Strategies to Solve Lithium Battery Thermal Runaway: From Mechanism to Modification

As the global energy policy gradually shifts from fossil energy to renewable energy, lithium batteries, as important energy storage devices, have a great advantage over other batteries and have attracted widespread attention. With the increasing energy density of lithium batteries, promotion of their safety is urgent. Thermal runaway is an inevitable safety problem in lithium battery research. Therefore, paying attention to the thermal hazards of lithium battery materials and taking corresponding preventive measures are of great significance. In this review, the heat source and thermal hazards of lithium batteries are discussed with an emphasis on the designs, modifications, and improvements to suppress thermal runaway based on the inherent structure of lithium batteries. According to the source of battery heat, we divide it into reversible heat and irreversible heat. Additionally, superfluous heat generation has profound effects, including thermal runaway, capacity loss, and electrical imbalance. Thereafter, we emphatically discuss the design and modification strategies for various battery components (anodes, cathodes, electrolytes, and separators) to suppress thermal runaway. Preparation of solid electrolyte interphase layers with excellent thermal stability and mechanical properties is the core of the modification strategy for anode materials. Additives, stable coatings, elemental substitution, and thermally responsive coating materials are commonly used to improve the safety of cathodes. Novel electrolyte additives, solid-state electrolytes, and thermally stable separators provide a good opportunity to solve the thermal runaway problem of next-generation high-performance electrochemical storage devices.