▎ 摘　　要

NOVELTY - Forming protective polymer film on surface of titanium-sodium phosphate cathode material involves: (1) uniformly mixing carbon-coated modified sodium titanium phosphate active material, conductive agent and binder according to a preset mass ratio, and coating on a current collector to prepare a carbon-coated modified sodium titanium phosphate cathode sheet as a cathode substrate; (2) preparing a composite plating solution comprising inorganic sodium salt aqueous solution and functional additive solution; and (3) adding the cathode substrate to the composite plating solution for constant potential electrochemical surface modification, and electrochemically depositing on the surface of the cathode substrate. USE - The method is useful for forming protective polymer film on surface of titanium-sodium phosphate cathode material used in sodium-ion battery (claimed). ADVANTAGE - The method provides protective polymer film on surface of titanium-sodium phosphate cathode material, which has excellent charge and discharge multiplying power performance and cycle stability, and Coulomb efficiency close to 100%. The protective polymer film is formed on the surface of the modified electrode, compared with the original electrode, which can be similar to the solid electrolyte interface film in traditional lithium-ion batteries, does not hinder the normal transport of sodium ions, and can block the direct contact between the cathode active material and the electrolyte, thus enhancing interface stability and improving utilization rate of the active material of the cathode. DETAILED DESCRIPTION - An INDEPENDENT CLAIM is included for a sodium-ion battery.