A Recyclable Energy Storage Wood Composite with Photothermal Conversion Properties for Regulating Building Temperature

Abstract Addressing the challenges of energy storage liquid leakage and long‐term stability in energy storage is crucial for achieving sustainable energy efficiency. In this study, polymethyl methacrylate (PMMA) is innovatively employed as an encapsulation film on the surface of the wood‐based phase change material, resulting in a recyclable wood‐based composite energy storage material (PPW). A novel energy storage liquid (PCMs) composed of lauric acid (LA), capric acid (CA), and polyethylene glycol (PEG) is immersed in the pretreated porous wood frame through vacuum impregnation. The PCMs imparted a phase change temperature of 21.0 °C, which is close to human comfort levels, and a high energy storage efficiency of 31.6 J g −1 to the PPW. Additionally, the PCMs provided the PPW with a photothermal conversion efficiency of 29.3%. Even after 200 freeze‐thaw cycles, the energy storage properties of the PPW remained nearly unchanged. Therefore, utilizing PMMA as an effective encapsulation material is a viable approach to prevent leakage of the phase change solution and enhance the recyclability of the PPW. Furthermore, the transparency of PMMA preserves the natural appearance of the wood, thereby broadening the application potential of PPW in residential buildings, thermal energy storage, and solar thermal conversion systems.