Design of phase change composite with hierarchical energy-transfer pathway via laser-induced graphene for efficient energy storage, conversion, and utilization

To achieve efficient energy harvesting and utilization, phase change composites (PCCs) with high energy storage density, thermal conductivity, and photothermal conversion ability have always been a research focus. Herein, a three-dimensional (3D) porous laser-induced graphene supporting matrix with the plant leaf-mimetic network (PLMN) for loading phase change materials (PCMs) was fabricated by direct laser writing on polybenzoxazine resin (Poly(PH-ddm)). PLMN is designed to consist of laser-induced graphene (LIG) with both vein-like and mesophyll-like structures, the former one mainly responsible for efficient energy harvesting as well as fast heat flow transport and the latter one as the dominant part for high encapsulation of polyethylene glycol (PEG) PCM. The obtained plant leaf-mimetic composite (PLMC) exhibits a large latent heat of 162.3 J/g and high thermal conductivity of 1.18 W/m center dot K (391.67 % increment than pure PEG). PLMC also shows a high solar energy con-version efficiency of 84.1 %, which benefits from the well-designed PLMN structure as well as the thermal insulation effect of the resin layer. In addition, the resin layer provides mechanical support and flame-retardant function, ensuring the use safety of PLMC. The applications of PLMC for efficient utilization of solar energy and thermal management of electronics have been well-demonstrated. This work provides novel insights into the design and fabrication of PCCs with great potential in solar energy utilization and other thermal energy-related processes.