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

Patent metadata

Field	Value
Publication number	US-10516153-B2
Application number	US-201615533255-A
Country	US
Kind code	B2
Filing date	Jan 18, 2016
Priority date	Jan 28, 2015
Publication date	Dec 24, 2019
Grant date	Dec 24, 2019

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 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 silicon particles (12) have a crystallite size of 40 nm or less. The crystallite size is calculated using the Scherrer equation from the half-width of the diffraction peak of the Si (111) plane in an XRD pattern obtained by XRD measurement of the negative-electrode active material particle 10.

First claim

The invention claimed is:

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} including Li 2 Si 2 O 5 and
silicon particles dispersed in the lithium silicate phase,
wherein the silicon particles have a crystallite size of 40 nm or less when calculated using a Scherrer equation from a half-width of a diffraction peak of a Si (111) plane in an XRD pattern obtained by XRD measurement,
wherein a half-width of a diffraction peak attributed to a (111) plane in an XRD pattern obtained by XRD measurement of the Li 2 Si 2 O 5 lithium silicate phase is in a range from 0.30° to 0.55°,
wherein the negative-electrode active material for a non-aqueous electrolyte secondary battery after charging and discharging contains no Li 4 SiO 4 .

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

3. 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.

4. The negative-electrode active material for a non-aqueous electrolyte secondary battery according to claim 2 , 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 lithium silicate phase is composed mainly of Li 2 Si 2 O 5 .

6. 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 Li 2 Si 2 O 5 .

7. 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 Li 2 Si 2 O 5 .

8. The negative-electrode active material for a non-aqueous electrolyte secondary battery according to claim 4 , wherein the lithium silicate phase is composed mainly of Li 2 Si 2 O 5 .

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

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 SiO 3 , and
a diffraction peak of a (111) plane of the Li 2 SiO 3 in the XRD pattern has a half-width of 0.10 degrees or more.

11. 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.

12. 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.

13. 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 7 ;
a positive electrode; and a non-aqueous electrolyte.

14. 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
silicon particles dispersed in the lithium silicate phase,
wherein the silicon particles have a crystallite size of 40 nm or less when calculated using a Scherrer equation from a half-width of a diffraction peak of a Si (111) plane in an XRD pattern obtained by XRD measurement,
wherein the negative-electrode active material for a non-aqueous electrolyte secondary battery after charging and discharging contains no Li 4 SiO 4 ,
wherein the lithium silicate phase contains Li 2 Si 2 O 5 at 80% or more by mass of the total mass of the lithium silicate phase.

Assignees

• Sanyo Electric Co

Inventors

• Sunano Taizou
• Minami Hiroshi
• Kato Yoshio
• Uchiyama Yohei

Classifications

• H01M4/38

  of elements or alloys · CPC title

• H01M4/366

  as layered products · CPC title

• H01M2004/021

  Physical characteristics, e.g. porosity, surface area · CPC title

• H01M4/134

  Electrodes based on metals, Si or alloys · CPC title

• H01M4/131 Primary

  Electrodes based on mixed oxides or hydroxides, or on mixtures of oxides or hydroxides, e.g. LiCoOx · CPC title