A Simulation Study on Early Stage Thermal Runaway of Lithium Iron Phosphate Energy Storage Batteries Due to Overcharging

The thermal effects of lithium-ion batteries have always been a crucial concern in the development of lithium-ion battery energy storage technology. To investigate the temperature changes caused by overcharging of lithium-ion batteries, we constructed a 100 Ah experimental platform using lithium iron phosphate (LiFePO4) batteries. Overcharging tests were conducted at a 0.5C rate at different states of charge (SOC), and the resulting temperature evolution was recorded. The experimental results demonstrate that a higher initial SOC leads to an earlier occurrence of thermal runaway in the battery. Once the battery reaches 100% SOC, the temperature rises significantly until thermal runaway occurs. Based on the experimental results of battery discharging at different SOC stages and the heat generation mechanism of lithium iron phosphate batteries during thermal runaway, a simulation model of overcharging-induced thermal runaway in LiFePO4 battery was established. The overcharging-induced thermal runaway process of lithium-ion batteries at different SOC was subsequently examined through simulation and compared with the experimental results. The simulation results indicate that the lithium battery model can accurately predict the temperature distribution on the battery surface following thermal runaway caused by overcharging.