Plate-like particle of cathode active material for lithium secondary battery, cathode of the lithium secondary battery and lithium secondary battery

Patent metadata

Field	Value
Publication number	US-9257702-B2
Application number	US-201113165365-A
Country	US
Kind code	B2
Filing date	Jun 21, 2011
Priority date	Jun 23, 2010
Publication date	Feb 9, 2016
Grant date	Feb 9, 2016

Abstract

To provide a lithium secondary battery which has high capacity while maintaining excellent charge-discharge characteristic, and to provide a cathode of the lithium secondary battery and a plate-like particle for cathode active material to be contained in the cathode. The plate-like particle of cathode active material for a lithium secondary battery of the present invention has a layered rock salt structure, a thickness of 5 μm or more and less than 30 μm, 2 or less of [003]/[104] which is a ratio of intensity of X-ray diffraction by the (003) plane to intensity of X-ray diffraction by the (104) plane, a voidage of 3% or more and less than 30%, and an open pore ratio of 70% or higher.

First claim

What is claimed is:

1. A plate-like particle of a cathode active material for a lithium secondary battery, wherein the plate-like particle has a structure in which numerous primary particles are bound to one another, each primary particle having a layered rock salt structure, wherein the plate-like particle has a thickness of 5 μm or more and less than 30 μm, a ratio of intensity of X-ray diffraction by the (003) plane to intensity of X-ray diffraction by the (104) plane, [003]/[104], of 2 or less, a voidage of 3% or more and less than 30%, and an open pore ratio of 70% or higher,
wherein the intensity of X-ray diffraction is attained by measuring an X-ray diffraction profile of only a plate surface of the plate-like particle.

2. The plate-like particle of a cathode active material according to claim 1 , wherein the plate-like particle has a ratio w/t of 3 or more, wherein t represents the thickness of the plate-like particle, and wherein w represents the minimum size of the plate-like particle as measured in a direction orthogonal to the thickness direction which defines the thickness t.

3. The plate-like particle of a cathode active material according to claim 1 , wherein the primary particles have a primary particle size of 5 μm or less.

4. A cathode of a lithium secondary battery having a cathode active material layer which contains a plate-like particle having a structure in which numerous primary particles are bound to one another, wherein the plate-like particle has a thickness of 5 μm or more and less than 30 μm, a ratio of intensity of X-ray diffraction by the (003) plane to intensity of X-ray diffraction by the (104) plane, [003]/[104], of 2 or less, a voidage of 3% or more and less than 30%, and an open pore ratio of 70% or higher, and
wherein the intensity of X-ray diffraction is attained by measuring an X-ray diffraction profile of only a plate surface of the plate-like particle.

5. The cathode of a lithium secondary battery according to claim 4 , wherein the plate-like particle has a ratio w/t of 3 or more, wherein t represents the thickness of the plate-like particle, and wherein w represents the minimum size of the plate-like particle as measured in a direction orthogonal to the thickness direction which defines the thickness t.

6. The cathode of a lithium secondary battery according to claim 4 , wherein the primary particles have a primary particle size of 5 μm or less.

7. The cathode of a lithium secondary battery according to claim 4 , wherein the cathode active material layer comprises a binder and the plate-like particles and an electroconducting aid dispersed in the binder.

8. A lithium secondary battery comprising at least:
a cathode having a cathode active material layer which contains a plate-like particle having a structure in which numerous primary particles are bound to one another, each primary particle having a layered rock salt structure, wherein the plate-like particle has a ratio of intensity of X-ray diffraction by the (003) plane to intensity of X-ray diffraction by the (104) plane, [003]/[104], of 2 or less, a thickness of 5 μm or more and less than 30 μm, a voidage of 3% or more and less than 30%, and an open pore ratio of 70% or higher, and
wherein the intensity of X-ray diffraction is attained by measuring an X-ray diffraction profile of only a plate surface of the plate-like particle;
an anode containing a carbonaceous material or a lithium-occluding substance as an anode active material; and
an electrolyte disposed so as to intervene between the cathode and the anode.

9. The lithium secondary battery according to claim 8 , wherein the plate-like particle has a ratio w/t of 3 or more, wherein t represents the thickness of the plate-like particle, and wherein w represents the minimum size of the plate-like particle as measured in a direction orthogonal to the thickness direction which defines the thickness t.

10. The lithium secondary battery according to claim 8 , wherein the primary particles have a primary particle size of 5 μm or less.

11. The lithium secondary battery according to claim 8 , wherein the cathode active material layer comprises a binder and the plate-like particles and an electroconducting aid dispersed in the binder.

12. The plate-like particle according to claim 1 , wherein the plate-like particle has the ratio [003]/[104] of intensity of X-ray diffraction of 0.8 or less.

13. The cathode of a lithium secondary battery according to claim 4 , wherein the plate-like particle has the ratio of [003]/[104] of intensity of X-ray diffraction of 0.8 or less.

14. The lithium secondary battery according to claim 8 , wherein the plate-like particle has the ratio [003]/[104] of intensity of X-ray diffraction of 0.8 or less.

Assignees

• Sugiura Ryuta
• Kobayashi Nobuyuki
• Nanataki Tsutomu
• Ngk Insulators Ltd

Inventors

• Sugiura Ryuta
• Kobayashi Nobuyuki
• Nanataki Tsutomu

Classifications

• C01P2004/62

  Submicrometer sized, i.e. from 0.1-1 micrometer · CPC title

• C01P2006/16

  Pore diameter · CPC title

• Y10T428/2982

  Particulate matter [e.g., sphere, flake, etc.] · CPC title

• C01G53/04

  Oxides · CPC title

• H01M10/052

  Li-accumulators · CPC title