Recent advances of overcharge investigation of lithium-ion batteries

Lithium-ion batteries have been widely used in the power-driven system and energy storage system, while overcharge safety for high-capacity and high-power lithium-ion batteries has been constantly concerned all over the world due to the thermal runaway problems by overcharge occurred in recent years. Therefore, it is very important to study the thermal runaway mechanism and improve the safety of the battery during overcharge. In this work, depending on the external appearance, voltage, and temperature changes, the whole overcharge to TR process was divided into 5 stages. By analyzing the side reactions in five stages, the mechanism of heat production during overcharge is summarized, and the order of heat generation is Q(Ca+An) > Q(anode) > Q(electrolyte) > Q(cathode) > Q(SEI) > Q(ISC). Key factors for battery overcharge safety, such as cathode materials, electrolyte safety, and charging current are concluded in this review. Compared to external protection devices (such as BMS, OSD, CID), the internal protection of overcharge additives are more effective. A complex polymer with aromatic functional groups, epoxy or propionate, will become a hot spot in the research of overcharge additives for lithium-ion batteries. This review is expected to offer effective overcharge safety strategies and promote the development of lithium-ion battery with high-energy density.

Automated summary

This study divides the process of overcharge to thermal runaway into 5 stages based on external appearance, voltage, and temperature changes, and summarizes the mechanism of heat production during overcharge. Key factors affecting overcharge safety include cathode materials, electrolyte safety, and charging current. Internal overcharge additives are more effective in protection compared to external protection devices.