Revealing the evolutionary mechanism of overcharge tolerance for lithium-ion batteries under various operation conditions

Lithium-ion battery tolerance changes with internal degradation during service. To achieve battery safety protection throughout the whole lifecycle, it is essential to understand the evolution of battery tolerance during the aging process. This work evaluates the battery tolerance by overcharging. By conducting overcharging tests on lithium-ion batteries with varying aging degrees under different degradation paths, the evolution patterns of battery tolerance under different degradation paths are revealed. Battery overcharge tolerance decreases with aging under different degradation paths and exhibits path dependence. This decrease is most severe under low-temperature cycling and high-rate cycling conditions. Meanwhile, the overcharge-induced hazards decrease with aging without exhibiting path dependence. Further, the mechanism of tolerance decrease during the aging process is revealed through multi-angle characterization, and thermal stability tests reveal that lithium plating of the anode and transition metal dissolution of the cathode are the primary causes of battery thermal instability, leading to decreased overcharge tolerance. The corresponding results can provide guidance for optimal design and safety management of lithium-ion batteries throughout the whole lifecycle. • Overcharge performance and failure mechanism under various aging paths are investigated. • Overcharge tolerance decreases with aging while the change degree varies under different aging paths. • Lithium plating is the common degradation mechanism while the formation mechanism is different. • Lithium plating and transition metal dissolution are the major cause for the decreased overcharge tolerance.