Thermal runaway and gas production characteristics of semi-solid electrolyte and liquid electrolyte lithium-Ion batteries: A comparative study

Solid-state electrolytes have attracted considerable attention as an alternative to liquid electrolytes for lithiumion batteries. This study compares the thermal runaway and gas production of two commercially available lithium-ion batteries (i.e., the liquid electrolyte lithium iron phosphate battery (LFP-L) and the semi-solid electrolyte lithium iron phosphate battery (LFP-SS)) under different environments and states of charge (SOCs). The main findings include the following aspects: Regarding thermal runaway characteristics and gas production kinetics, LFP-SS exhibits a slower temperature rise rate but a higher per Ah pressure increase. The total gas production volume of LFP-SS is lower, but the gas production volume per Ah is approximately 1.5 times that of LFP-L batteries. The LFP-L produces gas rate per Ah more rapidly than the LFP-SS. As for the produced gas components, LFP-L has higher concentrations of H2 and hydrocarbons than LFP-SS. Concerning explosion limits, both the upper and lower explosion limits of LFP-SS are higher than those of LFP-L at 100 % SOC. However, for 110 % SOC, the upper explosion limit of LFP-SS is lower than that of LFP-L. Quantitative analysis of the safety performance of these batteries under different conditions shows that LFP-SS exhibits the best safety performance at 100 % SOC in a nitrogen environment. These results are hoped to guide battery selection and safety protection design for lithium-ion battery packs.