Graphene‐Skinned Al ₂ O ₃ Enables High Thermal Conductivity Phase Change Composites for Thermal Management

ABSTRACT Phase change materials (PCMs) have exhibited significant application potential in thermal management and thermal energy storage, owing to their high latent heat and low cost. However, inherent drawbacks of certain PCMs (e.g., paraffin (PA)), such as low thermal conductivity (0.2 W·m ⁻¹ ·K ⁻¹ ) and liquid leakage during phase transition, lead to delayed thermal response and reliability issues, restricting their utilization in high‐precision thermal control scenarios. Herein, we propose an “interface enhancement” design strategy: constructing a composite system with graphene‐skinned alumina micropowder (G‐Al ₂ O ₃ ) as the cross‐scale thermal bridges to enhance the 3D thermally conductive skeleton of expanded graphite in PA phase change matrix. The high‐thermal‐conductivity network is synergistically coupled with the phase change medium during vacuum impregnation due to the well‐wetting behavior. The composite material achieves a thermal conductivity of 6.1 W·m ⁻¹ ·K ⁻¹ , representing a 2033% increase compared to pure PA, while retaining a high phase change latent heat of 210 J·g ⁻¹ . After 200 thermal cycles, the composite material exhibits a leakage rate of <5% and a latent heat attenuation rate of <2%. This study provides a novel approach for designing high‐efficiency thermal control materials, with potential applications in temperature stabilization of high‐power electronic devices and thermal storage systems for aerospace satellites.