Negative-electrode active material for non-aqueous electrolyte secondary battery, and non-aqueous electrolyte secondary battery

Patent metadata

Field	Value
Publication number	US-2018287148-A1
Application number	US-201615524395-A
Country	US
Kind code	A1
Filing date	Jan 18, 2016
Priority date	Jan 28, 2015
Publication date	Oct 4, 2018
Grant date	—

Abstract

A negative-electrode active material for a non-aqueous electrolyte secondary battery containing a silicon material, wherein the negative-electrode active material can constitute a non-aqueous electrolyte secondary battery having high charge capacity, high initial charge/discharge efficiency, and good cycle characteristics. A negative-electrode active material particle according to an embodiment includes a lithium silicate phase represented by Li2zSiO(2+z) {0<z<2} and particles dispersed in the lithium silicate phase. Each of the particles includes a silicon core particle and a surface layer formed of an iron alloy containing Si (FeSi alloy). In an XRD pattern of the negative-electrode active material particle obtained by XRD measurement, a diffraction peak of the FeSi alloy at 2θ=approximately 45 degrees has a half-width of 0.40 degrees or more, and a diffraction peak of a Si (111) plane at 2θ=approximately 28 degrees has a half-width of 0.40 degrees or more.

First claim

1 . A negative-electrode active material for a non-aqueous electrolyte secondary battery, comprising:
a lithium silicate phase represented by Li 2z SiO (2+z) {0<z<2}; and particles dispersed in the lithium silicate phase, the particles containing a silicon (Si) core particle and a surface layer formed of an iron alloy containing Si (FeSi alloy), wherein in an XRD pattern obtained by XRD measurement, a diffraction peak of the FeSi alloy at 2θ=approximately 45 degrees has a half-width of 0.40 degrees or more, and a diffraction peak of a Si (111) plane at 2θ=approximately 28 degrees has a half-width of 0.40 degrees or more.

2 . 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 the XRD pattern has a half-width of 0.05 degrees or more.

3 . The negative-electrode active material for a non-aqueous electrolyte secondary battery according to claim 1 , wherein an Fe content is 5% or less by mass of a total mass of a base particle composed of the lithium silicate phase and the particles.

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

5 . The negative-electrode active material for a non-aqueous electrolyte secondary battery according to claim 1 , wherein the core particle has an average particle size of 200 nm or less before initial charging.

6 . The negative-electrode active material for a non-aqueous electrolyte secondary battery according to claim 1 , wherein the lithium silicate phase comprises of Li 2 Si 2 O 5 .

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

8 . 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.

9 . The negative-electrode active material for a non-aqueous electrolyte secondary battery according to claim 1 , wherein the lithium silicate phase comprises of Li 2 SiO 3 .

10 . 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 Li 2 Si 2 O 5 .

11 . 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 Li 2 SiO 3 .

12 . The negative-electrode active material for a non-aqueous electrolyte secondary battery according to claim 1 , wherein the negative-electrode active material for a non-aqueous electrolyte secondary battery after charging and discharging contains no Li 4 SiO 4 .

Assignees

• Sanyo Electric Co

Inventors

• Akira Tatsuya
• Minami Hiroshi
• Sunano Taizou

Classifications

• H01M4/366

  as layered products · CPC title

• H01M4/1395

  of electrodes based on metals, Si or alloys · CPC title

• H01M2004/027

  Negative electrodes · CPC title

• H01M4/136

  Electrodes based on inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy · CPC title

• C01B33/113 Primary

  Silicon oxides; Hydrates thereof {(preparing monoxide by reduction of siliceous material C01B33/182)} · CPC title