▎ 摘　　要

NOVELTY - A graphene/graphite composite cathode material preparing method involves preparing large sized graphene oxide by mixing flake graphite with sulfuric acid and nitric acid, stirring, filtering, washing, drying, adding potassium permanganate and sulfuric acid, incubating, cooling, adding hydrogen peroxide solution, centrifuging and drying to obtain large-sized graphene oxide. The large-sized graphene oxide is added to deionized water and stirred to obtain mixture of large-sized graphene oxide and graphite, followed by placing mixture in annealing furnace to obtain the finished product. USE - Method for preparing graphene/graphite composite cathode material. ADVANTAGE - The method enables preparing composite cathode material with high discharge capacity. DETAILED DESCRIPTION - A graphene/graphite composite cathode material preparing method involves preparing large sized graphene oxide by mixing 300-500 mu m diameter flake graphite with mixture of sulfuric acid and nitric acid at volume ratio of 3 g:400-450 ml, stirring at a speed of 300 rpm for 24-48 hours and filtering to obtain a black powder. The black powder is washed with distilled water for 3-5 times and drying at 60-80 degrees C for 12-24 hours to obtain dried black powder. The dried black powder is placed in microwave oven at 500-1000 W for 60-80 seconds to obtain worm-like graphite. The worm-like graphite is added with potassium permanganate and 98% sulfuric acid, placed in ice bath for 1-2 hours to give mixture A. The mixture A is incubated at 30-40 degrees C for 1-3 hours, added with deionized water, placed at 90-95 degrees C for 30-50 minutes and cooled at room temperature to obtain a mixture B. The mixture B is added with 35% hydrogen peroxide solution, stirred at room temperature for 10-30 minutes to give a dilute aqueous solution of graphite oxide. The dilute aqueous solution of graphite oxide is stirred at a speed of 6000-10000 rpm for and centrifuged to obtain precipitate. The precipitate is dried at 60-80 degrees C for 12-48 hours to obtain large-sized graphene oxide. The large-sized graphene oxide is added to deionized water to obtain graphite oxide dilute solution having concentration of 0.5-2 mg/ml. The graphite oxide dilute solution is added to deionized water, treated under ultrasonic power at 500-1000 W for 2-5 hours, stirred at speed of 200-500 rpm for 2-5 hours to obtain graphite suspension having concentration of 0.5-2 mg/ml. The graphite oxide dilute solution is dropped in graphite suspension with a dropping speed of 60-120 drops/minute, ultrasonicated at 500-1000 W for 2-3 hours and stirred at a speed of 200-500 rpm for 24-48 hours to obtain mixture of large-sized graphene oxide and graphite, followed by placing mixture of large-sized graphene oxide and graphite in high-temperature annealing furnace at 800-1000 degrees C for 1-5 hours under argon atmosphere to obtain the finished product, where the volume ratio of sulfuric acid and nitric acid is 3:1, the quality ratio of worm-like graphite and potassium permanganate is 1:5, the quality ratio of worm-like graphite and sulfuric acid is 1 g:200 ml, the quality ratio of worm-like graphite and deionized water is 1 g:130-140 ml, the volume ratio of mixture B and 35% hydrogen peroxide solution is 50:1-2, and the volume ratio of graphite oxide and graphite suspension liquid is 1:17-99.