Positive electrode active material for non-aqueous electrolyte secondary battery and method for producing the same
An object is to provide a positive electrode active material which can exhibit sufficient cycle characteristics in a non-aqueous electrolyte secondary battery. The positive electrode active material for a non-aqueous electrolyte secondary battery of the present invention is represented by Composition Formula (2): Li x [Ni (1/3-a) [M] a Mn 2/3 ]O 2 (in the formula, M represents at least one element selected from the group consisting of Cu, Zn, Mg, Fe, Al, Co, Sc, Ti, V, Cr, Ga, Ge, Bi, Sn, Ca, B, and Zr, 0≦a≦⅙, and x represents the number of Li satisfying the atomic valence). In addition, the positive electrode active material for a non-aqueous electrolyte secondary battery is characterized in that it is obtained by reduction-ion exchange of a precursor of the positive electrode active material that is represented by Composition Formula (1): Na 2/3 [Ni (1/3-a) [M] a Mn 2/3 ]O 2 (in the formula, M and a are as defined in Composition Formula (2)).
1. A positive electrode active material for a non-aqueous electrolyte secondary battery represented by Composition Formula (2): Li x [Ni (1/3-a) [M] a Mn 2/3 ]O 2 (in the formula, M represents at least one element selected from the group consisting of Cu, Zn, Mg, Fe, Al, Co, Sc, Ti, V, Cr, Ga, Ge, Bi, Sn, Ca, B, and Zr, 0≦a≦⅙, and x represents the number of Li satisfying the atomic valence), which is obtained by reduction-ion exchange of a precursor of the positive electrode active material that is represented by Composition Formula (1): Na 2/3 [Ni (1/3-a) [M] a Mn 2/3 ]O 2 (in the formula, M represents at least one element selected from the group consisting of Cu, Zn, Mg, Fe, Al, Co, Sc, Ti, V, Cr, Ga, Ge, Bi, Sn, Ca, B, and Zr and 0≦a≦⅙).
2. A positive electrode active material for a non-aqueous electrolyte secondary battery represented by Composition Formula (2): Li x [Ni (1/3-a) [M] a Mn 2/3 ]O 2 (in the formula, M represents at least one element selected from the group consisting of Cu, Zn, Mg, Fe, Al, Co, Sc, Ti, V, Cr, Ga, Ge, Bi, Sn, Ca, B, and Zr, 0≦a≦⅙, and x represents the number of Li satisfying the atomic valence), which has diffraction peaks at 20°-23°, 35°-40°, 42°-46°, and 64°-65°/65°-66° according to X-ray diffraction measurement and a peak intensity ratio of 42°-46° (104) relative to 17°-20° (003) of 0.60 or less.