| abstract |
The present invention provides a center comprising a first lithium transition metal oxide having an average composition represented by the following Chemical Formula 1; and a surface portion comprising a second lithium transition metal oxide having an average composition represented by the following formula (2); do. [Formula 1] Li 1+a1 (Ni b1 Co c1 Mn d1 Al e1 M 1 f1 )O 2 In Formula 1, -0.1≤a1≤0.2, 0.8≤b1<1.0, 0<c1≤0.2, 0<d1≤0.1, 0<e1≤0.05, 0≤f1≤0.05, b1/c1≤25, b1 /d1≥20, and M 1 is at least one selected from the group consisting of Mg, Ti, Zr, Nb and W. [Formula 2] Li 1+a2 (Ni b2 Co c2 Mn d2 Al e2 M 1 f2 )O 2 In Formula 2, -0.1≤a2≤0.2, 0.6≤b2≤0.95, 0<c2≤0.2, 0<d2≤0.1, 0<e2≤0.05, 0≤f2≤0.05, b2/c2<13, b2 /d2≥3, and M 1 is at least one selected from the group consisting of Mg, Ti, Zr, Nb and W. |