锂二次电池的高温循环性能及其容量损失

Research on cycle performance and capacity fading of lithium-ion secondary batteries

研究了锂离子电池在常温和高温60℃时电池的循环性能和容量衰减原因。采用恒流-恒压(CC-CV)充放电制度对锂离子电池在不同温度下进行了300次的充放电循环测试,运用扫描电子显微镜法(SEM)和X射线衍射光谱法(XRD)测试手段对不同温度下循环300次后的锂离子电池电极材料的形貌和结构进行了表征,并运用充放电测试和交流阻抗技术对电池电化学性能进行了研究。结果表明,升高温度后锂离子电池表现出较高的初始容量,但电池的循环稳定性降低,容量衰减速率加快。充电过程中电极极化加剧是导致高温下电池容量迅速衰减的主要原因,而在高温条件下电荷传输电阻增加和由于大量气体的产生使电极发生形变,使放电容量进一步衰减。

The cycle performance and capacity fading of lithium-ion secondary batteries cycled both at RT and 60 ℃ were studied. The charge-discharge cycle of lithium-ion batteries was tested for 300 cycles at different temperatures by conventional constant current-constant voltage （CC-CV） protocol. The characteristics of morphology and structure after cycle were investigated by SEM and XRD, and the electrochemistry properties were studied by charge/discharge cycle and EIS. The results show that the initial capacity increases, but cycle stability of lithium-ion batteries decreases and capacity fading accelerates at elevated temperatures. Capacity fading of lithium-ion batteries at elevated temperature can be attributed primarily to the increase of electrochemistry polarization of cathode materials and the deterioration of the morphology and structure, and it gets even worse due to the structure change of active materials resulting from a mass of gas produced at elevated temperatures.