Self-heating reaction and thermal runaway criticality of the lithium ion battery

Thermal runaway of lithium ion batteries (LIBs) attracts more and more attentions. In this paper, the self-heating reaction of LIBs with different states of charge (SOCs) is investigated by the standard accelerating rate calorimeter (ARC). The onset temperature of self-heating and trigger temperature of thermal runaway are measured. The kinetics of self-heating reaction is obtained, and the self-accelerating decomposition temperatures (SADTs, i.e. the maximum safe storage temperature) are calculated based on thermal explosion model (Semenov model and Thomas model). The results show that the fully-charged LIB (18650-type, Li(Ni0.5Co0.2Mn0.3)O2/graphite) self-ignites if the storage temperature exceeds 149.6 °C under the natural convection condition (the battery surface heat transfer coefficient is 10 W m−2 K−1). The logarithmic relationship between SADT and heat dissipation condition suggests that it is effective to reduce the fire risk of LIB by modifying the heat dissipation at low heat transfer coefficient (U), while it becomes inefficient when U is high.