Experimental and numerical modeling of the heat generation characteristics of lithium iron phosphate battery under nail penetration

This study conducted nail penetration tests on 20 Ah prismatic LiFePO4 batteries and simulated the slow release of Joule heat and side reaction heat by combining a new thermal model with a parameter optimization method. The results indicate that the 50% and 80% SOC LiFePO4 batteries only release Joule heat under penetration, while the side reaction heat is acquired under 100% SOC besides Joule heat. Moreover, approximately 56.4% of the stored electrical energy is converted into Joule heat, which accounts for the majority of the total heat production of 100% SOC LiFePO4 battery under penetration, while side reaction heat accounts for only 6.4%. Furthermore, the exothermic side reactions of 100% SOC LiFePO4 battery under penetration can be effectively suppressed when the electrical energy release ratio is less than 0.52, or the convection coefficient between the battery and its surroundings exceeds 12 W/m2K. This numerical study expands the analysis of the heat generation characteristics of LiFePO4 batteries during penetration and provides practical guidance for system safety design.