Study on thermal performance and structural optimization of energy storage lithium-ion batteries using composite phase change materials coupled with air cooling

Taking lithium iron phosphate batteries as the research object, a composite battery thermal management system with an H-type structure, coupling composite phase change materials (CPCM) and air cooling, was proposed to address the heat generation during battery discharge. By constructing a single-cell experimental platform, dynamic internal resistance data of the battery during discharge under multiple operating conditions were obtained, and a user-defined function (UDF) program for the battery source term was developed. Based on the heat generation model, a numerical model for evaluating the thermal management performance of the composite system was constructed. The influence of different air inlet and outlet configurations on system performance was analyzed, and orthogonal experimental design was employed to optimize the configuration. In addition, the system's thermal management performance was enhanced by integrating aluminum metal shells. The results show that under high temperature or high discharge conditions, the air inlet and outlet configuration significantly affects the maximum temperature difference within the battery pack, while having a relatively minor impact on the peak temperature. Besides, schemes I-H and II-H exhibit higher power consumption and CPCM maximum liquid phase ratios compared to schemes III-H and IV-H, while the III-H scheme demonstrating the best overall thermal management performance. After orthogonal optimization, a significant improvement was achieved with the maximum temperature difference and power consumption respectively decreases by approximately 21.7 and 94.3. Furthermore, coupling aluminum metal shells can effectively enhance the system's thermal performance, with the dual-arc aluminum shell structure achieving the best results. The findings can provide valuable insights for the design and application of thermal management systems for energy storage batteries.