电化学阻抗测量锂电池老化程度
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I. INTRODUCTION
The U.S. Department of Energy (DOE) initiated the Advanced Technology Development (ATD) Program in 1998 to address the outstanding barriers that limit the commercialization of high-power lithium-ion batteries, specifically for hybrid electric vehicle applications. As part of the program, 18650-size cells are aged using calendar- and cycle-life tests developed under the Partnership for a New Generation of Vehicles (PNGV) Power Assist goals. Reference [1] provides additional information about the ATD Program. [Note: In January 2002 at the Detroit Auto Show, Energy Secretary Spencer Abraham announced that PNGV would be superceded by the formation of a new program between the U.S. Government and the U.S. Council for Automotive Research, dubbed FreedomCAR (Freedom
Electrochemical Impedance Spectroscopy Testing on the Advanced Technology Development Program Lithium-Ion Cells
Jon P. Christophersen, David F. Glenn, Chester G. Motloch, Randy B. Wright, Chinh D. Ho
III. CELL TESTING The Idaho National Engineering and Environmental Laboratory (INEEL) is cycle-life testing the Gen 2 cells in two
0-7803-7467-3/02/$17.00 ©2002 IEEE.
Washington, DC
Abstract—The U.S. DOE Advanced Technology Development (ATD) Program is investigating Electrochemical Impedance Spectroscopy (EIS) as a new measure of cell degradation. As part of the program, the Idaho National Engineering and Environmental Laboratory (INEEL) is aging 18650-size cells using cycle-life tests developed under the Partnership for a New Generation of Vehicles, which has been superceded by FreedomCAR in January 2002. At beginning of life and every four weeks thereafter, cycle-life testing is interrupted for reference performance tests (RPT) to assess capacity and power fade rates. The EIS impedance is measured at 60% state-ofcharge over a range of frequencies at each RPT. The resulting Nyquist plots show that the two semi-circles, representing the anode and cathode impedance growth, are poorly resolved due to the influence of the high frequency capacitive tail and the lowfrequency Warburg impedance. However, impedance growth is clearly visible at the trough frequency of the second semi-circle. The magnitude at this frequency is comparable to the standard measure of cell degradation, which is based on the percent-fade in power as a function of test time while delivering 300 Wh. The percent growth in EIS magnitude at the trough frequency highly correlates with the power fade. This suggests that the EIS test is a useful alternate measure of cell degradation.
Keywords—Electrochemical Impedance Spectroscopy; trough frequency; Hybrid Pulse Power Chararacterization test; power fade; Advanced Technology Development
At BOL and every four weeks (i.e., 33,600 cycle-life profiles) thereafter, cycle-life testing is interrupted for reference performance testing (RPT) which are used to quantify capacity and power fade rates. The RPTs consist of a C1/1 static capacity test, a low-current hybrid pulse power characterization (L-HPPC) test, a C1/25 static capacity test, and an Electrochemical Impedance Spectroscopy (EIS) test. All RPT’s are performed at 25°C. To minimize temperature fluctuations, the cells remain in environmental chambers during testing activities.
• Positive Electrode
− 84 wt% LiNi0.8Co0.15Al0.05O2 − 4 wt% carbon black − 4 wt% SFG-6 − 8 wt% PVDF binder
• Negative Electrode
− 92 wt% MAG-10 − 8 wt% PVDF binder
• Electrolyte
− 1.2 M LiPF6 in EC/EMC (3:7 wt%)
• Separator
− 25 µm thick PE Celgard
The Variant C cell chemistry differs from the baseline chemistry by an increase to the aluminum dopant from 5% to 10% and a decrease to the cobalt from 15% to 10% in the cathode (i.e., LiNi0.8Co0.1Al0.1O2). This change resulted in a 20% drop in rated capacity (0.8 Ah) at beginning of life (BOL) compared to the Baseline cell rated capacity of 1.0 Ah.
Transportation Technologies and Infrastructure Department Idaho National Engineering and Environmental Laboratory
Idaho Falls, ID
Vincent S. Battaglia
DOE Technical Contact Argonne NaΒιβλιοθήκη Baiduional Laboratory
II. CELL CHEMISTRY Advanced Technology Development testing of the second generation of cells (referred to as Gen 2 cells) is now underway. The 18650-size Gen 2 cells consist of a baseline cell chemistry and one variant chemistry (referred to as Variant C). The Baseline cells were manufactured to the following specifications, as developed by Argonne National Laboratory [2]:
1851
temperature groups (fifteen Baseline cells at 25°C and fifteen Baseline and Variant C cells each at 45°C), as described in the cell-specific test plan [3]. Cycle-life testing is performed using the PNGV 25-Wh Power Assist profile defined in the PNGV Battery Test Manual, Revision 3 [4]. It consists of a constant power discharge and regen pulse with interspersed rest periods centered around 60% state-of-charge (SOC). The cumulative length of a single profile is 72 seconds and constitutes one cycle. This cycle is repeated continuously during life testing.
Cooperative Automotive Research). Its emphasis will be the development of fuel cell-powered vehicles. “The long-term results of this cooperative effort will be cars and trucks that are more efficient, cheaper to operate, pollution-free, and competitive in the showroom.” It is believed that advanced high-power batteries will continue to be a critical component in this new program.]
The U.S. Department of Energy (DOE) initiated the Advanced Technology Development (ATD) Program in 1998 to address the outstanding barriers that limit the commercialization of high-power lithium-ion batteries, specifically for hybrid electric vehicle applications. As part of the program, 18650-size cells are aged using calendar- and cycle-life tests developed under the Partnership for a New Generation of Vehicles (PNGV) Power Assist goals. Reference [1] provides additional information about the ATD Program. [Note: In January 2002 at the Detroit Auto Show, Energy Secretary Spencer Abraham announced that PNGV would be superceded by the formation of a new program between the U.S. Government and the U.S. Council for Automotive Research, dubbed FreedomCAR (Freedom
Electrochemical Impedance Spectroscopy Testing on the Advanced Technology Development Program Lithium-Ion Cells
Jon P. Christophersen, David F. Glenn, Chester G. Motloch, Randy B. Wright, Chinh D. Ho
III. CELL TESTING The Idaho National Engineering and Environmental Laboratory (INEEL) is cycle-life testing the Gen 2 cells in two
0-7803-7467-3/02/$17.00 ©2002 IEEE.
Washington, DC
Abstract—The U.S. DOE Advanced Technology Development (ATD) Program is investigating Electrochemical Impedance Spectroscopy (EIS) as a new measure of cell degradation. As part of the program, the Idaho National Engineering and Environmental Laboratory (INEEL) is aging 18650-size cells using cycle-life tests developed under the Partnership for a New Generation of Vehicles, which has been superceded by FreedomCAR in January 2002. At beginning of life and every four weeks thereafter, cycle-life testing is interrupted for reference performance tests (RPT) to assess capacity and power fade rates. The EIS impedance is measured at 60% state-ofcharge over a range of frequencies at each RPT. The resulting Nyquist plots show that the two semi-circles, representing the anode and cathode impedance growth, are poorly resolved due to the influence of the high frequency capacitive tail and the lowfrequency Warburg impedance. However, impedance growth is clearly visible at the trough frequency of the second semi-circle. The magnitude at this frequency is comparable to the standard measure of cell degradation, which is based on the percent-fade in power as a function of test time while delivering 300 Wh. The percent growth in EIS magnitude at the trough frequency highly correlates with the power fade. This suggests that the EIS test is a useful alternate measure of cell degradation.
Keywords—Electrochemical Impedance Spectroscopy; trough frequency; Hybrid Pulse Power Chararacterization test; power fade; Advanced Technology Development
At BOL and every four weeks (i.e., 33,600 cycle-life profiles) thereafter, cycle-life testing is interrupted for reference performance testing (RPT) which are used to quantify capacity and power fade rates. The RPTs consist of a C1/1 static capacity test, a low-current hybrid pulse power characterization (L-HPPC) test, a C1/25 static capacity test, and an Electrochemical Impedance Spectroscopy (EIS) test. All RPT’s are performed at 25°C. To minimize temperature fluctuations, the cells remain in environmental chambers during testing activities.
• Positive Electrode
− 84 wt% LiNi0.8Co0.15Al0.05O2 − 4 wt% carbon black − 4 wt% SFG-6 − 8 wt% PVDF binder
• Negative Electrode
− 92 wt% MAG-10 − 8 wt% PVDF binder
• Electrolyte
− 1.2 M LiPF6 in EC/EMC (3:7 wt%)
• Separator
− 25 µm thick PE Celgard
The Variant C cell chemistry differs from the baseline chemistry by an increase to the aluminum dopant from 5% to 10% and a decrease to the cobalt from 15% to 10% in the cathode (i.e., LiNi0.8Co0.1Al0.1O2). This change resulted in a 20% drop in rated capacity (0.8 Ah) at beginning of life (BOL) compared to the Baseline cell rated capacity of 1.0 Ah.
Transportation Technologies and Infrastructure Department Idaho National Engineering and Environmental Laboratory
Idaho Falls, ID
Vincent S. Battaglia
DOE Technical Contact Argonne NaΒιβλιοθήκη Baiduional Laboratory
II. CELL CHEMISTRY Advanced Technology Development testing of the second generation of cells (referred to as Gen 2 cells) is now underway. The 18650-size Gen 2 cells consist of a baseline cell chemistry and one variant chemistry (referred to as Variant C). The Baseline cells were manufactured to the following specifications, as developed by Argonne National Laboratory [2]:
1851
temperature groups (fifteen Baseline cells at 25°C and fifteen Baseline and Variant C cells each at 45°C), as described in the cell-specific test plan [3]. Cycle-life testing is performed using the PNGV 25-Wh Power Assist profile defined in the PNGV Battery Test Manual, Revision 3 [4]. It consists of a constant power discharge and regen pulse with interspersed rest periods centered around 60% state-of-charge (SOC). The cumulative length of a single profile is 72 seconds and constitutes one cycle. This cycle is repeated continuously during life testing.
Cooperative Automotive Research). Its emphasis will be the development of fuel cell-powered vehicles. “The long-term results of this cooperative effort will be cars and trucks that are more efficient, cheaper to operate, pollution-free, and competitive in the showroom.” It is believed that advanced high-power batteries will continue to be a critical component in this new program.]