Modified P2-type layered Mn-based oxide, preparation method thereof and application of modified P2-type layered Mn-based oxide as positive electrode material in sodium-ion battery

The preparation method comprises the following steps: mixing a solvent and tetraethoxysilane, dropwise adding dilute nitric acid until the solution is clear and transparent to obtain a solution A, mixing water and zirconyl nitrate, then adding citric acid, uniformly mixing, then adding NaNO3, stirring at 60-80 DEG C for 10 minutes, and then adding sodium hydroxide to obtain a solution B; the preparation method comprises the following steps: dissolving a P2-type layered Mn-based oxide in water to obtain a solution B, mixing the solution A and the solution B, adding 1-1.5 parts by mass of ammonium dihydrogen phosphate, stirring at 80-90 DEG C for at least 30 minutes, diluting to 500 parts by volume to obtain a uniform and clear Na3Zr2Si2PO12 precursor solution, uniformly mixing the P2-type layered Mn-based oxide and the Na3Zr2Si2PO12 precursor solution, drying at 80-100 DEG C to obtain solid powder, carrying out heat preservation on the solid powder at 400-650 DEG C for 1-3 hours, and then carrying out heat pre