Thermal runaway and heat generation of low-temperature cycling batteries under external heating and the influencing factors

Abstract

Safety of lithium-ion battery is an urgent issue to be solved during its use. Thermal stability of low-temperature cycling battery decreases much. Influence of multi factors on thermal runaway under external heating for low-temperature cycling battery is not clear. This is studied in this work. The results indicate that thermal runaway time and the total heat needed for thermal runaway under external heating decrease with the decrease of state of health (SOH). Compared to 90% SOH, hazard risk of battery with 80% and 70% SOH decreases more. The difference between center and surface temperature is higher than hundreds of degrees except for battery with 70% SOH. Thermal runaway propagation in 18,650-type battery is found in this study. Exothermic side reactions are very violent for battery with 70% SOH. Heat from external heating contributes the most to the total heat needed for thermal runaway induced by external heating. Thermal runaway time and total heat needed for thermal runaway increase with the decrease of state of charge (SOC) and ambient temperature. Maximum temperature of battery decreases with the decrease of SOC after thermal runaway. Safety of battery with 60% SOC increases more compared to battery with 100% SOC. Ambient temperature affects the exothermic side reactions of aged batteries less before thermal runaway.