▎ 摘　　要

NOVELTY - Preparing high performance lithium iron phosphate/three-dimensional graphene composite material by change in morphology and size of iron phosphate, involves preparing graphite oxide gel by using improved Hummers method. The prepared graphite oxide is placed in a dialysis bag, dialyzed in deionized water, and replaced with water for 3-5 times per day, after 4-7 days, and it is changed to freeze-drying for 5-7 days to obtain solid graphite oxide. The water is added to obtain a graphite oxide suspension with a concentration of 1-10 milligram per liter. The 0.001-0.1 mole iron source and 0.001-0.1 mole phosphate are dissolved in 30-50 milliliter deionized water separately, mixed two solutions uniformly, adjusted pH value to 2-3 with 0.5-5 mole per liter ammonia water, stirred for 1-5 hours, and then kept reaction solution into 50-100 milliliter reaction vessel of the lining is tempered at a high temperature, after cooling to room temperature. USE - Method for preparing high performance lithium iron phosphate/three-dimensional graphene composite material by change in morphology and size of iron phosphate. ADVANTAGE - The method enables to prepare high performance lithium iron phosphate/three-dimensional graphene composite material by change in morphology and size of iron phosphate which is simple to process, eco-friendly and cost-effective, and good crystallization, uniform distribution, small size and three-dimensional graphene coating, and obviously improves electrochemical performance of material. DETAILED DESCRIPTION - The product is suction filtered, washed with deionized water and absolute ethanol for 3-5 times, and dried at 60-100 degrees C for 24-48 hours to obtain a pale green powder. The obtained pale green powder is weighed in 10-100 milliliter of obtained graphite oxide suspension at a concentration of 1-10 milligram per liter, stirred at room temperature for 1 hour, and then added 0.01-0.1 gram nickel chloride hexahydrate, after ultrasonic treatment for 2 hours, it is placed in a 50-100 milliliter Teflon-lined stainless steel autoclave, after the reaction at high temperature, it is naturally cooled to room temperature, and the gel is taken out from the autoclave and washed with deionized water and absolute ethanol for 3-5 times, after freezing for 24-8 hours. The three-dimensional graphene gel is placed in the freezer. The dryer is placed in a tube furnace with argon gas for 48-96 hours, and heated at 350-750 degrees C at a heating rate of 5-10 degrees C per minute and calcined for 2-10 hours to obtain a black powder. The obtained 0.1-1 gram black powder is weighed in 1-5 millimole lithium source and 0.1-1 millimole carbon source, added 10 milliliter of absolute ethanol and ground thoroughly to powder, and then passed through the tube furnace filled with argon gas at a heating rate of 5-10 degrees C per minute, it is heated at 350-550 degrees C for 5-10 hours, and then naturally cooled to room temperature. The 0.1-1 millimole carbon source is added to the mixture, and then the tube is filled with argon gas in the furnace, the temperature is raised to 450-750 degrees C at a heating rate of 5 to 10 degrees C / min and calcined for 5-12 hours to obtain a lithium iron phosphate/three-dimensional graphene composite material. The lithium source is lithium acetate, lithium carbonate and one or more of lithium hydroxide. The iron source is one or more of ferric chloride, ferric nitrate and ferric sulfate. The phosphate is ammonium phosphate, ammonium dihydrogen phosphate and hydrogen phosphate. The carbon source is one or more of ascorbic acid, glucose, and sucrose.