Evaluating the thermal failure risk of large-format lithium-ion batteries using a cone calorimeter

A series of experiments were conducted to study the thermal failure hazard of large-format commercial lithium-ion batteries with typical states of charge in a calorimeter apparatus. The results indicate that the thermal failure penetration of the lithium-ion battery with 70% state of charge is faster than the lithium-ion battery with 50% state of charge. Two typical thermal failure modes, Gas-driven mode and Flame-driven mode, were also observed, corresponding to lithium-ion battery with 70% state of charge and 50% state of charge, respectively. Significant heat release, accompanied by large amount of carbon dioxide (CO2) release, took place for lithium-ion battery with 50% state of charge. Inversely, lithium-ion battery with 70% state of charge presented a lower heat release while more carbon monoxide (CO) generation and obvious mass loss trend. This study may serve as a reference for safe storage, application, and transportation in lithium-ion batteries.