Experimental study on gas production characteristics of electrolyte of lithium-ion battery under pyrolysis conditions

The fires of lithium-ion batteries are mainly due to the vent gas generated from electrolyte decomposition in the thermal runaway process. The gas production characteristics from lithium-ion battery electrolytes are studied experimentally. Furthermore, the effects of varying ratios of lithium cathode, temperature, and state of charge on the volume of electrolyte gas production, thermal runaway trigger time, gas composition, and gas component content are investigated in this study. The results show that the volume of electrolyte gas production gradually increases with rising temperature, reaching a “turning point” temperature between 180 °C and 210 °C. Above this temperature threshold, the growth rate of gas volume accelerates. The gas composition of the electrolyte is high sensitivity to temperature, with CO2 being the predominant gas followed by H2 and CO. High concentrations of H2 (30.3 mmol) and CO (19.1 mmol) serve as effective indicators for early detection of lithium battery thermal runaway. Approximately 55 % or more of the gas generated in thermal runaway are combustible gases, which is the primary factor leading to fire. The gas production volume at 100 % state of charge is approximately 2.5 times higher than that at 0 state of charge.