From sawdust waste to high-value hierarchical ceramics-based phase change materials: Efficient dual functional thermal and solar energy storage

Latent heat thermal energy storage (LHTES) technology is gaining extensive attention due to its capability to balance supply and demand mismatch in solar energy utilization. However, phase change material as the core of storing latent heat still suffers from low thermal conductivity and poor shape stability, which severely restricts its practical application. Here, an eco-friendly strategy for achieving high-performance dual functional thermal and solar energy storage is proposed via turning wood processing waste into high-value hierarchical porous SiC ceramic-based composite phase change materials. The porosity of prepared porous SiC skeletons is highly adjustable from 59.4% to 90.2%, overcoming low porosity limitations of traditional wood materials and enabling tunable energy storage density for various applications. High thermal conductivity is achieved by benefiting from large grains and continuous skeletons with a value up to 37.93 and 1.87 W/(m K) for porosity of 59.4% and 90.2%, respectively. Excellent stabilities are demonstrated with only slight decreases of thermal conductivity and energy storage density over 1000 cycles and good anti-leakage properties are confirmed due to capillary adsorption forces induced by hierarchical pores. Benefiting from high thermal conductivity and high solar absorptance, fast and efficient solar thermal energy storage is successfully demonstrated. This work provides a new strategy for the high-value utilization of wood processing waste and efficient thermal/solar energy storage.