Precursors for cathode material with improved secondary battery performance and method to prepare the precursors

1. A crystalline precursor compound for manufacturing a lithium transition metal based oxide powder usable as an active positive electrode material in lithium-ion batteries, the precursor having a general formula M(O) x (OH) 2-x-y (CO 3 ) y , with 0≤x≤1, 0<y≤0.03 and M=Ni a Mn b Co c A d , A being a dopant, with 0.30≤a≤0.90, 0.10≤b≤0.40, 0.10≤c≤0.40, d≤0.05 and a+b+c+d=1, the precursor having a Na content less than 200 ppm, a S content less than 250 ppm, the precursor having a specific surface area with a BET value expressed in m 2 /g and a tap density TD expressed in g/cm 3 , with a ratio BET/TD≥30.10 4 cm 5 /g 2 .

2. The crystalline precursor compound of claim 1 , having a tap density TD≥1.0 g/cm 3 .

3. The crystalline precursor compound of claim 1 , having a BET value≥35 m 2 /g.

4. The crystalline precursor compound of claim 1 , having a Na content less than 100 ppm, a S content less than 200 ppm, and the sum of the Na and the S content being less than 300 ppm.

5. The crystalline precursor compound of claim 1 , having a BET value≥45 m 2 /g.

6. The crystalline precursor compound of claim 1 , having a tap density TD≥1.2 g/cm 3 .

7. The crystalline precursor compound of claim 1 , having a median particle size (D50) between 5-25 μm.

8. The crystalline precursor compound of claim 1 , having a carbon content ≤0.15 wt %.

9. A method for preparing the crystalline precursor compound according to claim 1 , the method comprising the steps of:

providing a MSO 4 sulfate feed solution comprising Ni—, Mn—, Co— and A-ions,

providing an ionic solution comprising one or both of a carbonate and a bicarbonate solution, the ionic solution further comprising one or both of Na— and K-ions,

mixing the sulfate feed solution and the ionic solution in a reactor with a CO 3 /M molar ratio≥1.0, thereby precipitating a M-carbonate intermediate product, and

dispersing the M-carbonate intermediate product in a NaOH solution at a temperature between 70 and 95° C. with a OH/M molar ratio≥2.0, thereby precipitating a crystalline precursor.

10. The method according to claim 9 , wherein the OH/M molar ratio is between 2.0 and 2.1.

11. The method according to claim 9 , wherein the molar ratio CO 3 /M≥1.05.

12. The method according to claim 9 , further comprising the additional steps of:

filtering and washing the precursor until the conductivity of the filtrate reaches at most 50 μS/cm, and

drying the filtered and washed precursor at a temperature between 120 and 160° C. for 12-36 hrs. in an air atmosphere.

13. The method according to claim 9 , wherein the MSO 4 sulfate feed solution has a molar content M feed , and the method further comprises

in addition to the MSO 4 sulfate feed and the ionic solution, providing a slurry comprising seeds comprising M′-ions and having a molar metal content M′ seeds , wherein M′═Ni x′ Mn y′ Co z′ A′ n′ , A′ being a dopant, with 0≤x′≤1, 0≤y′≤1, 0≤z′≤1, 0≤n′≤1 and x′+y′+z′+n′=1,

mixing the sulfate feed solution, the ionic solution and the slurry in a reactor with a CO 3 /M molar ratio≥1.0 and a molar ratio M′ seeds /M feed between 0.001 and 0.1, thereby precipitating the M-carbonate intermediate product on the seeds, and

dispersing the M-carbonate intermediate product precipitated on the seeds in the NaOH solution.

14. The method according to claim 13 , wherein M=M′.

15. The method according to claim 13 , wherein the seeds have a median particle size D50 between 0.1 and 3 μm, and wherein the M′-ions are present in a water insoluble compound that is one of M′CO 3 , M′(OH) 2 , M′-oxide or M′OOH.