# US 10,312,522 B2 · Binder composition for lithium ion secondary battery positive electrode, slurry composition for lithium ion secondary battery positive electrode, positive electrode for lithium ion secondary battery and lithium ion secondary battery

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- Number: US 10,312,522 B2
- Document ID: US10312522B2
- Status: Granted
- Kind: B2
- Application number: 15/558,634
- Filed: 2016-03-23
- Published: 2018-03-29
- Granted: 2019-06-04
- Earliest claimed: 2015-03-27
- Assignees: Zeon Corporation
- Applicants: Zeon Corporation
- Inventors: Mayumi Fukumine; Takumi Sugimoto
- Web page: https://patentgrep.com/patent/US10312522B2

## CPC

- H01M 4/622: {being polymers}
- C08F 2/38: Polymerisation using regulators, e.g. chain terminating agents {, e.g. telomerisation}
- C08F 236/04: conjugated
- C08F 236/12: with nitriles
- H01M 4/04: Processes of manufacture in general
- H01M 4/364: {as mixtures}
- H01M 4/62: Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
- H01M 10/052: Li-accumulators
- H01M 10/0525: Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
- H01M 10/0566: Liquid materials
- H01M 2004/028: {Positive electrodes}
- Y02E 60/10: Energy storage using batteries
- H01M: PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- C08F: MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
- Y02E: REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION

## Abstract

Provided is a binder composition for a lithium ion secondary battery positive electrode that can suppress expansion of a positive electrode. The disclosed binder composition for a lithium ion secondary battery positive electrode includes a copolymer containing a nitrile group-containing monomer unit and a conjugated diene monomer unit and a solvent. A degree of swelling in electrolysis solution of the copolymer is at least 200 mass % and no greater than 700 mass % and a storage elastic modulus of a binder coating obtained through film formation of the binder composition is at least 1×104 and no greater than 1×109 Pa.

## Claims

### Claim 1

A binder composition for a lithium ion secondary battery positive electrode including a copolymer containing a nitrile group-containing monomer unit and a conjugated diene monomer unit and a solvent, wherein,
a degree of swelling in electrolysis solution of the copolymer is at least 200 mass % and no greater than 700 mass %,
a storage elastic modulus of a binder coating obtained through a film formation of the binder composition is at least 1×104 Pa and no greater than 1×109 Pa, and
the copolymer includes an alkylthio group of a carbon number from 12 to 16 having at least three tertiary or higher carbon atoms and a sulfur atom directly bonded to at least one of the tertiary or higher carbon atoms.

### Claim 2

A binder composition for a lithium ion secondary battery positive electrode including a copolymer containing a nitrile group-containing monomer unit, a conjugated diene monomer unit and an alkylthio group and a solvent, wherein
a degree of swelling in electrolysis solution of the copolymer is at least 200 mass % and no greater than 700 mass %, and
the alkylthio group is an alkylthio group of a carbon number from 12 to 16 having at least three tertiary or higher carbon atoms and a sulfur atom directly bonded to at least one of the tertiary or higher carbon atoms.

### Claim 3 (depends on 2)

The binder composition for a lithium ion secondary battery positive electrode according to claim 2, wherein the copolymer includes at least 0.03 mol of the alkylthio group per 100 mol of a monomer unit constituting the copolymer.

### Claim 4 (depends on 2)

The binder composition for a lithium ion secondary battery positive electrode according to claim 2, wherein the alkylthio group is at least one type selected from 1,1-di(2,2-dimethylpropyl)-1-ethylthio group and 1-(2,2-dimethylpropyl)-1-(2,2,4,4-tetramethylpentyl)-1-ethylthio group.

### Claim 5 (depends on 2)

The binder composition for a lithium ion secondary battery positive electrode according to claim 2, wherein an iodine value of the copolymer is at least 0.01 mg/100 mg and no greater than 70 mg/100 mg.

### Claim 6 (depends on 2)

The binder composition for a lithium ion secondary battery positive electrode according to claim 2, wherein the copolymer contains the nitrile group-containing monomer unit of at least 5 mass % and no greater than 70 mass % and the conjugated diene monomer unit of at least 30 mass % and no greater than 95 mass %.

### Claim 7 (depends on 2)

The binder composition for a lithium ion secondary battery positive electrode according to claim 2, wherein a Mooney viscosity of the copolymer is at least 20 and no greater than 300.

### Claim 8 (depends on 2)

A slurry composition for a lithium ion secondary battery positive electrode containing a positive electrode active material, a conductive agent and the binder composition for a lithium ion secondary battery positive electrode according to claim 2.

### Claim 9 (depends on 8)

A positive electrode for a lithium ion secondary battery comprising a positive electrode mixed material layer formed by using the slurry composition for a lithium ion secondary battery positive electrode according to claim 8.

### Claim 10 (depends on 9)

A lithium ion secondary battery comprising the positive electrode for a lithium ion secondary battery according to claim 9, a negative electrode, an electrolysis solution and a separator.