# US 2019/0355974 A1 · Negative electrode for secondary battery and method for producing same

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- Number: US 2019/0355974 A1
- Document ID: US20190355974A1
- Status: Published application
- Kind: A1
- Application number: 16/477,441
- Filed: 2017-12-27
- Published: 2019-11-21
- Earliest claimed: 2017-04-06
- Assignees: LG Chem, Ltd.
- Applicants: LG Chem, Ltd.
- Inventors: Young Jae KIM; Je Young KIM
- Web page: https://patentgrep.com/patent/US20190355974A1

## CPC

- H01M 4/0404: {by coating on electrode collectors}
- H01M 4/133: Electrodes based on carbonaceous material, e.g. graphite-intercalation compounds or CFx
- H01M 4/134: Electrodes based on metals, Si or alloys
- H01M 4/1393: of electrodes based on carbonaceous material, e.g. graphite-intercalation compounds or CFx
- H01M 4/1395: of electrodes based on metals, Si or alloys
- H01M 4/364: {as mixtures}
- H01M 4/386: {Silicon or alloys based on silicon}
- H01M 4/587: for inserting or intercalating light metals
- H01M 4/622: {being polymers}
- H01M 10/052: Li-accumulators
- H01M 2004/027: {Negative 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 negative electrode for a secondary battery, and a method for producing the same, and more particularly, to a negative electrode for a secondary battery used for a negative electrode of a secondary battery, and a method for producing the same. A negative electrode for a secondary battery may include a carbon-based active material; a conductive material; and a silicon-based active material-polymer binder combination including a silicon-based active material, and a polymer binder for suppressing the expansion of the silicon-based active material bonded to a particle surface of the silicon-based active material.

## Claims

### Claim 1

A negative electrode for a secondary battery comprising:
a carbon-based active material;
a conductive material; and
a silicon-based active material-polymer binder combination comprising a silicon-based active material, and a polymer binder bonded to a surface of the silicon-based active material, wherein the polymer binder suppresses expansion of the silicon-based active material.

### Claim 2 (depends on 1)

The negative electrode for a secondary battery of claim 1, wherein the silicon-based active material is included in an amount of 5 to 15 wt % based on a total weight of active material including the carbon-based active material and the silicon-based active material.

### Claim 3 (depends on 1)

The negative electrode for a secondary battery of claim 1, wherein the polymer binder is included in an amount of 25 to 45 wt % based on a weight of the silicon-based active material.

### Claim 4 (depends on 1)

The negative electrode for a secondary battery of claim 1, wherein the polymer binder comprises a hydrophilic polymer material having a hydroxy group (—OH).

### Claim 5 (depends on 1)

The negative electrode for a secondary battery of claim 1, wherein the polymer binder comprises at least one of polyacrylic acid (PAA), polyvinyl alcohol (PVA), or sodium-polyacrylate (Na-PA).

### Claim 6 (depends on 1)

The negative electrode for a secondary battery of claim 1 having an initial discharge capacity of 470 mAh or greater.

### Claim 7 (depends on 1)

The negative electrode for a secondary battery of claim 1 having an initial charge/discharge efficiency of 87% or greater.

### Claim 8

A method for producing a negative electrode for a secondary battery, comprising:
preparing a carbon-based active material;
preparing a pre-dispersion slurry by mixing a silicon-based active material, a conductive material, and a polymer binder in a dispersion medium;
preparing a negative electrode slurry by mixing the pre-dispersion slurry and the carbon-based active material;
applying the prepared negative electrode slurry on a current collector; and
forming a negative electrode by removing moisture from the negative electrode slurry.

### Claim 9 (depends on 8)

The method of claim 8, wherein the pre-dispersion slurry is formed by dispersing a silicon-based active material-polymer binder combination in which the silicon-based active material and the polymer binder are bonded, and the conductive material.

### Claim 10 (depends on 8)

The method of claim 8, wherein a solid content of the pre-dispersion slurry is controlled by a viscosity of the pre-dispersion slurry.

### Claim 11 (depends on 10)

The method of claim 10, wherein the solid content of the pre-dispersion slurry is controlled such that the pre-dispersion slurry has a viscosity of 3000 to 10000 cp.

### Claim 12 (depends on 8)

The method of claim 8, wherein the pre-dispersion slurry has a solid content of 15 to 25 wt % based on a total weight of the pre-dispersion slurry.

### Claim 13 (depends on 8)

The method of claim 8, wherein the preparing of the negative electrode slurry comprises:
preparing a first negative electrode slurry by first mixing a portion of the pre-dispersion slurry and the carbon-based active material; and
preparing a second negative electrode slurry by mixing the first negative electrode slurry and a remaining portion of the pre-dispersion slurry.

### Claim 14 (depends on 8)

The method of claim 8, wherein the negative electrode slurry has a solid content of 40 to 50 wt % based on a total weight of the negative electrode slurry.