Lithium metal oxide cathode powders for high voltage lithium-ion batteries

A lithium metal oxide powder for use as a cathode material in a rechargeable battery, comprising a core and a surface layer, the core having a layered crystal structure comprising the elements Li, M and oxygen, wherein M has the formula M=(Niz(Ni1/2Mn1/2)yCox)1-kAk, with 0.15≤x≤0.30, 0.20≤z≤0.55, x+y+z=1 and 0≤k≤0.1, wherein A is a dopant, wherein the Li content is stoichiometrically controlled with a molar ratio 0.95≤Li:M≤1.10;

• and wherein the surface layer comprises the elements Li, M′ and oxygen, wherein M′ has the formula M′=(Niz′(Ni1/2Mn1/2)y′Cox′)1-k′Ak′, with x′+y′+z′=1 and 0≤k′≤0.1, and wherein y′/(y+2z′)≥1.1*[y/(y+2z)] and 2x/(y+2z)=2x′/(y′+2z′), and wherein the surface layer has an outer interface and an inner interface, the inner interface being in contact with the core, and wherein the surface layer has a Mn content that increases continuously from a concentration at the inner interface to a higher concentration at the outer interface, wherein x, y, z and k are measured by ICP and x', y', z' and k' are measured by XPS depth profile.