# US 12,763,318 B2 · Nonaqueous electrolyte secondary battery

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- Number: US 12,763,318 B2
- Document ID: US12763318B2
- Status: Granted
- Kind: B2
- Application number: 16/126,311
- Filed: 2018-09-10
- Published: 2019-03-14
- Granted: 2026-10-13
- Earliest claimed: 2017-09-11
- Assignees: Toyota Jidosha Kabushiki Kaisha
- Applicants: Toyota Jidosha Kabushiki Kaisha
- Inventors: Tetsuri Nakayama
- Web page: https://patentgrep.com/patent/US12763318B2

## CPC

- H01M 4/364: {as mixtures}
- H01M 4/505: of mixed oxides or hydroxides containing manganese for inserting or intercalating light metals, e.g. LiMn2O4 or LiMn2OxFy
- 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
- H01M 4/62: Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
- H01M 10/0525: Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
- H01M 10/4235: {Safety or regulating additives or arrangements in electrodes, separators or electrolyte (H01M10/4242 takes precedence)}
- H01M 2004/028: {Positive electrodes}
- H01M: PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY

## Abstract

Provided is a nonaqueous electrolyte secondary battery in which Li3PO4 is added to a positive electrode active material layer and which has excellent high-temperature storage characteristic. The nonaqueous electrolyte secondary battery disclosed herein includes a positive electrode, a negative electrode, and a nonaqueous electrolytic solution. The positive electrode includes a positive electrode active material layer. The positive electrode active material layer includes Li3PO4, Li2WO4, and, as a positive electrode active material, a lithium transition metal complex oxide including at least lithium, nickel, manganese, and cobalt. The mass ratio of Li3PO4 to the positive electrode active material is 1% by mass or more and 5% by mass or less. The mass ratio of Li2WO4 to the positive electrode active material is 0.2% by mass or more and 0.9% by mass or less.

## Claims

### Claim 1

A nonaqueous electrolyte secondary battery comprising a positive electrode, a negative electrode, a battery case, a positive electrode terminal, a negative electrode terminal, a safety valve and a nonaqueous electrolytic solution, wherein
the battery case is a flat angular battery case,
the positive electrode terminal, the negative electrode terminal, and the safety valve are provided on a same face of the battery case,
the positive electrode includes a positive electrode active material layer;
the positive electrode active material layer includes Li3PO4, Li2WO4, and, as a positive electrode active material, a lithium transition metal complex oxide including at least lithium, nickel, manganese, and cobalt;
a mass ratio of Li3PO4 to the positive electrode active material is 1% by mass or more and 3% by mass or less;
a mass ratio of Li2WO4 to the positive electrode active material is 0.5% by mass or more and 0.9% by mass or less;
an average particle diameter of the Li3PO4 is 1 μm or more and 10 μm or less;
an average particle diameter of the Li2WO4 is 0.01 μm or more and less than 0.1 μm;
the lithium transition metal composite oxide is represented by a following Formula (I):
LiaNixMnyCozO2 (I),
wherein, in Formula (I), a satisfies 0.98≤a≤1.20; x, y, and z satisfy x+y+z=1; x satisfies 0.20≤x≤0.60; y satisfies 0<y≤0.50; and z satisfies 0<z≤0.50;
the negative electrode includes a negative electrode active material layer;
the negative electrode active material layer includes a negative electrode active material, a binder, and a thickener;
the negative electrode active material of the negative electrode active material layer consists essentially of graphite;
a content of the graphite in the negative electrode active material layer is 95% by mass or more and 99% by mass or less,
the binder includes styrene butadiene rubber;
a content of the styrene butadiene rubber in the negative electrode active material layer is 0.5% by mass or more and 3% by mass or less,
the thickener includes carboxymethyl cellulose, and
a coating film derived from decomposition of both Li3PO4 and Li2WO4 and including phosphorus atoms and tungsten atoms is formed on the positive electrode active material.

### Claim 2 (depends on 1)

The nonaqueous electrolyte secondary battery according to claim 1, wherein x satisfies 0.34≤x≤0.60.

### Claim 3 (depends on 1)

The nonaqueous electrolyte secondary battery according to claim 1, wherein the Li2WO4 is present as particles separate from the positive electrode active material and the Li3PO4.