Lithium secondary battery and cathode of the lithium secondary battery

Patent metadata

Field	Value
Publication number	US-9379375-B2
Application number	US-201113166087-A
Country	US
Kind code	B2
Filing date	Jun 22, 2011
Priority date	Jun 23, 2010
Publication date	Jun 28, 2016
Grant date	Jun 28, 2016

Abstract

To provide a lithium secondary battery which has high capacity while maintaining excellent cycle characteristic. The lithium secondary battery cathode of the present invention includes a cathode collector formed of a conductive substance, and a cathode active material layer formed of a sintered lithium composite oxide sheet. The cathode active material layer is bonded to the cathode collector by the mediation of a conductive bonding layer. A characteristic feature of the present invention resides in that the cathode active material layer has a thickness of 30 μm or more, a voidage of 3 to 30%, and an open pore ratio of 70% or higher.

First claim

What is claimed is:

1. A lithium secondary battery cathode comprising:
a cathode collector formed of a conductive substance, and
a cathode active material layer which is formed of a sintered lithium composite oxide sheet having a thickness of 30 μm or more, a voidage of 3 to 30%, and an open pore ratio of 70% or higher, and which is bonded to the cathode collector by the mediation of a conductive bonding layer,
wherein the sintered lithium composite oxide sheet has a layered rock salt structure,
wherein the sintered lithium composite oxide sheet exhibits 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,
wherein the intensity of X-ray diffraction is attained by measuring an X-ray diffraction profile of the surface of the sintered lithium composite oxide sheet, and
wherein the (104) plane is oriented in a direction parallel to the surface of the sintered lithium composite oxide sheet.

2. The lithium secondary battery cathode according to claim 1 , wherein the sintered lithium composite oxide sheet has a ratio w/t of 3 or more, wherein t represents the thickness of the sheet, and w represents the minimum size of the sheet as measured in a direction orthogonal to the thickness direction which defines the thickness t.

3. The lithium secondary battery cathode according to claim 1 , wherein the sintered lithium composite oxide sheet has a structure in which numerous primary particles have been bound to one another, and the primary particles have a primary particle size of 5 μm or less.

4. A lithium secondary battery comprising at least the following:
a cathode having a cathode active material layer which is formed of a sintered lithium composite oxide sheet having a thickness of 30 μm or more, a voidage of 3 to 30%, and an open pore ratio of 70% or higher, and a cathode collector bonded to the cathode active material layer by the mediation of a conductive bonding layer;
wherein the sintered lithium composite oxide sheet has a layered rock salt structure,
an anode containing as an anode active material a carbonaceous material or a lithium-occluding substance; and
an electrolyte disposed so as to intervene between the cathode and the anode,
wherein the sintered lithium composite oxide sheet exhibits 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,
wherein the intensity of X-ray diffraction is attained by measuring an X-ray diffraction profile of the Mate surface of the sintered lithium composite oxide sheet, and
wherein the (104) plane is oriented in a direction parallel to the surface of the sintered lithium composite oxide sheet.

5. The lithium secondary battery according to claim 4 , wherein the sintered lithium composite oxide sheet has a ratio w/t of 3 or more, wherein t represents the thickness of the sheet, and w represents the minimum size of the sheet as measured in a direction orthogonal to the thickness direction which defines the thickness t.

6. The lithium secondary battery according to claim 4 , wherein the sintered lithium composite oxide sheet has a structure in which numerous primary particles have been bound to one another, and the primary particles have a primary particle size of 5 μm or less.

7. The lithium secondary battery cathode according to claim 1 , wherein the [003]/[104] intensity ratio is 1.4 or less.

8. The lithium secondary battery cathode according to claim 4 , wherein the [003]/[104] intensity ratio is 1.4 or less.

Assignees

• Sugiura Ryuta
• Kobayashi Nobuyuki
• Nanataki Tsutomu
• Ugaji Masaya
• Nagata Kaoru
• Ngk Insulators Ltd

Inventors

• Sugiura Ryuta
• Kobayashi Nobuyuki
• Nanataki Tsutomu
• Ugaji Masaya
• Nagata Kaoru

Classifications

• H01M4/0404

  by coating on electrode collectors · CPC title

• H01M10/0525

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

• H01M4/131

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

• H01M4/505

  of mixed oxides or hydroxides containing manganese for inserting or intercalating light metals, e.g. LiMn2O4 or LiMn2OxFy · CPC title

• H01M4/0471 Primary

  involving thermal treatment, e.g. firing, sintering, backing particulate active material, thermal decomposition, pyrolysis · CPC title