# US 10,374,223 B2 · Positive electrode active material/graphene composite particles, positive electrode material for lithium ion cell, and method for manufacturing positive electrode active material/graphene composite particles

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- Number: US 10,374,223 B2
- Document ID: US10374223B2
- Status: Granted
- Kind: B2
- Application number: 14/653,755
- Filed: 2014-01-20
- Published: 2015-11-19
- Granted: 2019-08-06
- Earliest claimed: 2013-01-23
- Assignees: Toray Industries, Inc.
- Applicants: Toray Industries, Inc.
- Inventors: Eiichiro Tamaki; Yasuo Kubota; Hiroaki Kawamura; Hanxiao Yang; Mayumi Hara
- Web page: https://patentgrep.com/patent/US10374223B2

## CPC

- H01M 4/364: {as mixtures}
- H01M 4/131: Electrodes based on mixed oxides or hydroxides, or on mixtures of oxides or hydroxides, e.g. LiCoOx
- H01M 4/133: Electrodes based on carbonaceous material, e.g. graphite-intercalation compounds or CFx
- H01M 4/366: {as layered products}
- H01M 4/485: of mixed oxides or hydroxides for inserting or intercalating light metals, e.g. LiTi2O4 or LiTi2OxFy (H01M4/505, H01M4/525 take precedence)
- 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 4/5825: {Oxygenated metallic salts or polyanionic structures, e.g. borates, phosphates, silicates, olivines}
- H01M 4/587: for inserting or intercalating light metals
- H01M 4/625: {Carbon or graphite}
- H01M 10/0525: Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
- H01M 2004/021: {Physical characteristics, e.g. porosity, surface area}
- 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
- Y02E: REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION

## Abstract

A conventional positive electrode material for lithium ion batteries that is made of positive electrode active material/graphene composite particles has low graphene material ion conductivity and is incapable of providing favorable battery performance. In the present invention, positive electrode active material/graphene composite particles are conferred with high electron conductivity and ion conductivity by formation of an appropriately functionalized graphene/positive electrode active material composite, and are capable of yielding a high-capacity/high-output lithium ion secondary battery when used as a positive electrode active material for a lithium ion battery.

## Claims

### Claim 1

Positive electrode active material and graphene composite particles which comprise:
positive electrode active material particles and
a matrix containing partially functionalized graphene,
wherein
the partially functionalized graphene comprises graphene modified with a hydroxyl, carboxyl, ketone or epoxy group, and
the composite particles have a ratio of functionalization that is not less than 0.15 and not more than 0.80, the ratio of functionalization being determined, based on measurements by X-ray photoelectron spectroscopic measurement of the composite particles, from the following equation:
Ratio of functionalization=[(peak area based on C—O single bond)+(peak area based on C═O double bond)+(peak area based on COO bond)]/(peak area based on C—C, C═C and C—H bonds).

### Claim 2 (depends on 1)

The positive electrode active material and graphene composite particles according to claim 1, wherein the composite particle ratio of functionalization is not less than 0.30 and not more than 0.80.

### Claim 3 (depends on 1)

The positive electrode active material and graphene composite particles according to claim 1, wherein the composite particles have a mass ratio of carbon, in terms of percent, of less than 2% and not more than 20%.

### Claim 4 (depends on 1)

The positive electrode active material and graphene composite particles according to claim 1, wherein the positive electrode active material is an olivine-based active material particle or a layered oxide active material particle.

### Claim 5 (depends on 4)

The positive electrode active material and graphene composite particles according to claim 4, wherein the layered oxide active material particle is a Li-rich active material particle.

### Claim 6 (depends on 1)

A positive electrode material for a lithium ion battery which contains the positive electrode active material and graphene composite particles according to claim 1.

### Claim 7 (depends on 1)

The positive electrode active material and graphene composite particles according to claim 1, wherein upon being subjected to Raman spectroscopy the composite particles exhibit a Raman spectrometric G band peak position of 1600 cm−1 or more and a peak half bandwidth is 90 cm−1 or less.

### Claim 8 (depends on 1)

The positive electrode active material and graphene composite particles according to claim 1, wherein the matrix has voids.

### Claim 9 (depends on 8)

The positive electrode active material and graphene composite particles according to claim 8, wherein a void ratio of the matrix is not less than 10% and not more than 50%.