Eco-friendly and large porosity wood-derived SiC ceramics for rapid solar thermal energy storage

Solar thermal energy storage based on phase change materials (PCMs) plays a significant role in overcoming the intermittent and fluctuating nature of solar irradiation. However, the weak solar absorptance, intrinsic low thermal conductivity, and leakage problems preclude efficient solar energy storage harvesting and storage. Herein, eco-friendly, anisotropic, large porosity wood-derived SiC ceramics is proposed to overcome the above bottleneck problems and achieve rapid solar thermal energy storage. We report a synergetic strategy to fabricate composite phase change materials (CPCMs) with high thermal conductivity and large energy storage density by partially removing the interwoven lignin and hemicellulose from natural wood. The porosity of the porous wood-derived SiC ceramics can be increased from 55% to 80%, beyond the porosity limitation of conventional wood. Vertically aligned channels and compact SiC grains serve as thermal transport highways and enable resultant CPCMs to exhibit a high thermal conductivity of 31.2 W/mK even at a porosity of up to 80%. The solar absorptance of proposed composites (89%) is significantly higher than that of pure PCMs, enabling them to capture solar energy effectively. This work provides a synergetic strategy for achieving efficient solar energy harvesting, fast conversion, and high-density storage simultaneously via proposed eco-friendly and large porosity wood-derived SiC ceramics-based phase change composites.