Highly Crystalline lithium transition metal oxides
A powderous lithium transition metal oxide having a layered crystal structure Li 1+a M 1−a O 2±b M′ k S m with −0.03<a<0.06, b≅0, 0≦m≦0.6, m being expressed in mol %, M being a transition metal compound, consisting of at least 95% of either one or more elements of the group Ni, Mn, Co and Ti; M′ being present on the surface of the powderous oxide, and consisting of either one or more elements of the group Ca, Sr, Y, La, Ce and Zr, wherein: either k=0 and M=Ni 1−c−d Mn c CO d , with 0<c<1, and 0<d<1; or 0.015<k<0.15, k being expressed in wt % of said lithium transition metal oxide; characterized in that for said powderous oxide, the X-ray diffraction peak at 44.5±0.3 degree, having as index 104, measured with K alpha radiation, has a FWHM value of ≦0.1 degree. By optimizing the sintering temperature of the metal oxide the FWHM value can be minimized.
1. A powderous lithium transition metal oxide having a layered crystal structure Li 1+a M 1−a O 2±b M′ k S m with −0.03<a <0.06, b≈0, and 0≦m≦0.6, m being expressed in mol %, wherein
M is a transition metal compound, comprising at least 95% of one or more elements selected from the group consisting of Ni, Mn, Co and Ti; wherein the powderous lithium transition metal oxide is a solid state solution and wherein
M′ is present on the surface of the powderous oxide and comprises one or more elements selected from the group consisting of Ca, Sr, Y, La, Ce and Zr; and
wherein either k=0 and M=Ni 1−c−d Mn c Co d , with 0<c<1, and 0<d<1; or
0.015<k<0.15, k being expressed in wt % of said lithium transition metal oxide; wherein for said powderous oxide, the X-ray diffraction peak at 44.5±0.3 degree, having as index 104, measured with K alpha radiation, has an FWHM value of ≦0.1 degree.
2. The powderous lithium transition metal oxide of claim 1 , wherein the X-ray diffraction peak at 18.6±0.2 degree, having as index 003, also has an FWHM value of ≦0.1 degree.
3. The powderous lithium transition metal oxide of claim 1 , wherein 0.15<m≦0.6, m being expressed in mol %.
4. The powderous lithium transition metal oxide of claim 1 , wherein 0.0250<k≦0.1 in wt %.
5. The powderous lithium transition metal oxide of claim 1 , wherein M′ is Ca, with 0.0250≦k≦0.0500, in wt %, and 0.25≦m≦0.6, in mol %.
6. The powderous lithium transition metal oxide of claim 5 , wherein k≦0.0400, in wt %.
7. The powderous lithium transition metal oxide of claim 1 , wherein 0<k<0.15, k being expressed in wt % of said metal oxide, and M=Ni 1−c−d Mn c Co d , with 0<c<1, and 0<d<1.
8. The powderous lithium transition metal oxide of claim 7 , wherein c=d=0.333.
9. A process for improving the crystallinity of the powderous lithium transition metal oxide of claim 1 , comprising sintering an M-hydroxide, -oxyhydroxide or carbonate precursor together with a Li precursor, at a sintering temperature T of at least 900° C., for a time t between 1 and 48 hrs, wherein a value for (1+a)/(1−a) is selected between 0.99 and 1.1, and said sintering temperature is selected such that the X-ray diffraction peak of said lithium transition metal oxide at 44.5±0.3 degree, having as index 104, measured with K alpha radiation, has an FWHM value of ≦0.1 degree.
10. The process of claim 9 , wherein said sintering temperature is selected such that the X-ray diffraction peak of said lithium transition metal oxide at 18.6±0.2 degree, having as index 003, has an FWHM value of ≦0.1 degree.
11. The process of claim 10 , wherein the FWHM value is ≦0.08.
12. The process of claim 9 , wherein the sintering temperature is at least 950° C.
13. The process of claim 9 , wherein the Li precursor is lithium carbonate.