Mathematical model for thermal behavior of lithium-ion battery pack under overheating

The thermal runaway (TR) propagation model during thermally-induced failure of lithium-ion battery (LIB) pack was built based on the single battery TR model. The TR model was verified by the experimental test results of heating at 95 kW∙m⁻³, 107 kW∙m⁻³ and 119 kW∙m⁻³. The heat production ratio of the side reactions was analyzed based on the TR model, and the effects of heating power and convection coefficient on battery TR were discussed. Moreover, the effects of battery gap, clamp, and thermal insulation material on the TR propagation were studied. The results showed that the model considering Joule heat generated by internal short circuit (ISC) as the main heat source was in good agreement with the experimental results. With the increase of heating power per unit volume from 95 kW∙m⁻³ to 155 kW∙m⁻³, the TR critical time decreased and TR critical temperature increased. The TR cannot occur at 143 kW∙m⁻³ when the air convection coefficient was higher than 15 W·m⁻²·K⁻¹. The TR propagation of the battery pack can be effectively restrained by appropriately increasing the thermal resistance between the batteries and between the battery pack and the clamp.