▎ 摘　　要

NOVELTY - Double-carbon modified polyanionic sodium-ion battery cathode material, comprises sodium-manganese-chromium phosphate and carbon-based material modified on the surface of sodium-manganese-chromium phosphate and carbon-based material b embedded in sodium-manganese-chromium phosphate. USE - The double-carbon modified polyanionic sodium-ion battery cathode material is useful in the preparation of sodium ion batteries (claimed). ADVANTAGE - The method : is simple, and suitable for large-scale industrial production; improves the rate performance and cycle stability, and the electrochemical performance of sodium storage is better than that of pure NaxMnyCrz(PO4)n material. DETAILED DESCRIPTION - An INDEPENDENT CLAIM is also included for a method for preparing double-carbon modified polyanionic sodium-ion battery cathode material, comprising (1) preparing a mixed solution of sodium acetate solution, manganese acetate tetrahydrate solution, chromium nitrate solution, ammonium dihydrogen phosphate and carbon-based material a, respectively, and stirring them in a water bath, preparing a dispersion of carbon-based material b, and ultrasonically dispersing, (2) adding the dispersion liquid of carbon-based material b, sodium acetate solution, manganese acetate tetrahydrate solution and chromium nitrate solution dropwise to the mixed solution of ammonium dihydrogen phosphate and carbon-based material a raw material, drying in a water bath after stirring to obtain a double-carbon modified polyanion type sodium-ion battery cathode material precursor, and (3) performing programmed sintering on the double-carbon modified polyanion type sodium ion battery cathode material precursor obtained in step (2) to obtain a double carbon modified polyanion type sodium ion battery cathode material.