A novel dielectric fluid immersion cooling technology for Li-ion battery thermal management

Abstract

The objective of this study is to investigate direct cooling performance characteristics of Li-ion battery and battery pack for electric vehicles using dielectric fluid immersion cooling (DFIC) technology. The experimental results showed that Li-ion pouch cell immersed in flowing dielectric fluid assisted with tab cooling showed better cooling performance with 46.8% reduction in the maximum temperature at the positive tab compared to natural convection at 3C discharge rate. The electrochemical-thermal model of Li-ion pouch cell immersed in flowing dielectric fluid assisted with tab cooling was developed using Multi-Scale Multi-Domain (MSMD) approach with Newman, Tiedemann, Gu, and Kim (NTGK) model. A good agreement within ± 5% was found between the results of numerical study and experimental data. The 50 V battery pack maximum temperature was maintained below 40 °C for 5C discharge at the ideal pumping power of 81.7 W. With the application of the proposed DFIC assisted with tab cooling technology, the maximum battery pack temperature was 9.3% lower than the indirect cooling method, confirming the improved cooling performance compared to the conventional cooling method. Under thermal abuse condition with internal short circuit, the peak temperature of 341.7 °C was observed for the battery pack and thermal runaway of battery pack was prevented except the affected cell. This study demonstrated the DFIC assisted with tab cooling as a safe and efficient thermal management technology for high-density and high capacity Li-ion battery application in electric vehicles.