▎ 摘　　要

NOVELTY - The preparation method of a sodium iron pyrophosphate phosphate material involves: uniformly mixing sodium pyrophosphate, metal iron powder, iron phosphate, doped element phosphate and a conductive agent or a conductive agent precursor, where the molar ratio of the doped element phosphate is 0-100%; and placing the ball-milled product in an inert atmosphere or a hydrogen-argon mixed atmosphere, heating at a heating speed of 3-10 ℃/minute, roasting at the constant temperature of 450-650 ℃ for 2-5 hours, and then cooling to room temperature to obtain the carbon-coated ferric sodium pyrophosphate phosphate powder. USE - Sodium iron pyrophosphate phosphate material used in the preparation of a positive electrode material for a sodium ion battery (claimed). ADVANTAGE - The pure phase can be obtained by short-time heat treatment, and there are no by-products in the reaction process, which is a green atom-economic reaction. It avoids the problem of impurity phase and by-product generation that may exist in other synthetic routes using hydrogen phosphate as a reactant. The method adopts a mechanical solid-phase synthesis process, and the reactant particles are crushed by the energy generated by high-energy ball milling, and at the same time, a chemical reaction occurs between the powder particles through thermochemical action. To obtain the target product of pure phase sodium iron pyrophosphate phosphate material, the process route has low energy consumption, avoiding the problem that conventional high-temperature solid-phase synthesis requires long-time sintering and consumes a lot of energy. The method for preparing sodium iron pyrophosphate phosphate by the mechanical solid-phase synthesis process has the advantages of easy-to-obtain raw materials, easy control of product formulation, high purity of the synthesized product, and excellent electrochemical performance. The sodium sheet was assembled into a test battery, which was charged and discharged at a rate of 0.1C, with a reversible specific capacity of 103.2mAh/g and excellent cycle stability. In the method for synthesizing sodium ferric pyrophosphate phosphate of the invention, the raw materials used are all bulk chemical products, the process is simple and easy to operate, and it is easy to realize industrial-scale clean production, and no three wastes are discharged. DETAILED DESCRIPTION - An INDEPENDENT CLAIM is included for the sodium iron pyrophosphate phosphate material. DESCRIPTION OF DRAWING(S) - The drawing shows the X-ray diffraction pattern of the sodium iron pyrophosphate phosphate cathode material.