# US 8,771,872 B2 · Negative-electrode material and lithium secondary battery using same

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- Number: US 8,771,872 B2
- Document ID: US8771872B2
- Status: Granted
- Kind: B2
- Application number: 13/319,589
- Filed: 2010-05-13
- Published: 2012-03-15
- Granted: 2014-07-08
- Earliest claimed: 2009-05-14
- Assignees: National Institute for Materials Science
- Applicants: Kazunori Takada; Bui Thi Hang; Tsuyoshi Ohnishi
- Inventors: Kazunori Takada; Bui Thi Hang; Tsuyoshi Ohnishi
- Web page: https://patentgrep.com/patent/US8771872B2

## CPC

- H01M 10/0562: Solid materials
- H01M 4/0421: {involving vapour deposition}
- H01M 4/136: Electrodes based on inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy
- H01M 4/1397: of electrodes based on inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy
- H01M 4/624: {Electric conductive fillers}
- H01M 10/052: Li-accumulators
- Y02E 60/10: Energy storage using batteries
- Y02T 10/70: Energy storage systems for electromobility, e.g. 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
- Y02T: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION

## Abstract

An embodiment of the present application aims at providing a material which repeatedly undergoes a conversion reaction and an alloying reaction to have an improved columbic efficiency in a first cycle of the repeating, and thereby allowing the material to serve as a high-electrical capacity negative electrode of a lithium secondary battery. In order to attain the object, a negative-electrode material is made by mixed dispersion of (i) nanoparticles of an electrical conducting material having electronic conduction and (ii) nanoparticles of an electrode active material which is reducible to a simple substance which undergoes an alloying reaction with lithium. The electrical conducting material is a sulfide having electronic conduction, and the electrode active material is a sulfide of an element which undergoes the alloying reaction with lithium. Further, the element which undergoes the alloying reaction with lithium is silicon.

## Claims

### Claim 1

A negative-electrode material for a lithium battery comprising a mixture of:
(i) an electrical conducting material having electronic conduction, wherein the electrical conducting material consists of a sulfide; and
(ii) an electrode active material comprising a sulfide of an element, wherein the electrode active material can be reduced via a conversion reaction to the element, and further wherein the element can under go an alloying reaction with lithium; and
wherein the negative-electrode material is capable of charging and discharging through the conversion reaction and the alloying reaction with lithium.

### Claim 2 (depends on 1)

The negative-electrode material as set forth in claim 1, wherein the element is silicon.

### Claim 3 (depends on 1)

The negative-electrode material as set forth in claim 1, wherein a ratio by weight between the electrical conducting material and the electrode active material is 1:5 to 1:50 in the mixture material.

### Claim 4 (depends on 1)

A lithium secondary battery comprising:
a negative electrode;
a positive electrode; and
a lithium-ion conducting electrolyte provided between said negative electrode and said positive electrode,
wherein said negative electrode comprises the negative-electrode material as set forth in claim 1.

### Claim 5 (depends on 4)

The lithium secondary battery as set forth in claim 4, wherein said lithium-ion conducting electrolyte is a lithium-ion conducting inorganic solid electrolyte.