Abstract: To prevent the risk of battery thermal runaway fire, 280 Ah square lithium iron phosphate batteries were selected for the study of strain parameter-based monitoring and early warning technology for thermal runaway of lithium-ion battery. The variation of strain parameters with respect to voltage and temperature parameters under different test conditions was obtained. The results show that the strain sensor can accurately capture the expansion changes of the lithium-ion battery in the early stage of thermal runaway. In overcharge to thermal runaway environments, the strain parameter reaches its maximum magnitude first compared to the voltage and temperature parameters. In heating to thermal runaway environments, the strain parameter changes faster and reaches its maximum magnitude first compared to the voltage and temperature parameters. In a comprehensive comparison, the strain parameter have a better degree of sensitivity and response during the thermal runaway gestation phase. Therefore, using strain parameters can achieve early monitoring and warning of lithium-ion battery thermal runaway, and has the advantages of rapid change, high accuracy, easy installation, and low cost.

Key words: lithium-ion battery, battery module, strain, thermal runaway, status monitoring