▎ 摘　　要

NOVELTY - Preparing nitrogen-containing doped graphene comprises e.g. (1) adding concentrated sulfuric acid to graphite powder, mixing with nitric acid after 20 minutes, slowly adding potassium permanganate; heating, stirring; heating to 60 degrees C, stirring for more than 6 hours, heating solution to 90 degrees C for half hour; cooling the solution to below 10 degrees C, adding ice cubes, cooling to 0 degrees C; adding hydrogen peroxide, solution immediately emits large number of bubbles and turns into golden yellow, at this time, solution is graphene oxide; and (2) subjecting the solution obtained in the step (1) to ultrasonic treatment, adding aqueous ammonia to solution for dilution, so that pH of the solution is 7, heating mixture in water bath, centrifuging the solution, repeated centrifuging for 7-8 times, centrifuging and drying to obtain nitrogen-containing doped graphene product. USE - The doped graphene is useful for manufacturing lithium battery cathode (claimed). ADVANTAGE - The method: is simple, and economical. The doped graphene: has large specific surface area, relatively good film, more uniform surface, good conductivity and more excellent cycle performance; and can greatly improves lithium ion battery capacity. DETAILED DESCRIPTION - Preparing nitrogen-containing doped graphene comprises (1) adding 200 g concentrated sulfuric acid to 2 g graphite powder, mixing with 20 ml nitric acid after 20 minutes, slowly adding 12 g potassium permanganate; heating to 45 degrees C, stirring for 40-60 minutes; heating to 60 degrees C, stirring for more than 6 hours, heating the solution to 90 degrees C for half hour; cooling the solution to below 10 degrees C, adding ice cubes, cooling to 0 degrees C; adding hydrogen peroxide, solution immediately emits large number of bubbles and turns into golden yellow, at this time, solution is graphene oxide; where the concentration of hydrogen peroxide used is 30%, and the potassium permanganate content is greater than 99.5%; and (2) subjecting the solution obtained in the step (1) to ultrasonic treatment, adding aqueous ammonia to solution for dilution, so that pH of the solution is 7, heating mixture in water bath for 12 hours, centrifuging the solution for 5 minutes under 1100 revolutions/minute, repeated centrifuging for 7-8 times, centrifuging and drying to obtain nitrogen-containing doped graphene product; where the water bath is heated in high temperature reactor at temperature of 190 degrees C. An INDEPENDENT CLAIM is also included for manufacturing lithium battery cathode by using nitrogen-containing doped graphene comprising (A) using slurry coating method for electrode preparation, dissolving the active material nitrogen-containing doped graphene, superconducting graphite, and binder polyvinylidene difluoride (PVDF) in N-methyl-2-pyrrolidone (NMP) according to mass ratio of 8:1:1, and stirring for 30 minutes to obtain slurry, carefully applying the electrode material slurry evenly on carrier-carrying copper foil with blade; treating in vacuum drying oven at 80 degrees C for 8 hours, drying and pressing into electrode sheets; and (B) using battery case, using lithium metal piece as anode in vacuum glove box, assembling anode shell, electrode sheet, diaphragm, spring piece, lithium piece, gasket, appropriate electrolyte solution and cathode case into button battery, and sealing the battery with manual sealing machine.