Enhanced passive thermal management of lithium-ion batteries with conical cylindrical chamber incorporating various phase change materials.

The effective thermal management of Lithium-Ion Batteries (LIBs) is essential for ensuring safety, extending cycle life, and maintaining performance in electric vehicle applications. Among various approaches, passive battery thermal management systems (PBTMS) using phase change materials (PCMs) provide a cost-effective and reliable solution compared to conventional active cooling. This study proposes a novel conical cylindrical chamber (CCC) design for PCM encapsulation and evaluates its impact on LIB temperature regulation. A three-dimensional Computational fluid dynamics (CFD) model based on the enthalpy-porosity method was developed to simulate coupled heat transfer and phase change phenomena under dynamic discharge conditions. The effects of chamber geometry (top and bottom radii), different PCM types, and discharge rates (1-3 C) were systematically investigated. Results show that chamber configuration strongly influences PCM melting efficiency and battery thermal response. For example, the optimized CCC geometry reduced peak battery temperature by nearly 30 °C compared to less efficient designs, while poorly configured chambers left up to 38% of the PCM unmelted at end of discharge. The study demonstrates that balancing CCC surface area and PCM volume is critical for maximizing heat absorption, minimizing thermal gradients, and enhancing passive cooling. These findings provide design guidelines for next-generation passive thermal management systems in LIB applications.