Negative electrode material for lithium ion secondary battery, method for manufacturing same, negative electrode for lithium ion secondary battery, and lithium ion secondary battery

Patent metadata

Field	Value
Publication number	US-9614216-B2
Application number	US-201113992388-A
Country	US
Kind code	B2
Filing date	Dec 9, 2011
Priority date	Dec 10, 2010
Publication date	Apr 4, 2017
Grant date	Apr 4, 2017

Abstract

The invention provides a negative electrode material for lithium ion secondary battery, including a composite particle of a first particle containing a carbonic substance A and a second particle containing silicon, which are combined with a carbonic substance B, wherein, when a cross-section of the composite particle is observed with respect to: the content of silicon atom in a core region in a circle having a center thereof on the midpoint of the major axis, which constitutes the maximum length, and having a radius of ⅛ of the length of the minor axis orthogonally intersecting the major axis at the midpoint thereof, and the content thereof in a rim region extending from the circumference to a depth of ⅛ of the length of the minor axis, the ratio of the content in the rim region to that in the core region is 2 or higher.

First claim

The invention claimed is:

1. A negative electrode material for a lithium ion secondary battery, the material comprising a composite particle of a first particle comprising a carbonic substance A and a second particle comprising silicon atoms, the first particle and the second particle combined by a carbonic substance B different from the carbonic substance A,
wherein the first particle comprises a graphite particle having pores formed by assembling or binding a plurality of flat-shaped particles in such a manner that orientation planes thereof are nonparallel to each other, and
wherein, when a cross-section of the composite particle is observed with respect to:
a content of the silicon atoms included in a core region in a circle, the circle having a center thereof on a midpoint of a major axis constituting a maximum length of the composite particle, and having a radius of ⅛ of the length of a minor axis that orthogonally intersects the major axis at the midpoint thereof, and
a content of the silicon atoms in a rim region of the composite particle, which extends from a circumference of the composite particle to a depth of ⅛ of the length of the minor axis,
a ratio of the content of the silicon atoms in the rim region to the content of the silicon atoms in the core region is 2 or higher.

2. The negative electrode material for a lithium ion secondary battery according to claim 1 , wherein a ratio of the content of the silicon atoms included in the core region in the circle to a total content of the silicon atoms included in the cross-section of the composite particle is 0.2 or smaller.

3. The negative electrode material for a lithium ion secondary battery according to claim 1 , wherein the first particle further comprises a graphite particle with a circularity of from 0.60 to 1.00.

4. The negative electrode material for a lithium ion secondary battery according to claim 1 , wherein the first particle has a volume average particle size of from 5 μm to 40 μm.

5. The negative electrode material for a lithium ion secondary battery according to claim 1 , wherein the first particle has an aspect ratio of from 1.2 to 5.0.

6. The negative electrode material for a lithium ion secondary battery according to claim 1 , wherein a volume average particle size of the flat-shaped particles is ⅔ or less of the volume average particle size of the first particle.

7. The negative electrode material for a lithium ion secondary battery according to claim 1 , wherein a content of the carbonic substance B in the entire composite particle is from 1 mass % to 10 mass %, and the carbonic substance B comprises a carbonized organic substance.

8. The negative electrode material for a lithium ion secondary battery according to claim 1 , further comprising a substance having electrical conductivity.

9. A method of producing the negative electrode material for a lithium ion secondary battery according to claim 1 , the method comprising: combining the first particle comprising the carbonic substance A and the second particle comprising the silicon atoms using the carbonic substance B different from the carbonic substance A to obtain the composite particle having a volume average particle size of from 1.0 to 1.3 times the volume average particle size of the first particle.

10. A negative electrode for a lithium ion secondary battery, comprising:
a collector; and
a negative electrode material layer provided on the collector, the negative electrode material layer comprising the negative electrode material for a lithium ion secondary battery according to claim 1 .

11. A lithium ion secondary battery, comprising:
the negative electrode for a lithium ion secondary battery according to claim 10 ;
a positive electrode; and
an electrolyte.

12. The negative electrode material for a lithium ion secondary battery according to claim 1 , wherein the ratio of the volume average particle size of the composite particle to the volume average particle size of the first particle is from 1.01 to 1.25.

Assignees

• Kouzu Masayuki
• Hoshi Kento
• Shimazaki Toshikatsu
• Hitachi Chemical Co Ltd

Inventors

• Kouzu Masayuki
• Hoshi Kento
• Shimazaki Toshikatsu

Classifications

• H01M4/587 Primary

  for inserting or intercalating light metals · CPC title

• H01M4/364 Primary

  as mixtures · CPC title

• H01M4/362

  Composites · CPC title

• H01M10/0525

  Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries · CPC title

• H01M4/386

  Silicon or alloys based on silicon · CPC title