▎ 摘　　要

NOVELTY - Preparing lithium iron phosphate/graphene composite material comprises e.g. adding waste lithium iron phosphate cathode piece into ethyl acetate and alcohol mixed organic solvent, filtering, drying, then adding into planetary ball mill, calcining with lithium carbonate, quenching calcined material in water, adding natural graphite flake graphite and sodium nitrate into sulfuric acid solution, then adding potassium permanganate under continuous stirring, adding nitric oxide, then centrifugally washing and drying, and then calcining to obtain final product. USE - The method is useful for preparing lithium iron phosphate/graphene composite material (claimed). ADVANTAGE - The method has simple preparation processes, and low cost; and has excellent conductivity. DETAILED DESCRIPTION - Preparing lithium iron phosphate/graphene composite material comprises (i) adding waste lithium iron phosphate cathode piece into ethyl acetate and alcohol mixed organic solvent, soaking, where volume ratio between ethyl acetate and alcohol is 1-10:1, then soaking with ultrasonic treatment, stirring speed at 150-180 revolution per minute for 0.5-3 hours, filtering, drying at 30-90 degrees C for 1-2h to obtain cathode material, (ii) adding cathode material obtained in step (i) into planetary ball mill for 0.5-10 hours, and ball mill rotating speed is 50-1000 revolution per minute, (ii) calcining the obtained product in step (ii) at a calcination temperature of 500-850 degrees C with lithium carbonate to obtain a calcined material, where calcined material is lithium, iron and phosphorus in a molar ratio of 0.95-1.1:0.9-1.1:0.9-1.1, (iv) quenching calcined material obtained in step (iii) in water at 0-50 degrees C and then drying at 30-120 degrees C for 0.5-10 hours, (v) calcining drying the material obtained in step (iv) with conductive carbon black at 500-850 degrees C for 8-30 hours under nitrogen gas atmosphere to obtain lithium iron phosphate material, where mass ratio between dried material and conductive carbon black is 1:0.01-2, (vi) adding natural graphite flake graphite and sodium nitrate into 1-10 mol/l sulfuric acid solution, then adding potassium permanganate under continuous stirring, reacting for 80-90 min, then controlling the reaction temperature to 0-45 degrees C, and then adding nitric oxide at a temperature of 80-90 degrees C for 40-60 minutes, then centrifugally washing and drying at 30-100 degrees C to obtain graphene oxide, and (vii) mixing lithium iron phosphate material obtained in step (v) and graphene oxide obtained in step (vi) in a mass ratio of 8-100:1, adding N-methyl-2-pyrrolidone as dispersing agent, and then calcining at 500-850 degrees C for 8-30 hours under nitrogen gas atmosphere to obtain final product.