Passive thermal management of a Li-ion battery module using phase change materials (PCM)

Abstract

This thesis investigates the effectiveness of phase change material-based thermal management systems in regulating the temperature of lithium-ion battery modules. Two 3p4s-configured battery modules, each with 12 NCA chemistry cells, were constructed, with one module filled with RT35HC paraffin PCM and the other left without PCM. Cycling tests were conducted at various C-rates (1C, 1,5C, and 2C) to evaluate the temperature performance of both modules. The results show that PCM-based thermal management successfully reduced temperature peaks, particularly at moderate charging rates (1,5C). At 1,5C, the maximum temperature difference between the battery's peak and minimum temperatures during the charging cycle was reduced by 3°C compared to the module without PCM, where the temperature difference reached 12°C. Similarly, the average temperature difference between the battery's maximum temperature and the ambient temperature was reduced by 9°C at 1,5C (from 26°C without PCM to 17°C with PCM). However, at higher charging rates (2C), the PCM approached its maximum heat storage capacity, leading to a slight increase in temperature swing, with the temperature variation reaching 7°C as compared to 3°C at 1,5C. This indicates that the PCM’s performance is limited at higher rates, but it remains effective in mitigating temperature extremes. The study suggests that optimizing the PCM's melting point (31°C to 35°C for RT35HC paraffin) and specific heat capacity can enhance thermal performance, particularly at faster charging rates. Future research should focus on long-term cycle testing to assess the durability of PCM and its impact on battery ageing. This work lays the foundation for cost-effective PCM-based solutions for battery thermal management.