Optimising extended fin design and heat transfer coefficient for improved heat transfer and PCM recover time in thermal management of batteries

Abstract

The thermal sensitivity of lithium-ion batteries (LIBs), crucial for electric vehicles, poses a significant challenge, especially under harsh ambient conditions. This study introduces an innovative cooling strategy that combines phase change materials (PCMs) with active cooling to achieve uniform temperature distribution across LIBs and optimize recovery time for PCM solidification. Using the Newman, Tiedemann, Gu, and Kim (NTGK) model for numerical analysis, this study investigates the heat transfer behaviour of a single Li-ion cell equipped with PCM for passive cooling under different battery C-rates, ambient temperatures, PCM thickness, internal and external fins, and convective heat transfer coefficients during 3C–0C and 3C–1C discharging–charging cycles. The addition of a 2 mm layer of PCM to the cell results in a reduction of the maximum temperature by 28.2 °C at a discharging rate of 3C at 20 W/m²·K when compared to an uncooled, bare cell configuration at the ambient temperature of 30 °C. Adding six internal fins decreases the cell temperature by 0.63 °C and the PCM temperature by 0.73 °C at the ambient temperature of 30 °C. Furthermore, increasing the convective heat transfer coefficient to 100 W/m²·K and extending with 6 fins of 4 mm each reduces the maximum battery temperature by 40.63 °C, optimizing the solidification time of PCM to 800 s at an ambient temperature of 40 °C. The findings reveal that optimally configured extended fins integrated with PCM reduce peak temperatures during high C-rate operations and shorten the PCM recovery time during the discharging-standalone and discharging-charging phases, facilitating uninterrupted functionality across repeated cycles, even in extreme ambient environments.