Mitigation of lithium-ion battery thermal runaway and inhibition of thermal runaway propagation using inorganic salt hydrate with integrated latent heat and thermochemical storage

Thermal runaway and its propagation in lithium-ion batteries is a severe problem that can result in fire or explosion. In this study, we propose an innovative thermal storage material that integrates latent heat and thermochemical storage to protect the battery during thermal runaway. Sodium acetate trihydrate-urea/expanded graphite—an inorganic salt hydrate—undergoes a solid-liquid phase change at 50.3 °C, with a corresponding latent heat storage density of 181 kJ/kg, and thermal decomposition at 114.0 °C, with a corresponding thermochemical storage density of 567.3 kJ/kg. The latent heat storage density ensures that the battery remains cool during minor accidents, such as an external short circuit, and the dual-stage thermal storage effectively suppresses thermal runaway propagation due to severe accidents involving the thermal or mechanical abuse of the battery. We also establish a mathematical model to describe the multistage latent heat and thermochemical storage processes and predict their impacts on battery temperature. The numerical results were in good agreement with the experimental data, with a maximum error of less than 5%. Compared to conventional phase change materials, the thermochemical storage of the inorganic salt hydrate provides a high thermal storage density at a safe temperature. Thus, the proposed thermal storage material can effectively prevent the incidence and propagation of battery thermal runaway.