▎ 摘　　要

NOVELTY - Synthesizing carbon-coated lithium iron phosphate material comprises e.g. (1) mixing lithium source material, iron source material, phosphorus source material and auxiliary materials in the molar ratio of 0.2-5:1:0.9-2:0.2-5 to obtain the mixture A, the solid content of the mixture A is 1-30%, (2) adding mixture A in a reaction kettle for solvothermal reaction to obtain mixture B, where the pressure of reaction kettle is 0.1-35 MPa, and the temperature is 45-650 degrees C, (3) performing solid-liquid separation of mixture B to obtain a solid mixture C and a liquid mixture D, and drying the solid mixture C, (4) mixing and drying the dried mixture C, carbon source and additives to obtain mixture E, where the mass ratio of the mixture C to the carbon source is 1:0.005-0.15, and (5) performing calcination of mixture E in a protective atmosphere at 600-900 degrees C at heating rate of 5 degrees C/minute for 1-25 hours to obtain a carbon-coated lithium iron phosphate material. USE - The method is useful for synthesizing carbon-coated lithium iron phosphate material. ADVANTAGE - The phosphate material has a discharge capacity at 20 degrees C of more than 70% of that at 25 degrees C, and 5C discharge capacity of more than 90% at 1C. DETAILED DESCRIPTION - Synthesizing carbon-coated lithium iron phosphate material comprises (1) mixing lithium source material, iron source material, phosphorus source material and auxiliary materials in the molar ratio of 0.2-5:1:0.9-2:0.2-5 to obtain the mixture A, the solid content of the mixture A is 1-30%, (2) adding mixture A in a reaction kettle for solvothermal reaction to obtain mixture B, where the pressure of the reaction kettle is 0.1-35 MPa, and the temperature is 45-650 degrees C, (3) performing solid-liquid separation of the mixture B to obtain a solid mixture C and a liquid mixture D, and drying the solid mixture C, (4) mixing and drying the dried mixture C, carbon source and additives to obtain the mixture E, where the mass ratio of the mixture C to the carbon source is 1:0.005-0.15, and the mass ratio of the mixture C to the additive is 1:0.002-0.05, (5) performing calcination of mixture E in a protective atmosphere at 600-900 degrees C at heating rate of 5 degrees C/minute for 1-25 hours to obtain a carbon-coated lithium iron phosphate material, where the auxiliary materials includes sulfuric acid, hydrochloric acid, nitric acid, oxalic acid, acetic acid, citric acid, sodium citrate, ascorbic acid, sodium ascorbate, sodium hydroxide, and/or ammonia, the solid-liquid separation method includes centrifugal separation, gravity sedimentation, pressure filtration separation, electric field magnetic field separation, and/or resin filtration separation, and the additives includes magnesium oxide, manganese oxide, titanium oxide, vanadium pentoxide, hydrogen peroxide, lithium oxide, lithium carbonate, lithium nitrate, lithium nitrite, lithium phosphate, lithium dihydrogen phosphate, niobium oxide, phosphoric acid, ammonium dihydrogen phosphate, diammonium phosphate, ammonium phosphate, yttrium oxide, and/or gallium oxide. INDEPENDENT CLAIMS are also included for: (1) carbon-coated lithium iron phosphate material; (2) lithium ion battery anode comprising carbon-coated lithium iron phosphate material; (3) preparing lithium salt comprising (i) mixing lithium source material, iron source material, phosphorus source material and auxiliary materials in the molar ratio of 0.2-5:1:0.9-2:0.2-5 to obtain the mixture A, where the solid content of the mixture A is 1-30%, (ii) adding mixture A in a reaction kettle for solvothermal reaction to obtain mixture B, where the pressure of the reaction kettle is 0.1-35 MPa, and the temperature is 45-650 degrees C, (iii) performing solid-liquid separation of mixture B to obtain solid mixture C and liquid mixture D, and (iv) adding a soluble lithium salt or a precipitating agent to the liquid mixture D to obtain a lithium salt material, where the soluble lithium salt including lithium sulfate, lithium chloride, lithium nitrate, lithium phosphate, lithium dihydrogen phosphate, and/or lithium acetate, and the precipitating agent including sodium carbonate, sodium bicarbonate, sodium phosphate, sodium monohydrogen phosphate, sodium dihydrogen phosphate, sodium oxalate, and/or oxalic acid; and (4) method for recycling the anode material on the waste anode sheet after disassembling a scrapped lithium iron phosphate battery comprising (I) mixing 1 mol scrapped lithium iron phosphate anode material and 2-12 mol additives to obtain a mixture A1, and controlling the solid content of the mixture A1 to 1-30%, where the additive includes phosphorus source, iron source, lithium source and/or auxiliary materials, (II) adding the mixture A1 in a reaction kettle for solvothermal reaction to obtain a mixture B1, where the pressure of the reaction kettle is 0.1-35MPa, and the temperature is 45-650 degrees C, (III) separating the mixture B1 into solid and liquid to obtain a solid mixture C1 and a liquid mixture D1, and drying the solid mixture C1, (IV) mixing and drying the dried mixture C1, carbon source and additives to obtain a mixture E1, where the mass ratio of the mixture C1 to the carbon source is 1:0.005-0.15, and the mass ratio of the mixture C1 to the additive is 1:0.002-0.05, (V) performing calcination of the mixture E1 in a protective atmosphere at 600-900 degrees C at heating rate of 5 degrees C/minute for 1-25 hours to obtain a carbon-coated lithium iron phosphate material, where the auxiliary material includes sulfuric acid, hydrochloric acid, nitric acid, oxalic acid, acetic acid, citric acid, sodium citrate, ascorbic acid, sodium ascorbate, sodium hydroxide, and/or ammonia, the solid-liquid separation methods include centrifugal separation, gravity sedimentation, pressure filtration separation, electric field and magnetic field separation, and resin filtration separation, and the additives include magnesium oxide, manganese oxide, titanium oxide, vanadium pentoxide, hydrogen peroxide, lithium oxide, lithium carbonate, lithium nitrate, lithium nitrite, lithium phosphate, lithium dihydrogen phosphate, niobium oxide, phosphoric acid, ammonium dihydrogen phosphate, diammonium phosphate, ammonium phosphate, yttrium oxide, and/or gallium oxide.