A review on mechanisms, characteristics and relating hazards of vent gases from thermally abused Li-ion batteries

Lithium-ion batteries (LIBs) are the pivotal component of electric vehicles and have emerged as the foremost component in various application markets, including mobile devices and grid energy storage. Nonetheless, in the occurrence of thermal runaway (TR), LIBs may release a considerable quantity of flammable and toxic gases, particularly in enclosed or partially enclosed spaces, which pose a risk of explosion. This study provides a comprehensive review on various aspects related to the gas evolution during TR of LIBs, including the underlying mechanisms and temporal evolution of the process, testing methods for TR gases, the impact of different cathode materials and states of charge (SOC) on gas generation during TR, the combustion and explosion characteristics of TR gases, as well as the thermal hazards and toxicity risks associated with such gases. The results of this study have implications for the development of effective strategies to suppress the gas generation during TR of LIBs, as well as to mitigate the associated risks of combustion, explosion, and toxicity. The insights gained from this study can contribute to the enhancement of the reliability and safety of energy storage systems and electric vehicles.