Experimental study on the burning behaviors of 21700 lithium-ion batteries with high specific energy after different immersion duration

The seawater immersion test is one of the essential indicators for evaluating the safety of lithium-ion batteries (LIBs). In this work, 3.5 wt% salt in water as surrogate seawater was used in LIB immersion experiments, and the combustion behaviors, surface temperature, mass loss, and heat flux during thermal runaway (TR) of LIBs were analyzed after different immersion duration (tim, 0 h, 2 h, 3 h, 6 h), to evaluate the thermal stability of cells. The experimental results showed that the fire behavior of the 21700 cylinders with 50% state of charge (SOC) was less severe than that with 100% SOC. For 100% SOC cells, the maximum temperature decreased sharply suffering tim of 6 h, whose temperature of TR (Ttr) was lower than that of 50% SOC cells, and the maximum battery surface temperature (Tmax) was higher than that of the 50% SOC cases. Total mass loss (TML) decreased with the increase of tim for 100% and 50% SOC batteries, which of 50% SOC LIBs was much lower than that of 100% SOC LIBs. For LIBs after different tim, the heat flux presented almost the same tendency during combustion tests. This work further investigated the TR characteristics of 21700 cylinders after immersion, which could help improve LIB safety.Graphical abstractThe burning behaviors of 21700 cylinders after different immersion duration were investigated, which might help evaluate the fire risk of batteries and improve safety