A preparation method of a polydopamine-coated
sodium ion battery positive
electrode material comprises the following steps: 1, preparing an MxFeyMnz (OH) 2 precursor through a
coprecipitation method, 0 < x < = 0.5, 0 < = y < = 0.33, 0 < z < = 0.5, x + y + z = 1, and M is a
transition metal ion; 2, mixing the precursor and a
sodium source according to a
molar ratio of 1: (1-1.1); the preparation method comprises the following steps: mixing the raw materials,
sintering at a high temperature of 850-1100 DEG C for 10-20 hours to obtain the positive
electrode material with the general formula of NaaMxFeyMnzO2, and a is more than 0.67 and less than 1.1; 3, adding the positive
electrode material into the dispersing
solvent, stirring and dispersing to obtain a first turbid liquid, and enabling the concentration of the positive
electrode material in the first turbid liquid to be 0.1-0.5 g / mL; when the pH value of the first suspension is stabilized at 8-12, adding
dopamine hydrochloride, and reacting for 10-30 hours at normal temperature and normal pressure in a dry environment to obtain a second suspension; and 4, filtering, washing and
drying the second suspension to obtain the polydopamine-coated
sodium ion battery positive
electrode material. The
coating layer is high in uniformity and excellent in storage performance in air, the thickness of the
polymer coating layer is adjustable, the
side reaction of the positive
electrode material in
electrolyte can be effectively inhibited in the circulation process, and the circulation stability of the
sodium ion battery is improved.