Assessment of the complete chain evolution process of LIBs from micro internal short circuit failure to thermal runaway under mechanical abuse conditions

ABS T R A C T Lithium-ion batteries (LIBs) are widely used in various devices, ranging from mobile phones and laptop computers to electric vehicles and energy storage systems. However, internal short circuits (ISCs) can occur for a variety of reasons, such as internal foreign matter, overcharging, and mechanical abuse. Micro short circuit (MSC) usually shows a long incubation period and is hard to detect, which leads to many thermal runaway (TR) accidents of LIBs. For mobile phone batteries, bending is a very common abuse condition that may be encountered in daily use. This paper explores the microstructural changes, electrochemical performance, thermal behavior, and the critical point of TR under three-point bending abuse test. Key findings include the impact of bending on the ion diffusion coefficient, the correlation between bending degree and heat generation during charge-discharge cycles, and the identification of a critical angle for TR at 60 degrees. A competing relationship between irreversible heat due to bending and Joule heat from ISC was found, where there exists a critical point of bending angle, after which the total heat generated will be higher than that of normal batteries.