▎ 摘　　要

NOVELTY - Preparing carbon-coated lithium manganese iron phosphate graphene composite nano material comprises taking concentrated sulfuric acid, and taking graphite, sodium nitrate and potassium permanganate, adding concentrated sulfuric acid, graphite, sodium nitrate and potassium permanganate into a container, mixing and reacting, cleaning, drying, mixing, performing ultrasonic; taking lithium source, phosphorus source and blend of manganese source and iron source and stirring, dissolving; mixing admixture of manganese source and the iron source, dissolving, diluting; dispersing phosphorus source in ethylene glycol, stirring, removing; adding the dried graphene composite lithium iron phosphate manganese precursor dispersed into the poloxamer solution, drying, pre-calcining the obtained solid product, placing the solid product contained into the container and mixing gas of argon gas and hydrogen, and heating the temperature to the sixth preset temperature for sintering. USE - The method is useful for preparing carbon-coated lithium manganese iron phosphate graphene composite nano material. DETAILED DESCRIPTION - Preparing carbon-coated lithium manganese iron phosphate graphene composite nano material comprises (i) taking concentrated sulfuric acid, and taking graphite, sodium nitrate and potassium permanganate according to the mass ratio is 1-2:1-2:3-5, where the graphite, sodium nitrate and potassium permanganate, total mass of mass fraction of concentrated sulfuric acid is 20-30%, adding concentrated sulfuric acid, graphite, sodium nitrate and potassium permanganate into a container, uniformly mixing and reacting for the first predetermined time at a first preset temperature, placing the second pre-set time at the second preset temperature to obtain a first mixture, adding de-ionized water into the first mixture at a third predetermined temperature, reacting for a third preset time to obtain the second mixture, where the mass ratio of the first mixture to de-ionized water is 1:1-3, and then adding hydrogen peroxide, graphite total mass fraction of concentrated sulfuric acid, sodium nitrate and potassium permanganate is 25-35 % into second mixture, cleaning with dilute hydrochloric acid and de-ionized water, drying to obtain graphite oxide, finally adding graphite oxide into de-ionized water, mixing, performing ultrasonic treatment to obtain oxidized graphite alkene aqueous suspension, where the graphite oxide accounts for 20-50 % of de-ionized water with mass of graphite oxide and de-ionized water, (ii) taking lithium source, phosphorus source and blend of manganese source and iron source according to the mass ratio of 2-4:0.5-1.5:0.5-1.5, and stirring, dissolving the lithium source into glycol to obtain the third mixture, where the mass ratio of the lithium source to glycol is 1:20-50, adding the graphene oxide water suspension into the third mixture, where the mass ratio of lithium source and quality and glycol, oxidized graphite alkene aqueous suspension is 2-6:20-50, absorbing oxygen-containing functional group causes lithium+ and oxidized graphene aqueous solution with negative electricity on the graphene oxide surface by electrostatic force, (iii) mixing the admixture of manganese source and the iron source, dissolving in the de-ionized water to obtain a fourth mixture, adding the graphene oxide water suspension into the fourth mixture to obtain mixed solution, where the mass ratio of the oxide graphene suspension: admixture of manganese source and iron source, de-ionized water is 1:1-3:1-5, promoting manganese and ferrous ion absorbed after the graphene oxide aqueous suspension surface, finally using ethylene glycol, diluting the mixed solution to obtain a fifth mixture, where the mass ratio the graphene oxide water suspension of manganese source and iron source of admixture, de-ionized water and ethylene glycol is 1:1-3: 1-5:10-30, (iv) uniformly dispersing the phosphorus source in ethylene glycol to obtain a sixth mixture, where the mass ratio of the phosphorus and the ethylene glycol is 1:3-8, dropping the sixth mixture, stirring to obtain a seventh mixture in the third mixture, and adding the step three in the fifth mixture into the seventh mixture, stirring uniformly to obtain an eighth mixture, adding the eighth mixture into a vessel and reacting the fourth preset time in the fourth preset temperature, removing sulfate with poloxamer solution to obtain graphene composite lithium iron phosphate manganese precursor and (v) adding the dried graphene composite lithium iron phosphate manganese precursor dispersed into the poloxamer solution obtain a ninth mixture, where the mass ratio of the lithium iron phosphate manganese graphene composite precursor solution with poloxamer is 1:15 to -25, and then adding 20-30 % the lithium iron phosphate grapheme composite carbon manganese precursor mass percentage into ninth mixture, and drying at the fifth preset temperature, pre-calcining the obtained solid product, placing the solid product contained into the container and mixing gas of argon gas and hydrogen, and heating the temperature to the sixth preset temperature for sintering, where the volume ratio of the argon gas and hydrogen is 93-98:7-2 to obtain the carbon-encapsulated lithium iron phosphate manganese graphene composite nano material.