Numerical Analysis of Phase Change Materials with Different Melting Behaviors in Battery Systems

Abstract Recently, phase change materials (PCMs) have been extensively utilized in thermal management systems of batteries because of their low energy requirements and heat-suppressing effects. Properties such as thermal conductivity, specific heat, melting point, and latent heat value play an important role in phase change material (PCM) selection. PCMs exhibit different melting behavior depending on whether they are pure or not. Pure PCMs have a melting point that is either a single point or a narrow temperature range, whereas impure PCMs melt within a melting temperature range. In this study, n-eicosane (PCM-1) with a fixed melting temperature and RT42 (PCM-2) with a regional melting temperature were numerically compared at different thicknesses of 2, 4, and 6 mm and at various ambient temperatures of 20°C and 30°C. During modeling, an 18,650 cylindrical lithium-ion battery was placed inside an aluminum container with PCM in between. The results revealed that the maximum battery temperature remained constant in the system created with PCM-1, which has a fixed melting point, and that the temperature began to rise again with the onset of local complete melting when PCM-1 was used at low thickness. Therefore, it was observed that the use of pure PCM at an appropriate thickness could maintain the maximum battery temperature constant.