# US 10,483,528 B2 · Negative-electrode active material for non-aqueous electrolyte secondary battery and non-aqueous electrolyte secondary battery

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- Number: US 10,483,528 B2
- Document ID: US10483528B2
- Status: Granted
- Kind: B2
- Application number: 15/526,532
- Filed: 2016-01-18
- Published: 2017-11-09
- Granted: 2019-11-19
- Earliest claimed: 2015-01-28
- Assignees: SANYO Electronics Co., Ltd.
- Applicants: Sanyo Electric Co., Ltd.
- Inventors: Norihisa Yamamoto; Taizou Sunano; Hiroshi Minami; Yoshio Kato; Yohei Uchiyama
- Web page: https://patentgrep.com/patent/US10483528B2

## CPC

- H01M 4/364: {as mixtures}
- H01M 4/366: {as layered products}
- H01M 4/386: {Silicon or alloys based on silicon}
- H01M 4/5825: {Oxygenated metallic salts or polyanionic structures, e.g. borates, phosphates, silicates, olivines}
- H01M 4/625: {Carbon or graphite}
- H01M 2004/027: {Negative electrodes}
- H01M: PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY

## Abstract

The initial charge/discharge efficiency and cycle characteristics of a non-aqueous electrolyte secondary battery that contains a silicon material as a negative-electrode active material are improved. A negative-electrode active material particle (10) according to an embodiment contains a base particle (13), which includes a lithium silicate phase (11) represented by Li2zSiO(2+z) {0<z<2} and silicon particles (12) dispersed in the lithium silicate phase (11). The symmetry determined by an image analysis of a backscattered electron image of a cross section of the base particle (13) is 1.5 or less. The symmetry refers to the ratio (b/a) of the half width at half maximum b of a peak on the high-gray-scale side to the half width at half maximum a of the peak on the low-gray-scale side in a histogram of color distinction based on 256 gray levels for each pixel of the backscattered electron image.

## Claims

### Claim 1

A negative-electrode active material for a non-aqueous electrolyte secondary battery, comprising:
a base particle, which includes
a lithium silicate phase represented by Li2zSiO(2+z) {0<z<2} including Li2Si2O5 and
silicon particles dispersed in the lithium silicate phase,
wherein a symmetry determined by an image analysis of a backscattered electron image of a cross section of the base particle is 1.5 or less, and
the symmetry refers to a ratio (b/a) of a half width at half maximum b of a peak on a high-gray-scale side to a half width at half maximum a of the peak on a low-gray-scale side in a histogram of color distinction based on 256 gray levels for each pixel of the backscattered electron image,
wherein a half-width of a diffraction peak attributed to a (111) plane in an XRD pattern obtained by XRD measurement of the Li2Si2O5 lithium silicate phase is in a range from 0.431° to 0.55°,
wherein the negative-electrode active material for a non-aqueous electrolyte secondary battery after charging and discharging contains no Li4SiO4.

### Claim 2 (depends on 1)

The negative-electrode active material for a non-aqueous electrolyte secondary battery according to claim 1, wherein a Si (111) plane has a higher diffraction peak intensity than a (111) plane of a lithium silicate in an XRD pattern obtained by XRD measurement.

### Claim 3 (depends on 2)

The negative-electrode active material for a non-aqueous electrolyte secondary battery according to claim 2, wherein no diffraction peak of SiO2 is observed at 2θ=25 degrees in the XRD pattern.

### Claim 4 (depends on 3)

The negative-electrode active material for a non-aqueous electrolyte secondary battery according to claim 3, wherein the lithium silicate phase is composed mainly of Li2Si2O5.

### Claim 5 (depends on 4)

A non-aqueous electrolyte secondary battery comprising: a negative electrode containing the negative-electrode active material for a non-aqueous electrolyte secondary battery according to claim 4; a positive electrode; and a non-aqueous electrolyte.

### Claim 6 (depends on 2)

The negative-electrode active material for a non-aqueous electrolyte secondary battery according to claim 2, wherein the lithium silicate phase is composed mainly of Li2Si2O5.

### Claim 7 (depends on 1)

The negative-electrode active material for a non-aqueous electrolyte secondary battery according to claim 1, wherein no diffraction peak of SiO2 is observed at 2θ=25 degrees in a XRD pattern obtained by XRD measurement.

### Claim 8 (depends on 7)

The negative-electrode active material for a non-aqueous electrolyte secondary battery according to claim 7, wherein the lithium silicate phase is composed mainly of Li2Si2O5.

### Claim 9 (depends on 1)

The negative-electrode active material for a non-aqueous electrolyte secondary battery according to claim 1, wherein the lithium silicate phase is composed mainly of Li2Si2O5.

### Claim 10 (depends on 1)

The negative-electrode active material for a non-aqueous electrolyte secondary battery according to claim 1, wherein a diffraction peak of a (111) plane of a lithium silicate in an XRD pattern obtained by XRD measurement has a half-width of 0.05 degrees or more.

### Claim 11 (depends on 1)

The negative-electrode active material for a non-aqueous electrolyte secondary battery according to claim 1, wherein the lithium silicate phase is composed mainly of Li2SiO3, and a diffraction peak of a (111) plane of the Li2SiO3 in a XRD pattern obtained by XRD measurement has a half-width of 0.10 degrees or more.

### Claim 12 (depends on 1)

The negative-electrode active material for a non-aqueous electrolyte secondary battery according to claim 1, wherein the lithium silicate phase and the silicon particles constitute a base particle, and the base particle is covered with an electrically conductive layer.

### Claim 13 (depends on 1)

A non-aqueous electrolyte secondary battery comprising: a negative electrode containing the negative-electrode active material for a non-aqueous electrolyte secondary battery according to claim 1; a positive electrode; and a non-aqueous electrolyte.

### Claim 14

A negative-electrode active material for a non-aqueous electrolyte secondary battery, comprising:
a lithium silicate phase represented by Li2zSiO(2+z) {0<z<2} and
silicon particles dispersed in the lithium silicate phase,
wherein a symmetry determined by an image analysis of a backscattered electron image of a cross section of the base particle is 1.5 or less, and
the symmetry refers to a ratio (b/a) of a half width at half maximum b of a peak on a high-gray-scale side to a half width at half maximum a of the peak on a low-gray-scale side in a histogram of color distinction based on 256 gray levels for each pixel of the backscattered electron image,
wherein the negative-electrode active material for a non-aqueous electrolyte secondary battery after charging and discharging contains no Li4SiO4,
wherein the lithium silicate phase contains Li2Si2O5 at 80% or more by mass of the total mass of the lithium silicate phase.