Abstract: To investigate the effect of liquid nitrogen （LN） on thermal runaway （TR） in lithium iron phosphate energy storage batteries, a TR suppression experimental platform was constructed. The effect of LN on TR was analyzed by varying the occasion and dose of LN injection. Prior to LN inhibition of TR, blank experiments were conducted to determine the TR characteristics of the battery used. The results demonstrate that LN effectively inhibits TR. Specifically, injecting 1.2 kg of LN before the safety valve opened can prevent TR. However, during the early stages of TR, the injection of 1.2 kg of LN only provides temporary temperature reduction and cannot inhibit TR. By increasing the LN injection dose to 6.7 kg, TR can be successfully inhibited. In the period of severe TR, injecting 7.2 kg of LN can effectively inhibit TR. Additionally, the cooling and inhibition effect of LN on TR increases with increasing LN dose. The cooling effect of 8 kg LN injection on TR of lithium?ion battery is about 5.8 times of 6.2 kg LN injection, and the cooling rate is about 4.95 times of injection of 6.2 kg LN. However, the effective utilization rate of LN did not increase with the increase in LN injection dose.

Key words: lithium?ion battery, thermal runaway, liquid nitrogen, inhibition effect