Process for making an electrode active material

Abstract

Process for making an electrode active material for a lithium ion battery, said process comprising the following steps: (a) Contacting a mixture of (A) a precursor of a mixed oxide according to general formula Li.sub.1+xTM.sub.1−xO.sub.2, wherein TM is a combination of two or more transition metals selected from Mn, Co and Ni, optionally in combination with at least one more metal selected from Ba, Al, Ti, Zr, W, Fe, Cr, K, Mo, Nb, Mg, Na and V, and x is in the range of from zero to 0.2, and (B) at least one lithium compound, with (C) Br.sub.2, I.sub.2, or at least one compound selected from carbon perhalides selected from the bromides and iodides, and interhalogen compounds comprising bromine or iodine, and (b) Subjecting said mixture to heat treatment at a temperature in the range of from 700 to 1000° C.

Claims

1. An electrode active material comprising from 0.01% to 1.0% by weight of bromine or iodine, as determined by coulometric titration, and comprising a mixed oxide according to general formula Li.sub.1+xTM.sub.1−xO.sub.2, wherein TM is a combination according to formula (II)
(Ni.sub.aCo.sub.bMn.sub.c).sub.1−dM.sub.d  (II) with a ranging from 0.6 to 0.9, b ranging from 0.05 to 0.2, c ranging from zero to 0.2, and d ranging from zero to 0.1, M is Al, Ti, or Zr, and a+b+c=1, and x ranging from zero to 0.2, wherein the bromine or iodine is in an oxidation state of at least +III, and wherein the electrode active material has an average particle diameter (D50), as measured by light scattering, ranging from 7 μm to 15 μm, and a D99 particle diameter ranging from 30 μm to 40 μm.

2. A lithium ion battery comprising the electrode active material according to claim 1.

3. A process for making an electrode active material for a lithium ion battery, wherein the process comprises: (a) contacting a mixture of (A) a precursor of a mixed oxide according to general formula Li.sub.1+xTM.sub.1−xO.sub.2, wherein x ranges from zero to 0.2, and wherein TM is a combination according to formula (II)
(Ni.sub.aCo.sub.bMn.sub.c).sub.1−dM.sub.d  (II) with a ranging from 0.6 to 0.9, b ranging from 0.05 to 0.2, c ranging from zero to 0.2, and d ranging from zero to 0.1, M is Al, Ti Zr, and a+b+c=1, and (B) at least one lithium compound, with (C) Br.sub.2, I.sub.2, or at least one or more compounds are carbon perbromides, carbon periodides, or interhalogen compounds comprising bromine or iodine, and (b) subjecting the mixture to heat treatment at a temperature ranging from 700° C. to 1000° C.; wherein the electrode active material is an electrode active material according to claim 1.

4. The process according to claim 3, wherein the mixed oxide is synthesized from a mixture of at least one lithium compound (B) and a precursor (A): wherein the precursor (A) is a mixed metal oxide, a mixed metal hydroxide, or a mixed metal oxyhydroxide of TM.

5. The process according to claim 3, wherein the lithium compound (B) is lithium hydroxide or lithium carbonate.

6. The process according to claim 3, wherein TM is a combination according to formula (II)
(Ni.sub.aCo.sub.bMn.sub.c).sub.1−dM.sub.d  (II) with a ranging from 0.6 to 0.9, b ranging from 0.05 to 0.2, c ranging from zero to 0.2, and d ranging from zero to 0.1, M is Al, Ti, or Zr, and a+b+c=1.

7. The process according to claim 3, wherein in (a) the precursor (A) is treated with Br.sub.2, I.sub.2, or at least one or more compounds are carbon perbromides, carbon periodides, and interhalogen compounds comprising bromine or iodine (C) in a solution.

8. The process according to claim 3, wherein in (a) the mixture of precursor (A) and lithium compound (B) is treated with Br.sub.2, I.sub.2, or at least one or more compounds are carbon perbromides, carbon periodides, and interhalogen compounds comprising bromine or iodine (C) in an organic solvent or in a combination of at least two organic solvents followed by removal of the organic solvent(s).

9. The process according to claim 3, wherein (b) is performed under a forced flow of gas.

10. The process according to claim 3, wherein (b) is performed in a roller hearth kiln, a pusher kiln or a rotary hearth kiln.

Description

EXAMPLE 1

(1) An amount of 16.95 g of precursor (A.1) and 8.05 g (B.1) were mixed. The molar ratio of TM/Li was 1:1.015.

(2) An amount of 2.5 g of 12 (99.8% purity) were dissolved in 50 ml of ethanol, (technical grade: 6.5% by vol water.

(3) Step (a.1): A 100-ml-beaker from polyethylene was charged with the above solution of iodine. Then, the mixture of precursor (A.1) and lithium compound (B.1) was added and agitated. Then, the solvents were evaporated at ambient temperature until loose agglomerates of slightly moist powder remained.

(4) The slightly moist powder so obtained was then transferred into a metal rotary bulb (Ni-alloy) and external heating by an electrical split tube furnace was commenced. A constant stream of air with a flow rate of 60 Nl/h was applied.

(5) Within 10 minutes, the temperature in the bulb reached 200° C. For the next 15 minutes, the temperature was maintained at ca. 210° C. Evaporation of residual solvent and removal of unreacted iodine could be observed.

(6) Step (b.1): Then, the powder was heated to 710° C. within 70 minutes and then maintained at that temperature for 60 minutes, followed by rapid cooling in air of ambient temperature by means of opening the split tube furnace. After 1 hour of cooling, the temperature dropped to 70° C.

(7) An electrode active material of general formula Li.sub.(1+x)(Ni.sub.0.9Co.sub.0.1).sub.(1−x)O.sub.2 was obtained. The iodine content was 0.5% by weight, determined by coulometric titration. The average particle diameter (D50) of 10 μm and a diameter (D99) of 32 μm. It had excellent morphology with no lumps or aggregated particles of more than 15 μm particle diameter. Electrochemical data were excellent.

(8) Comparison Experiment:

(9) A mixture of 33.90 g of (A.1) and 16.1 g of (B.1) were mixed without performing a step (a). The mixture so obtained was placed in the above described rotary bulb. A constant stream of pure oxygen with a flow rate of 60 Nl/h was applied. The temperature was ramped up from room conditions to 700° C. within 140 min and maintained for 60 min. Cooling of the sample to 60° C. took place with an exponential decay within 150 min.

(10) An comparison electrode active material of general formula Li.sub.(1+x)(Ni.sub.0.9Co.sub.0.1).sub.(1−x)O.sub.2 was obtained. However, more than 50% of the sample was agglomerated to massive lumps of 1-5 mm diameter.

EXAMPLE 2

(11) An amount of 35.35 g of precursor (A.2) and 14.65 g (B.1) were mixed. The molar ratio of TM/Li was 1.1.03.

(12) An amount of 0.23 g of 12 (99.8% purity) were dissolved in 50 ml of ethanol (95% purity)

(13) Step (a.2): A 100-ml-beaker from polyethylene was charged with the above solution of iodine.

(14) Then, the mixture of precursor (A.2) and lithium compound (B.1) was added and agitated. Then, the solvents were evaporated at ambient temperature until loose agglomerates of slightly moist powder remained.

(15) The slightly moist powder so obtained was then transferred into a metal rotary bulb (Ni-alloy) and external heating by an electrical split tube furnace was commenced. A constant stream of pure oxygen with a flow rate of 60 Nl/h was applied.

(16) Step (b.2): Then, the powder was heated to 805° C. within 80 minutes and then maintained at that temperature for 300 minutes, followed by rapid external cooling of the bulb in air of ambient temperature by means of opening the split tube furnace. After 0.5 hour of cooling, the temperature dropped to 60° C. The flow of oxygen was maintained until cooling was finished.

(17) An electrode active material of general formula Li.sub.(1+x)(Ni.sub.0.8Co.sub.0.1Mn.sub.0.1).sub.(1−x)O.sub.2 was obtained. The iodine content was 0.7% by weight, determined by combustion ion chromatography. It had excellent morphology with no lumps or aggregated particles. Electrochemical performance was excellent.