01. Experimental/Computational Fluid Dynamics

Lithium-ion batteries (LIBs) are crucial for electric vehicles (EVs) due to their high energy storage capacity. Effective thermal management is vital, as these batteries need to operate within an optimal temperature range of 15 to 45 °C to ensure longevity and prevent thermal runaway. This study investigates the necessary heat transfer coefficient (h) required for the solidification of phase change materials (PCMs) during continuous use across various high-rate discharging-charging cycles. Utilizing the Newman-Tiedemann-Gu-Kim (NTGK) model, the research simulates the performance of the SAMSUNG ICR 18650-26J Lithium-ion battery. This battery is encased by a copper shell, followed by the addition of the PCM, and then further encapsulated by another copper shell. A cap is also added on the top. The effectiveness of the NTGK model was validated through simulations, which confirmed its accuracy in predicting thermal behaviors under varied conditions. The present study tested the configurations, including a range of heat transfer coefficients from 10 W/m²·K to 100 W/m²·K. At an ambient temperature of 30 °C and a 3C discharge rate, the maximum temperature recorded was 42.3 °C for an h of 100 W/m²·K, and 75.57 °C for an h of 20 W/m²·K, demonstrating effective thermal regulation. The discharging-charging cycles analyzed include high discharging rates like 3C, 4C, and 5C followed by a standalone period and discharging-charging cycle with 3C-1C, 4C-1C, and 5C-1C configurations. The findings reveal critical convective heat transfer coefficient values are necessary to maintain battery temperature within the targeted range, ensuring effective and continuous use of PCMs. Moreover, the impact of different PCMs, specifically OM42, n-Heneicosane, and n-Docosane, on thermal management during these cycles is assessed. This research provides essential insights for optimizing thermal management systems in LIBs for EVs, enhancing both performance and safety.