Abstract: High-rate overcharging can have a serious impact on the thermal safety of lithium-ion batteries. In order to explore the overcharge behavior and heat generation characteristics of 18650 ternary lithium-ion batteries applied in aircraft at different charging rates，based on the overcharge test platform, the changes of surface temperature, voltage, characteristic time, mass loss and heat production of lithium-ion batteries during overcharging are analyzed, and the heat production characteristics of batteries under different charging rates are quantitatively evaluated. The results show that the overcharging process of the battery can be divided into four stages according to the change of characteristic voltage：normal charging, lithium plating, side reactions between lithium plating and electrolyte, electrolyte decomposition and internal short circuit. As the charging rate increases, the maximum temperature on the surface of the battery increases，the temperature rise is more severe, the time required for battery failure is shorter, the mass loss increases linearly, and the safety becomes poorer. This is mainly due to the high charging rate resulting in rapid lithium plating, which in turn leads to side reactions inside the battery. The heat of side reaction is the main source of heat accumulated during battery overcharging, and its contribution to heat production decreases with the increase of charging rate. This study is helpful to accurately predict and evaluate the performance of aviation airborne batteries under extreme conditions, and provides a new idea for optimizing aircraft battery design and thermal management systems.

Key words: lithium-ion battery, overcharge, safety, charging rate, heat generation