Enhancing lithium-ion battery cooling efficiency using composite phase change material packed mini-chambers: A numerical study

The present work proposes a compact, energy efficient and safer battery cooling system for EV lithium ion batteries by enhancing the heat transfer rate through composite phase change material (CPCM) packed in minichambers. The main advantage of proposed CPCM packed in mini-chambers cooling system that it can dissipate heat at a high rate in a limited volume. To evaluate the system's effectiveness, a three dimensional numerical model is developed and validated with experimental data to compare battery discharge performance with and without cooling. The study examines three different PCM with distinct thermo-physical properties and compares the performance of the PCM block structure and the PCM mini-chamber structure battery cooling system at discharge rates of 1C, 2C, 3C, and 4C. The results show that using a mini-chamber structure with composite phase change material (CPCM) (Paraffin/expanded graphite) improves temperature stability, melting characteristics, and thermal conductivity, compared to using pure PCM n-octadecane and RT-35. The residual heat and sensible heat for liquid phase are reduced by 29 % and 70 %, respectively, for a CPCM mini-chamber structure compared to a block structure. Overall, the study concludes that a battery with PCM mini-chamber and CPCM as PCM is an efficient way to extract heat from the battery for discharge rates up to 4C.