▎ 摘　　要

NOVELTY - A graphene microcrystal is three-dimensional network structure of chemically bonded graphene crystallites. The graphene crystallite is composed of graphene segment of sp2 carbon atoms. The graphene segments composed of sp2 carbon atoms are covalently bonded by sp3 carbon atom to form three-dimensional network structure. USE - Graphene microcrystal. ADVANTAGE - The environmentally-friendly graphene microcrystal has renewable resource and low production cost. DETAILED DESCRIPTION - An INDEPENDENT CLAIM is included for preparation of graphene microcrystals, which involves using lignin, extracting, melting, thermal cracking, carbonizing at high temperature, carrying out graphitization treatment, annealing and cooling the product.