flexible PET PMDA Graphene Supercapacitors AC (S)

Electrochemical characterization 3 3
Submitted to Cyclic voltammetry (CV) curves obtained at scan rates of 0.01-2000 V s-1, galvanostatic charge and discharge profiles measured at varying current densities of 0.1 to 20 A/m2, and electrochemical impedance spectra recorded in the frequency range of 1-100 kHz with a 5mV ac amplitude were obtained using a CHI 760D electrochemical workstation. The capacitance values were calculated from the discharge CV data according to the following equation (1):
Materials characterization The morphological and structural characterizations were conducted using an SEM (Gemini 1530 LEO), optical microscope, AFM (Veeco Dimension 3100), surface profiler (KLA Tencor P-16+), and Raman spectrometer (Bruker, 532 nm). The electrical conductivity of the films was measured using a standard four-point probe system with a Keithley 2700 Multimeter.
Fabrication of ultrathin printable supercapacitors 2 2
Submitted to To prepare ultrathin printable supercapacitors (UPSCs), the ultrathin PET substrate was first carefully attached on the polydimethylsiloxane (PDMS) substrate, which acts as a stable yet flat support to allow for good control over the formation of a uniform film on a PET substrate and the assembly of the device. Second, a thin 30-nm-thick gold layer (Premion, 99.9985% metals basis, Alfa Aesar) was thermally evaporated (EDWARDS FL400) on the PET/PDMS substrate at a rate of ~2.0 Å s-1 and a chamber pressure of ~2 x 10-6 Torr. Third, using an air brush pistol, the stable EG/PH1000 ink was spray coated to form the designated thickness films on the gold-coated PET/PDMS substrates. After drying, the resulting films on the substrates were cut to the designated electrode size, e.g., 4.5 cm × 1.0 cm, and the conductive Pt wire was connected at one end of the film using silver paste. Fourth, the polyvinyl alcohol (PVA)/H2SO4 gel electrolyte was introduced as both the solid electrolyte and the separator, which was prepared by mixing 6 g of PVA and 6 g of H2SO4 into 60 ml of deionized water and heating at 80 °C for 1 h under stirring. After that, the gel electrolyte was carefully coated on the film electrode on PET/PDMS substrates and solidified overnight. Subsequently, two electrolyte-coated film electrodes on PET/PDMS substrates were symmetrically assembled together, and then, the PDMS substrates were carefully peel off from the assembled device. Finally, an all-solid-state graphene-based UPSC was obtained.
Submitted to
Supporting Information
for Adv. Mater., DOI: 10.1002/adma.201501208 Ultrathin Printable Graphene Supercapacitors with ac Line-Filtering Performance By Zhong-Shuai Wu, Zhaoyang Liu, Khaled Parvez, Xinliang Feng,* and Klaus Müllen*
Copyright WILEY-VCH Verlag GmbH & Co. KGaA, 69469 Weinheim, Germany, 2015.
Supporting Information
for Adv. Mater., DOI: 10.1002/adma.201501208
Ultrathin Printable Graphene Supercapacitors with AC LineFiltering Performance Zhong-Shuai Wu, Zhaoyang Liu, Khaled Parvez, Xinliang Feng,* and Klaus Müllen*
C
Vf 1 I (V )dV v(V f Vi ) Vi
(1) ,
where C is the capacitance from the electrodes, v is the scan rate (V/s), V f and Vi are the integration potential limits of the voltammetric curve, and I (V ) is the discharge current (A). The areal capacitance C areal (F/cm2) and volumetric capacitance C volumetric (F/cm3) were calculated based on the area and volume of the single film electrode according to the following formula:
Fabrication of the EG/PH1000 films The ink was prepared by dispersing the EG solution with the assistance of the highly enedioxythiophene)-poly(styrenesulfonate), PEDOT/PSS, solid content of 1.3 wt%, sheet resistance of <300 Ω/square, Heraeus Clevios GmbH). Typically, 200 μl of PH1000 was slowly added into 10m L of EG suspension (1 mg/ml in DMF) and vigorously stirred for 1 h. After that, a stable solution-processed ink with an EG:PH1000 ratio of 8:2 was obtained. The resulting ink was carefully spray coated with a hand-held airbrush (Harder & Steenbeck AIRBRUSH, Infinity CRplus) on pre-heated ultrathin PET substrates (2.5 μm thickness, Chemplex Industries, Inc.) and any other substrates (e.g., silicon wafer for morphological characterization) at 90 ºC under a pressure of 3 bar supported by nitrogen gas. Note that a short pause of 10 s after each spray coating was implemented to allow the film to dry.