Unlocking the coupling mechanical-electrochemical behavior of lithium-ion battery upon dynamic mechanical loading

Dynamic mechanical loading, e.g. impact, is one of the major catastrophic factors that trigger short-circuit, thermal runaway, or even fire/explosion consequences of lithium-ion batteries (LIBs). In this study, the mechanical integrity and electrical coupling behaviors of lithium-ion pouch cells under dynamical loading were investigated. Two types of experiments, namely compression and drop-weight tests, are designed and conducted. The state-of-charge (SOC) and loading rate dependencies of batteries, as well as their coupling effect, are examined. Furthermore, the interaction between force response and electrical behavior of battery is investigated through real-time monitoring of voltage change during loading. Experiments on LiCoO2 lithium-ion pouch cells show that the higher SOC and loading rates increases battery structure stiffness. In addition, loading rate intensifies battery structure stiffening with the SOC effect. Results indicate that the deformation and material failure of battery component together determine the electrical behavior of battery. Higher loading rate leads to faster voltage drop and more severe internal short-circuit. This short-circuit discharging process in turn affects the force response in dynamic loading. Results may provide useful insights into the fundamental understanding of electrical and mechanical coupled integrity of LIBs and lay a solid basis for their crash safety design. (C) 2018 Elsevier Ltd. All rights reserved.