Thermal runaway procedure and residue analysis of LiFePO4 batteries with different charging states under nail penetrating

• Published in: Journal of applied electrochemistry Vol. 54; no. 7; pp. 1485 - 1500
• Main Authors: Liu, Songtao, Li, Yang, Han, Dengchao, Sun, Junli, Wang, Huaibin
• Format: Journal Article
• Language: English
• Published: Dordrecht Springer Netherlands 2024; Springer Nature B.V
• Subjects: Accident investigation; Accident investigations; Chemistry; Chemistry and Materials Science; Electric charge; Electric potential; Electrochemistry; Energy storage; Industrial Chemistry/Chemical Engineering; Iron; Lithium; Lithium-ion batteries; Microwave heating; Physical Chemistry; Power plants; Qualitative analysis; Rechargeable batteries; Research Article; Short circuits; Smoke; Smoothness; State of charge; Temperature; Thermal runaway; Voltage; LiFePO; Fire investigation; Pattern features; battery
• ISSN: 0021-891X; 1572-8838
• DOI: 10.1007/s10800-023-02059-8

The frequent occurrence of thermal runaway accidents of lithium-ion batteries has seriously hindered their large-scale application in new energy vehicles and energy storage power plants. Careful analysis of lithium-ion batteries can essentially determine the cause of the accident and then reduce the likelihood of lithium-ion battery thermal runaway accidents. However, there are few current studies on lithium-ion battery accident investigation, and the destruction of traces due to the violent reaction of the battery’s thermal runaway increases the difficulty of battery accident investigation. The thermal runaway accident scenarios of lithium-ion batteries with different states of charge will show different regular characteristics of the thermal runaway properties and trace characteristics of lithium-ion batteries. Establishing the relationship between the thermal runaway characteristics of lithium-ion batteries, the trace law and the state of charge can effectively improve the technology of in-depth battery accident investigation. This study investigated the thermal runaway and trace characteristics of lithium-ion batteries triggered by nail penetrating at different states of charge using 8 Ah soft pack lithium iron phosphate batteries as the research object. The results show that lithium iron phosphate Li-ion batteries do not trigger thermal runaway under nail penetrating conditions when the state of charge is less than 20%, with no obvious phenomena and slight changes in the voltage and surface temperature of the battery, with the temperature only rising by 5 ℃. Both the 60% and 100% SOC LiFePO 4 batteries underwent thermal runaway within a few seconds after the needle puncture and produced a large amount of white smoke, with the voltage rapidly dropping to 0 V and the maximum temperature on the front of the battery reached 93 ℃ and 125 ℃, respectively, and the rate of temperature rise was significantly higher in the latter than in the former, with both reaching temperatures above 200 ℃ at the penetration point and higher than at the entry point, while the 100% SOC battery showed electrical sparks and more smoke after the puncture due to a more violent internal short-circuit. The state of charge affects the cracks and particle spacing on the surface of the anode electrode and the smoothness of the surface. The results of this paper provide ideas for qualitative and quantitative analysis of lithium-ion battery accident causation, which can provide guidance for effectively improving the ability to investigate lithium-ion battery accidents. Graphical Abstract