Experimental study on thermal runaway propagation characteristics of NCM811 lithium-ion batteries with different SOCs induced by dual heat sources

Thermal runaway propagation (TRP) of lithium-ion batteries (LIBs) is one of the important causes of safety accidents in new energy vehicles. In order to investigate the theoretical system of TRP of Li(Ni0.8Co0.1Mn0.1)O2 (NCM811) cell/module under dual heat sources, an experimental platform of coupled thermal abuse stimulation was built to study the TRP and combustion behavior of NCM811 module in different states-of-charges (SOCs). The results show that the time to reach thermal runaway (TR) of LIB under dual heat sources is shortened by 952.3 s on average, and the possibility of TRP of the cell module is greatly enhanced. With the increase of SOC from 25% to 100%, the TR trigger time of the cell is shortened from 2773 s to 2311 s, the TR trigger temperature is reduced from 263.7 °C to 175.7 °C. The TRP of the cell module under dual heat sources induction can occur at different SOCs, and the TRP duration increases from 57 s at 25% SOC to 174 s at 100% SOC. In addition, the cell eruption and combustion behaviors induced by dual heat sources become more intense with the increase of SOC, the cell mass loss rate also increases rapidly with the increase of eruption and combustion behaviors.