Abstract:

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.

Key words: lithium-ion batteries, accelerated aging, aging abuse, temperature stress