Positive electrode active material for lithium-ion secondary batteries, lithium-ion secondary batteries

Abstract

A positive electrode active material for lithium-ion secondary batteries is provided, comprising lithium composite oxide particles. This lithium composite oxide contains Li, Ni, Mn, Zr, and additive element M(M). The molar ratio of Li, Ni, Mn, Zr, and additive element M(M) is Li:Ni:Mn:Zr:M = a:b:c:d:e (0.95≦a≦1.20, 0.10≦b<0.70, 0.01≦c≦0.50, 0.0003≦d≦0). 0.02, 0.01≦e≦0.50, the added element M is one or more elements selected from Co, W, Mo, V, Mg, Ca, Al, Ti, and Ta), wherein the full width at half maximum (FWHM) of the peak on the (003) plane and the full width at half maximum (FWHM) of the peak on the (104) plane, calculated from the X-ray diffraction pattern of the lithium composite oxide, satisfy the relationship FWHM(104)≧FWHM(003)×2.90-0.10. ; None