Performance analysis of phase change material in battery thermal management with biomimetic honeycomb fin

Abstract As a passive thermal management system for vehicle batteries, low thermal conductivity is a key problem that limits the application of phase change materials (PCMs). As a product of natural selection, the honeycomb structure is lightweight and can effectively improve the overall thermal conductivity of PCM; hence, it has been widely used in thermal control systems. In this study, based on the heat generation characteristics of a rectangular soft-pack battery, a numerical simulation is performed using a CFD model based on the enthalpy–porosity method. Results show that compared with not using a fin, the addition of a honeycomb fin can retain the battery temperature below 50 °C under the extreme 10 C discharging rate of the battery, in which the temperature drop of the structure with a honeycomb fin increases by 61%. The honeycomb fin can evenly distribute the heat of the PCM in the vertical direction, and the PCM at different thicknesses melts almost simultaneously, thereby optimizing the heat absorption effect of the PCM. In this study, by investigating the effects of different porosities of honeycomb fin on batteries and PCMs, an optimal value for the porosity is obtained, i.e., approximately 0.78. The results of different cooling plate thicknesses show that the greater the thickness of the cooling plate, the lower the cell temperature, and the smaller PCM melting liquid phase fraction. Therefore, the thickness should not be too large, and about 3 mm is better. It can be seen from the effect of different honeycomb holes, the more holes, i.e., the smaller the pore diameter under the same porosity, the lower the cell temperature. Increasing the number of holes does not make the battery temperature infinitely lower. Therefore, selecting the number of 30 holes can maintain the cell temperature in the comfortable zone.