Improved heat dissipation of high-rate lithium-ion battery using hybrid composite phase change material and nanofluid cooling

The rapid growth of electric vehicles has intensified the need for advanced thermal management strategies capable of regulating both elevated temperature rise and temperature non-uniformity in high-rate lithium-ion batteries. To address these challenges, the present study proposes a hybrid Battery Thermal Management System (BTMS) that integrates composite phase change material (CPCM) with novel liquid cooling configuration featuring ternary hybrid nanofluid flows through converging, twisted channels possessing a Reuleaux cross-section. A coupled electrochemical–thermal numerical model is developed to examine the system performance under aggressive discharge conditions. Results indicate that the hybrid BTMS substantially reduces the maximum cell temperature compared with CPCM only and liquid based cooling, achieving an additional 2 K reduction due to the enhanced convective transport generated by the twisted, converging channel geometry. Incorporation of the ternary nanofluid (Al₂O₃–Fe₃O₄–SiO₂/water) further enhances heat removal, lowering T _max by 3.4 K at ϕ = 5% and limiting CPCM liquid fraction to 0.80, thereby maintaining latent-heat absorption throughout discharge process. Increasing coolant flow from 0.1 × 10⁻³ to 0.5 × 10⁻³ kgs⁻¹ yielded an additional 7 K drop in T _max . Alternating-flow configuration yields a notable improvement in temperature uniformity, reducing ΔT by up to 1.23 K relative to unidirectional flow. Alternating flow direction provided further gains, and melting-pattern analysis confirmed anisotropic heat transport within the pouch cell.