High-directional thermally conductive stearic acid/expanded graphite - Graphene films for efficient photothermal energy storage

Phase change materials (PCMs) have garnered significant attention as a prospective solution for photothermal energy storage, attributed to their notable energy density. Nonetheless, the constrained thermal conductivity of PCMs leads to delayed heat storage from the photothermal conversion surface, causing a build-up of heat at the surface and significant heat dissipation into the surroundings. Additionally, the risk of PCM leakage poses a significant challenge to the long-term reliability of these systems. To address these issues, we propose a novel approach that synergistically utilizes expanded graphite-encapsulated phase change material (stearic acid) in conjunction with highly directional graphene films, co-assembled through hot pressing, to create laminated phase change composites with superior thermal conductivity. This innovative approach significantly enhances the thermal conductivity of the phase change composite, achieving an impressive 27.1 W/(m·K) with only 12.6 wt% of thermal filler. Remarkably, an exceptionally high thermal conductivity of 105.6 W/(m·K) can be attained with less than 26.4 wt% thermal filler. Moreover, we have introduced an advanced high-photothermal conversion layer that synergizes with our directionally conductive phase change composite. This strategic combination culminates in the creation of a highly efficient integrated photothermal storage device, markedly boosting the overall efficiency of photothermal energy integration. This innovative design offers a practical and scalable solution for high-capacity and high-intensity solar thermal energy storage.