# US 2018/0026257 A1 · Negative active material for rechargeable lithium battery, method of preparing same, and rechargeable lithium battery including same

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- Number: US 2018/0026257 A1
- Document ID: US20180026257A1
- Status: Published application
- Kind: A1
- Application number: 15/655,258
- Filed: 2017-07-20
- Published: 2018-01-25
- Earliest claimed: 2016-07-21
- Assignees: Samsung SDI Co., Ltd.
- Applicants: Samsung SDI Co., Ltd.
- Inventors: Doori OH; Chul YOUM
- Web page: https://patentgrep.com/patent/US20180026257A1

## CPC

- H01M 4/133: Electrodes based on carbonaceous material, e.g. graphite-intercalation compounds or CFx
- H01M 4/0471: {involving thermal treatment, e.g. firing, sintering, backing particulate active material, thermal decomposition, pyrolysis}
- 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 4/366: {as layered products}
- H01M 4/386: {Silicon or alloys based on silicon}
- 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 4/587: 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
- G01N 23/2273: Measuring photoelectron spectrum, e.g. electron spectroscopy for chemical analysis [ESCA] or X-ray photoelectron spectroscopy [XPS]
- 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
- G01N: INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES (measuring or testing apparatus or processes other than immunoassay, involving enzymes or microorganisms C12M, C12Q)
- Y02E: REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION

## Abstract

A negative active material for a rechargeable lithium battery includes a silicon-carbon composite including a core including a crystalline carbon material, a silicon oxide, and a silicon particle and an amorphous carbon-containing coating layer on the surface of the core. An intensity ratio (Si/SiO2) of a Si peak relative to a SiO2 peak ranges from about 2.0 to about 3.0 as measured using an X-ray photoelectron spectroscopy for the negative active material.

## Claims

### Claim 1

A negative active material for a rechargeable lithium battery, the negative active material comprising:
a silicon-carbon composite including a core including a crystalline carbon material, a silicon oxide, and a silicon particle, and an amorphous carbon-containing coating layer on the surface of the core,
wherein an intensity ratio (Si/SiO2) of a Si peak relative to a SiO2 peak ranges from about 2.0 to about 3.0 as measured using an X-ray photoelectron spectroscopy for the negative active material.

### Claim 2 (depends on 1)

The negative active material as claimed in claim 1, wherein the negative active material includes about 70 atom % to about 80 atom % of silicon and about 30 atom % to about 20 atom % of oxygen as measured using energy dispersive spectroscopy.

### Claim 3 (depends on 1)

The negative active material as claimed in claim 1, wherein a content of the silicon oxide ranges from about 8 wt % to about 13 wt % based on 100 wt % of the silicon-carbon composite.

### Claim 4 (depends on 1)

The negative active material as claimed in claim 1, wherein a maximum particle diameter of the silicon particle is less than or equal to about 250 nm.

### Claim 5 (depends on 1)

The negative active material as claimed in claim 1, wherein a maximum particle diameter of the silicon particle is about 30 nm to about 250 nm.

### Claim 6

A method of preparing a negative active material for a rechargeable lithium battery, the method comprising:
mixing silicon and the antioxidant in a mixing ratio of about 9 wt % to about 11 wt % of an antioxidant relative to 100 wt % of silicon in a solvent to prepare a mixture;
ball milling the mixture to prepare a silicon mixture of a silicon oxide and a silicon particle coated with the antioxidant;
mixing the silicon mixture with a crystalline carbon-based material to prepare a silicon-crystalline carbon-based material mixture;
adding an amorphous carbon precursor to the silicon-crystalline carbon-based material mixture, and
heat-treating the resultant.

### Claim 7 (depends on 6)

The method as claimed in claim 6, wherein the antioxidant is stearic acid, polyvinylpyrrolidone, or a combination thereof.

### Claim 8 (depends on 6)

The method as claimed in claim 6, wherein the solvent is an alcohol.

### Claim 9 (depends on 6)

The method as claimed in claim 6, wherein a maximum particle diameter of the silicon particle is less than or equal to about 250 nm.

### Claim 10 (depends on 6)

The method as claimed in claim 6, wherein a maximum particle diameter of the silicon particle is about 30 nm to about 250 nm.

### Claim 11 (depends on 1)

A rechargeable lithium battery, comprising:
a negative electrode including the negative active material according as claimed in claim 1;
a positive electrode including a positive active material; and
an electrolyte.