Experimental Evaluation of a Graphite/MXene‐Based Composite Phase Change Material for Thermal Management in 3S3P Lithium‐Ion Battery Pack

Proper temperature management plays a critical role in ensuring the safety, reliability, and long‐term performance of lithium‐ion battery (LIB) systems, particularly under high discharge rates where excessive heat is generated. Inadequate thermal regulation can lead to faster degradation, inconsistent performance, and safety risks. This study introduces a novel thermally stable composite phase change material (TS‐CPCM) aimed at improving the heat management of a 3S3P LIB pack. The TS‐CPCM is formulated using lauric acid as the phase change medium, integrated with graphite powder, MXene nanosheets and encapsulated in melamine formaldehyde resin to improve thermal conductivity, stability, and prevent leakage. Five formulations are developed and analysed for their thermal conductivity, phase transition behaviour, and stability. Among them, TS‐CPCM 5 exhibited the best performance with a high decomposition temperature of 280°C, thermal conductivity of 0.754 W/m K and strong shape stability. When applied to a 3S3P battery pack, reduced the maximum temperature ( T max ) to 49.33°C and minimized temperature difference (Δ T max ) to 3.91°C at 3C discharge rate, representing reduction of 12.79°C and 1.81°C, respectively, compared to natural air cooling. These results confirm TS‐CPCM 5 effectively enhances battery thermal management and performance under high stress conditions.