Method for manufacturing graphene-coated object, negative electrode of secondary battery including graphene-coated object, and secondary battery including the negative electrode

Patent metadata

Field	Value
Publication number	US-9815691-B2
Application number	US-201213586126-A
Country	US
Kind code	B2
Filing date	Aug 15, 2012
Priority date	Aug 19, 2011
Publication date	Nov 14, 2017
Grant date	Nov 14, 2017

Abstract

To form graphene to a practically even thickness on an object having an uneven surface or a complex surface, in particular, an object having a surface with a three-dimensional structure due to complex unevenness, or an object having a curved surface. The object and an electrode are immersed in a graphene oxide solution, and voltage is applied between the object and the electrode. At this time, the object serves as an anode. Graphene oxide is attracted to the anode because of being negatively charged, and deposited on the surface of the object to have a practically even thickness. A portion where graphene oxide is deposited is unlikely coated with another graphene oxide. Thus, deposited graphene oxide is reduced to graphene, whereby graphene can be formed to have a practically even thickness on an object having surface with complex unevenness.

First claim

The invention claimed is:

1. A method for manufacturing an electrode of a battery, comprising:
preparing an object having an uneven surface, the object comprising an oxide of silicon at an upper surface of the object, wherein the uneven surface comprises a plurality of projections, wherein a diameter of each of the plurality of projections is 50 nm to 10 μm inclusive, and wherein a length along an axis of each of the plurality of projections is 0.5 μm to 1000 μm inclusive;
immersing an electrode and the object in a solution including graphene oxide;
applying bias voltage to the electrode and the object so that the graphene oxide having a substantially even thickness is deposited to entirely cover the uneven surface of the object; and
heating the graphene oxide deposited on the uneven surface of the object in a vacuum or a reducing atmosphere to reduce the graphene oxide to form a carbon-based material comprising graphene,
wherein deposition of the graphene oxide does not proceed in a part of the uneven surface which is negatively charged by another graphene oxide,
wherein a thickness of the carbon-based material is 2 nm or less, and
wherein the carbon-based material continuously extends over the plurality of projections.

2. The method according to claim 1 ,
wherein the plurality of projections of the object has a whisker-like shape.

3. The method according to claim 1 ,
wherein the graphene contains an element other than carbon at 30 at. % or less.

4. The method according to claim 1 ,
wherein the object is an electrode of a lithium-ion secondary battery.

5. The method according to claim 1 ,
wherein the object comprises a titanium sheet provided with a plurality of silicon whiskers.

6. The method according to claim 1 ,
wherein the object comprises a titanium sheet provided with a plurality of silicon whiskers,
wherein one of the plurality of silicon whiskers comprises a core and a shell,
wherein the core comprises crystalline silicon, and
wherein the shell comprises amorphous silicon.

7. The method according to claim 1 ,
wherein the diameter of each of the plurality of projections is 500 nm to 3 μm inclusive, and
wherein the length along the axis of each of the plurality of projections is 1 μm to 100 μm inclusive.

8. The method according to claim 1 ,
wherein shapes of the plurality of projections are different from each other.

9. A method for manufacturing an electrode of a battery comprising:
immersing an electrode and an object in a solution including graphene oxide, the object comprising an oxide of silicon at an upper surface thereof;
applying bias voltage to the electrode and the object so that the graphene oxide is deposited on the object; and
heating the graphene oxide deposited on the object in a vacuum or a reducing atmosphere to reduce the graphene oxide to form a carbon-based material comprising graphene,
wherein a thickness of the carbon based material is 2 nm or less,
wherein the object includes at least a first projection and a second projection, and
wherein the carbon-based material continuously extends over the first projection, the second projection and a region between the first projection and the second projection.

10. The method according to claim 9 , wherein a length of one side of the graphene oxide is 10 μm or less.

11. The method according to claim 1 , wherein the oxide of silicon is a natural oxide.

Assignees

• Oguni Teppei
• Osada Takeshi
• Takeuchi Toshihiko
• Semiconductor Energy Lab

Inventors

• Oguni Teppei
• Osada Takeshi
• Takeuchi Toshihiko

Classifications

• H01M4/139

  Processes of manufacture · CPC title

• H01M4/366

  as layered products · CPC title

• C25D13/02 Primary

  with inorganic material · CPC title

• H01M4/587

  for inserting or intercalating light metals · CPC title

• H01M4/0416

  involving impregnation with a solution, dispersion, paste or dry powder (H01M4/0438 takes precedence) · CPC title