Hybrid PCM–Liquid Cooling System with Optimized Channel Design for Enhanced Thermal Management of Lithium–Ion Batteries

The increasing demand for high-efficiency cooling technologies necessitates improved methods to prevent degradation and ensure reliable operation of lithium–ion batteries. Conventional PCM (phase change material)-based cooling systems are limited by low thermal conductivity and uneven phase change processes, which lead to non-uniform thermal distribution and diminished performance. In response to these challenges, this study introduces a hybrid thermal management system that combines an indirect liquid-cooling structure with multiple cooling channel configurations within a PCM-based battery pack. Numerical simulations were conducted to systematically assess the thermal performance of the proposed design. Experimental validation with various cooling media showed that PCM achieved the greatest reduction in temperature (47%) and the longest isothermal duration (56 min) under air-cooled conditions, surpassing thermally conductive adhesive (40%) and silicone oil (26%) for temperature decrease. Vertical temperature differentials were effectively reduced, staying below only 2 °C for silicone oil and reaching a maximum of 4 °C for PCM. Phase change evaluation indicated that after 30 min of operation, only 37% of the PCM volume had melted, highlighting localized constraints in heat transfer. Comparative analysis among four liquid-cooling channel arrangements (A–D) and a standalone PCM system demonstrated that configuration D exhibited the highest cooling capability, lowering the battery surface temperature by as much as 9 °C (17.8%). Flow rate analysis determined that increases above 0.2 L/min resulted in only modest thermal improvements (<1 °C), with 0.108 L/min identified as the most efficient rate. Relative to PCM-only designs, the advanced hybrid cooling system achieved significantly enhanced thermal regulation and temperature uniformity, underscoring its promise as a superior solution for lithium–ion battery thermal management.