Cathode material for lithium ion secondary battery, method of producing the same, and lithium ion secondary battery

A cathode material for lithium ion secondary battery, wherein the cathode material is in the form of powder particles, the powder particle includes a bulk portion and a coating portion coated on the outer surface of the bulk portion, the bulk portion is formed of at least one first cathode material which is a lithium-nickel based composite oxide, the first cathode material has electrochemical activity and has high charging-discharging specific capacity at a charged voltage of 4.2V versus Li/Li+, the coating portion is formed of at least one second cathode material, the second cathode material has no electrochemical activity or has low charging-discharging specific capacity at a charged voltage of 4.2V versus Li/Li+, wherein the first cathode material has a general formula of Li1+δ [Ni1−x−yCoxMy]O2, wherein M is selected at least one metal element from Mn, Na, K, Mg, Ca, Sr, Ba, Al, Ga, In, Ge, Sn, Ti, V, Cr, Fe, Cu, Zn, Y, Zr, Nb, Mo, Cd, W, La, Ce, Nd and Sm, wherein 0<δ<0.2, 0<x<0.5, 0<x+y<0.5, and wherein the second cathode material has a general formula of Li 1+η[Mn2−aM′a]O4, wherein M′ is selected at least one metal element from Ni, Co, Na, K, Mg, C, Sr, Ba, A, Ga, In, Ge, Sn, Ti, V, Cr, Fe, Cu, Zn, Y, Zr, Nb, Mo, Cd, W, La, Ce, Nd and Sm, wherein 0<η<0.2, 0<a<1.