Studying the multi-field coupling interaction under extreme conditions is helpful for further understanding the thermal runaway mechanism of Li-ion battery.The overcharge voltage of the 1380200 type pouch lithium iron phosphate power Li-ion battery is increased from 4.07 V to 5.42 V step by step in an overheated environment at 85℃.The battery has gas pressure relief but no fire or explosion,indicating that the battery has strong overcharge resistance even under overheated conditions.During the pressure relief process,the signal of hydrogen is first detected,then flammable gases such as carbon monoxide,alkanes and olefins are detected.XRD analysis shows that the cathode active material LiFePO4 is fully delithiated to form FePO4 after overcharging.The SEM results show that some of the FePO4 particles have cracks after overcharging,but the structure is not further destroyed,indicating the high thermal stability of LiFePO4.
关键词
锂离子电池/动力电池/磷酸铁锂/多因素耦合/过充电测试/过热
Key words
Li-ion battery/power battery/lithium iron phosphate/multiple factor coupling/overcharge test/overheat
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