Capacity fading and degradation mechanism of A123 battery

Taking the 2 200 mA·h lithium iron phosphate (LiFePO4, LFP) battery manufactured by A123 systems Inc. as research object, 3500 cycles of fully charged and discharged test for 2 200 mA·h LFP battery is performed under the current rate of 3C at the ambient temperature of 25℃, meanwhile the test is interrupted after every 200 cycles, and at this point the charging and discharging under the current rate of 1C, the fading of resistance and internal resistance of the battery and the open circuit voltage-state of charge (OCV-SOC) curve as well as the peak curve variation of dQ/dV under the current rate of 1/20C are measured. To validate above-mentioned method to analyze the capacity fading mechanism, the A123 2 200 mA·h LFP battery underwent full test cycle is disassembled in the glove box and reassembled as the button half-cell, and the test results of the half-cell with positive polarity and that with negative polarity as well as the analysis on the capacity matching before and after the disassembly show that the proposed analysis method for the capacity fading of LFP battery is correct and effective. ©, 2015, Power System Technology Press. All right reserved.