Elucidation of Side Reactions in Lithium-ion Batteries with Electrolyte Decomposition Products via Overdischarge for Li[Li1/3Ti5/3]O4/Li[Li0.1Al0.1Mn1.8]O4 Cells with an Imbalanced State-of-Charge

Abstract

A major factor in the capacity fading of lithium-ion batteries is the imbalance in the state-of-charge (SOC) between the positive and negative electrodes, which is caused by the difference in the side-reaction current between the two electrodes. Therefore, it is crucial to understand these side reactions to extend battery life. There are two types of side-reaction current, ISR: “intrinsic”-ISR results from electrolyte decomposition, while “additional”-ISR results from the reaction of decomposition products. The “additional”-ISR is closely related to crosstalk reactions. In this study, we conducted overdischarge tests on Li[Li1/3Ti5/3]O4 (LTO)/Li[Li0.1Al0.1Mn1.8]O4 (LAMO) cells with the SOC of the positive and negative electrodes intentionally imbalanced to understand the nature of the “additional”-ISR. While the cell capacity initially increased after the overdischarge, the recovered capacity decreased in subsequent cycles. This phenomenon can be explained well by a side-reaction model that considers the oxidant generated in the cell due to overdischarge, which indicates that the concentrations of oxidants and reductants in the cell are important for the ISR.

Keywords

• lithium-ion battery
• capacity fading
• side reaction
• crosstalk reaction