Design and Lattice Boltzmann Simulation of Phase Change Material Encapsulation for a Horizontally Oriented Lithium-Ion Battery Pack Under Natural Convection

Abstract Despite extensive studies on phase change material (PCM)-based battery cooling, optimization of PCM vessel shape remains relatively underexplored. This study utilizes the thermal lattice Boltzmann method on a graphics processing unit to analyze natural convection on 18650 lithium-ion batteries encapsulated by PCM. The impact of vessel shapes, i.e., circular, square and hexagonal, on the cooling of batteries horizontally placed within a pack is evaluated, together with PCM thickness and void fraction (VF) effects. Results reveal that the circular PCM vessel achieves the highest heat absorption in the closed battery pack among all shapes. In the ventilated battery pack, the square vessel exhibits superior heat dissipation across all configurations, while the hexagonal shape ensures improved temperature uniformity throughout the pack. Subsequently, a modified vessel shape is proposed for a ventilated battery pack to enhance heat dissipation. These findings highlight the importance of optimizing vessel geometry, thickness and VF for effective battery thermal management under different cooling conditions.