Hybrid Cooling System of Lithium-Ion Battery Using Star-Shaped Channels and Phase-Change Materials

Abstract

Cooling lithium-ion batteries using phase change material and star-shaped channel for flowing fluid is presented in this paper. The proposed design is tested on six 21700 cylindrical lithium-ion battery cells. The six battery cells are placed in a case filled with wax as a phase change material, where this case is cooled using four water channels with star-shaped cross-section. The flow is assumed to be steady, fully developed, and laminar. This study is conducted using COMSOL Multiphysics 5.6 software, assuming lumped analysis for the batteries and incompressible flow for both wax and water. It was shown from the results that the temperature lowered by a range of 9.43°C to 11.07°C when discharged to 15% by 4C rate with the star-shaped channels and paraffin wax. While the temperature lowered by a range of 9.13°C to 10.51°C with paraffin wax and circular channels. When the study was carried out without any cooling method during discharge, battery 6 reached 39.528°C, while battery 1 reached 39.468°C. However, after cooling using star-shaped channels and paraffin wax case, the temperature of battery 6 dropped to 29.788°C, while battery 1 was 30.034°C, and the lowest temperature was 28.440°C for battery 5. The temperatures of the batteries with circular channels for cooling were recorded as 30.146°C, 30.339°C, and 28.996°C for batteries 6, 1, and 5, respectively. When paraffin wax was replaced by n-Octadecane wax, all battery temperatures dropped to approximately 27.4°C. The results showed that cooling using phase change material and star-shaped channels achieved the lowest temperatures compared to other cooling designs and methods. By comparing the present results with the published results, it was found that the present study is in good agreement with previous findings and shows notable improvements.