Patent attributes
The positive electrode of the lithium ion secondary battery includes active material particles containing a lithium composite oxide represented by:LivNi1-w-x-y-zCowCaxMgyMzO2 (0.85≦v≦1.25, 0<w≦0.75, 0<x≦0.1, 0<y≦0.1, 0≦z≦0.75, 0<w+x+y+z≦0.80, and element M is an element other than Co, Ca, and Mg), and(i) when 0<z, element M includes element Me of at least one selected from the group consisting of Mn, Al, B, W, Nb, Ta, In, Mo, Sn, Ti, Zr, and Y; and element Mc of at least one selected from the group consisting of Ca, Mg, and element Me is distributed more in the surface layer portion compared with the inner portion of the active material particles, and(ii) when 0=z, element Mc of at least one selected from the group consisting of Ca and Mg is distributed more in the surface layer portion compared with the inner portion of the active material particles.
