Positive electrode active material for nonaqueous electrolyte secondary battery, method for producing same, and nonaqueous electrolyte secondary battery using said positive electrode active material

Patent metadata

Field	Value
Publication number	US-10784507-B2
Application number	US-201515531616-A
Country	US
Kind code	B2
Filing date	Nov 27, 2015
Priority date	Nov 28, 2014
Publication date	Sep 22, 2020
Grant date	Sep 22, 2020

Abstract

Provided is a method for producing a positive electrode active material for nonaqueous electrolyte secondary batteries, the method including: a mixing step of obtaining a W-containing mixture of Li-metal composite oxide particles represented by the formula: LizNi1-x-yCoxMyO2 and composed of primary particles and secondary particles formed by aggregation of the primary particles, 2 mass % or more of water with respect to the oxide particles, and a W compound or a W compound and a Li compound, the W-containing mixture having a molar ratio of the total amount of Li contained in the water and the solid W compound, or the W compound and the Li compound of 1.5 or more and less than 3.0 with respect to the amount of W contained therein; and a heat treatment step of heating the W-containing mixture to form lithium tungstate on the surface of the primary particles.

First claim

The invention claimed is:

1. A positive electrode active material for nonaqueous electrolyte secondary batteries composed of a lithium-metal composite oxide powder having a layered crystal structure constituted by primary particles and secondary particles formed by aggregation of the primary particles, wherein:
the positive electrode active material is represented by a general formula: Li z Ni 1-x-y CO x M y W a O 2+α (where 0<x≤0.35, 0≤y≤0.35, 0.95≤z≤1.30, 0<a≤0.03, and 0 ≤α≤0.15 are satisfied, and M is at least one element selected from Mn, V, Mg, Mo, Nb, Ti, and Al), and has lithium tungstate on a surface of the primary particles of the lithium-metal composite oxide,
Li 2 WO 4 is contained in the lithium tungstate at a proportion of 50 to 95 mol %; and
tungsten is contained in the lithium tungstate in an amount of 0.05 to 2.0 at % in terms of the number of W atoms with respect to the total number of atoms of Ni, Co, and M contained in the lithium-metal composite oxide.

2. The positive electrode active material for nonaqueous electrolyte secondary batteries according to claim 1 , wherein
lithium contained in a lithium compound other than the lithium tungstate present on the surface of the lithium-metal composite oxide is in an amount of 0.08 mass % or less with respect to a total amount of the positive electrode active material.

3. The positive electrode active material for nonaqueous electrolyte secondary batteries according to claim 1 , wherein
the lithium tungstate is present on the surface of the primary particles of the lithium-metal composite oxide as fine particles having a particle size of 1 to 200 nm.

4. The positive electrode active material for nonaqueous electrolyte secondary batteries according to claim 1 , wherein
the lithium tungstate is present on the surface of the primary particles of the lithium-metal composite oxide as a coating film having a film thickness of 1 to 150 nm.

5. The positive electrode active material for nonaqueous electrolyte secondary batteries according to claim 1 , wherein
the lithium tungstate is present on the surface of the primary particles of the lithium-metal composite oxide in both forms of fine particles having a particle size of 1 to 200 nm and a coating film having a film thickness of 1 to 150 nm.

6. A nonaqueous electrolyte secondary battery comprising:
a positive electrode comprising the positive electrode active material for nonaqueous electrolyte secondary batteries according to claim 1 .

7. A method of producing the positive electrode active material for nonaqueous electrolyte secondary batteries of claim 1 , comprising:
a mixing step of obtaining a tungsten-containing mixture of:
a lithium-metal composite oxide powder represented by a general formula: Li z Ni 1-x-y Co x M y O 2 (where 0<+≤0.35, 0≤y≤0.35, and 0.95 ≤z≤1.30 are satisfied, and M is at least one element selected from Mn, V, Mg, Mo, Nb, Ti, and Al) and having a layered crystal structure constituted by primary particles and secondary particles formed by aggregation of the primary particles,

2 mass% or more of water with respect to the lithium-metal composite oxide powder, and
a tungsten compound or a tungsten compound and a lithium compound,
wherein the mixing step is carried out so that the tungsten-containing mixture has a molar ratio of a total amount of lithium contained in the water and the tungsten compound as a solid component, or in the water, and the tungsten compound and the lithium compound as a solid component of 1.5 or more and less than 3.0, with respect to an amount of tungsten contained therein; and
the method further comprising
a heat treatment step of heating the tungsten-containing mixture obtained in the mixing step to form lithium tungstate on a surface of the primary particles of the lithium-metal composite oxide.

8. The method of producing a positive electrode active material for nonaqueous electrolyte secondary batteries according to claim 7 , further comprising, prior to the mixing step:
a water washing step of washing the lithium-metal composite oxide powder with water by mixing the lithium-metal composite oxide powder with the water to form a slurry; and
a solid-liquid separation step of subjecting the slurry to solid-liquid separation subsequently to the water washing step.

9. The method of producing a positive electrode active material for nonaqueous electrolyte secondary batteries according to claim 8 , wherein
the lithium-metal composite oxide powder is contained in the slurry at a concentration of 200 to 5000 g per 1 L of water.

10. The method of producing a positive electrode active material for nonaqueous electrolyte secondary batteries according to claims 8 , wherein
the tungsten compound is added at least during the water washing step or after the solid-liquid separation step to obtain the tungsten-containing mixture.

11. The method of producing a positive electrode active material for nonaqueous electrolyte secondary batteries according to claim 10 , wherein
in the water washing step, the lithium-metal composite oxide powder is mixed with an aqueous solution of the tungsten compound to form the slurry.

12. The method of producing a positive electrode active material for nonaqueous electrolyte secondary batteries according to claim 10 , wherein
the tungsten compound is in powder form.

13. The method of producing a positive electrode active material for nonaqueous electrolyte secondary batteries according to claim 7 , wherein
the heat treatment is performed at 100 to 600° C.

14. The method of producing a positive electrode active material for nonaqueous electrolyte secondary batteries according to claim 7 , wherein
an amount of tungsten contained in the tungsten-containing mixture is adjusted to 0.05 to 2.0 at % with respect to the total number of atoms of Ni, Co, and M contained in the lithium-metal composite oxide powder.

15. The method of producing a positive electrode active material for nonaqueous electrolyte secondary batteries according to claim 7 , wherein
an amount of the water in the tungsten-containing mixture is 3 to 15 mass % with respect to the lithium-metal composite oxide powder.

Assignees

• Sumitomo Metal Mining Co

Inventors

• Furuichi Yuki
• Komukai Tetsufumi

Classifications

• C01P2002/87

  by chromatography data, e.g. HPLC, gas chromatography · CPC title

• H01M4/628

  Inhibitors, e.g. gassing inhibitors, corrosion inhibitors · CPC title

• C01G41/00 Primary

  Compounds of tungsten · CPC title

• C01P2004/80

  Particles consisting of a mixture of two or more inorganic phases · CPC title

• C01P2004/82

  two phases having the same anion, e.g. both oxidic phases · CPC title