Patent ID: 8790827
Filing Date: 2014-07-29
Classification: C01G,C01P,H01M,Y02E

Abstract:
1. A positive electrode active material comprising: a secondary particle obtained upon aggregation of a primary particle that is a lithium complex oxide particle in which at least nickel (Ni) and cobalt (Co) are solid-solved as transition metals, wherein an average composition of the whole of the secondary particle is represented by: wherein M represents at least one element selected from the group consisting of boron (B), magnesium (Mg), aluminum (Al), silicon (Si), phosphorus (P), sulfur (S), titanium (Ti), chromium (Cr), manganese (Mn), iron (Fe), copper (Cu), zinc (Zn), gallium (Ga), germanium (Ge), yttrium (Y), zirconium (Zr), molybdenum (Mo), silver (Ag), barium (Ba), tungsten (W), indium (In), strontium (Sr), tin (Sn), lead (Pb) and antimony (Sb); X represents a halogen atom; and x, y, z, a and b are values falling within the ranges of (0.8<x≦1.2), (0<y≦0.5), (0.5≦z≦1.0), (1.8≦b≦2.2) and (0≦a≦1.0), respectively; an amount of cobalt (Co) becomes large from a center of the primary particle toward the surface thereof; and an amount of cobalt (Co) in the primary particle existing in a vicinity of a surface of the secondary particle is larger than an amount of cobalt (Co) in the primary particle existing in a vicinity of the center of a secondary particle.