Thermal runaway propagation behavior within 18,650 lithium-ion battery packs: A modeling study

Abstract Thermal runaway and subsequent propagation are the main factors to cause catastrophic consequences in lithium-ion battery packs. Exploring the thermal runaway propagation is thus of great fundamental and practical interest in understanding the mechanism of battery safety. A thermal runaway propagation mathematical model is established by combining the 0 D thermal runaway, and electrical and thermal conduction models that are verified by a series of experiments where thermal runways are triggered by mechanical abusive loading. Two thermal runaway propagation modes are observed and it is found that overheating of the local area or high overall temperature determines the propagation mode. The governing factors of thermal runaway propagation speed, including ambient temperature, packing spacing, and stacking form, are further analyzed. Our analysis reveals a complete link between engineering design variables and the thermal runaway behaviors of a specific battery pack. Our study paves a novel avenue to design the safer and higher energy density lithium-ion battery pack and elevates the limits of battery pack energy density without sacrificing safety risks.