Abstract Nowadays, the most used thermal management system (TMS) is air-cooling, but due to weight and volume limitations, more promising cooling methods such as PCMs with high latent heat seems to be attractive. However, their disadvantages, like low thermal conductivity, should be managed to have an efficient TMS. Hence, aluminum-foil (PCM-Al) is added to the PCM in this work to enhance the PCM conductivity, and accurate experiments are accomplished to verify the simulation results. In this paper, a phase change material (PCM) with aluminum mesh grid foil is proposed to enhance cooling and temperature uniformity of a high-power dual-cell lithium capacitor (LiC) module. The optimization objective is keeping the temperature of the system below the safe range while maximizing the uniformity and minimizing the cost of the system. The effect of forced-convection (zero-PCM strategy), pure PCM, PCM-Al, PCM thickness, and influence of dual PCMs by different phase change temperatures on the thermal behavior of the module are studied numerically. The results indicate that the PCM-Al technique shows better thermal performance while reducing the maximum module temperature by 20%, and 13% in comparison with forced-convection and pure PCM, respectively. Moreover, 7 mm thickness is quite optimal, considering the cost, weight, and volume.