Production process for highly conducting and oriented graphene film
View Patent ↗A process for producing a highly conducting film of conductor-bonded graphene sheets that are highly oriented, comprising: (a) preparing a graphene dispersion or graphene oxide (GO) gel; (b) depositing the dispersion or gel onto a supporting solid substrate under a shear stress to form a wet layer; (c) drying the wet layer to form a dried layer having oriented graphene sheets or GO molecules with an inter-planar spacing d 002 of 0.4 nm to 1.2 nm; (d) heat treating the dried layer at a temperature from 55° C. to 3,200° C. for a desired length of time to produce a porous graphitic film having pores and constituent graphene sheets or a 3D network of graphene pore walls having an inter-planar spacing d 002 less than 0.4 nm; and (e) impregnating the porous graphitic film with a conductor material that bonds the constituent graphene sheets or graphene pore walls to form the conducting film.
1. A process for producing a thermally conducting film of conductor-bonded graphene sheets that are oriented, said process comprising:
(a) preparing either a graphene dispersion having discrete graphene sheets dispersed in a fluid medium or a graphene oxide gel having graphene oxide molecules dissolved in a fluid medium, wherein said graphene oxide molecules contain an oxygen content from 5% to 50% by weight;
(b) dispensing and depositing said graphene dispersion or graphene oxide gel onto a surface of supporting solid substrate under a shear stress to form a wet layer of graphene or graphene oxide, having oriented graphene sheets or graphene oxide molecules, on said supporting substrate;
(c) at least partially removing said fluid medium from the wet layer of graphene or graphene oxide to form a dried layer of graphene, or dried layer of graphene oxide having an inter-planar spacing d 002 from 0.4 nm to 1.2 nm as determined by X-ray diffraction;
(d) heat treating the dried layer of graphene or graphene oxide at a heat treatment temperature from 55° C. to 3,200° C. for a desired length of time to produce a porous graphitic film having pores and constituent graphene sheets or a 3D network of graphene pore walls having an inter-planar spacing d 002 from 0.3354 nm to 0.4 nm, wherein said porous graphitic film has chemically bonded graphene planes that are all essentially oriented parallel to one another; and
(e) impregnating said porous graphitic film with a liquid or vapor phase metal conductor material or liquid or vapor phase metal conductor material precursor that bonds said constituent graphene sheets or 3D network of graphene pore walls to form said conducting film having a continuous network of electron-conducting and phonon-conducting pathways wherein said conductor material bridge gaps or interruptions in graphene planes, enabling barrier-free transport of electrons and phonons between graphene planes.
2. The process of claim 1 , further comprising a step (f) of mechanically compressing or consolidating said conducting film.
3. A process for producing a thermally conducting film of conductor-bonded graphene sheets that are oriented, said process comprising:
(a) preparing either a graphene dispersion having discrete graphene sheets dispersed in a fluid medium or a graphene oxide gel having graphene oxide molecules dissolved in a fluid medium, wherein said graphene oxide molecules contain an oxygen content from 5% to 50% by weight;
(b) dispensing and depositing said graphene dispersion or graphene oxide gel onto a surface of supporting solid substrate under a shear stress to form a wet layer of graphene or graphene oxide, having oriented graphene sheets or graphene oxide molecules, on said supporting substrate;
(c) at least partially removing said fluid medium from the wet layer of graphene or graphene oxide to form a dried layer of graphene, or dried layer of graphene oxide having an inter-planar spacing d 002 from 0.4 nm to 1.2 nm as determined by X-ray diffraction;
(d) heat treating the dried layer of graphene or graphene oxide at a heat treatment temperature from 55° C. to 3,200° C. for a desired length of time to produce a porous graphitic film having pores and constituent graphene sheets or a 3D network of graphene pore walls having an inter-planar spacing d 002 from 0.3354 nm to 0.4 nm, wherein said porous graphitic film has chemically bonded graphene planes that are all essentially oriented parallel to one another;
(e) impregnating said porous graphitic film with a conductor material or conductor material precursor that bonds said constituent graphene sheets or 3D network of graphene pore walls to form said conducting film having a continuous network of electron-conducting and phonon-conducting pathways wherein said conductor material bridge gaps or interruptions in graphene planes, enabling barrier-free transport of electrons and phonons between graphene planes and wherein said conductor material or conductor material precursor is selected from an intrinsically conductive polymer, a conductive organic compound, or a combination thereof, wherein said intrinsically conductive polymer is selected from poly(fluorene), polyphenylene, polypyrene, polyazulene, polynaphthalene, polycarbazole, polyindole, polyazepine, poly(3,4-ethylenedioxythiophene) (PEDOT), poly(p-phenylene sulfide) (PPS), poly(acetylene) (PAC), or poly(p-phenylene vinylene) (PPV).
4. The process of claim 1 , wherein said liquid or vapor phase metal conductor material or liquid or vapor phase metal conductor material precursor comprises a metal selected from Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Zr, Mo, Pd, Ag, Cd, Au, Pt, W, Al, Sn, In, Pb, Bi, an alloy thereof, or a mixture thereof.
5. The process of claim 1 , wherein said liquid or vapor phase metal conductor material or liquid or vapor phase metal conductor material precursor comprises a metal selected from Cu, Al, Ti, Sn, Ag, Au, Fe, or an alloy thereof.
6. A process for producing a thermally conducting film of conductor-bonded graphene sheets that are oriented, said process comprising:
(a) preparing either a graphene dispersion having discrete graphene sheets dispersed in a fluid medium or a graphene oxide gel having graphene oxide molecules dissolved in a fluid medium, wherein said graphene oxide molecules contain an oxygen content from 5% to 50% by weight;
(b) dispensing and depositing said graphene dispersion or graphene oxide gel onto a surface of supporting solid substrate under a shear stress to form a wet layer of graphene or graphene oxide, having oriented graphene sheets or graphene oxide molecules, on said supporting substrate;
(c) at least partially removing said fluid medium from the wet layer of graphene or graphene oxide to form a dried layer of graphene, or dried layer of graphene oxide having an inter-planar spacing d 002 from 0.4 nm to 1.2 nm as determined by X-ray diffraction;
(d) heat treating the dried layer of graphene or graphene oxide at a heat treatment temperature from 55° C. to 3,200° C. for a desired length of time to produce a porous graphitic film having pores and constituent graphene sheets or a 3D network of graphene pore walls having an inter-planar spacing d 002 from 0.3354 nm to 0.4 nm, wherein said porous graphitic film has chemically bonded graphene planes that are all essentially oriented parallel to one another;
(e) impregnating said porous graphitic film with a conductor material or conductor material precursor that bonds said constituent graphene sheets or 3D network of graphene pore walls to form said conducting film having a continuous network of electron-conducting and phonon-conducting pathways wherein said conductor material bridges gaps or interruptions in graphene planes, enabling barrier-free transport of electrons and phonons between graphene planes and wherein said conductor material or conductor material precursor contains a conductive organic compound selected from isotropic pitch, mesophase pitch, a polycyclic aromatic compound, pentacene, anthracene, rubrene, or a combination thereof.
7. The process of claim 1 , wherein said conductor material occupies a weight fraction of 0.1%-50% based on the total weight of said conducting film.
8. The process of claim 1 , wherein said conductor material occupies a weight fraction of 1%-20% based on the total weight of said conducting film.
9. The process of claim 1 , wherein said conductor material bonds said constituent graphene sheets at least in an end-to-end manner, or said conductor material fills into pores of said porous graphitic film.
10. The process of claim 1 , wherein said dispensing and depositing step includes an operation of spraying, casting, printing, coating, or a combination thereof.
11. The process of claim 10 , wherein said coating operation includes spin coating, dip coating, immersion dip coating, air knife coating, Anilox coating, Flexo coating, gap coating or knife-over-roll coating, gravure coating, metering-rod coating, kissing coating, slot-die coating, slot-die bead coating, slide coating, tensioned-web slot die coating, roller coating, silk screen coating, rotary screen coating, extrusion coating, comma coating, curtain coating, or a combination thereof.
12. The process of claim 10 , wherein said coating operation includes slot-die coating, comma coating, or reverse roll transfer coating, or said casting operation includes spin casting, spray casting, or combined casting-coating.
13. The process of claim 1 , wherein said heat treatment temperature is from 80 to 1,500° C.
14. The process of claim 1 , wherein said step of impregnating said porous graphitic film with a conductor material includes an operation of electrochemical deposition or plating, pulse power deposition, solution impregnation, electrophoretic deposition, electroless plating or deposition, metal melt impregnation, metal precursor impregnation, chemical deposition, physical vapor deposition, physical vapor infiltration, chemical vapor deposition, chemical vapor infiltration, sputtering, or a combination thereof.
15. The process of claim 1 , wherein said step of impregnating said porous graphitic film with a conductor material and said step of heat treating are conducted concurrently.
16. The process of claim 1 , further comprising a step of aging said wet or dried layer of graphene oxide at an aging temperature from 25° C. to 100° C. and a humidity level from 20% to 99% for an aging time of 1 hour to 7 days to form an aged layer of graphene oxide prior to said step (d) of heat treating.
17. The process of claim 1 , wherein said step (d) of heat treating is conducted for a length of time sufficient for decreasing an inter-plane spacing d 002 to a value of from 0.3354 nm to 0.36 nm and decreasing the oxygen content to less than 2% by weight in said graphitic film.
18. The process of claim 1 , wherein said fluid medium consists of water and/or an alcohol.
19. The process of claim 1 , wherein said graphene sheets in said graphene dispersion occupy a weight fraction of 0.1% to 25% based on the total weight of graphene sheets and liquid medium combined.
20. The process of claim 1 , wherein said graphene oxide molecules in said graphene oxide gel occupy a weight fraction of 0.5% to 15% based on the total weight of graphene oxide molecules and liquid medium combined.
21. The process of claim 19 , wherein said graphene sheets in said graphene dispersion occupy a weight fraction of 3% to 15% based on the total weight of graphene sheets and liquid medium combined.
22. The process of claim 1 , wherein said graphene dispersion or graphene oxide gel has greater than 3% by weight of graphene or graphene oxide dispersed or dissolved in said fluid medium to form a liquid crystal phase.
23. The process of claim 1 , wherein said conducting film has a thickness from 10 nm to 500 μm.
24. The process of claim 1 , wherein said conducting film has a thickness from 100 nm to 100 μm.
25. The process of claim 1 , wherein said graphene 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.
26. The process of claim 3 , wherein said 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 from 0.3354 nm to 0.345 nm, a thermal conductivity from 1,000 W/mK to 1,750 W/mK, and/or an electrical conductivity from 3,000 S/cm to 20,000 S/cm.
27. The process of claim 6 , wherein said heat 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 from 0.337 nm, a thermal conductivity from 1,300 W/mK to 1,750 W/mK, and/or an electrical conductivity from 5,000 S/cm to 20,000 S/cm.
28. The process of claim 1 , wherein said heat treatment temperature contains a temperature from 2,500° C. to 3,250° C. and the graphitic film has an oxygen content no greater than 0.001%, an inter-graphene spacing from 0.3354 nm to 0.336 nm, a mosaic spread value from 0.2 to 0.7, a thermal conductivity from 1,500 W/mK to 1,750 W/mK, and/or an electrical conductivity from 10,000 S/cm to 20,000 S/cm.
29. The process of claim 1 , wherein the porous graphitic film exhibits an inter-graphene spacing from 0.3354 nm to 0.337 nm and a mosaic spread value from 0.2 to 1.0.
30. The process of claim 3 , wherein the porous graphitic film exhibits a degree of graphitization no less than 80% and/or a mosaic spread value from 0.2 to 0.4.
31. The process of claim 1 , wherein the porous graphitic film exhibits a degree of graphitization no less than 90% and/or a mosaic spread value from 0.2 to 0.4.
32. The process of claim 1 , wherein said graphene 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 graphite grain size.
33. The process of claim 1 , wherein said graphene dispersion or graphene oxide gel is obtained from a graphitic material having multiple graphite crystallites exhibiting random crystalline orientation as determined by an X-ray diffraction or electron diffraction method and wherein said graphitic film is a single crystal or a poly-crystal graphene structure having a non-random crystalline orientation as determined by said X-ray diffraction or electron diffraction method.
34. The process of claim 1 , wherein said step of heat-treating induces chemical linking, merging, or chemical bonding of graphene oxide molecules in an edge-to-edge manner.