Positive electrode for secondary battery and secondary battery including the same

Patent metadata

Field	Value
Publication number	US-2018248195-A1
Application number	US-201615754479-A
Country	US
Kind code	A1
Filing date	Nov 30, 2016
Priority date	Nov 30, 2015
Publication date	Aug 30, 2018
Grant date	—

Abstract

Provided are a positive electrode for a secondary battery which includes a positive electrode collector, a porous positive electrode active material layer disposed on a surface of the positive electrode collector and including a positive electrode active material and first carbon nanotubes, and a conductive layer disposed on a surface of the positive electrode active material layer, wherein the conductive layer includes a porous network structure formed by a plurality of second carbon nanotubes and has a porosity equal to or greater than a porosity of the positive electrode active material layer+10 vol %, and a secondary battery including the same.

First claim

1 . A positive electrode for a secondary battery, the positive electrode comprising:
a positive electrode collector; a porous positive electrode active material layer disposed on a surface of the positive electrode collector and including a positive electrode active material and first carbon nanotubes; and a conductive layer disposed on a surface of the positive electrode active material layer, wherein the conductive layer comprises a porous network structure formed by a plurality of second carbon nanotubes and has a porosity equal to or greater than a porosity of the positive electrode active material layer+10 vol %.

2 . The positive electrode for a secondary battery of claim 1 , wherein the porosity of the porous positive electrode active material layer is in a range of 10 vol % to 50 vol %, and the porosity of the conductive layer is in a range of 20 vol % to 60 vol %.

3 . The positive electrode for a secondary battery of claim 1 , wherein the porous network structure is connected to the first carbon nanotubes in the positive electrode active material layer to form an electrically conductive path.

4 . The positive electrode for a secondary battery of claim 1 , wherein the first and second carbon nanotubes are each independently bundle-type carbon nanotubes.

5 . The positive electrode for a secondary battery of claim 1 , wherein the first and second carbon nanotubes each independently have a diameter of a carbon nanotube unit of 10 nm to 100 nm and a length of the carbon nanotube unit of 3 μm to 10 μm.

6 . The positive electrode for a secondary battery of claim 1 , wherein the first and second carbon nanotubes each independently have a specific surface area of 20 m 2 /g to 2,000 m 2 /g.

7 . The positive electrode for a secondary battery of claim 1 , wherein the positive electrode active material has an average particle diameter (D 50 ) of 3 μm to 20 μm.

8 . The positive electrode for a secondary battery of claim 1 , wherein a thickness ratio of the positive electrode active material layer:the conductive layer is in a range of 1:0.001 to 1:0.05.

9 . The positive electrode for a secondary battery of claim 8 , wherein the thickness ratio of the positive electrode active material layer:the conductive layer is in a range of 1:0.001 to 1:0.01.

10 . The positive electrode for a secondary battery of claim 8 , wherein the thickness ratio of the positive electrode active material layer:the conductive layer is in a range of 1:0.001 to 1:0.005.

11 . The positive electrode for a secondary battery of claim 1 , wherein a weight ratio of the first carbon nanotubes:the second carbon nanotubes is in a range of 1:0.08 to 1:0.42.

12 . A method of preparing the positive electrode for a secondary battery of claim 1 , the method comprising:
adding second carbon nanotubes in a dispersion medium to prepare a composition for forming a conductive layer in which a second carbon nanotube layer is formed on a surface of the dispersion medium; and after impregnating an electrode assembly, in which a positive electrode active material layer including a positive electrode active material and first carbon nanotubes is formed on at least one side of a positive electrode collector, in the composition for forming a conductive layer, forming a conductive layer by lifting the electrode assembly so that the second carbon nanotube layer is disposed on a surface of the positive electrode active material layer.

13 . A lithium secondary battery comprising the positive electrode of claim 1 .

Assignees

• Lg Chemical Ltd

Inventors

• Choi Young Geun
• Kim Hyo Sik
• Baek Joo Yul
• Oh Song Taek

Classifications

• B82Y40/00

  Manufacture or treatment of nanostructures · CPC title

• H01M4/0404

  by coating on electrode collectors · CPC title

• H01M4/131

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

• H01M10/0525

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

• H01M2004/021

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