Cycling Fatigue Induced on Electrochemical Energy Storage Cells as a Result of High C Pulsed Charging

A 3Ah lithium-ion battery, LiNixCoyAl1-x-yO2, has been repeatedlyrecharged at an elevated C rate in a pulsed fashion to understand theimpact this has on cell lifetime. A peak charge rate of 33C, ~100 A, isapplied in 3 s increments with 6 s of idle time between pulses. Betweenrecharges, the cell is discharged at a constant current (CC) 1C rate. Cellfatigue is determined using electrochemical impedance spectroscopy (EIS)and capacity measurements. During each elevated recharge, the cellsvoltage, current, and temperature are monitored using high speed dataacquisition systems. EIS measurements are made before and after each1C-CC discharge. A second cell of the same type is also cycled on apotentiostat using a 1C-CC, constant voltage (CV) recharge and 1C-CCdischarge. The goal is to compare the aging of the two cells in order tounderstand the differences introduced from elevated recharge rates.