Production of graphene

Patent metadata

Field	Value
Publication number	US-10549999-B2
Application number	US-201615765062-A
Country	US
Kind code	B2
Filing date	Oct 7, 2016
Priority date	Oct 8, 2015
Publication date	Feb 4, 2020
Grant date	Feb 4, 2020

Abstract

Methods for the production in an electrochemical cell of graphene and graphite nanoplatelet structures having a thickness of less than 100 nm in a cell having a negative electrode which is graphitic and an electrolyte which consists of ions in a solvent, where the cations are sulfur-containing ions or phosphorus containing ions, wherein the method comprises the step of passing a current through the cell to intercalate ions into the graphitic negative electrode so as to exfoliate the graphitic negative electrode.

First claim

The invention claimed is:

1. A method for the production in an electrochemical cell of graphene and graphite nanoplatelet structures having a thickness of less than 100 nm, wherein the electrochemical cell comprises:
(a) a negative electrode which is graphitic;
(b) a positive electrode which may be graphitic or another material; and
(c) an electrolyte having ions in a solvent, wherein the ions include cations and counteranions, and wherein the cations are sulfur-containing cations;
and wherein the method comprises the step of passing a current through the electrochemical cell to intercalate ions into the graphitic negative electrode so as to exfoliate the graphitic negative electrode.

2. A method according to claim 1 , wherein the sulfur-containing cations are organosulfur cations.

3. A method according to claim 2 , where the organosulfur cations are sulfonium ions.

4. A method according to claim 3 , wherein the sulfonium ions are trialkyl sulfonium ions.

5. The method according to claim 4 wherein the trialkyl sulfonium ions are triethyl sulfonium or trimethyl sulfonium.

6. A method according to claim 1 , wherein the counteranions are selected from bis(trifluoromethylsulfonyl)imide, bromide, tetrafluoroborate (BF 4 − ), perchlorate (ClO 4 − ) and hexafluorophosphate (PF 6 − ).

7. A method according to claim 1 , wherein the solvent is a non-aqueous solvent.

8. The method according to claim 7 wherein the non-aqueous solvent is dimethyl sulfoxide, N-methyl-2-pyrrolidone, N,N′-dimethyl formamide or mixtures thereof.

9. A method for the production in an electrochemical cell of graphene and graphite nanoplatelet structures having a thickness of less than 100 nm, wherein the electrochemical cell comprises:
(a) a negative electrode which is graphitic;
(b) a positive electrode which may be graphitic or another material; and
(c) an electrolyte having ions in a solvent, wherein the ions include cations and counteranions, and wherein the cations are phosphorous-containing ions and wherein the electrolyte is substantially free of metal cations;
and wherein the method comprises the step of passing a current through the electrochemical cell to intercalate ions into the graphitic negative electrode so as to exfoliate the graphitic negative electrode.

10. A method according to claim 9 , wherein the phosphorous-containing cations are phosphonium ions.

11. A method according to claim 10 , where the phosphonium ions are tetraalkyl phosphonium ions.

12. A method according to claim 11 , wherein the tetraalkyl phosphonium ions are selected from tetrabutyl phosphonium, tetraethyl phosphonium and tetramethyl phosphonium.

13. A method according to claim 9 , wherein the counteranions are selected from hydroxide, bromide, tetrafluoroborate (BF 4 − ), perchlorate (ClO 4 − ) and hexafluorophosphate (PF 6 − ).

14. A method according to claim 9 , wherein the solvent is a non-aqueous solvent.

15. The method according to claim 14 wherein the non-aqueous solvent is dimethyl sulfoxide, N-methyl-2-pyrrolidone, N,N′-dimethyl formamide or mixtures thereof.

16. A method according to claim 9 , wherein the negative electrode is an electrode comprising one or more selected from highly ordered pyrolytic graphite, natural graphite and synthetic graphite.

17. A method according to claim 9 , which is carried out a temperature from 20° C. to 150° C.

18. A method according to claim 9 , wherein the graphene or graphite nanoplatelet structures having a thickness of less than 100 nm are separated from the electrolyte by at least one technique selected from:
(a) filtering;
(b) using centrifugal forces to precipitate the graphene or graphite nanoplatelet structures; and
(c) collecting the graphene or graphite nanoplatelet structures at the interface of two immiscible solvents.

19. A method according to claim 9 , wherein the electrochemically exfoliated graphene or graphite nanoplatelet structures are further treated using ultrasonic energy and/or thermal energy.

20. A method according to claim 9 , wherein the method further includes the step of isolating the graphene or graphite nanoplatelet structures.

Assignees

• Univ Manchester

Inventors

• Abdelkader Amr
• Kinloch Ian
• Dryfe Robert

Classifications

• C01B32/22

  Intercalation · CPC title

• B82Y40/00

  Manufacture or treatment of nanostructures · CPC title

• B82Y30/00

  Nanotechnology for materials or surface science, e.g. nanocomposites · CPC title

• C25B1/00

  Electrolytic production of inorganic compounds or non-metals · CPC title

• C01B2204/04

  Specific amount of layers or specific thickness · CPC title