Experimental-numerical studies on thermal conductivity anisotropy of lithium-ion batteries

The thermal conductivity of lithium-ion battery cells is strongly anisotropic, however, the current studies for this anisotropy are inadequate. This work proposes an in-situ characterization method of integrating experimental measurement and numerical simulation to study the anisotropic property of the cell thermal conductivity. Experimental measurements are first conducted to obtain the cell's temperature evolution, and then the thermal distribution is simulated numerically by considering the cell's longitudinal thermal conductivity 7// as a multiple of its normal thermal conductivity 7 perpendicular to to capture a closer agreement between the results of measurement and simulation. Meanwhile, two pieces of standard quartz-glass are employed as standard samples for the effectiveness authenticating of the current method. It is shown that the longitudinal thermal conductivity in the cell is significantly larger than its normal thermal conductivity, which the ratio of the longitudinal direction to the normal direction (7///7 perpendicular to) for the prismatic and cylindrical cells' thermal conductivities reaches up to 40.5 and 20.3, respectively. Experimental verification shows that the current method of characterizing the cell's thermal conductivity anisotropy is highly feasible. This study has valuable implications for one to learn more about the anisotropic property characterization of battery thermal conductivity.