Investigation on the Impact of High-Temperature Calendar and Cyclic Aging on Battery Overcharge Performance

With the degradation of lithium-ion batteries, the battery safety performance changes, which further influences the safe working window. In this paper, the pouch ternary lithium-ion battery whose rated capacity is 4.2 Ah is used as the research object to investigate the impact of the high-temperature calendar and cyclic aging on tolerance performance. The overcharge-to-thermal-runaway test is performed on the fresh cell and aged cell (90% SOH). The inflection point of voltage for aged cells appears earlier than that of the fresh cell, while the voltage corresponding to the inflection point is the same for them, which means that the voltage at which lithium plating occurs is the same. However, the voltage plateau and the crest voltage before thermal runaway of aged cell are significantly higher than that of the fresh cell. Besides, ohmic heat, reversible heat, and side reaction heat make contribution to the thermal runaway triggering. Among them, the side reaction heat plays a dominant role. Moreover, the ratio of heat generated by side reactions increases with aging. Compared with fresh cells, the thermal runaway triggering temperature of the high-temperature aging cell is increased. However, the duration of high-temperature cyclic aging cell is reduced, while the duration of high-temperature calendar aging cell is increased. Furthermore, although the maximum temperature of the aged cell has not changed significantly, the maximum temperature rise rate is significantly reduced, which may be caused by the loss of active materials. The aim of this article is to provide guidance for the design of battery safety management systems.