Cathode active materials with a core-shell structure and their manufacture

A cathode active material comprising:

• (A) a core material according to general formula Li1+xTM1−xO2 wherein TM is a combination of Ni and at least two of Mn, Co and Al, and, optionally, at least one more metal selected from the group consisting of Mg, Ti, Zr, Nb, Ta, and W, and x is in the range of from −0.05 to +0.05, and wherein the nickel content is in the range of from 80 to 99 mol-% of TM,
• (B) particles of cobalt compound(s) in which at least some cobalt is in the oxidation state of +III and selected from the group consisting of Liy1 CoO2 with spinel structure,
• LiCoO2, and LiCoy2Ni1−y2O2 wherein 0<y1<0.6 and 0.5<y2<1, and
• (C) a shell comprising at least one compound selected from the group consisting of B2O3, WO3, LiBO2, Li2B4O7, and Li2WO4,
• wherein the core material (A) is a polycrystalline material whose secondary particles are composed of primary particles, and particles of cobalt compounds (B) are enriched at the surface of said secondary particles.