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

A 3Ah lithium-ion battery, LiNixCoyAl1-x-yO2, has been repeatedly recharged at an elevated C rate in a pulsed fashion to understand the impact this has on cell lifetime. A peak charge rate of 33C, similar to 100 A, is applied in 3 s increments with 6 s of idle time between pulses. Between recharges, the cell is discharged at a constant current (CC) 1C rate. Cell fatigue is determined using electrochemical impedance spectroscopy (EIS) and capacity measurements. During each elevated recharge, the cells voltage, current, and temperature are monitored using high speed data acquisition systems. EIS measurements are made before and after each 1C-CC discharge. A second cell of the same type is also cycled on a potentiostat using a 1C-CC, constant voltage (CV) recharge and 1C-CC discharge. The goal is to compare the aging of the two cells in order to understand the differences introduced from elevated recharge rates.