Role of foam anisotropy used in the phase-change composite material for the hybrid thermal management system of lithium-ion battery

Abstract Hybrid kind of thermal management systems (TMSs) is emerging as a powerful, reliable, and efficient cooling device for controlling the temperature of Li-ion cells in the battery pack of an electric vehicle. Adding metal foams to a pure PCM (which results in a composite material) is a suitable way for the enhancement of the passive part's performance. In this paper, a novel hybrid TMS that uses cooling water channels (as the active part of TMS) and a composite of paraffin PCM and Al foam surrounding each lithium 18650 cylindrical cell (as the passive part of TMS) is introduced, and the role of foam anisotropy (according to the three main axial, radial, and tangential directions in the cylindrical coordinate system) on its performance is investigated, for the first time. The results of this study show that the hybrid operating mode of TMS consists of two periods: PCM recovery and cell cooling. In the first period, most of the water's cooling capability is paid for the solidification of PCM through a progressive process from top to bottom; and hence, less cell cooling effect is achievable. The results demonstrate that only increasing the tangential conductivity has a notable positive effect on the average cell temperature and the liquid fraction. Additionally, only increasing the axial thermal conductivity has a positive effect on the controlling of the maximum temperature difference through the cell.