The Impact of Thermal Damage Accumulation on Thermal Runaway Behavior of Lithium-Ion Batteries

Abstract

The aging of lithium-ion batteries under critical high-temperature conditions has been less discussed in existing research, yet it frequently occurs in practical scenarios. This paper investigates the impact of thermal damage accumulation under critical high temperatures on the triggering conditions and phenomena of thermal runaway in lithium-ion batteries, elucidating the aging mechanism. Initially, batteries undergo thermal aging at a critical high temperature of 55°C. Subsequently, batteries experiencing varying degrees of thermal damage undergo electrochemical performance testing, mechanical abuse testing, and adiabatic thermal runaway testing. Finally, by comparing the morphology and composition of electrodes before and after aging, the thermal damage aging mechanism is studied. By elucidating the aging mechanism, we clarify the evolution process of electrochemical performance, mechanical integrity, and thermal safety stability of thermally damaged batteries.The results indicate that under prolonged exposure to critical high temperatures and low potentials, lithium undergoes deintercalation from the anode, leading to partial degradation of graphite. The thickening of the solid electrolyte interface (SEI) membrane gradually enhances the thermal stability of the battery while also increasing impedance, thereby tempering the severity of internal short circuits. However, the incubation period for thermal runaway significantly shortens, resulting in decreased thermal safety. Furthermore, cathode particles undergo fissuring, resulting in the loss of active lithium and active materials. Prolonged exposure of the battery to high temperatures and high potentials leads to electrolyte decomposition, and the deposition of substances with active lithium reduces the mechanical safety of the battery.

Keywords: Lithium-ion cell, Aging, DRT, Mechanical abuse, Thermal abuse, Safety