克森的M.S.Whittingham采用硫化钛作为正极材料，金属锂作为负极材料，制成首个锂电池。

1982年伊利诺伊理工大学(the Illinois Institute of Technology)的R.R.Agarwal和J.R.Selman发现锂离子具有嵌入石墨的特性，此过程是快速的，并且可逆。

与此同时，采用金属锂制成的锂电池，其安全隐患备受关注，因此人们尝试利用锂离子嵌入石墨的特性制作充电电池。

首个可用的锂离子石墨电极由贝尔实验室试制成功。

1983年M.Thackeray、J.Goodenough等人发现锰尖晶石是优良的正极材料，具有低价、稳定和优良的导电、导锂性能。

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其中可溶性淀粉、蔗糖、柠檬酸作碳前驱体时用第一种方法合成，间苯二酚甲醛聚合物作碳前驱体时用第二种方法合成。

得到样品后用XRD,TEM ,拉曼波谱和循环伏安法对制得样品的晶体结构，形貌，相成分以及电化学特性进行测试研究。

在制得的四种样品中，使用间二苯酚甲醛聚合物作碳的前驱体时，样品的首次放电比容量最高（室温下0.2 C 时放电比容量为138.4 mAh/ g）,倍率性能最好。

第一章引言LiFePO4作为锂离子电池正极材料由于其理论比容量高（170mAh/g），环保，热稳定性好而受到广泛关注。

然而其低于10−13Scm−1的电导率限制了其电池性能【1】，例如在高电流密度下功率的显著减小是其商业化发展的主要障碍。

在这些方法中，制备LiFePO4/C 复合材料是最受关注的。

此外，碳还可以用作还原剂使Fe3+降价为Fe2+。

值得提及的是包括纳米尺寸的磷酸铁锂的合成在内的很多研究用昂贵的Fe2+盐作前驱体【3.16-20】，例如FeC2O4·2H2O 和(CH 3COO)2Fe。

因此，研究新的制备方法和应用廉价的材料对磷酸铁锂作为锂离子电池正极材料的产业发展至关重要。

这里我们报道分别用国内生产的非晶体纳米FePO4作离子前驱体以及可溶性淀粉、蔗糖、柠檬酸和间二苯酚甲醛聚合物作碳的前驱体，用两种方法制备的纳米复合材料LiFePO4/C的合成方法、性能描述和电化学性质测试结果。

在两种方法中，用FePO4作反应物合成LiFePO4材料的方法经济，环保。

这里我们特别给出一种能够制备出均匀碳膜包覆的LiFePO4正极材料的新方法，这种方法包含一种在FePO4表面进行的间二苯酚和甲醛的原位反应。

电化学测试显示这种材料在室温下放电倍率0.2C时初始放电容量为138. 4 m Ah/g，在放电倍率为0.5C和1C时也表现出较好的循环性能。

第二章实验2.1非晶型纳米FePO4的制备非晶纳米FePO4由水溶液中的自然沉淀制得。

60°C温度下等物质的量的磷酸溶液加到Fe(NO3)3·9H2O的溶液中，搅拌并添加少量表面活性剂PEG-400，然后慢慢将氨水加入混合溶液，并快速搅拌，很快会形成奶白色的沉淀物，此过程中溶液的pH值保持在 2.0。

将得到的沉淀用蒸馏水进行多次过滤和洗涤后放入真空烘箱中在120°C下烘干12小时得到黄白色无定形FePO4。

2.2 LiFePO4/C的制备本文中用两种方法制备LiFePO4/C复合材料2.2.1 制备方法一用液相法【21】合成LiFePO4 / C复合材料。

用一定化学计量的非晶FePO4，LiOH·H2O作反应原料，可溶性淀粉（50.0 g/1mol LiOH·H2O），蔗糖（35.0g/ 1 mol LiOH·H2O），一水柠檬酸（21.0g/1mol LiOH·H2O）分别作碳前驱体。

在加热环境下将这些碳前驱体分别溶解在适量的蒸馏水中并不断搅拌，然后加入非晶FePO4和LiOH·H2O并加快搅拌速度，接下来混合物分别在120°C，350°C（Ar气氛），750°C（Ar气氛）条件下干燥6h，1h，12h，然后研磨。

最后，获得LiFePO4 / C样品并分别标记为样品A，样品B和样品C。

2.2.2 制备方法二在一个标准的合成过程中，将0.10 g的CTAB在连续搅拌下溶解在30毫升的蒸馏水溶液中。

然后，依次将1.52gFePO4·3H2o，0.055g间苯二酚（R）和0.10ml甲醛（F）加入溶液中。

当水浴温度达到85℃时，加入LiOH·H2O。

在黑暗状态下保持搅拌混合物2小时，然后将混合物在120°C烘箱中烘干6小时，然后在氩气气氛下加热至350°C处理1h，然后在氩气气氛下加热至750°C处理12小时，最后研磨获得LiFePO4 / C复合材料（记为样品D）。

表一为四种样品和对应的参数，样品中的碳含量用四种样品在空气中燃烧时的损耗来计算。

2.3 特性描述热重量（TG）和示差热分析（DTA）的分析用EXSTAR6000热分析系统在升温速率为10°C /min 下进行。

用粉末X-射线衍射（(XRD, X' Pert Pro MPD, Philips）来鉴别制备材料的晶相。

拉曼光谱在457.5 nm激励光源下被记录在Renishaw RM-1000拉曼显微分光仪上，在室温需要10 mW 的功率。

低倍率和高放大倍率TEM图像用JEM-2010透射电子显微镜图像拍摄得到（使用一个200千伏的加速电压）。

用制备的碳包覆LiFePO4粉末（80 wt. %），炭黑( 12 wt. %) ，和聚偏二氟乙烯(8 wt.%)组装成电极，把浆液涂敷到铝箔上，并在120°C下真空干燥12小时。

在实验单元电池中碳包覆磷酸铁锂的载入量为2 mg/ cm2 。

单元电池都聚集在一个充满氩气气氛的真空设备用手套式操作箱中。

电解液为含有1 M LiPF6的碳酸乙烯酯（EC）和碳酸二甲酯（DMC）的混合物，（1:1体积）。

单元电池恒流充电和放电利用LAND电池测试系统在电压范围为2.5 - 4.2 V的室温下进行。

循环伏安图在IM6阻抗和电化学测量系统(Zahner, Germany)上以0.1 mV/s的扫描速率运，电压介于2.5和4.0 V。

第三章结果和讨论图1为非晶纳米FePO4的TEM图像，可以看出FePO4样品的形态为不规则的颗粒状，平均粒径为30nm。

由于颗粒尺寸小而引起的高表面使大多数的颗粒相互连接。

图2a是FePO4 粉末在空气中以速率10°C /min从室温升高到850°C的TG/ DTA曲线。

DTA曲线在150℃附近，有一个非常强烈的吸热峰，结合TG曲线中明显的重量损耗，说明这些明显的变化是与FePO4·3H2O的快速脱水有关的。

在150-550℃的区间中，TG曲线上26.3％的重量损失表示FePO4·3H2O中剩余的水慢慢排出，正与FePO4·3H2O结晶水的损失对应。

较高的温度590℃时的放热峰，在TG曲线中不伴有明显的重量损失，表明非晶FePO4转变为六角FePO4晶体，煅烧前后的FePO4·3H2O的XRD图在图2b中给出。

在a图中，可以看出在焙烧前没有衍射峰的证据，表明合成的FePO4·3H2O是无定形的。

而对于在600℃的空气中煅烧6h的FePO4·3H2O，显示出很强很尖锐的峰表明b图中是.结晶很好的材料。

制备的FePO4的所有的衍射峰都结构对应，与标准卡（JCPDS卡号码：72 - 2124）符合的很好，无任何杂质。

不同碳前驱体制备的LiFePO4/ C粉末的XRD衍射图案如图3所示，所有峰可以对应具有有序的橄榄石结构的单相（JCPDS卡83-2092），其正交空间群Pnmb。

得到的晶格参数分别为：样品A：a = 10.2956Å，b= 6.0367Å和c=4.7001Å，样品B：a=10.1992Å，b=6.0483Å，和c= 4.6971 Å，样品C：a= 10.2472Å，b= 6.0208 Å，c = 4.6882 Å，样品D：a = 10.3372 Å，b=5.9993 Å，c=4.6932Å。

尽管在TEM图像（见图4）中可以看到一些无定形物质和薄膜与磷酸铁锂颗粒接触在一起，但没有碳的衍射峰的证据，这表明碳含量非常低。

LiFePO4 / C样品的形貌如图4所示。

样品明显的表现出LiFePO4的粒子表面不同的碳分布。

从图4a，c，e和g中我们观察到样品由成团的颗粒组成，其尺寸范围从50到300nm。

在图4b和d中，没有足够的碳涂层将基材颗粒全部包覆。

与样品A和样品B对比下，样品C和样品D中的颗粒表面覆盖有均匀且很薄的碳薄膜，厚度大约分别为2.5nm（图4 f）和4 .5 nm（图4h）。

形成此差异的原因可能在于，不同碳前驱体对FePO4·3H2O颗粒表面有不同的吸附力，导致了后处理后LiFePO4表面上不同的碳分布。

可溶性淀粉和蔗糖具有丰富的羟基，通过这些羟基可溶性淀粉和蔗糖分子才可能以氢键方式微弱的吸附在FePO4·3 H2O颗粒表面。

在后处理过程中，一部分可溶性淀粉和蔗糖分子从FePO4·3H2O颗粒表面脱吸附，导致颗粒表面缺乏碳涂层。

但是，柠檬酸含有羧基，这些羟基在FePO4·3H2O粒子表面有可能被羟基部分酯化并形成一个紧密连接。

因此经过后处理后能留下更完整的碳涂层。

对于样品D，我们假设，在目前的合成体系中，表面活性剂CTAB可能会将间苯二酚-甲醛（RF）聚合物分子和FePO4·3H2O粒子限制在大量的微小空间中，所以聚合物分子会紧紧地和FePO4·3H2O粒子相连。

经过后处理后，聚合物分子转化到碳膜里面，紧紧卡在LiFePO4的粒子表面上。

此外，从样品D的高分辨图像（图4h）中看到，0. 294 nm d间距对应LiFePO4（211）晶面。

拉曼光谱测量作为一种重要的研究碳结构的辅助工具，测量结果显示在图5中。

每一个拉曼光谱包含940 cm-1宽的一个细条纹，对应在LiFePO4中对称的PO4伸缩振动。

在1350和1590 cm-1的明亮宽条纹可以归因于碳的拉曼光谱特性。

在1590 cm-1处的谱带主要对应G带石墨结构碳，而在1350 cm-1处对应D带【22,23】的无序结构碳。

石墨碳包含sp2杂化键合，这是和碳的电子导电性正相关的，无序碳主要对应sp3杂化键合。

正如图5所示，用不同碳前驱体合成的LiFePO4/C复合材料的SP2/SP3的整体强度比分别为0.865（曲线A），0.857（曲线B），0.856（曲线C）和0.860（曲线d）。

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