Optimization of Lithium-ion battery thermal performance using dielectric fluid immersion cooling technique

Lithium-ion batteries (LIBs) are crucial for portable electronics, electric vehicles, and renewable energy systems. However, conventional cooling techniques for LIBs struggle to efficiently dissipate heat during rapid charging and discharging, potentially compromising performance and safety. This study explores the immersion cooling technique to optimize the thermal performance of 4S2P LIB module at 3 C discharge rate. The MSMD-NTGK battery model is utilized in numerical simulation to analyze the electrochemical and thermal characteristics of LIBs. Initially, static and forced convection immersion cooling methods are compared using two different cooling media: ester-oil and air. Static convection with ester oil reduces temperature rise by 8.3 % compared to natural air convection, while forced convection with ester oil achieves optimal temperatures (< 5 °C) at a fluid velocity of 0.077 m/s (20 LPM), lower than forced air convection. Furthermore, the study enhances forced convection with ester oil-based immersion cooling for LIB with different inlet and outlet structural designs. Among these, the middle inlet and middle outlet-center (MIMO-C) flow model demonstrates optimal temperature at reduced flow rate of 5 LPM and minimal pressure drop of 230 Pa compared to others. These findings underscore the potential of forced convection-based immersion cooling to improve LIB performance and lifespan.