Stoichiometrically controlled lithium cobalt oxide based compounds
A lithium metal oxide powder for use as a cathode material in a rechargeable battery, consisting of a core material and a surface layer, the core having a layered crystal structure consisting of the elements Li, a metal M and oxygen, wherein the Li content is stoichiometrically controlled, wherein the metal M has the formula M=Co 1-a M′ a , with 0≤a≤0.05, wherein M′ is either one or more metals of the group consisting of Al, Ga and B; and the surface layer consisting of a mixture of the elements of the core material and inorganic N-based oxides, wherein N is either one or more metals of the group consisting of Mg, Ti, Fe, Cu, Ca, Ba, Y, Sn, Sb, Na, Zn, Zr and Si.
1. A lithium metal oxide powder for a cathode material in a rechargeable battery, comprising a core material and a surface layer, the core material having a layered crystal structure consisting of the elements Li, a metal M and oxygen, wherein the metal M has the formula M=Co 1-a M′ a , with 0≤a≤0.05, wherein M′ is Al or M′ is Al and one or more elements selected from the group consisting of Mg, Ti, Ga and B;
wherein the surface layer comprises Li and Co;
wherein the surface layer further comprises inorganic N-based oxides or inorganic N-based lithiated oxides, wherein N is Al, Ti and Mg or N is Al, Ti, and Mg and one or more metals selected from the group consisting of Fe, Cu, Ca, Ba, Y, Sn, Sb, Na, Zn, Zr and Si;
wherein the molar ratio (Mg+Al):Co of the lithium metal oxide powder is higher than 0.004; and
wherein the sum of Mg, Al and Ti molar contents in the core material is less than the sum of Mg, Al and Ti molar contents in the surface layer.
2. The lithium metal oxide powder of claim 1 , wherein the molar ratio Li:(Co+Al) is more than 0.98 and less than 1.01.
3. The lithium metal oxide powder of claim 1 , having a mean particle size D50 of at least 15 μm.
4. The lithium metal based powder of claim 1 , wherein the powder has a bimodal particle shape distribution where the small particle size fraction has a D50≤5 μm and is between 3 to 20 Vol %, and where the large particle size fraction has a D50≥15 μm.
5. The lithium metal oxide powder of claim 1 , wherein the thickness of the surface layer is 1 μm or less.
6. The lithium metal oxide powder of claim 1 , wherein a>0 and the Al:Co molar ratio in the surface layer is more than 2a/(1−a).
7. The lithium metal oxide powder of claim 1 , wherein either one or more of the Mg:Co and Ti:Co molar ratios in the surface layer is more than 2 times the corresponding Mg:Co or Ti:Co molar ratios in the lithium metal oxide powder.
8. The lithium metal oxide powder of claim 1 , wherein the molar ratio Mg:Co in the lithium metal oxide powder and the molar ratio Al:Co in the lithium metal oxide powder are both higher than 0.009.
9. The lithium metal oxide powder of claim 1 , comprising monolithic, potato-shaped and non-agglomerated particles.
10. The lithium metal oxide powder of claim 1 , having a Brunauer-Emmett-Teller (BET) surface area lower than 0.3 m 2 /g.
11. The lithium metal oxide powder of claim 1 , having a Carbon content less than 50 ppm.
12. The lithium metal oxide powder of claim 1 , having a soluble base content less than 25 μmol/g.
13. A cathode in an electrochemical cell comprising the lithium metal oxide powder according to claim 1 .
14. The lithium metal oxide powder of claim 1 , wherein the molar ratio Mg:Co of the lithium metal oxide powder or the molar ratio Al:Co of the lithium metal oxide powder is higher than 0.004.
15. The lithium metal oxide powder of claim 1 , wherein the molar ratio Mg:Co of the lithium metal oxide powder and the molar ratio Al:Co of the lithium metal oxide powder are both higher than 0.004.
16. The lithium metal oxide powder of claim 1 , wherein a>0.
17. A lithium metal oxide powder for a cathode material in a rechargeable battery, comprising a core material and a surface layer, the core material having a layered crystal structure consisting of the elements Li, a metal M and oxygen, wherein the metal M has the formula M=Co 1-a M′ a , with 0<a≤0.05, wherein M′ is Al and one or more elements selected from the group consisting of Mg, Ti, Ga and B;
wherein the surface layer comprises Li and Co;
wherein the surface layer further comprises inorganic N-based oxides or inorganic N-based lithiated oxides, and wherein N is Al, Ti and Mg or N is Al, Ti, and Mg and one or more metals selected from the group consisting of Fe, Cu, Ca, Ba, Y, Sn, Sb, Na, Zn, Zr and Si;
wherein the molar ratio (Mg+Al):Co of the lithium metal oxide powder is higher than 0.004; and
wherein the sum of Mg, Al and Ti molar contents in the core material is less than the sum of Mg, Al and Ti molar contents in the surface layer.
18. A lithium metal oxide powder for a cathode material in a rechargeable battery, comprising a core material and a surface layer, the core material having a layered crystal structure consisting of the elements Li, a metal M and oxygen, wherein the metal M has the formula M=Co 1-a M′ a , with 0<a≤0.05, and wherein M′ comprises Ti, Ga or B;
wherein the surface layer comprises inorganic N-based oxides or inorganic N-based lithiated oxides, wherein N is Al, Ti and Mg or N is Al, Ti, and Mg and one or more metals selected from the group consisting of Fe, Cu, Ca, Ba, Y, Sn, Sb, Na, Zn, Zr and Si;
wherein the molar ratio (Mg+Al):Co of the lithium metal oxide powder is higher than 0.004; and
wherein the sum of Mg, Al and Ti molar contents in the core material is less than the sum of Mg, Al and Ti molar contents in the surface layer.