Synthesis of three-dimensional graphene foam: use as supercapacitors

• US 9,352,500 B2
• Filed: 06/03/2013
• Issued: 05/31/2016
• Est. Priority Date: 06/01/2012
• Status: Active Grant

• Current Assignee: National University of Singapore
• Original Assignee: National University of Singapore
• Inventors: Lee, Jonghak, Ozyilmaz, Barbaros, Kahya, Orhan
• Primary Examiner(s): YI, STELLA KIM
• Application Number:
  US14/396,000
• Publication Number:
  US 20150104634A1
• Time in Patent Office: 1,093 Days
• US Class Current: 1/1
• CPC Class Codes: B29C 43/003 characterised by the choice of material
• CPC Class Codes: B29K 2105/04 cellular or porous
• CPC Class Codes: B29L 2031/00 Other particular articles
• CPC Class Codes: C01B 32/182 Graphene
• CPC Class Codes: C01B 32/198 Graphene oxide
• CPC Class Codes: C23F 4/04 by physical dissolution
• CPC Class Codes: H01G 11/28 arranged or disposed on a current collector; Layers or phases between electrodes and current collectors, e.g. adhesives
• CPC Class Codes: H01G 11/36 Nanostructures, e.g. nanofibres, nanotubes or fullerenes
• CPC Class Codes: H01G 11/38 Carbon pastes or blends; Binders or additives therein
• CPC Class Codes: H01G 11/48 Conductive polymers
• CPC Class Codes: H01G 11/68 characterised by their material
• CPC Class Codes: H01G 11/70 characterised by their structure
• CPC Class Codes: H01G 11/86 specially adapted for electrodes carbonisation or activation of carbon for the manufacture of electrodes H01G11/34
• CPC Class Codes: H01L 31/0224 Electrodes
• CPC Class Codes: Y02E 60/13 Energy storage using capacitors
• CPC Class Codes: Y10T 29/43 Electric condenser making
• CPC Class Codes: Y10T 428/24997 Of metal-containing material

Abstract

The application discloses methods of fabricating three-dimensional (3D) graphene crystalline foam, based on mixing a carbon source with a skelet (scaffold) powder. In one embodiment heat and pressure are used to compact the carbon and a metal powder into a close packed structure. In another embodiment a 3D crystalline graphene foam is fabricated with a large surface area (550 m²/g) from a 3D metal foam, depositing a layer of graphene using chemical vapor deposition (CVD), depositing a polymer support and removing the metal via wet chemical etching, such that the graphene retains the configuration, and then finally removing the polymer. A method of fabricating the metal foam framework and coating the metal with graphene are also disclosed.

Claims

1. A method of fabricating a three-dimensional graphene crystalline foam, comprising:

a) mixing a carbon source and a skelet powder together to obtain a uniform mixture, wherein the carbon source is optionally coated on a group IV-B element;

b) applying pressure to the uniform mixture obtained in step (a) to obtain a closed packed structure;

c) applying temperature and pressure to the closed packed structure to form a graphene sheet layered around the skelet powder and the group IV-B element if present; and

d) removing the skelet powder from the closed packed structure using a chemical bath to dissolve the skelet powder away from the closed packed structure leaving voids, resulting in a three-dimensional crystalline foam comprising graphene and optionally a group IV-B element.

2. The method of claim 1, wherein the carbon source is carbon black, amorphous carbon, or a combination thereof.

3. The method of claim 1, wherein the optional group IV-B element is silicon (Si), germanium (Ge), tin (Sn), lead (Pb), or a combination thereof.

4. The method of claim 1, wherein the carbon-coated group IV-B element is carbon-coated silicon nanoparticle.

5. The method of claim 1, wherein the skelet powder is silicon dioxide (SiO2), aluminum oxide (A12O3), sodium chloride (NaCl), magnesium oxide (MgO), hafnium oxide (HfO2), zirconium dioxide (ZrO2), or a combination thereof.

6. The method of claim 1, wherein the skelet powder has a particle size of between about 1 nm to 10 μ

m.

7. The method of claim 1, wherein the pressure is applied in a uniform direction.

8. The method of claim 1, wherein the chemical bath is aqueous potassium hydroxide or aqueous sodium hydroxide.

9. A method of fabricating a three-dimensional crystalline graphene foam, comprising:

a) providing a three-dimensional metal foam framework having a surface area of at least about 500 m2/g, for fabricating a three-dimensional graphene foam;

b) depositing a layer of graphene onto the metal foam of step (a) by template-directed chemical vapor deposition (CVD);

c) depositing a polymer support onto the graphene layer;

d) removing the three-dimensional metal foam framework via wet chemical etching, such that the graphene layer and the polymer support retain the three-dimensional configuration provided by the metal foam framework; and

e) removing the polymer support using a solvent to thereby obtain the three-dimensional crystalline graphene foams wherein the metal foam framework of step (a) is fabricated by;

i) mixing a metal powder and a skelet powder together to obtain a uniform mixture;

ii) applying pressure to the uniform mixture of the metal powder and the skelet powder to obtain a closed packed structure;

iii) applying temperature and pressure to the closed packed structure obtained in step (ii) to melt the metal powder around the skelet powder; and

iv) removing the skelet powder using a chemical bath to dissolve the skelet powder away from the closed packed structure leaving voids, resulting in a metal foam.

10. The method of claim 9, wherein the metal powder is composed of nickel (Ni), cobalt (Co), copper (Cu), iron (Fe), platinum (Pt), or a combination thereof.

11. The method of claim 9, wherein the skelet powder is silicon dioxide (SiO2), aluminum oxide (A12O3), sodium chloride (NaCl), magnesium oxide (MgO), hafnium oxide (HfO2), zirconium dioxide (ZrO2), or a combination thereof.

12. The method of claim 9, wherein the skelet powder has a particle size of between about 1 nm to 10 gm.1.

13. The method of claim 9, wherein the pressure is applied in a uniform direction.