Process for making an at least partially coated electrode active material

Abstract

A process for making an at least partially coated electrode active material may involve, with an electrode active material of formula Li.sub.1−xTM.sub.1−xO.sub.2, wherein TM is a combination of Ni, Co and, optionally, Mn, and, optionally, at least one metal selected from Al, Ti and Zr, and x is in the range of from 0 to 0.2, treating the electrode active material with at least one compound of W or Mo that bears at least one group or ion that is replaced or displaced when such compound reacts with the surface of the electrode active material particle, treating the surface-reacted material with an agent to decompose the compound of W or Mo, repeating the sequence 1 to 100 times, wherein the average thickness of the resulting coating is in the range of from 0.1 to 50 nm.

Claims

1. A process for making an at least partially coated electrode active material, the process comprising: treating an initial electrode active material, of formula Li.sub.1+xTM.sub.1−xO.sub.2, wherein TM is a combination of Ni, Co, optionally Mn, and optionally Al, Ti, and/or Zr, and x ranges from 0 to 0.2, with at least one compound of W or Mo comprising a group or ion that is replaced or displaced when the compound reacts with a surface of the initial electrode active material, to obtain a treated material; subjecting the treated material to an agent to decompose the compound of W or Mo, to obtain an intermediate material; and repeating the treating and the subjecting steps from 1 to 100 times substituting each subsequent intermediate material for the initial electrode active material, to obtain the at least partially coated electrode active material, wherein the at least partially coated electrode active material has an average coating thickness ranging from 0.1 nm to 50 nm.

2. The process of claim 1, wherein the treating and the subjecting are performed in gas phase.

3. The process of claim 1, wherein the compound for treating comprises a carbonyl of W, a carbonyl of Mo, a C.sub.1-C.sub.5-alkyl of W, a C.sub.1-C.sub.5-alkyl of Mo, an amide of W, an amide of Mo, an alkoxide of W, an alkoxide of Mo, a halide of W, and/or a halide of Mo.

4. The process of claim 1, wherein from the compound in the treating is W(CO).sub.6 or Mo(CO).sub.6.

5. The process of claim 1, wherein the agent comprises oxygen, a peroxide, and/or ozone.

6. The process of claim 1, wherein the agent comprises hydrogen, water, and/or a C1-C4-alkyl alcohol.

7. The process of claim 1, further comprising: thermally post-treating the obtained at least partially coated electrode active material.

8. The process of claim 1, wherein the treating, the subjecting, and the repeating steps are performed in a rotary kiln, a free fall mixer, a continuous vibrating bed, or a fluidized bed.

9. The process of claim 1, further comprising, between each of the treating and subjecting steps: purging an environment of the treated material.

10. The process of claim 1, wherein TM has a formula (I)
(Ni.sub.aCo.sub.bMn.sub.c).sub.1-dM.sub.d  (I) wherein a is in a range of from 0.6 to 0.9, b is in a range of from 0.05 to 0.2, c is in a range of from 0 to 0.2, d is in a range of from 0 to 0.1, M is Ti, Zr, or Al, and
a+b+c=1.

11. The process of claim 10, wherein TM is Ni.sub.0.85Co.sub.0.1Al.sub.0.05, N.sub.0.6Co.sub.0.2Mn.sub.0.2, Ni.sub.0.7Co.sub.0.2Mn.sub.0.1 Ni.sub.0.8Co.sub.0.1Mn.sub.0.1, Ni.sub.0.85Co.sub.0.1Mn.sub.0.05, or (Ni.sub.0.6Co.sub.0.2Mn.sub.0.2).sub.1-dAl.sub.d.

12. The process of claim 1, further comprising: further coating the obtained at least partially coated electrode active material with an oxide comprising Al, Zn, Ti, Si, P, Zr, Hf, Ni, Li, and/or Co.

13. The process of claim 1, wherein TM is Ni.sub.0.85Co.sub.0.1Al.sub.0.05.

14. The process of claim 1, wherein TM is Ni.sub.6Co.sub.0.2Mn.sub.0.2.

15. The process of claim 1, wherein TM is Ni.sub.0.7Co.sub.0.2Mn.sub.0.1.

16. The process of claim 1, wherein TM is Ni.sub.0.8Co.sub.0.1Mn.sub.0.1.

17. The process of claim 1, wherein TM is Ni.sub.0.85Co.sub.0.1Mn.sub.0.05.

18. The process of claim 10, wherein TM is (Ni.sub.0.6Co.sub.0.2Mn.sub.0.2).sub.1-dAl.sub.d.

Description

WORKING EXAMPLES

(1) General Remarks

(2) sccm: standard cubic centimeter per minute, standard: 20° C./1 atm

(3) ICP-OES: Inductively coupled plasma optical emission spectroscopy

(4) I. Cathode Active Materials

(5) I.1. Preparation of a Precursor for Cathode Active Materials

(6) A stirred tank reactor was filled with deionized water. The precipitation of mixed transition metal hydroxide precursor was started by simultaneous feed of an aqueous transition metal solution and an alkaline precipitation agent at a flow rate ratio of 1.9, and a total flow rate resulting in a residence time of 8 hours. The aqueous transition metal solution contained Ni, Co and Mn at a molar ratio of 6:2:2 as sulfates each and a total transition metal concentration of 1.65 mol/kg. The alkaline precipitation agent consisted of 25 wt. % sodium hydroxide solution and 25 wt. % ammonia solution in a weight ratio of 25. The pH value was kept at 12.0 by separate feed of an aqueous sodium hydroxide solution. After stabilization of particle size the resulting suspension was removed continuously from the stirred vessel. The mixed transition metal (TM) oxyhydroxide precursor was obtained by filtration of the resulting suspension, washing with distilled water, drying at 120° C. in air and sieving.

(7) C-CAM.1 (a.1): The mixed transition metal oxyhydroxide precursor obtained according to 1.1 was mixed with Al.sub.2O.sub.3 (average particle diameter 6 nm) and LiOH monohydrate to obtain a concentration of 0.3 mole-% Al relative to Ni+Co+Mn+Al and a Li/(TM+Al) molar ratio of 1.03. The mixture was heated to 885° C. and kept for 8 hours in a forced flow of oxygen to obtain the electrode active material C-CAM 1.

(8) D50=10 μm determined using the technique of laser diffraction in a Mastersize 3000 instrument from Malvern Instruments.

(9) II. Coating with W(CO).sub.6 and ozone

(10) II.1 Manufacture of Inventive Electrode Active Material CAM.2

(11) A fluidized bed reactor with external heating jacket was charged with 100 g of C-CAM.1, and under an average pressure of 5 mbar C-CAM.1 was fluidized with Ar at a constant flow rate of 20 sccm. The fluidized bed reactor was heated to 200° C. and kept at 200° C. for 4 hours (step (a.1). To decrease filter congestion and aid in powder fluidization, the deposition encompassed regular reverse pulses of carrier gas alternating with pneumatic hammer impacts.

(12) Step (b.1): After said 4 hours, the temperature was raised to 220° C. In a vessel, W(CO).sub.6 was heated to 65 to 70° C.

(13) W(CO).sub.6 in the gaseous state was introduced into the fluidized bed reactor through a sintered metal filter plate by opening a valve to a precursor reservoir that was charged with W(CO) in solid form and then kept at 65 to 70° C. in order to generate sufficient vapor pressure for the introduction into the fluidized bed reactor. The W(CO).sub.6 was diluted with argon as carrier gas. After a reaction period of five minutes non-reacted W(CO).sub.6 was removed through the Ar stream, and the reactor was purged with Ar for 5 minutes.

(14) Step (c.1): Then, ozone as an 8% by volume mixture with O.sub.2 was introduced into the fluidized bed reactor by opening a valve to an ozone generator that produced ozone from oxygen. After a reaction period of 5 minutes non-reacted ozone was removed through the argon stream, and the reactor was purged with argon for another 5 minutes.

(15) Step (d.1): The above sequence of (b.1) and (c.1) was repeated twenty times.

(16) The reactor was then cooled to 25° C. and the material so obtained was discharged. The resultant CAM.2 displayed the following properties: D50=10 μm determined using the technique of laser diffraction in a Mastersize 3000 instrument from Malvern Instruments. W-content: 330 ppm, determined by ICP-OES.

(17) II.2: Manufacture of Inventive Electrode Active Material CAM.3

(18) Experiment II.1 was repeated but steps (b.2) and (c.2) were performed at 200° C. The reactor was then cooled to 25° C. and the material so obtained was discharged. The resultant CAM.3 displayed the following properties: D50=10 μm determined using the technique of laser diffraction in a Mastersize 3000 instrument from Malvern Instruments. W-content: 300 ppm, determined by ICP-OES.

(19) II.3: Manufacture of Inventive Electrode Active Material CAM.4

(20) Experiment II.1 was repeated but steps (b.3) and (c.3) were performed at 240° C. The reactor was then cooled to 25° C. and the material so obtained was discharged. The resultant CAM.4 displayed the following properties: D50=10 μm determined using the technique of laser diffraction in a Mastersize 3000 instrument from Malvern Instruments. W-content: 250 ppm, determined by ICP-OES.

(21) II.4: Manufacture of Inventive Electrode Active Material CAM.5

(22) Experiment II.1 was repeated but the fluidized bed reactor was not discharged after the last sequence of W(CO).sub.6/ozone treatment. Instead, step (f.4) was performed.

(23) The temperature of the fluidized bed reactor was lowered to 180° C. Trimethylaluminum (TMA) in the gaseous state was introduced into the fluidized bed reactor through a sintered filter plate by opening a valve to a precursor reservoir that contained TMA in liquid form and that was kept at 25° C. The TMA was diluted with Ar as carrier gas with 10 sccm. After a reaction period of 210 seconds non-reacted TMA was removed through the Ar stream, and the reactor was purged with Ar for 10 minutes, flow: 30 sccm. Then, water in the gaseous state was introduced into the fluidized bed reactor by opening a valve to a reservoir that contained liquid water kept at 25° C., with Ar as carrier gas with 10 sccm. After a reaction period of 120 seconds non-reacted water was removed through the Ar stream, and the reactor was purged with Ar at flow rate of 30 sccm for 10 min. The above sequence was repeated four times. The reactor was cooled to 25° C. and the material so obtained was discharged.

(24) The determined Al uptake from ICP-OES was 260 ppm.

(25) II.5: Manufacture of a Further Comparative Material, C-CAM.6

(26) Experiment II.4 was repeated but with C-CAM.1 as starting material instead of CAM.4. Comparative material C-CAM.6 was obtained. C-CAM.6 does not contain any W. Al-content: 420 ppm, determined by ICP-OES.

(27) The electrochemical performance of the inventive electrode active materials was excellent.