Capacity fading and thermal stability of LiNixCoyMnzO2/graphite battery after overcharging

Lithium ion batteries are widely used in many fields due to their excellent properties. Overcharging occurs during their usage because of malfunction of charge control, inappropriate battery management system and inconsistency among batteries. This work studies whether the battery is suitable for use after overcharging or not based on aging and thermal stability analysis. The results indicate that overcharging (Voltage < 5 V) has a small influence on capacity fading of battery. Onset temperature of exothermic reactions, thermal runaway and maximum thermal runaway temperatures decrease and thermal stability of battery becomes worse. This is mainly caused by SEI growth and structure damage of cathode. And the thermal stability of battery decreases with the increase of overcharging voltage. Considering that slight overcharging influences capacity fading less, the battery with LiNixCoyMnzO2 and graphite as cathode and anode respectively can be used after slight overcharging. Considering the influences of slight overcharging on thermal stability, some measures should be employed to maintain the operation temperature range of battery under the self-exothermic temperature indicated in this research.