Determination on the inherent thermal conductivity and thermal contact resistance of individual thin-layer materials in Li-ion batteries

With the increasing prevalence of electric vehicles, it is imperative to investigate the inherent thermal transport within battery cells to accurately characterize the thermal behavior and ensure secure operation of Lithium -ion batteries (LIBs). This study focuses on determining the anisotropic thermal conductivity and thermal contact resistance (TCR) of individual thin -layer materials in LIBs. A customized steady-state instrument and a commercial thermal constant analyzer are employed to measure, respectively, the through -plane and in -plane thermal conductivities. Accurate measurement on the inter -layer TCR is also performed. The results reveal the anisotropic thermal conductivity of thin -layer electrode materials, with the through -plane conductivity being significantly lower. The TCR of inter -layer materials within a battery constitutes approximately a quarter of its total thermal resistance. The temperature and pressure dependence of the thermal conductivity and TCR is also studied. The through -plane thermal conductivity of the thin -layers decreases slightly with increasing the temperature, while it increases marginally along with pressure. The TCR, however, reduces greatly with the increase of both temperature and pressure. Our findings provide insights into the significance of considering the substantial anisotropy in the thermal conductivity of electrode materials as well as the inter -layer TCR in thermal design, modeling and analysis of LIBs.