▎ 摘　　要

NOVELTY - A graphene aerogel comprises an anisotropic graphene sheets having a regular and orderly three-dimensional porous network structure, and has density of 0.025-0.150 g/cm3, porosity of 75-99.5%, axial thermal conductivity of 0.5-2.5 W/mK, radial thermal conductivity of 0.1-0.5 W/mK, axial conductivity of 150-350 S/m, radial conductivity of 10-150 S/m, specific surface area of 50-900 m2/g, and compressive modulus of 1-30 MPa. The ratio of axial conductivity and radial conductivity, and ratio of axial thermal conductivity and radial thermal conductivity of the aerogel is 1.5-15:1. USE - Graphene aerogel is used in phase-change composite material for storing thermal energy (all claimed). ADVANTAGE - The graphene aerogel has excellent thermal, electrical and mechanical properties, and can be prepared by simple and environmentally-friendly process with reduced energy consumption under mild reaction condition. DETAILED DESCRIPTION - A graphene aerogel comprises an anisotropic graphene sheets having a regular and orderly three-dimensional porous network structure, and has micropores having a pore size of 2 nm or less, mesopores having a pore size of 2-50 nm, and a macropores having a pore size of more than 50 nm. The micropores and mesopores are mainly distributed in the pore walls of the macropores in a regular order. The graphene aerogel has density of 0.025-0.150 g/cm3, porosity of 75-99.5%, axial thermal conductivity of 0.5-2.5 W/mK, radial thermal conductivity of 0.1-0.5 W/mK, axial conductivity of 150-350 S/m, radial conductivity of 10-150 S/m, specific surface area of 50-900 m2/g, and compressive modulus of 1-30 MPa. The ratio of axial conductivity and radial conductivity, and ratio of axial thermal conductivity and radial thermal conductivity of the graphene aerogel is 1.5-15:1, each. The axial direction is a direction parallel to the cell wall of the cell in the nanoporous structure. The radial direction is a direction perpendicular to the cell wall of the cell in the nano-multi-cell structure. INDEPENDENT CLAIMS are included for the following: (1) preparation of graphene aerogel, which involves providing graphene oxide liquid crystals, orienting the graphene oxide liquid crystal to obtain long-range ordered graphene oxide liquid crystals, adding a crosslinking agent to the long-range orderly graphene oxide liquid crystal to obtain a graphene oxide hydrogel having a liquid crystal texture, covering the graphene oxide hydrogel with an aqueous solution of a reducing agent to obtain a graphene hydrogel, drying and annealing at a high temperature; (2) phase-change composite material; and (3) usage method of phase-change composite material for storing thermal energy.