▎ 摘　　要

NOVELTY - Preparing a silica-graphene composite material by supercritical carbon dioxide fluid comprises (i) introducing the crystalline flake graphite by Hummers method and freezing and drying, (ii) mixing ethyl orthosilicate to the graphite oxide, adding the mixture and balls into a ball milling tank, vacuumizing, pumping, (iii) finishing the reaction, cooling to room temperature, adding the carbon dioxide gas into the high pressure ball tank, removing the liquid from the ball milling tank, placing polytetrafluoroethylene into hydrothermal kettle, reacting with de-ionized water, placing the product into 0.1 mol/l diluted hydrochloric acid solution, soaking, filtering and drying, (iv) heating the product to carbonize at the heating speed of 1-20 degrees C /minutes under the protection of nitrogen or argon gas, carbonizing, cooling and grinding to obtain silicon dioxide/graphene composite material. USE - The composite material is useful for lithium metal batteries (claimed). ADVANTAGE - The method has good batch, small silica particles, uniform distribution and strong transmission ability of lithium ion. DETAILED DESCRIPTION - Preparing a silica-graphene composite material by supercritical carbon dioxide fluid comprises (i) introducing the crystalline flake graphite by Hummers method to obtain oxidized graphene and then freezing and drying, (ii) mixing the ethyl orthosilicate to the graphite oxide, adding the mixture and balls into a ball milling tank according to a certain proportion into high-pressure, vacuumizing the high-pressure milling, pumping the carbon dioxide into high pressure ball milling, (iii) finishing the reaction, cooling to room temperature, adding the carbon dioxide gas into the high pressure ball tank, removing the liquid from the ball milling tank, placing the polytetrafluoroethylene into hydrothermal kettle, reacting with de-ionized water at 100-200 degrees C for 6-60 hours, placing the product into 0.1 mol/l diluted hydrochloric acid solution, soaking for 3-48 hours, filtering and drying and (iv) heating product to 400-1000 degrees C to carbonize at the heating speed of 1-20 degrees C /minutes under the protection of nitrogen or argon gas, where the heat preservation time is 0.5-12 hours, carbonizing, cooling and grinding to obtain silicon dioxide/graphene composite material.