Study on the impact of temperature-dependent anisotropic thermal conductivity on thermal diffusion in lithium-ion batteries

The thermal conductivity of 32650 ternary lithium batteries in the temperature range of 20 degrees C-120 degrees C is measured for the first time by Hot Disk device. The variation of axial and radial thermal conductivities with temperature is complex and completely different. High-temperature thermal runaway (TR) experiments on lithium batteries are conducted using an Accelerating Rate Calorimeter (ARC) device, categorizing the TR process into a self-heating stage and a severe heating stage based on the temperature change curve. A TR propagation model is constructed accordingly. Using this model, the impact of thermal conductivity is investigated, considering temperature effects on TR propagation. The simulation results show that when the convective heat transfer coefficient (CHTC) is 5 W m- 2 K-1, the temperature effect on thermal conductivity results in a difference in TR initiation time of 9.3 min, with a relative deviation of up to 18.25 %. When the CHTC increases to 10 W m- 2 K-1, the relative deviation between the thermal conductivity as a temperature function and its constant can reach 22.13 %. Therefore, TR propagation models for lithium batteries should incorporate temperaturedependent thermal conductivity to enhance the accuracy of simulation results and provide valuable guidance for preventing and mitigating battery TR and its propagation.