▎ 摘　　要

NOVELTY - Controllably synthesizing lithium iron phosphate composite electrode material by using nitrogen-doped graphene, involves using lithium hydroxide monohydrate (LiOH.H2O) as the raw material, using ethylene glycol as the solvent, stirring to form a homogeneous solution, then adding phosphoric acid (H3PO4) dropwise, until the pH value is 7±0.2, and then adding appropriate amount of graphene oxide dispersion to the solution, magnetically stirring, and then ultrasonically treating to get solution A, using ferrous sulfate heptahydrate as the raw material, ascorbic acid as the antioxidant, melamine as the nitrogen dopant, and deionized water as the solvent, stir evenly to obtain a transparent solution B, which is added solution B dropwise to solution A, and then stirred well. The mixed solution is subjected to solvothermal reaction. The resulting product is washed and dried in vacuum to obtain nitrogen-doped reduced graphene oxide/lithium iron phosphate. USE - Method for controllably synthesizing lithium iron phosphate composite electrode material by using nitrogen-doped graphene. ADVANTAGE - The method improves the electrical conductivity of the composite system by using nitrogen doping to reduce graphene oxide, also realizes the effective control of the crystal structure, morphology and particle size of lithium iron phosphate at the nitrogen doping site, and significantly improves rate performance of the composite electrode material and the reversible discharge specific capacity of the electrode material at a rate of 10C can reach 133.1 mAh/g under an appropriate nitrogen doping amount. DETAILED DESCRIPTION - Controllably synthesizing lithium iron phosphate composite electrode material by using nitrogen-doped graphene, involves using lithium hydroxide monohydrate (LiOH.H2O) as the raw material, using ethylene glycol as the solvent, stirring to form a homogeneous solution, then adding phosphoric acid (H3PO4) dropwise, until the pH value is 7±0.2, and then adding appropriate amount of graphene oxide dispersion to the solution, magnetically stirring, and then ultrasonically treating to get solution A, using ferrous sulfate heptahydrate as the raw material, ascorbic acid as the antioxidant, melamine as the nitrogen dopant, and deionized water as the solvent, stir evenly to obtain a transparent solution B, which is added solution B dropwise to solution A, and then stirred well. The mixed solution is subjected to solvothermal reaction. The resulting product is washed and dried in vacuum to obtain nitrogen-doped reduced graphene oxide/lithium iron phosphate. The nitrogen-doped reduced graphene oxide/lithium iron phosphate and glucose is dissolved in deionized water, and stirred to form a mixed solution. The mixed solution is evaporated to dryness with stirring at 60℃, dried in vacuum, and the dried sample is calcined at a high temperature under a nitrogen atmosphere, to obtain nitrogen-doped reduced graphene oxide/carbon-coated lithium iron phosphate as a final product.