Positive electrode material and preparation method therefor

A method for preparing a positive electrode material for lithium-ion batteries, wherein the positive electrode material is in a form of secondary particles having a core and shell, wherein the positive electrode material is a doped nickel containing positive electrode material, and the method is characterized by comprising the steps of:

• (1) subjecting a solution of soluble salts containing Ni, Co and M and a dispersion containing D to the first co-precipitation, to form the core of the secondary particles;
• (2) subjecting a solution of soluble salts containing Ni, Co and M and a dispersion containing G to a second co-precipitation in the presence of the core in step (1), to form the shell on the core, to obtain the secondary particles having the core and the shell;
• wherein the first co-precipitation is operated at a pH lower than that for the second co-precipitation, and a temperature lower than that for the second co-precipitation, and
• wherein the core has a porosity greater than that of the shell, wherein the core has a porosity of 50-90%, the shell has a porosity of 10-50%, and the ratio of the porosity of the core to that of the shell is greater than 1.2;
• and
• (3) converting the secondary particles obtained in step (2) into the positive electrode material by:
• contacting the secondary particles obtained in step (2) with a lithium source material at 300-900° ° C. to obtain the positive electrode material, wherein the lithium source material is one or more of Li2O, LiOH, LiOH, H2O, LiNO3 and Li2CO3,
• wherein M is one or two of Mn and Al,
• D is one or more of Mo, Ti, Y, W, Ta, Nb, Cr, Sm, Sb, V, La, Ca, Hf and Zr, and
• G is one or more of Mo, Ta, Zn, Ti, Y, Zr, W, Nb, Cr, Sm, Al, V, La, Ca, Sb, Hf, Mg and B.