▎ 摘　　要

NOVELTY - A magnesium oxide nanocrystal-coated graphene composite material comprises lamellar-structured magnesium oxide-surface coated graphene having thickness of 5-10 nm. USE - Magnesium oxide nanocrystal-coated graphene composite material used for thermal insulation material. ADVANTAGE - The composite material has simple structure, high efficiency, low cost huge potential for industrial production, low electrical conductivity, and high thermal conductivity. DETAILED DESCRIPTION - An INDEPENDENT CLAIM is included for preparation of composite material comprising adding graphite oxide into deionized water, ultrasonically dispersing for 0.5-2 hours to obtain graphene oxide solution, adding soluble magnesium salt, heating to 60-100 degrees C while stirring, dropping alkaline solution, refluxing for 4-12 hours, suction-filtering, and drying filtrate; and ultrasonically dispersing in deionized water for 0.5-2 hours, adding reducing agent while stirring, heat-refluxing to 60-100 degrees C for 3-24 hours, filtering, drying, and calcining to 500-700 degrees C for 2-5 hours.