Thermochemical heat storage system for preventing battery thermal runaway propagation using sodium acetate trihydrate/expanded graphite

Thermal runaway (TR) of lithium-ion batteries (LIBs) is a critical problem that hinders their application. To inhibit TR propagation in battery packs, we propose a novel passive battery thermal management system based on an inorganic composite phase change material (CPCM): sodium acetate trihydrate (SAT)/expanded graphite (EG). SAT has two stages of heat storage, namely, latent heat storage (LHS, 58 °C) and thermochemical heat storage (TCHS, 106–140 °C), which can be used for the thermal management of batteries and prevention of TR, respectively. Furthermore, a novel TCHS model is developed for SAT/EG to describe the two-stage heat storage process of SAT. The proposed heat storage model provides an insight into the heat transfer between CPCM and batteries. This model is experimentally verified, and numerical results appropriately agree with the experimental data. To verify the excellent performance of SAT/EG in inhibiting TR propagation, a numerical simulation on penetration-induced TR propagation in a battery pack with/without CPCM is performed. Results show that without protection, the TR cascade in the battery pack is inevitable, whereas TR propagation can be successfully prevented using the SAT/EG composite. The proposed model offers a beneficial guidance for researchers to study the thermal behaviors of other decomposition reactions.