Graded metal foam structures to improve cooling performance of phase change material-based battery thermal management

This study presents an integrated experimental and numerical investigation of a hybrid Battery Thermal Management System (BTMS) using phase change material (PCM) enhanced with metal foam structures to mitigate excessive heat generation in lithium-ion batteries. The core innovation lies in the design and evaluation of multi-scale or graded metal foam configurations, which strategically vary pore density across the structure to optimize thermal performance under varying discharge rates. Two PCMs, low melting point (25×) and high melting point (48×) were tested under identical boundary conditions. While 25× proved more effective at 1C and 2C (reducing surface temperature to 297 K at 1C), 48× showed superior performance at higher rates, achieving 319 K at 5C with temperature gradients under 1 K. The integration of copper and aluminum foams improved heat transfer and melting dynamics. Embedding 20 PPI copper foam reduced the surface temperature to 310 K and the temperature gradient to 3.2 K at 5C, compared to 349 K and 27.3 K with pure PCM. The study then introduced four-layer vertical and three-layer radial graded foam configurations. The negative-gradient vertical design (40–20–10–5 PPI) demonstrated lower peak temperatures (312.5 K at 3C) and improved temperature uniformity (gradient of 3.5 K). Among all graded designs, the radial configuration demonstrated best thermal performance over vertical layering, achieving a maximum temperature of 311.2 K and temperature gradient of 4.5 K at 3C, though with a 1.6 K and 3.9 K increase, respectively, compared to the uniform 20 PPI foam due to interfacial resistance. These findings highlight the effectiveness of multi-scale metal foams in enhancing passive BTMS, especially under high C-rate operations.