Thermite Reaction-Induced Thermal Runaway of Lithium-Ion Batteries.

Safety is a primary concern for the widespread use of lithium-ion batteries (LIBs) in electric vehicles as well as energy storage. Despite the numerous mechanisms proposed to explain thermal runaway (TR) and the various methods implemented to mitigate it, battery explosions still occur. This is predominantly due to an insufficient understanding of the TR mechanism. Herein, by combining various advanced analytical techniques with comprehensive analysis, it is found that aluminum (Al) foil, typically employed as the cathode current collector in LIBs, can react with some cathode active materials to form thermites. These thermite reactions generate substantial heat, contributing to explosions of LIBs, a mechanism that has been largely overlooked. Based on these findings, it is proposed that coating the Al foil with carbon can partially suppress these thermite reactions and substantially enhance the thermal stability of LIBs. This study offers new insights into the TR of LIBs and provides important guidance for developing safer batteries.