Method for producing positive electrode active material for nonaqueous electrolyte secondary battery

Patent metadata

Field	Value
Publication number	US-11108043-B2
Application number	US-201916661632-A
Country	US
Kind code	B2
Filing date	Oct 23, 2019
Priority date	Dec 26, 2014
Publication date	Aug 31, 2021
Grant date	Aug 31, 2021

Abstract

Provided is a method for producing a positive electrode active material for nonaqueous electrolyte secondary batteries, including: a water-washing step of mixing, with water, Li—Ni composite oxide particles represented by the formula: Li z Ni 1-x-y Co x M y O 2 and composed of primary particles and secondary particles formed by aggregation of the primary particles to water-wash it, and performing solid-liquid separation to obtain a washed cake; a mixing step of mixing a W compound powder free from Li with the washed cake to obtain a W-containing mixture; and a heat treatment step of heating the W-containing mixture, the heat treatment step including: a first heat treatment step of heating the W-containing mixture to disperse W on the surface of the primary particles; and subsequently, a second heat treatment step of heating it at a higher temperature than in the first heat treatment step to form a lithium tungstate compound on the surface of the primary particles.

First claim

What is claimed is:

1. A method of producing a positive electrode active material for nonaqueous electrolyte secondary batteries, comprising
a water washing step of mixing, with water, a lithium-nickel composite oxide powder represented by a general formula: Li z Ni 1-x-y Co x M y O 2 , where 0≤x≤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, the lithium-nickel composite oxide powder having a layered crystal structure composed of primary particles and secondary particles formed by aggregation of the primary particles to form a slurry, and the water washing step including washing the lithium-nickel composite oxide powder with the water, and then subjecting the slurry to solid-liquid separation to obtain a washed cake constituted by washed lithium-nickel composite oxide particles;
a mixing step of mixing a tungsten compound powder not containing lithium with the washed cake to obtain a tungsten-containing mixture; and
a heat treatment step of heating the tungsten-containing mixture, wherein
the heat treatment step includes:
a first heat treatment step of heating the tungsten-containing mixture to allow a lithium compound present on a surface of the primary particles of the washed lithium-nickel composite oxide to react with the tungsten compound so as to dissolve the tungsten compound therein, thereby forming lithium-nickel composite oxide particles with tungsten dispersed on the surface of the primary particles; and
subsequent to the first heat treatment step, a second heat treatment step of performing heat treatment at a higher temperature than in the first heat treatment step to form lithium-nickel composite oxide particles with a lithium tungstate compound formed on the surface of the primary particles of the lithium-nickel composite oxide.

2. The method of producing a positive electrode active material for nonaqueous electrolyte secondary batteries according to claim 1 , wherein
the slurry in the water washing step has a concentration of 500 to 2500 g/L.

3. The method of producing a positive electrode active material for nonaqueous electrolyte secondary batteries according to claim 1 , wherein
the slurry in the water washing step has a temperature of 20 to 30° C.

4. The method of producing a positive electrode active material for nonaqueous electrolyte secondary batteries according to claim 1 , wherein
the washed cake obtained in the water washing step has a water content controlled to 3.0 to 15.0 mass %.

5. The method of producing a positive electrode active material for nonaqueous electrolyte secondary batteries according to claim 1 , wherein
the tungsten compound not containing lithium used in the mixing step is tungsten oxide (WO 3 ) or tungstic acid (WO 3 .H 2 O).

6. The method of producing a positive electrode active material for nonaqueous electrolyte secondary batteries according to claim 1 , wherein
an amount of tungsten contained in the tungsten-containing mixture is 0.05 to 2.0 at % with respect to the total number of atoms of Ni, Co, and M contained in the lithium-nickel composite oxide particles.

7. The method of producing a positive electrode active material for nonaqueous electrolyte secondary batteries according to claim 1 , wherein
the heat treatment step is performed in any one atmosphere of decarbonated air, inert gas, and vacuum.

8. The method of producing a positive electrode active material for nonaqueous electrolyte secondary batteries according to claim 1 , wherein
the first heat treatment step is performed at a heat treatment temperature of 60 to 80° C.

9. The method of producing a positive electrode active material for nonaqueous electrolyte secondary batteries according to claim 1 , wherein
the second heat treatment step is performed at a heat treatment temperature of 100 to 200° C.

Assignees

• Sumitomo Metal Mining Co

Inventors

• Kondo Kentaro
• Yokoyama Jun
• Furuichi Yuki
• Komukai Tetsufumi

Classifications

• C01P2006/40

  Electric properties · CPC title

• C01P2004/62

  Submicrometer sized, i.e. from 0.1-1 micrometer · CPC title

• C01P2002/20

  Two-dimensional structures · CPC title

• C01P2004/03

  obtained by SEM · CPC title

• C01G53/42 Primary

  containing alkali metals, e.g. LiNiO2 · CPC title