▎ 摘　　要

NOVELTY - A graphite layer filled lithium iron phosphate composite nano material preparing method involves dispersing graphene and surfactant in ethylene glycol to prepare suspension containing graphene. The suspension is added with lithium iron phosphate and graphene. The resultant suspension is added with lithium hydroxide, lithium acetate, lithium carbonate or lithium nitrate, and ferrous chloride, ferrous sulfate, ferrous phosphate and ferrous citrate, phosphoric acid, ammonia dihydrogen phosphate and diammonium phosphate under ultrasonic treatment to obtain a mixture. USE - Method for preparing graphite layer filled lithium iron phosphate composite nano material for use in an anode material of the lithium ion battery. ADVANTAGE - The method enables preparing graphite layer filled lithium iron phosphate composite nano material with sandwich overlapped structure, and improving charging and discharging performance of the lithium ion battery in a simple manner. DETAILED DESCRIPTION - A graphite layer filled lithium iron phosphate composite nano material preparing method involves dispersing graphene and surfactant at a mass ratio of 1:1 in ethylene glycol to prepare suspension containing 0.29-2.29 g/l graphene. The suspension is added with lithium iron phosphate and graphene at a mass ratio of 1:0.5-5 according to molar ratio of lithium, iron and phosphate at 2.7:1:1. The resultant suspension is added with lithium hydroxide, lithium acetate, lithium carbonate or lithium nitrate, and ferrous chloride, ferrous sulfate, ferrous phosphate and ferrous citrate, phosphoric acid, ammonia dihydrogen phosphate and diammonium phosphate under ultrasonic treatment for 5-10 minutes at room temperature to obtain mixture. The mixture is stirred at 30-80 degrees C for 2-6 hours by applying magnetic force to obtain precursor solution. The precursor solution is placed in a kettle to carry out intrinsic reaction at 150-200 degrees C for 4-12 hours to obtain supernatant. The supernatant is washed using de-ionized water to adjust pH of the supernatant to 7. The washed supernatant is filtered to obtain a filtrate. The filtrate is crushed to powder. The powder is calcined at 60-120 degrees C and dried for 8-12 hours. The dried powder is transferred in a quartz boat, which is placed in a tubular furnace with argon gas flow rate of 100-300 ml/minute for 5-30 minutes. The resultant powder is heated to 400-600 degrees C at a heating rate of 7.5-10 degrees C/minute for 0.5-3 hours under protection of argon. The heated powder is cooled at a cooling rate of 5-10 degrees C/minutes till room temperature to obtain a finished product, where the surfactant comprises sodium dodecylbenzenesulfonate, sodium dodecyl sulfate and sodium III-tetradecyl dimethyl sulfopropyl betaine.