Mechanical-electrical-thermal responses of lithium-ion pouch cells under dynamic loading: A comparative study between fresh cells and aged ones

Abstract

Mechanical integrity is one of the study focuses of lithium-ion batteries, which is greatly influenced by the loading rate and the cycling ageing level. This paper investigates how dynamic loading and low-temperature ageing collectively affect the safety performance of lithium-ion batteries under indentation loadings, by monitoring and comparing the in-situ mechanical-electrical-thermal responses. For the mechanical response, results show that dynamic loading increases the battery stiffness while low-temperature ageing alleviates that. During the intrusion process, the electrical response is mostly influenced by the loading rate. Fast voltage dropping and recovering occur under dynamic loading scenarios, leaving a downward trench in the voltage profile. The higher the loading rate, the earlier the short circuit and the faster the voltage dropping. After the termination of the loading, the voltage dropping is mostly affected by the ageing level. Low-temperature ageing accelerates the long-term voltage dropping rate. As for the thermal response, it is highly related to the short circuit behavior. Upward temperature peaks are formed right after the short circuit under dynamic loadings, corresponding to the voltage trenches. Besides, aged cells have higher long-term temperature profiles, corresponding to the accelerated long-term voltage dropping rates.