DOPED LITHIUM POSITIVE ELECTRODE ACTIVE MATERIAL AND PROCESS FOR MANUFACTURE THEREOF

1 . A lithium positive electrode active material for a high voltage secondary battery, where the cathode is fully or partially operated above 4.4 V vs. Li/Li+, said lithium positive electrode active material comprising at least 95 wt % spinel having a chemical composition of Li x Ni y Mn 2-y-z D z O 4 , wherein 0.9≤x≤1.1, 0.4≤y≤0.5, 0.02≤z≤0.2, wherein D is a dopant chosen between the following elements: Co, Cu, Ti, Zn, Mg, Fe or combinations thereof, wherein the lithium positive electrode active material is a powder composed of secondary particles formed by primary particles, wherein said lithium positive electrode active material has a tap density of at least 1.9 g/cm 3 .

2 . A lithium positive electrode active material according to claim 1 , wherein the dopant D is distributed substantially uniformly throughout the lithium positive electrode material.

3 . A lithium positive electrode active material according to claim 1 , wherein at least 90% of said dopant D is incorporated in the spinel of said lithium positive electrode material.

4 . A lithium positive electrode active material according to claim 1 , wherein 0.96≤x≤1.0 in the composition Li x Ni y Mn 2-y-z D z O 4 .

5 . A lithium positive electrode active material according to claim 1 , wherein said lithium positive electrode active material is cation disordered.

6 . A lithium positive electrode active material according to claim 1 , wherein the BET surface area of the secondary particles is below 0.25 m 2 /g.

7 . A lithium positive electrode active material according to claim 1 , wherein the secondary particles are characterized by an average circularity higher than 0.55 and simultaneously an average aspect ratio lower than 1.60.

8 . A lithium positive electrode active material according to claim 1 , wherein D50 of the secondary particles is between 3 and 50 μm.

9 . A lithium positive electrode active material according to claim 8 , wherein the distribution of the agglomerate size of the secondary particles is characterized in that the ratio between D90 and D10 is smaller than or equal to 4.

10 . A lithium positive electrode active material according to claim 1 , wherein the diameter or the volume equivalent diameter of the primary particles larger than D5 is between 100 nm and 2 μm and where the diameter or the volume equivalent diameter of the secondary particles is between 1 μm and 25 μm.

11 . A lithium positive electrode active material according to claim 1 , wherein at least 90% of the dopant D is part of the spinel.

12 . A lithium positive electrode active material according to claim 1 , the capacity of the lithium positive electrode active material is above 120 mAh/g.

13 . A lithium positive electrode active material according to claim 1 , wherein the separation between the two Ni-plateaus around 4.7 V of the lithium positive electrode active material is at least 50 mV.

14 . A process for preparing a lithium positive electrode active material comprising at least 95 wt % spinel having a chemical composition of Li x Ni y Mn 2-y-z D z O 4 , wherein 0.9≤x≤1.1, 0.4≤y≤0.5, and 0.02≤z≤0.2 wherein D is a dopant chosen between the following elements: Co, Cu, Ti, Zn, Mg, Fe or combinations thereof, wherein the lithium positive electrode active material is composed of particles, wherein said lithium positive electrode active material has a tap density of at least 1.9 g/cm 3 and wherein said lithium positive electrode active material comprises at least 95 wt % spinel phase, said process comprising the steps of:

a) providing a lithium positive electrode active material comprising at least 95 wt % spinel having a chemical composition of Li x Ni y Mn 2-y O 4 , wherein 0.9≤x≤1.1, 0.4≤y≤0.5,

b) mixing the lithium positive electrode active material of step a) with a dopant precursor of the dopant D,

c) heating the mixture of step b) to a temperature of between 600° C. and 1000° C.

15 . A process for preparing a lithium positive electrode active material comprising at least 95 wt % spinel having a chemical composition of Li x Ni y Mn 2-y-z D z O 4 , wherein 0.9≤x≤1.1, 0.4≤y≤0.5, and 0.02≤z≤0.2, wherein D is a dopant chosen between the following elements: Co, Cu, Ti, Zn, Mg, Fe or combinations thereof, wherein the lithium positive electrode active material is composed of particles, wherein said lithium positive electrode active material has a tap density of at least 1.9 g/cm 3 and wherein said lithium positive electrode active material comprises at least 95 wt % spinel phase, said process comprising the steps of:

a) providing precursors for preparing a lithium positive electrode active material comprising at least 95 wt % spinel having a chemical composition of Li x Ni y Mn 2-y-z D z O 4 , wherein 0.9≤x≤1.1, 0.4≤y≤0.5, and 0.02≤z≤0.2, said precursors comprising Ni, Mn, Li and the dopant D, and

b) heating the precursors of step a) to a temperature of between 600° C. and 1000° C.

16 . A method according to claim 15 , wherein the precursors comprise both lithium carbonate and either nickel carbonate and manganese carbonate or nickel manganese carbonate.

17 . A secondary battery comprising a positive electrode which comprises the lithium positive electrode active material according to claim 1 .