Segmented fin design for air-cooled prismatic battery packs under non-uniform convective heat flux

Thermal management of lithium-ion batteries remains challenging due to non-uniform convective heat flux during operation, which leads to localized hotspots that accelerate degradation and increase safety risks. Air cooling offers cost and reliability advantages, but its performance is limited by conventional integral fins. To address the above issue, the present study proposes a three-segment fin structure with tailored height and thickness distributions. A uniform experimental design (UED)-a statistical method for efficient multi-factor experimental planning-is employed to screen 30 representative parameter combinations across the six geometric variables. Coupled CFD simulations and multivariate nonlinear regression are conducted to establish a quantitative relationship between fin geometry and thermal performance. Results show that the lower fin thickness ( d ₃) has the dominant influence, and the influence of geometric parameters is nonlinear with significant interactions. Compared with the integral fin, the optimized segmented fin reduces the maximum temperature by 4.0 °C (8.8%) to 41.6 °C, lowers the battery pack temperature difference by 3.2 °C (46%) to 4.9 °C, and decreases the thermal resistance by 37.7%. The convective heat transfer coefficient increases by 12.5% to 56.7 W/(m 2 ·K), while the pressure drop slightly decreases. Experiments confirm these trends: the segmented fin reduces thermal resistance by 44% and pressure drop by 7%. The proposed segmented fin provides a complementary solution for forced air cooling, balancing thermal performance, low flow resistance, and conventional manufacturability.