锂离子电池加速老化温度应力的滥用边界

Aging abuse boundary of lithium-ion cell above room temperature

为了探寻加速老化合适的温度应力区间,设计了温度变化为30~80℃的循环老化实验,通过电池外特性分析与解体分析等手段对锂离子电池老化机理进行了探讨。结果表明:老化速率随着温度的升高先降低、再升高。基于老化速率,将温度工况分为常温(30~56℃)、中高温(56~68℃)、高温(68~80℃)3个区域。在常温区域,老化速率随着温度升高而降低,锂离子电池存在析锂现象;在高温区域,电池电极出现活性物质脱落现象,导致锂离子电池容量的衰减;而在中高温区域,通过活化能计算判断电池老化机理为固体电解质界面膜(SEI)的生长。该研究成果可以指导加速老化实验的设计,也为寿命预测模型的开发提供参考。

The temperature stress levels within the range of 30 ℃ to 80 ℃ were investigated to determine the appropriated temperature range for conducting accelerated aging test. The aging mechanisms of lithium-ion cells were examined by using characteristics determined with ex situ characterization and post-mortem analysis methods. The results show that the aging rate is first reduced, and then increases with temperature rising. Based on the aging rate, the temperature range is divided into three regions. In the normal temperature region （30-56℃）, the aging rate decreases with the temperature rising, and the lithium plating is observed; in the high temperature region（56~68 ℃）, the diagnosis shows that the powder-off in the electrode resultes in capacity loss; in the medium temperature region（68-80 ℃）, lithium-ion battery aging mechanism is the solid electrolyte interphase （SEI） growth. The results can contribute to the design of accelerated aging experiment and the development of lithium-ion battery life prediction model.