Multi-dimensional liquid nitrogen intervention strategies for thermal runaway of 65 Ah LiFePO4 batteries
摘要
Lithium-ion batteries (LIBs) are susceptible to thermal runaway (TR) under external stimuli, compromising operational safety and reliability. This study induces TR in lithium iron phosphate batteries through heating and injects liquid nitrogen (LN) for cooling and suppression. The experimental results show that as the injection volume of LN increased from 6.2 kg to 8 kg, the maximum decreases in the surface temperature of the battery were 8.5 °C, 62.9 °C, 71.7 °C, and 98.5 °C, respectively, indicating that the increased mass of LN enhances the cooling effect of the battery. However, the cooling effects of the four injection volumes on the ambient temperature are nearly identical. As the pipe diameter increases from DN15 to DN20, both the maximum cooling rate and the average cooling rate of LN on the battery increase, while the surface temperature rise of the cooled battery decreases. However, when the pipe diameter increases to DN25, the cooling effect of LN on the surface temperature of the battery remains nearly unchanged. Moreover, as the pipe diameter increases, the flow rate of LN increases, leading to a stronger initial thermal shock to the battery surface, which results in significant disturbances in the ambient temperature. Specifically, in the early stage of LN injection, the ambient temperature rebound rate increases from 5.03 °C s–1 to 15.4 °C s–1. This research is crucial for enhancing the reliability and safety of LIBs in energy storage power stations, providing effective technical support for fire safety strategies.