Safety of LiFePO4/Graphite Li-ion pouch batteries under simulated external short-circuit (high rate) conditions

• Published in: Journal of power sources 2025-02, Vol.629, Article 236038
• Main Authors: An, Zhoujian, Jia, Ruixin, Li, Qingliang, Zhang, Dong, Du, Xiaoze, Li, Wenda, Shi, Tianlu
• Format: Article
• Language: English
• Subjects: Battery characteristics; Confined condition; External short circuit; Spatial-temporal temperature evolution
• ISSN: 0378-7753
• DOI: 10.1016/j.jpowsour.2024.236038

This paper examines the failure characteristics of 3Ah LiFePO4 (LFP) graphite pouch batteries under simulated external short-circuit (ESC) testing conditions from the perspective of spatial-temporal temperature evolution and the morphology of the electrodes. Moreover, the different behavior of ESC faults under confined conditions are qualitatively analyzed. The findings demonstrate that when subjected to ESC, surface temperatures continuously spread from the anode tab. The temperature threshold for battery leakage remains constant regardless of the initial state of charge (SOC) or short-circuit current. At this point, the maximum temperature at the center point of the battery reaches approximately 100 °C. Post-mortem analysis reveals that the electrolyte is consumed significantly during the ESC process. The results of scanning electron microscopy (SEM) indicate that the interlayer structure of the anode electrode is damaged and part of the active material is detached, while the structural stability of the cathode remains unchanged. In addition, compared to the unconfined conditions, the 50 % SOC battery under confined conditions exhibits a significant reduction in maximum temperature by approximately 25 °C after ESC at 50C. Notably, the microscopic electrode structure of the battery remains unchanged under confined conditions resembling a fresh battery. This demonstrates the positive impact of confinement conditions on battery performance and safety. •The effect of SOC and discharging rate on ESC behavior evolution is explored.•Spatial-temporal temperature mapping could be captured via thermal imaging.•Post-mortem destructive testing of electrodes damaged after ESC was analyzed.•Studied ESC behavior variations under confined scenarios with single battery.