Process for producing nano-scaled graphene platelet nanocomposite electrodes for supercapacitors

• US 20090092747A1
• Filed: 10/04/2007
• Published: 04/09/2009
• Est. Priority Date: 10/04/2007
• Status: Active Grant

• Current Assignee: Nanotek Instruments Group, LLC, Samsung Electronics Co. Ltd.
• Original Assignee: Nanotek Instruments, Inc.
• Inventors: Zhamu, Aruna, Jang, Bor Z.
• Granted Patent: US 7,875,219 B2
• Time in Patent Office: Days
• US Class Current: 427/80
• CPC Class Codes: H01G 11/22 Electrodes
• 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: Y02E 60/13 Energy storage using capacitors

Abstract

A process for producing meso-porous nanocomposite electrode comprising nano-scaled graphene platelets. The process comprises: (A) providing nano-scaled graphene platelets, wherein each of the platelets comprises a single graphene sheet or a stack of multiple graphene sheets, and the platelets have an average thickness no greater than 100 nm (preferably less than 5 nm and most preferably less than 2 nm in thickness); (B) combining a binder material, the graphene platelets, and a liquid to form a dispersion; (C) forming the dispersion into a desired shape and removing the liquid to produce a binder-platelet mixture; and (D) treating the binder material under a desired temperature or radiation environment to convert the binder-platelet mixture into a meso-porous nanocomposite electrode, wherein the platelets are bonded by the binder and the electrode has electrolyte-accessible pores characterized in that the nanocomposite has a surface area greater than about 100 m²/gm (preferably greater than 200 m²/gm, more preferably greater than 500 100 m²/gm, and most preferably greater than 1,000 m²/gm). A supercapacitor featuring such a nanocomposite exhibits an exceptionally high capacitance value.

Claims

1. A process for producing meso-porous nanocomposite electrode comprising nano-scaled graphene platelets, said process comprising:

(A) Providing nano-scaled graphene platelets, wherein each of the platelets comprises a single graphene sheet or a stack of multiple graphene sheets, and the platelets have an average thickness no greater than 100 nm;

(B) Combining a binder material, said graphene platelets, and a liquid to form a dispersion;

(C) Forming said dispersion into a desired shape and removing said liquid to produce a binder-platelet mixture; and

(D) Treating said binder material under a desired temperature or radiation environment to convert said binder-platelet mixture into said meso-porous nanocomposite electrode, wherein said platelets are bonded by said binder and said electrode has electrolyte-accessible pores characterized in that said nanocomposite has a surface area greater than about 100 m²/gm.

2. The process as defined in claim 1 wherein said platelets have an average thickness less than 5 nm or said nanocomposite has a surface area greater than about 200 m²/gm.

3. The process as defined in claim 1 wherein said platelets have an average thickness less than 2 nm or said nanocomposite has a surface area greater than about 500 m²/gm.

4. The process as defined in claim 1 wherein said binder material is a polymer and said liquid is a solvent for said polymer;

step (B) comprises dissolving at least a part of said polymer in said solvent to form a solution; and

step (C) comprises vaporizing said solvent.

5. The process as defined in claim 4 wherein said step (B) and step (C) comprise freeze-drying said liquid to produce pores.

6. The process as defined in claim 1 wherein said binder material is initially in a fine powder or filament form and said step (D) comprises melting said powder or filament to form a flowable melt, allowing said binder melt to attach to said platelets, and solidifying said binder to produce said nanocomposite electrode containing platelets bonded by a solid binder material.

7. The process as defined in claim 1 wherein said binder comprises a thermosetting resin or a polymerizable monomer and said step (D) comprises curing said resin or polymerizing said monomer to form a solid resin or polymer with the assistance of heat, radiation, an initiator, a catalyst, or a combination thereof.

8. The process as defined in claim 1 wherein said binder material is initially a polymer, coal tar pitch, petroleum pitch, meso-phase pitch, or organic precursor material and said step (D) further comprises thermally converting said binder material into a carbon material.

9. The process as defined in claim 7, further comprising a step of pyrolyzing said resin or polymer to obtain a polymeric carbon.

10. The process as defined in claim 1 wherein said binder material comprises a conductive material selected from the group consisting of a conducting polymer, a polymeric carbon, an amorphous carbon, a petroleum pitch or its derivative, a coal tar pitch or its derivative, and combinations thereof.

11. The process as defined in claim 1 wherein said binder material comprises a conductive polymer selected from polyaniline, polypyrrole, polythiophene, a derivative thereof, or a combination thereof.

12. The process as defined in claim 1 wherein said binder material comprises a non-conductive material selected from poly(vinylidene fluoride), poly(tetrafluoroethylene), polyvinyl fluoride, ethylene-propylene-diene copolymer, styrene-butadiene rubber, a copolymer thereof, a derivative thereof, or a combination thereof.

13. The process as defined in claim 1 wherein said binder material comprises a carbon material and step (D) further comprises a step of activating said carbon material and said platelets.

14. The process as defined in claim 1 wherein said binder material comprises a carbon material that is subjected to an activating treatment selected from CO₂ physical activation, steam activation, KOH chemical activation, NaOH chemical treatment, or exposure to nitric acid, fluorine, ammonia plasma, oxygen plasma, or a combination thereof.

15. The process as defined in claim 1 wherein said binder material comprises a carbon material and step (D) further comprises a step of surface-functionalizing said carbon material and graphene platelets.

16. The process as defined in claim 1 further comprising a step of surface-functionalizing said nanocomposite.

17. The process as defined in claim 16 wherein said step of surface functionalization comprises imparting to said nanocomposite a functional group selected from quinone, hydroquinone, quaternized aromatic amines, mercaptan, disulfide, sulfonate (—

SO₃), transition metal oxide, transition metal sulfide, or a combination thereof.

18. The process as defined in claim 1 wherein said binder material comprises a polymeric carbon derived from phenolic-formaldehyde, polyacrylonitrile, or cellulosic polymer.

19. The process as defined in claim 1, wherein step (B) further comprises adding to the dispersion a conductive filler selected from the group consisting of graphitic nano-fiber, carbon nano-fiber, carbon nanotube, carbon black, activated carbon, carbon fiber segment, nano-scaled metal particle, nano-scaled metal oxide, and combinations thereof.

20. A process for producing meso-porous nanocomposite electrode comprising nano-scaled graphene platelets, said process comprising:

(A) Providing nano-scaled graphene platelets, wherein each of the platelets comprises a single graphene sheet or a stack of multiple graphene sheets, and the platelets have an average thickness no greater than 100 nm;

(B) Combining a binder material in a liquid form and said graphene platelets to form a dispersion;

(C) Forming said dispersion into a desired shape; and

(D) Treating said binder material under a desired temperature or radiation environment to produce said meso-porous nanocomposite electrode, wherein said platelets are bonded by said binder and said electrode has electrolyte-accessible pores characterized in that said nanocomposite has a surface area greater than about 100 m²/gm.

21. The process as defined in claim 20 wherein said binder comprises a thermosetting resin or a polymerizable monomer and said step (D) comprises curing said resin or polymerizing said monomer to form a solid resin or polymer with the assistance of heat, radiation, an initiator, a catalyst, or a combination thereof.

22. The process as defined in claim 20 wherein said binder material is initially a polymer, coal tar pitch, petroleum pitch, meso-phase pitch, or organic precursor material and said step (D) further comprises thermally converting said binder material into a carbon material.

23. The process as defined in claim 20 wherein said binder material comprises a conductive material selected from the group consisting of a conducting polymer, a polymeric carbon, an amorphous carbon, a petroleum pitch or its derivative, a coal tar pitch or its derivative, and combinations thereof.

24. The process as defined in claim 20 wherein said binder material comprises a non-conductive material selected from poly(vinylidene fluoride), poly(tetrafluoroethylene), polyvinyl fluoride, ethylene-propylene-diene copolymer, styrene-butadiene rubber, a copolymer thereof, a derivative thereof, or a combination thereof.

25. The process as defined in claim 22, further comprising a step of activating said carbon material and said platelets.

26. The process as defined in claim 22, further comprising a step of surface-functionalizing said carbon material and graphene platelets.

27. The process as defined in claim 20, further comprising a step of surface-functionalizing said nanocomposite.

28. The process as defined in claim 27 wherein said step of surface functionalization comprises imparting to said nanocomposite a functional group selected from quinone, hydroquinone, quaternized aromatic amines, mercaptan, disulfide, sulfonate (—

SO₃), transition metal oxide, transition metal sulfide, or a combination thereof.

29. A process of continuously producing a supercapacitor electrode, said process comprising:

(A) Continuously providing a dispersion comprising a binder material, a liquid medium, and nano-scaled graphene platelets, wherein each of the platelets comprises a single graphene sheet or a stack of multiple graphene sheets, and the platelets have an average thickness no greater than 100 nm;

(B) Continuously forming said dispersion into a desired shape and removing said liquid to produce a binder-platelet mixture; and

(C) Continuously treating said binder material under a desired temperature or radiation environment to convert said binder-platelet mixture into said meso-porous nanocomposite electrode, wherein said platelets are bonded by said binder and said electrode has electrolyte-accessible pores characterized in that said nanocomposite has a surface area greater than about 100 m²/gm.

30. The process as defined in claim 29 wherein said binder comprises a thermosetting resin or a polymerizable monomer and said step (D) comprises curing said resin or polymerizing said monomer to form a solid resin or polymer with the assistance of heat, radiation, an initiator, a catalyst, or a combination thereof.

31. The process as defined in claim 29 wherein said binder material comprises a conductive material selected from the group consisting of a conducting polymer, a polymeric carbon, an amorphous carbon, a petroleum pitch or its derivative, a coal tar pitch or its derivative, and combinations thereof.

32. The process as defined in claim 29 wherein said binder material comprises a non-conductive material selected from poly(vinylidene fluoride), poly(tetrafluoroethylene), polyvinyl fluoride, ethylene-propylene-diene copolymer, styrene-butadiene rubber, a copolymer thereof, a derivative thereof, or a combination thereof.

33. The process as defined in claim 29, wherein said dispersion further comprises a conductive filler selected from the group consisting of graphitic nano-fiber, carbon nano-fiber, carbon nanotube, carbon black, activated carbon, carbon fiber segment, nano-scaled metal particle, nano-scaled metal oxide, and combinations thereof.

34. The process as defined in claim 29, wherein said graphene platelets are surface-functionalized.

35. A process of continuously producing a supercapacitor electrode, said process comprising:

(A) Continuously providing a dispersion comprising a binder material initially in a liquid form and nano-scaled graphene platelets suspended in said binder liquid, wherein each of the platelets comprises a single graphene sheet or a stack of multiple graphene sheets, and the platelets have an average thickness no greater than 100 nm;

(B) Continuously forming said dispersion into a desired shape; and

(C) Continuously treating said binder material under a desired temperature or radiation environment to produce said meso-porous nanocomposite electrode, wherein said platelets are bonded by said binder and said electrode has electrolyte-accessible pores characterized in that said nanocomposite has a surface area greater than about 100 m²/gm.

36. The process as defined in claim 35 wherein said binder comprises a thermosetting resin or a polymerizable monomer and said step (D) comprises curing said resin or polymerizing said monomer to form a solid resin or polymer with the assistance of heat, radiation, an initiator, a catalyst, or a combination thereof.

37. The process as defined in claim 35 wherein said binder material comprises a conductive material selected from the group consisting of a conducting polymer, a polymeric carbon, an amorphous carbon, a petroleum pitch or its derivative, a coal tar pitch or its derivative, and combinations thereof.

38. The process as defined in claim 35 wherein said binder material comprises a non-conductive material selected from poly(vinylidene fluoride), poly(tetrafluoroethylene), polyvinyl fluoride, ethylene-propylene-diene copolymer, styrene-butadiene rubber, a copolymer thereof, a derivative thereof, or a combination thereof.

39. The process as defined in claim 35, wherein said dispersion further comprises a conductive filler selected from the group consisting of graphitic nano-fiber, carbon nano-fiber, carbon nanotube, carbon black, activated carbon, carbon fiber segment, nano-scaled metal particle, nano-scaled metal oxide, and combinations thereof.

40. The process as defined in claim 35, wherein said graphene platelets are surface-functionalized.