Measurement of side-reaction currents on electrodes of lithium-ion cells using a battery cycler with a high-precision current source

Abstract

Capacity fading mainly caused by state-of-charge deviations between the positive and negative electrodes of lithium-ion batteries (LIBs) can be accurately predicted if the rates of side reactions occurring on these electrodes are known. Herein, we show that the rates of side reactions on LIB electrodes can be determined using an in-house-built high-current-precision battery cycler comprising galvanostat, charge/discharge control, and current switching units. An Li[Li1/3Ti5/3]O4/Li[Li1/3Ti5/3]O4 (LTO/LTO) symmetric cell is used to verify that the battery cycler provides currents accurate enough to determine side-reaction rates, and the rates of side reactions on LTO (negative) and LiNiMO (positive) electrodes in an LTO/LiNiMO cell are compared with intrinsic values obtained for the symmetric cell.