Effect of overdischarge on Li-ion battery performance under a fixed preload force
The performance of lithium iron phosphate/graphite Li-ion battery used in data centers under overdischarge is tested,both with and without preload force.The battery exhibits high rate and long cycle characteristics,can sustain 2 000 continuous discharges at 5.00 C.Through cycle tests in five overdischarge voltage ranges,including 0-3.65 V,0.20-3.65 V,0.50-3.65 V,0.80-3.65 V and 1.50-3.65 V,it is observed that as the discharge cutoff voltage decreases,the cycling attenuation increases.The addition of fixtures improves the battery's lifespan within the same cycle interval.Through electrochemical impedance spectroscopy(EIS),SEM and XRD tests,it is found that batteries with fixtures have smaller interface impedance and charge transfer impedance.External pressure can reduce electrode interface gaps,increase contact area,suppress Li+activity loss caused by gas production,improve cycle performance.The anode of batteries without fixtures will undergo microscopic changes during charge-discharge process,leading to more severe cycling attenuation.Batteries do not experience capacity decay even when stored at low voltages.
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维普
