Influencing factors of lithium-ion battery thermal runaway in confined space

Lithium-ion batteries with high state of charge (SOC), low state of health (SOH) and at summer are prone to fire accidents. The influence of these factors on thermal runaway triggered by external heating in confined space is studied in this manuscript. Based on the results of temperature, voltage changes and video, gas explosion occurs before thermal runaway in confined space. The results of heat calculation indicate that radiation and conduction contribute the most to thermal runaway. Thermal runaway of lithium-ion battery triggered by external heating is determined by the accumulated exothermic side reactions, remaining reactants and surface temperature of battery. Accumulated exothermic side reactions increase with higher SOC and lower SOH. Remaining reactants increase with the increase of SOC and SOH. Surface temperature of lithium-ion battery increases to high temperature at a shorter time for battery at higher initial temperature. Thermal runaway time interval decreases with the increase of SOC and ambient temperature, and the decrease of SOH. High SOC and ambient temperature and low SOH increase hazardous risk of lithium-ion battery to some extent. The results can explain why batteries with high SOC, low SOH and at high ambient temperature are prone to fire accidents. This is important for battery safety control.