LITHIUM COMPOUND, METHOD FOR PRODUCING THE LITHIUM COMPOUND, AND METHOD FOR PRODUCING POSITIVE ACTIVE MATERIAL FOR NONAQUEOUS ELECTROLYTE SECONDARY BATTERY

• US 20190312273A1
• Filed: 06/06/2017
• Published: 10/10/2019
• Est. Priority Date: 06/07/2016
• Status: Active Grant

• Current Assignee: Sumitomo Metal Mining Company Limited
• Original Assignee: Sumitomo Metal Mining Company Limited
• Inventors: TAGAMI, Azusa, ASAKAWA, Takeshi
• Granted Patent: US 11,056,688 B2
• Time in Patent Office: Days
• CPC Class Codes: B03C 1/00 Magnetic separation
• CPC Class Codes: B03C 1/002 High gradient magnetic separation
• CPC Class Codes: B03C 1/02 acting directly on the substance being separated
• CPC Class Codes: B03C 2201/20 Magnetic separation whereby the particles to be separated are in solid form
• CPC Class Codes: C01D 1/28 Purification; Separation
• CPC Class Codes: C01D 15/02 Oxides; Hydroxides
• CPC Class Codes: C01G 53/42 containing alkali metals, e.g. LiNiO2
• CPC Class Codes: C01P 2006/40 Electric properties
• CPC Class Codes: C01P 2006/80 Compositional purity
• CPC Class Codes: H01M 2004/028 Positive electrodes
• CPC Class Codes: H01M 4/525 of mixed oxides or hydroxides containing iron, cobalt or nickel for inserting or intercalating light metals, e.g. LiNiO2, LiCoO2 or LiCoOxFy
• CPC Class Codes: Y02E 60/10 Energy storage using batteries

Abstract

A lithium compound is provided, with which a positive active material containing a decreased amount of magnetically attractable substances can be easily obtained while shortening the total time for production of a positive electrode for a nonaqueous electrolyte secondary battery. The lithium compound is used for producing a positive active material for a nonaqueous electrolyte secondary battery, with which a lithium transition metal composite oxide can be obtained by mixing the lithium compound with a transition metal composite hydroxide or the like obtained by crystallization reaction, and then firing the mixture obtained by mixing, wherein when water and a magnet are added to and mixed and stirred with the lithium compound, the amount of magnetically attractable substances captured by the magnet is 0.0007 mass % or less with respect to the amount of lithium in the lithium compound. Therefore, a positive active material in which the amount of magnetically attractable substances contained is 0.02 mass ppm or less can be easily obtained while shortening the total time for production of the positive active material.

Claims

1. A lithium compound for production of a positive active material for a nonaqueous electrolyte secondary battery, with which a lithium transition metal composite oxide can be obtained by:

mixing the lithium compound with a transition metal composite hydroxide obtained by crystallization reaction, or a transition metal composite oxide obtained by heat treatment of the transition metal composite hydroxide; and

then

firing the thus mixed and obtained mixture, wherein

when water, and a magnet having a magnetic flux density of 0.9 tesla are added to and mixed with the lithium compound, and then the mixture is stirred for 30 minutes,

an amount of magnetically attractable substances to be captured by the magnet is 0.0007 mass % or less with respect to an amount of lithium contained in the lithium compound.

2. The lithium compound according to claim 1, wherein the lithium compound is any one of a lithium hydroxide, a hydrate of a lithium hydroxide, and a mixture of a lithium hydroxide and a hydrate thereof.

3. The lithium compound according to claim 1, wherein the amount of magnetically attractable substances is 0.0005 mass % or less with respect to the amount of lithium contained in the lithium compound.

4. The lithium compound according to claim 1, wherein the amount of magnetically attractable substances is calculated by cleaning the magnet with water by ultrasonic cleaning, dissolving magnetically attractable substances adhered to the surface by acid, and then performing chemical analysis.

8. A method for producing a positive active material for a nonaqueous electrolyte secondary battery, which comprises mixing the lithium compound according to claim 1 with a transition metal composite hydroxide obtained by crystallization reaction, and then firing the thus obtained mixture.

9. A method for producing a positive active material for a nonaqueous electrolyte secondary battery, which comprises mixing the lithium compound according to claim 1 with a transition metal composite oxide obtained by heat treatment of a transition metal composite hydroxide obtained by crystallization reaction, and then firing the thus obtained mixture.

10. The method for producing a positive active material for a nonaqueous electrolyte secondary battery according to claim 8, wherein the amount of magnetically attractable substances in the mixture is 0.02 mass ppm or less.

5. A method for producing a lithium compound for production of a positive active material for a nonaqueous electrolyte secondary battery, whereby an amount of magnetically attractable substances in the lithium compound is 0.0007 mass % or less with respect to an amount of lithium contained in the lithium compound through contact of a magnetized screen with the lithium compound and use of a magnetic separator for removing magnetically attractable substances.

6. The method for producing a lithium compound according to claim 5, wherein the lithium compound is subjected to dry magnetic separation.

7. The method for producing a lithium compound according to claim 5, wherein a surface of the screen has a magnetic flux density of 1 tesla or more.