The invention discloses a preparation method of carbon-coated iron-based
prussian blue. The preparation method comprises the following steps of S1, synthesizing uniform and carbon-coated
metal or
metal oxide to be used as a
metal M source; S2, taking the product in the step S1, performing strong stirring and enabling the product to be dispersed into water or an
organic solvent to form a solution;S3, taking
sodium ferrocyanide, and preparing into a solution, and enabling the solution to be mixed with the solution obtained in the step S2; and S4, adding an additive to the solution obtained in the step S3, and performing a reaction at a proper temperature to obtain the carbon-coated iron-based
prussian blue. The invention also discloses the carbon-coated iron-based
prussian blue. The invention also discloses a
sodium ion battery. According to the preparation method disclosed in the invention, the uniform and carbon-coated nanometer metal source and
sodium ferrocyanide are reacted to obtain iron-based prussian blue in in-situ growth in the carbon
raw material, and the surface is uniformly coated with carbon, so that prussian blue is more excellent in
conductivity, and less in contactwith an
electrolyte, thereby suppressing a secondary reaction between prussian blue and the
electrolyte in a
high potential.