Production of highly oriented graphene oxide films and graphitic films derived therefrom

Patent metadata

Field	Value
Publication number	US-10005099-B2
Application number	US-201514756006-A
Country	US
Kind code	B2
Filing date	Jul 20, 2015
Priority date	Jul 20, 2015
Publication date	Jun 26, 2018
Grant date	Jun 26, 2018

Abstract

A process for producing a highly oriented graphene oxide (GO) film, comprising: (a) preparing either a GO dispersion having GO sheets dispersed in a fluid medium or a GO gel having GO molecules dissolved in a fluid medium; (b) dispensing the GO dispersion or gel onto a surface of an application roller rotating in a first direction to form an applicator layer of GO and transferring the applicator layer to a surface of a supporting film driven in a second direction opposite to the first direction to form a wet layer of GO on the supporting film; and (c) removing said fluid medium from the wet layer of GO to form a dried layer of GO having an inter-planar spacing d 002 of 0.4 nm to 1.2 nm and an oxygen content no less than 5% by weight. This dried GO layer may be heat-treated to produce a graphitic film.

First claim

We claim:

1. A process for producing a highly oriented graphene oxide film, said process comprising:
(a) preparing either a graphene oxide dispersion having graphene oxide sheets dispersed in a fluid medium or a graphene oxide gel having graphene oxide molecules dissolved in a fluid medium, wherein said graphene oxide sheets or graphene oxide molecules contain an oxygen content higher than 5% by weight;
(b) dispensing said graphene oxide dispersion or graphene oxide gel onto a gap between an applicator roller and a metering roller wherein a relative motion or rotation between said metering roller and said applicator roller generates an applicator layer of graphene oxide onto a surface of said application roller rotating in a first direction at a first line velocity, wherein said application roller transfers said applicator layer of graphene oxide to a surface of a supporting film driven in a second direction opposite to said first direction at a second line velocity, to form a wet layer of graphene oxide on said supporting film; and
(c) at least partially removing said fluid medium from the wet layer of graphene oxide to form a dried layer of graphene oxide having all graphene oxide planes parallel to one another along the plane of the film and having an inter-planar spacing d 002 of 0.4 nm to 1.2 nm as determined by X-ray diffraction and an oxygen content no less than 5% by weight;
wherein said process further comprised a step of aging said wet or dried layer of graphene oxide in an aging room at an aging temperature from 25° C. to 55° C. and humidity level from 20% to 99% for an aging time of 1 hour to 7 days to form an aged layer of graphene oxide.

2. The process of claim 1 , wherein said supporting film is driven by a counter-rotating supporting roller disposed at a working distance from said application roller and rotating in said second direction opposite to said first direction.

3. The process of claim 1 , wherein said step of dispensing said graphene oxide dispersion or graphene oxide gel onto said surface of the application roller includes using a metering roller and/or a doctor's blade to provide a desired thickness of said applicator layer of graphene oxide on said application roller surface.

4. The process of claim 1 , wherein said process includes operating 2, 3, or 4 rollers.

5. The process of claim 1 , wherein said process includes a reverse roll transfer coating procedure.

6. The process of claim 1 , wherein said supporting film is fed from a feeder roller and said dried layer of graphene oxide supported by said supporting film is wound on a winding roller and said process is conducted in a roll-to-roll manner.

7. The process of claim 1 , wherein the velocity ratio, defined as (said second line velocity)/(said first line velocity), is from 1/5 to 5/1.

8. The process of claim 7 , wherein the velocity ratio is greater than 1/1 and less than 5/1.

9. The process of claim 1 , wherein said fluid medium further contains pristine graphene sheets and a pristine graphene to graphene oxide ratio is from 1/100 to 100/1.

10. The process of claim 9 , wherein said graphitic film has an electrical conductivity greater than 5,000 S/cm, a thermal conductivity from 800 W/mK to 1745 W/mK, a physical density greater than 1.9 g/cm3, a tensile strength greater than 80 MPa, and/or an elastic modulus greater than 60 GPa.

11. The process of claim 1 , wherein said fluid medium consists of water and/or an alcohol.

12. The process of claim 1 , wherein said graphene oxide sheets in said graphene oxide dispersion occupy a weight fraction of 0.1% to 25% based on the total weight of graphene oxide sheets and liquid medium combined.

13. The process of claim 12 , wherein said graphene oxide sheets in said graphene oxide dispersion occupy a weight fraction of 0.5% to 15% based on the total weight of graphene oxide sheets and liquid medium combined.

14. The process of claim 12 , wherein said graphene oxide sheets in said graphene oxide dispersion occupy a weight fraction of 3% to 15% based on the total weight of graphene oxide sheets and liquid medium combined.

15. The process of claim 1 , wherein said graphene oxide dispersion or graphene oxide gel has greater than 3% by weight of graphene oxide dispersed in said fluid medium to form a liquid crystal phase.

16. The process of claim 1 , wherein said graphene oxide dispersion or graphene oxide gel is prepared by immersing a graphitic material in a powder or fibrous form in an oxidizing liquid in a reaction vessel at a reaction temperature for a length of time sufficient to obtain said graphene oxide dispersion or said graphene oxide gel wherein said graphitic material is selected from natural graphite, artificial graphite, mesophase carbon, mesophase pitch, mesocarbon micro-bead, soft carbon, hard carbon, coke, carbon fiber, carbon nanofiber, carbon nanotube, or a combination thereof.

17. The process of claim 1 , further comprising a step of heat treating the dried layer of graphene oxide at a first heat treatment temperature higher than 55° C. but no greater than 2,200° C. for a desired length of time to produce a graphitic film having an inter-planar spacing d 002 less than 0.4 nm and an oxygen content less than 5% by weight.

18. The process of claim 17 , further comprising a compression step, during or after said step (d), to reduce a thickness of said graphitic film.

19. The process of claim 17 , wherein said graphitic film has a thickness from 100 μm to 500 μm.

20. The process of claim 17 , wherein said first heat treatment temperature contains a temperature in the range of 500° C.-1,500° C. and the graphitic film has an oxygen content less than 1%, an inter-graphene spacing less than 0.345 nm, a thermal conductivity from 1,000 W/mK to 1,745 W/mK, and/or an electrical conductivity from 3,000 S/cm to 12,000 S/cm.

21. The process of claim 17 , wherein said treatment temperature contains a temperature in the range of 1,500° C.-2,200° C. and the graphitic film has an oxygen content less than 0.01%, an inter-graphene spacing less than 0.337 nm, a thermal conductivity from 1,300 W/mK to 1,745 W/mK, and/or an electrical conductivity from 5,000 S/cm to 12,000 S/cm.

22. The process of claim 17 , wherein said heat treatment temperature contains a temperature from 2,500° C. to 2,800° C. and the graphitic film has an oxygen content no greater than 0.001%, an inter-graphene spacing less than 0.336 nm, a mosaic spread value no greater than 0.7, a thermal conductivity from 1,500 W/mK to 1745 W/mK, and/or an electrical conductivity from 10,000 S/cm to 12,000 S/cm.

23. The process of claim 17 , wherein said first heat treatment temperature contains a temperature from 2,500° C. to 2,800° C. and the graphitic film has an inter-graphene spacing less than 0.336 nm, a mosaic spread value no greater than 0.4, a thermal conductivity from 1,600 W/mK to 1745 W/mK, and/or an electrical conductivity from 10,000 S/cm to 12,000 S/cm.

24. The process of claim 17 , wherein said graphene oxide dispersion or graphene oxide gel is obtained from a graphitic material having a maximum original graphite grain size and said graphitic film is a poly-crystal graphene structure having a grain size larger than said maximum original grain size.

25. The process of claim 17 , wherein said graphene oxide dispersion or graphene oxide gel is obtained from a graphitic material having multiple graphite crystallites exhibiting no preferred crystall

Assignees

• Nanotek Instruments Inc

Inventors

• Lin Yi-Jun
• Lee Shaio-Yen
• Zhamu Aruna
• Jang Bor Z

Classifications

• C01B32/205

  Preparation · CPC title

• B82Y40/00

  Manufacture or treatment of nanostructures · CPC title

• C04B35/62655

  Drying, e.g. freeze-drying, spray-drying, microwave or supercritical drying · CPC title

• C04B35/522

  Graphite (C04B35/536 takes precedence) · CPC title

• C01B32/23

  Oxidation · CPC title