Lithium Nickel-Manganese-Cobalt Oxide Cathode Powders for High Voltage Lithium-Ion Batteries

A lithium metal oxide powder for a cathode material in a rechargeable battery, comprising a core and a surface layer, the surface layer being delimited by an outer and an inner interface, the inner interface being in contact with the core, 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, 0.10≦z≦0.55, x+y+z=1 and 0<k≦0.1, wherein the Li content is stoichiometrically controlled with a molar ratio 0.95≦Li:M≦1.10;

• wherein A is at least one dopant and comprises Al, wherein the core has an Al content of 0.3-3 mol % and a F content of less than 0.05 mol %;
• wherein the surface layer comprises an intimate mixture of Ni, Co, Mn, LiF and Al2O3;
• and wherein the surface layer has an Al content that increases from the Al content of the core at the inner interface to at least 10 mol % at the outer interface, and a F content that increases from less than 0.05 mol % at the inner interface to at least 3 mol % at the outer interface, the Al and F contents being determined by XPS.

A lithium metal oxide powder for a cathode material in a rechargeable battery, comprising a core and a surface layer, the surface layer being delimited by an outer and an inner interface, the inner interface being in contact with the core, 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 the Li content is stoichiometrically controlled with a molar ratio 0.95≦Li:M≦1.10;

• wherein A is at least one dopant and comprises Al, wherein the core has an Al content of 0.3-3 mol %;
• wherein the surface layer comprises an intimate mixture of Ni, Co, Mn, LiF and Al2O3;
• and wherein the surface layer has a Mn content that decreases from the Mn content of the core at the inner interface, to less than 50% of the Mn content of the core at the outer interface, the Al content in the core and the Mn content being determined by XPS.