▎ 摘　　要

NOVELTY - A flexible nano-cellulose-graphene composite film comprises 0.1-90 %mass graphene and 10-99.9 %mass nano-cellulose. USE - Flexible nano-cellulose-graphene composite film (claimed). ADVANTAGE - The flexible nano-cellulose-graphene composite film has parallel thermal conductivity of 2 W/m.K or more, vertical thermal conductivity of 0.3 W/m.K or less, and thermal conductivity anisotropy ratio of 5 or more. The agglomeration does not occur between the graphene sheets in the composite film. DETAILED DESCRIPTION - An INDEPENDENT CLAIM is included for preparation of flexible nano-cellulose-graphene composite film, which involves adding graphene oxide and nano-cellulose separately to a dispersant, obtaining 0.05-5 mg/mL graphene oxide dispersion and 0.05-5 mg/mL nano-cellulose dispersion, ultrasonically-dispersing, mixing two dispersions in volume ratio of 1:1, stirring, obtaining 0.05-5 mg/ml nano-cellulose-graphene dispersion (d1), adding dispersion (d1) to a reducing agent, heating, uniformly stirring, cooling to room temperature, obtaining nano-cellulose-graphene dispersion (d2), centrifugally-degassing the resultant product, vacuum-filtering, obtaining composite film, transferring the resultant product to an oven and vacuum drying. The dispersant is deionized water.