E.C.A.S

We studied the thermal runaway process of lithium-ion batteries (LIBs) caused by thermal abuse, with a particular focus on the effects of combustion. First, we observed a gradual increase in battery temperature during thermal runaway until it reached 190 °C, at which point it sharply rose to approximately 500 °C. However, thermal runaway induced by combustion was characterized by a sudden temperature increase at lower temperatures. Second, we analyzed the internal reactions occurring in a location far from the heat source resulting from combustion. We found that the solid electrolyte interface (SEI) decomposition contributed to nearly 90 % of the heat generated at lower temperatures, while the positive electrode-electrolyte reaction emerged as the major heat source at temperatures exceeding 195 °C. Finally, we also examined the internal reactions in a location close to the heat source caused by combustion. We identified that the internal reactions initiated at around 50 °C and occurred simultaneously. The heat generated by the negative electrode-electrolyte and positive electrode-electrolyte reactions accounted for approximately 47 % and 46 % of the total heat during thermal runaway, respectively. Consequently, we concluded that combustion accelerates thermal runaway in LIBs. We expect this study to enhance the prediction of heat propagation during thermal runaway.