Achieving high photo/electro-thermal efficiency and thermal anisotropy through oriented thermally conductive composite phase change material

The ability to improve the thermal conductivity of phase change materials (PCMs) is the key to widely promote the PCM in thermal energy storage. Usually adding high-conductivity materials to PCMs can enhance heat transfer and mitigate uneven temperature distribution but is typically accompanied by a substantial reduction in thermal storage density. Herein, we show a strategy for the modular fabrication of oriented thermally conductive composite phase-change material (OTC-CPCM), concurrently achieving directional thermal conduction and maintaining high thermal storage density. We improve thermal conductivity from 0.2 to 27.09 W/(m·K), and increase the anisotropy index of OTC-CPCM up to 3.43. This directional thermal transfer characteristics of the layered structures in OTC-CPCM enables an impressive photo-thermal conversion efficiency (~92.58 %) and electro-thermal conversion efficiency (~90.32 %), with only 7 % thermal storage density reduction. Different from the current photo-thermal conversion materials with directional thermal transfer characteristics presenting in powders, we can make an individual energy storage block with a dimensions of 40 mm × 40 mm × 40 mm (69 g) for practical photo/electro-thermal conservation and storage, which addresses the significant waste of wind and solar energy caused by their inherent instability and fluctuating electricity loads in photovoltaic/wind power systems.