Development of Highly Thermal Conductive Composites with Large Latent Heat

Investigating innovative methods for concurrently enhancing the thermal conductivity and preserving the high latent heat of phase change materials is crucial for improving their capacity to regulate the operating temperature of electronic devices by quickly collecting thermal energy within a small temperature range. Among these strategies, compositing the organic phase change matrix with prefabricated frameworks that provide high thermal conductivity and exceptional encapsulation capability is the most promising approach for efficiently boosting heat transfer while retaining its inherent high latent heat. Despite extensive efforts, constructing these frameworks using conventional casting methods remains challenging due to solid interlayer interaction and gravity-induced densification of high thermal conductivity nanosheet frameworks. In this study, a novel approach for the controllable casting of hierarchically aligned graphene frameworks was proposed by regulating the interface tension of the solvent, which imparted the eicosane matrix with a significantly enhanced thermal conductivity of up to 71.6 W m^-1K^-1 at 27.8 vol% graphene loading. Moreover, the constructed graphene-based framework featured numerous capillary channels that greatly enhanced the encapsulation capacity of the eicosane matrix, which exhibited a high composite latent heat of 129.6 J g^-1. We conducted visual and data-based characterizations as well as finite element-based simulations to confirm that our composites simultaneously improve thermal conduction and phase change matrix encapsulation capacity. We believe that our research will advance the construction paradigm of high thermal conductivity nanosheets toward controllable structures and contribute to enhancing the mechanical, electrical, and thermal properties of composites.