Internal pressure variation during the thermal runaway of lithium-ion batteries at different state-of-charge

Abstract

Thermal runaway of lithium-ion batteries, accompanied by violent eruptions, casts significant safety risks for electric vehicles and energy storage stations. The increased internal pressure inflates the structure of the battery pack and electrical components, thereby inducing arcing. Variations in the internal pressure during battery thermal runaway requires further study. Batteries experience oxidation–reduction reactions during thermal runaway, resulting in gas eruptions. This paper tries to measure the dynamic behavior of gas generation throughout the thermal runaway by installing a pressure sensor on the side of the battery. The influence of various states of charge on the internal pressure fluctuations and eruption behaviors during battery thermal runaway is investigated. The results indicate that as the state of charge increases, the internal pressure and mass loss notable rises. A higher state-of-charge brings shorter time for the battery to reach maximum temperature. Notably, the time for the maximum pressure usually occurs before the occurrence of the peak temperature. The maximum pressure commences 20.4 − 288.5 s prior to the moment when peak temperature occurs. A positive correlation has been identified between internal pressure and the mass loss rate during the eruption process. These results clarify the quantitative relationship among the state-of-charge, internal pressure, and eruption behaviors associated with thermal runaway. Therefore, this study offers valuable insights for the safety design of battery pack structures and the mitigation of arc hazards.