Tunable Graphene Frameworks Enable Advanced Phase Change Composites with both Ultrahigh Thermal Conductivity and Latent Heat

Abstract Developing advanced phase change materials (PCMs) with simultaneously enhanced thermal conductivity and preserved large latent heat is critical for efficient thermal management of electronics, enabling rapid heat harvesting within narrow temperature windows. Incorporating prefabricated high‐thermal‐conductivity frameworks into organic PCM matrices represents the most promising strategy to boost heat transfer while retaining intrinsic energy storage capacity. However, conventional casting methods face fundamental limitations: strong interlayer interactions and gravity‐induced densification hinder the construction of controllable nanosheet frameworks. Herein, a solvent‐surface‐tension‐regulated approach is proposed to fabricate hierarchically aligned graphene frameworks. The resulting eicosane‐based composite achieves an exceptional in‐plane thermal conductivity of 71.6 W m ⁻¹ K ⁻¹ at 27.8 vol.% graphene loading while maintaining a high latent heat of 123.8 J g ⁻¹ . Capillary channels within the oriented framework simultaneously enhance eicosane absorption capability from release. Through infrared thermography, finite element simulations, and performance benchmarking, superior thermal conduction and phase transition kinetics are validated. This work establishes a new paradigm for constructing orientation‐controlled thermal‐conductive networks, advancing next‐generation PCM composites in thermal management for high‐power electronics.