Analyses of failure by over-discharge of LiFePO4 Li-ion battery for energy storage
The failure behavior with over-discharge is closely related to the safety performance of battery.In order to improve the safety of energy storage power stations,research on the lithium iron phosphate Li-ion batteries (18 parallel) is carried out.If a battery in the module is subjected to thermal runaway,the voltage of the adjacent batteries drops to 0 V due to over-discharge,the volume bulges,but no thermal runaway occurs.The result of X-ray computed tomography (XCT) test shows that the body of adjacent cell is obviously deformed,showing a state of unevenness,the electrodes in local areas are separated seriously,the cathode and anode fluid collectors at the top of the core are misplaced to some extent.It is found that the active substances on both sides of the anode electrode are basically completely shed,and serious " burning" spots appear in the local area of the stripped copper foil after disassembling.The results of SEM and energy dispersive X-ray spectroscopy show that there is a high content of copper in the abnormal area of the cathode electrode surface,and the surface is covered with deposits assignable to the accumulation of copper ions.The sediment in the abnormal area of the anode electrode surface is more obvious,which may be the sediment of lithium salt.There is also a large amount of sediment on the surface of the separator abnormal area,the separator pore structure has been completely blocked.
lithium iron phosphate(LiFePO4)energy storageLi-ion batteryover-dischargefailuredeform
国家科技期刊平台
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