Advanced battery thermal management: Synergistic integration of heat pipes and two-phase immersion cooling for lithium-ion batteries

• Novel hybrid BTMS integrates heat pipes & two-phase immersion cooling for Li-ion batteries. • Superior cooling of T max rise <5.1°C & Δ T max <1.8°C even at 9C discharge was achieved. • Excellent durability with T max rise <0.3°C & 85.5% SOH after 1200 cycles was achieved. • Five heat pipes with ≥80% immersion depth keep T<34.9°C under 9C operation. With the escalating energy density of lithium-ion batteries, thermal-driven issues including capacity fade and thermal inconsistency have become critical challenges. This study develops a novel and cost-effective battery thermal management system (BTMS) integrating heat pipes with two-phase immersion cooling to address these limitations. Five heat pipe-based thermal management strategies are systematically compared: air cooling, liquid cooling, enhanced counterflow liquid cooling, phase change material cooling, and two-phase immersion cooling. The proposed system demonstrates superior performance, achieving optimal temperature control with the maximum temperature ( T max ) rise below 5.1°C and maximum temperature difference (∆ T max ) under 1.8°C even at 9C discharge. Long-term cycling tests reveal the system’s outstanding durability, maintaining temperature rise below 0.3°C ( T max ) and 0.2°C (∆ T max ) after 1200 cycles while remaining 85.5% state-of-health, outperforming conventional designs. Parametric studies identify an optimal configuration comprising five heat pipes with immersion depth ≥80%, which maintains temperatures below 34.9°C even under extreme 9C operating conditions. These findings provide critical design guidelines for next-generation BTMS, highlighting the synergistic benefits of heat pipe conduction and two-phase immersion boiling for battery applications.