WO2019195374A1 - Mousse de graphène métallisée à forte conductivité à travers les plans - Google Patents

Mousse de graphène métallisée à forte conductivité à travers les plans Download PDF

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Publication number
WO2019195374A1
WO2019195374A1 PCT/US2019/025514 US2019025514W WO2019195374A1 WO 2019195374 A1 WO2019195374 A1 WO 2019195374A1 US 2019025514 W US2019025514 W US 2019025514W WO 2019195374 A1 WO2019195374 A1 WO 2019195374A1
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graphene
metal
sheets
bonded
foam
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PCT/US2019/025514
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English (en)
Inventor
Yi-Jun Lin
Aruna Zhamu
Bor Z. Jang
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Nanotek Instruments, Inc.
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Priority claimed from US15/944,274 external-priority patent/US20190300372A1/en
Priority claimed from US15/944,162 external-priority patent/US20190301814A1/en
Application filed by Nanotek Instruments, Inc. filed Critical Nanotek Instruments, Inc.
Publication of WO2019195374A1 publication Critical patent/WO2019195374A1/fr

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    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B32/00—Carbon; Compounds thereof
    • C01B32/15—Nano-sized carbon materials
    • C01B32/182—Graphene
    • C01B32/198—Graphene oxide
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B32/00—Carbon; Compounds thereof
    • C01B32/15—Nano-sized carbon materials
    • C01B32/182—Graphene
    • C01B32/184—Preparation
    • C01B32/186—Preparation by chemical vapour deposition [CVD]
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B32/00—Carbon; Compounds thereof
    • C01B32/15—Nano-sized carbon materials
    • C01B32/182—Graphene
    • C01B32/184—Preparation
    • C01B32/19—Preparation by exfoliation
    • C01B32/192—Preparation by exfoliation starting from graphitic oxides
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B32/00—Carbon; Compounds thereof
    • C01B32/15—Nano-sized carbon materials
    • C01B32/182—Graphene
    • C01B32/194—After-treatment
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B32/00—Carbon; Compounds thereof
    • C01B32/20—Graphite
    • C01B32/205—Preparation
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B38/00—Porous mortars, concrete, artificial stone or ceramic ware; Preparation thereof
    • C04B38/02—Porous mortars, concrete, artificial stone or ceramic ware; Preparation thereof by adding chemical blowing agents
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B38/00—Porous mortars, concrete, artificial stone or ceramic ware; Preparation thereof
    • C04B38/04—Porous mortars, concrete, artificial stone or ceramic ware; Preparation thereof by dissolving-out added substances
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B38/00—Porous mortars, concrete, artificial stone or ceramic ware; Preparation thereof
    • C04B38/10—Porous mortars, concrete, artificial stone or ceramic ware; Preparation thereof by using foaming agents or by using mechanical means, e.g. adding preformed foam
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B41/00—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone
    • C04B41/009—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone characterised by the material treated
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B41/00—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone
    • C04B41/45—Coating or impregnating, e.g. injection in masonry, partial coating of green or fired ceramics, organic coating compositions for adhering together two concrete elements
    • C04B41/52—Multiple coating or impregnating multiple coating or impregnating with the same composition or with compositions only differing in the concentration of the constituents, is classified as single coating or impregnation
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B41/00—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone
    • C04B41/80—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone of only ceramics
    • C04B41/81—Coating or impregnation
    • C04B41/85—Coating or impregnation with inorganic materials
    • C04B41/88—Metals
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B41/00—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone
    • C04B41/80—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone of only ceramics
    • C04B41/81—Coating or impregnation
    • C04B41/89—Coating or impregnation for obtaining at least two superposed coatings having different compositions
    • C04B41/90—Coating or impregnation for obtaining at least two superposed coatings having different compositions at least one coating being a metal
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C1/00—Making non-ferrous alloys
    • C22C1/10—Alloys containing non-metals
    • C22C1/1005—Pretreatment of the non-metallic additives
    • C22C1/1015—Pretreatment of the non-metallic additives by preparing or treating a non-metallic additive preform
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B2111/00—Mortars, concrete or artificial stone or mixtures to prepare them, characterised by specific function, property or use
    • C04B2111/00474—Uses not provided for elsewhere in C04B2111/00
    • C04B2111/00844—Uses not provided for elsewhere in C04B2111/00 for electronic applications
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B2111/00—Mortars, concrete or artificial stone or mixtures to prepare them, characterised by specific function, property or use
    • C04B2111/00474—Uses not provided for elsewhere in C04B2111/00
    • C04B2111/00853—Uses not provided for elsewhere in C04B2111/00 in electrochemical cells or batteries, e.g. fuel cells

Definitions

  • the present invention relates generally to the field of graphene materials and, more particularly, to a highly conductive graphene foam structure composed of pores (cells) and cell walls constituted by metal-bonded or metal-coated graphene sheets.
  • Carbon is known to have five unique crystalline structures, including diamond, fullerene (0-D nanographitic material), carbon nanotube or carbon nanofiber (l-D nanographitic material), graphene (2-D nanographitic material), and graphite (3-D graphitic material).
  • the carbon nanotube (CNT) refers to a tubular structure grown with a single wall or multi-wall.
  • Carbon nanotubes (CNTs) and carbon nanofibers (CNFs) have a diameter on the order of a few nanometers to a few hundred nanometers.
  • Their longitudinal, hollow structures impart unique mechanical, electrical and chemical properties to the material.
  • the CNT or CNF is a one dimensional nanocarbon or l-D nanographite material.
  • Bulk natural graphite is a 3-D graphitic material with each graphite particle being composed of multiple grains (a grain being a graphite single crystal or crystallite) with grain boundaries (amorphous or defect zones) demarcating neighboring graphite single crystals.
  • Each grain is composed of multiple graphene planes that are oriented parallel to one another.
  • a graphene plane in a graphite crystallite is composed of carbon atoms occupying a two- dimensional, hexagonal lattice. In a given grain or single crystal, the graphene planes are stacked and bonded via van der Waal forces in the crystallographic c-direction (perpendicular to the graphene plane or basal plane).
  • the graphene planes in one grain are parallel to one another, typically the graphene planes in one grain and the graphene planes in an adjacent grain are inclined at different orientations. In other words, the orientations of the various grains in a graphite particle typically differ from one grain to another.
  • a graphite single crystal (crystallite) per se is anisotropic with a property measured along a direction in the basal plane (crystallographic a- or h-axis direction) being dramatically different than if measured along the crystallographic c-axis direction (thickness direction).
  • the thermal conductivity of a graphite single crystal can be up to approximately 1,920 W/mK (theoretical) or 1,800 W/mK (experimental) in the basal plane (crystallographic a- and h-axis directions), but that along the crystallographic c-axis direction is less than 10 W/mK (typically less than 5 W/mK).
  • the multiple grains or crystallites in a graphite particle are typically all oriented along different and random directions. Consequently, a natural graphite particle composed of multiple grains of different orientations exhibits an average property between these two extremes (i.e. between 5 W/mK and 1,800 W/mK).
  • the constituent graphene planes of a graphite crystallite in a natural or artificial graphite particle can be exfoliated and extracted or isolated to obtain individual graphene sheets of carbon atoms provided the inter-planar van der Waals forces can be overcome.
  • An isolated, individual graphene sheet of carbon atoms is commonly referred to as single-layer graphene.
  • a stack of multiple graphene planes bonded through van der Waals forces in the thickness direction with an inter-graphene plane spacing of approximately 0.3354 nm is commonly referred to as a multi layer graphene.
  • a multi-layer graphene platelet has up to 300 layers of graphene planes ( ⁇ 100 nm in thickness), but more typically up to 30 graphene planes ( ⁇ 10 nm in thickness), even more typically up to 20 graphene planes ( ⁇ 7 nm in thickness), and most typically up to 10 graphene planes (commonly referred to as few-layer graphene in scientific community).
  • Single-layer graphene and multi-layer graphene sheets are collectively called“nanographene platelets” (NGPs).
  • NGPs are a new class of carbon nanomaterial (a 2-D nanocarbon) that is distinct from the 0-D fullerene, the l-D CNT, and the 3-D graphite.
  • Graphene sheets or NGPs are often obtained by intercalating natural graphite particles with a strong acid and/or oxidizing agent to obtain a graphite intercalation compound (GIC) or graphite oxide.
  • GIC graphite intercalation compound
  • the presence of chemical species or functional groups in the interstitial spaces between graphene planes serves to increase the inter-graphene spacing (i/002, as determined by X- ray diffraction), thereby significantly weakening the van der Waals forces that otherwise hold graphene planes together along the c-axis direction.
  • interconnected or non-separated graphite flakes can be re-compressed to obtain flexible graphite sheets or foils that typically have a thickness in the range from 0.1 mm (100 pm) - 0.5 mm (500 pm).
  • a low-intensity air mill or shearing machine to simply break up the graphite worms for the purpose of producing the so-called“expanded graphite flakes” which contain mostly graphite flakes or platelets thicker than 100 nm (hence, not a nanomaterial by definition).
  • Exfoliated graphite worms, expanded graphite flakes, and the recompressed mass of graphite worms are all 3-D graphitic materials that are fundamentally different and patently distinct from either the l-D nanocarbon material (CNT or CNF) or the 2-D nanocarbon material (graphene sheets or platelets, NGPs).
  • the exfoliated graphite may be subjected to high-intensity mechanical shearing (e.g. using an ultrasonicator, high-shear mixer, high-intensity air jet mill, or high-energy ball mill) to form separated single-layer and multi-layer graphene sheets (collectively called NGPs), as disclosed in our US Application No. 10/858,814.
  • Single-layer graphene can be as thin as 0.34 nm, while multi-layer graphene can have a thickness up to 100 nm, but more typically less than 20 nm.
  • Ultrasonic power can be sufficient to further separate graphene plane sheets to form separated, isolated, or discrete graphene oxide (GO) sheets.
  • RGO reduced graphene oxides
  • NGPs include discrete sheets/platelets of single-layer and multi-layer pristine graphene, graphene oxide, reduced graphene oxide (RGO), graphene fluoride, graphene chloride, graphene bromide, graphene iodide, hydrogenated graphene, nitrogenated graphene, boron-doped graphene, nitrogen-doped graphene, chemically functionalized graphene, and combinations thereof.
  • Pristine graphene has essentially 0% oxygen (« 0.01% oxygen).
  • RGO typically has an oxygen content of 0.0l%-5% by weight.
  • Graphene oxide (including RGO) can have 0.00l%-50% by weight of oxygen.
  • a foam or foamed material is composed of pores (also referred to as “cells”) and pore walls (or cell walls, a solid material).
  • the pores or cells can be interconnected to form an open-cell foam.
  • a graphene foam is composed of pores and pore walls that contain a graphene material. There are four major methods of producing graphene foams:
  • the first method is the hydrothermal reduction of graphene oxide hydrogel that typically involves sealing graphene oxide (GO) aqueous suspension in a high-pressure autoclave and heating the GO suspension under a high pressure (tens or hundreds of atm) at a temperature typically in the range from l80-300°C for an extended period of time (typically 12-36 hours).
  • a useful reference for this method is given here: Y. Xu, et al.“Self-Assembled Graphene Hydrogel via a One-Step Hydrothermal Process,” ACS Nano 2010, 4, 4324-4330.
  • the second method is based on a template-assisted catalytic CVD process, which involves CVD deposition of graphene on a sacrificial template (e.g. Ni foam).
  • a sacrificial template e.g. Ni foam
  • the graphene material conforms to the shape and dimensions of the Ni foam structure.
  • the Ni foam is then etched away using an etching agent, leaving behind a monolith of graphene skeleton that is essentially an open-cell foam.
  • a useful reference for this method is given here: Zongping Chen, et al.,“Three-dimensional flexible and conductive interconnected graphene networks grown by chemical vapour deposition,” Nature Materials, 10 (June 2011) 424-428.
  • the third method of producing graphene foam also makes use of a sacrificial material (e.g. colloidal polystyrene particles, PS) that is coated with graphene oxide sheets using a self- assembly approach.
  • a sacrificial material e.g. colloidal polystyrene particles, PS
  • PS polystyrene particles
  • Choi, et al. prepared chemically modified graphene (CMG) paper in two steps: fabrication of free-standing PS/CMG films by vacuum filtration of a mixed aqueous colloidal suspension of CMG and PS (2.0 pm PS spheres), followed by removal of PS beads to generate 3D macro-pores.
  • CMG chemically modified graphene
  • the fourth method is based on the freeze-drying or freeze-casting procedure. This procedure was disclosed by the applicant’s research group (L. Song, J. Guo, A. Zhamu, and B. Z. Jang,“Nano-scaled Graphene Plate Nanocomposites for Supercapacitor Electrodes” US Patent Appl. No. 11/499,861 (08/07/2006) now US Patent No. 7,623,340) and later by Li, et al.
  • Another object of the present invention is to provide products (e.g. devices) that contain a metallized graphene foam and methods of operating these products. It is a specific object of the present invention to provide a metal-bonded solid graphene foam for use as a heat dissipation or heat spreading element in a smart phone, tablet computer, digital camera, display device, flat- panel TV, LED lighting device, etc. Such a sheet of graphene foam exhibits a high thermal conductivity and high electrical conductivity not just along the in-plane directions, but also in the through-plane direction (thickness-direction).
  • the present invention provides a metal-bonded graphene foam product, preferably in a sheet form or a roll of metal-bonded graphene foam.
  • the present invention also provides a process for producing such a conductive foam product.
  • the thickness of this foam product can be from 5 nm to 5 mm (or thicker), but more typically from 10 nm to 1 mm, and further more typically from 100 nm to 200 pm.
  • the present invention also provides a process for producing such a conductive graphene foam product.
  • the disclosed metal-bonded graphene foam product comprises: (a) a sheet or roll of solid graphene foam, having a sheet plane and a sheet thickness direction, composed of multiple pores (cells) and pore walls, wherein the pore walls contain a pristine graphene material having less than 0.01% by weight of non-carbon elements or a non- pristine graphene material having 0.01% to 20% by weight of non-carbon elements, wherein said non-pristine graphene is selected from graphene oxide, reduced graphene oxide, graphene fluoride, graphene chloride, graphene bromide, graphene iodide, hydrogenated graphene, nitrogenated graphene, boron-doped graphene, nitrogen-doped graphene, chemically functionalized graphene, or a combination thereof; and (b) a metal that fills in the pores and bonds the graphene sheets together, wherein the metal-bonded graphene foam product has a thickness-direction thermal conductivity from 1.0
  • the solid graphene foam may contain a three-dimensional network of interconnected and ordered open cells.
  • the solid graphene foam when measured without the metal, has a density ranging from about 0.001 g/cm to about 1.7 g/cm , more preferably and typically from about 0.01 g/cm to about 1.5 g/cm , and most preferably from about 0.01 g/cm to about 0.8 g/cm .
  • the metal-bonded graphene foam product typically and preferably has a thickness- direction thermal conductivity from 10 to 800 W/mK or a thickness-direction electrical conductivity from 40 S/cm to 3,200 S/cm.
  • the bonding metal is preferably 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.
  • the metal preferably occupies a weight fraction of 0.l%-95% (more preferably from 1% to 50%) based on the total metal-bonded graphene foam product weight.
  • the solid graphene foam in the metal-bonded graphene foam product further contains a carbon or graphite filler selected from a carbon or graphite fiber, carbon or graphite nanofiber, carbon nanotube, carbon nanorod, mesophase carbon particle, mesocarbon microbead, expanded graphite flake, needle coke, carbon black or acetylene black, activated carbon, or a combination thereof.
  • a carbon or graphite filler selected from a carbon or graphite fiber, carbon or graphite nanofiber, carbon nanotube, carbon nanorod, mesophase carbon particle, mesocarbon microbead, expanded graphite flake, needle coke, carbon black or acetylene black, activated carbon, or a combination thereof.
  • the chemically functionalized graphene sheets contain a functional group attached thereto to make the graphene sheets in a liquid medium exhibit a negative Zeta potential from -55 mV to -0.1 mV. In certain embodiments, the chemically functionalized graphene sheets do not include graphene oxide.
  • the chemically functionalized graphene sheets may have a chemical functional group selected from alkyl or aryl silane, alkyl or aralkyl group, hydroxyl group, carboxyl group, carboxylic group, amine group, sulfonate group (— S0 3 H), aldehydic group, quinoidal, fluorocarbon, or a combination thereof.
  • the chemically functionalized graphene comprises graphene sheets having a chemical functional group selected from a derivative of an azide compound selected from the group consisting of 2-azidoethanol, 3-azidopropan-l-amine, 4-(2-azidoethoxy)- 4-oxobutanoic acid, 2-azidoethyl-2-bromo-2-methylpropanoate, chlorocarbonate,
  • the chemically functionalized graphene comprises graphene sheets having a chemical functional group selected from an oxygenated group selected from the group consisting of hydroxyl, peroxide, ether, keto, and aldehyde.
  • the chemically functionalized graphene comprises graphene sheets having a chemical functional group selected from the group consisting of -S0 3 H, -COOH, -NH 2 , -OH, -R'CHOH, -CHO, -CN, -COC1, halide, -COSH, -SH, -COOR', -SR', -SiR' 3 , -Si(-OR'-) y R' 3 -y, -Si(-0-SiR' 2 -)0R', -R", Li, AlR' 2 , Hg— X, TlZ 2 and Mg— X; wherein y is an integer equal to or less than 3, R' is hydrogen, alkyl, aryl, cycloalkyl, or aralkyl, cycloaryl, or poly(alkylether), R" is fluoroalkyl, fluoroaryl,
  • the chemically functionalized graphene comprises graphene sheets having a chemical functional group selected from the group consisting of amidoamines, polyamides, aliphatic amines, modified aliphatic amines, cycloaliphatic amines, aromatic amines, anhydrides, ketimines, diethylenetriamine (DETA), triethylene-tetramine (TETA), tetraethylene-pentamine (TEPA), polyethylene polyamine, polyamine epoxy adduct, phenolic hardener, non-brominated curing agent, non-amine curatives, and combinations thereof.
  • a chemical functional group selected from the group consisting of amidoamines, polyamides, aliphatic amines, modified aliphatic amines, cycloaliphatic amines, aromatic amines, anhydrides, ketimines, diethylenetriamine (DETA), triethylene-tetramine (TETA), tetraethylene-pentamine (TEPA), polyethylene polyamine, polyamine epoxy ad
  • the present invention also provides a thermal management device containing the disclosed metal-bonded graphene foam product as a heat spreader or thermal interface material.
  • the present invention also provides a heat dissipation or heat spreading element containing the disclosed metal-bonded graphene foam product, wherein the element is disposed in a smart phone, tablet computer, digital camera, display device, flat-panel TV, or LED lighting device.
  • the present invention also provides a fuel cell bipolar plate containing the disclosed metal-bonded graphene foam product. Also provided is a battery current collector containing the metal-bonded graphene foam product.
  • the invention also includes a process for producing the metal-bonded graphene foam product, the process comprising:
  • graphene dispersion having multiple graphene sheets dispersed in a liquid medium, wherein the graphene sheets are selected from a pristine graphene or a non-pristine graphene material, having a content of non-carbon elements greater than 2% by weight, selected from graphene oxide, reduced graphene oxide, graphene fluoride, graphene chloride, graphene bromide, graphene iodide, hydrogenated graphene, nitrogenated graphene, chemically functionalized graphene, or a combination thereof and wherein said graphene dispersion contains an optional blowing agent having a blowing agent-to-graphene material weight ratio from 0/1.0 to 1.0/1.0;
  • the dispensing and depositing procedure may include subjecting the graphene dispersion to an orientation-inducing stress.
  • the process further includes a step of heat-treating the solid graphene foam at a second heat treatment temperature higher than the first heat treatment temperature for a length of time sufficient for increasing the thermal conductivity of the solid graphene foam wherein the pore walls contain stacked graphene planes having an inter-plane spacing doo2 from 0.3354 nm to 0.36 nm and a content of non-carbon elements less than 2% by weight.
  • the graphene sheets contain pristine graphene and said graphene dispersion contains a blowing agent having a blowing agent-to-pristine graphene weight ratio from 0.01/1.0 to 1.0/1.0.
  • the blowing agent is a physical blowing agent, a chemical blowing agent, a mixture thereof, a dissolution-and-leaching agent, or a mechanically introduced blowing agent.
  • the process may be a roll-to-roll process wherein said steps (b) and (c) include feeding said supporting substrate from a feeder roller to a deposition zone, continuously or intermittently depositing the graphene dispersion onto a surface of the supporting substrate to form the wet layer of graphene thereon, drying the wet layer of graphene, and collecting the dried layer of graphene material deposited on the supporting substrate on a collector roller
  • the first heat treatment temperature is preferably selected from l00°C to l,500°C.
  • the second heat treatment temperature may include at least a temperature selected from (A) 300 - l,500°C, (B) 1,500-2, l00°C, or (C) 2,l00-3,200°C.
  • the step (d) of heat treating the dried layer of graphene at a first heat treatment temperature may be conducted under a compressive stress.
  • the process may further comprise a compression step to reduce a thickness, a pore size, or a porosity level of the solid graphene foam.
  • the process may further comprise a step of chemically functionalizing graphene sheets in the solid graphene foam, after step (d), to promote metal impregnating via electroless plating or electro-plating.
  • the chemical functionalization step may include attaching a functional group recited earlier in this section.
  • the graphene sheets on the pore walls in the solid graphene foam may be chemically functionalized to make the graphene sheets in a liquid medium exhibit a negative Zeta potential from -55 mV to -0.1 mV.
  • Such a Zeta potential is significantly more effective in attracting metal ions to graphene surfaces of the solid graphene foam during subsequent electroless plating or electro-plating.
  • these graphene sheets Prior to the step of chemically functionalizing graphene sheets, these graphene sheets are essentially free of any significant amount of oxygen and hydrogen and they are no longer graphene oxide.
  • the process may further comprise, after step (e), of mechanically compressing or consolidating the metal-bonded graphene foam product.
  • the graphene dispersion may further contain particles or fibrils of a metal, carbon or graphite filler to induce orientation of said graphene sheets inclined at an angle of 15-90 degrees relative to said paper sheet plane, wherein said carbon or graphite filler is selected from a carbon or graphite fiber, carbon or graphite nanofiber, carbon nanotube, carbon nanorod, mesophase carbon particle, mesocarbon microbead, expanded graphite flake, needle coke, carbon black or acetylene black, activated carbon, or a combination thereof, and said metal filler is 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 and wherein said metal-, carbon-, or graphite-to-graphene ratio is from 1/100 to 1/1.
  • a metal, carbon-, or graphite filler to induce orientation of
  • the step of impregnating metal includes an operation of electrochemical plating, pulse power deposition, solution deposition, electrophoretic deposition, electroless plating, chemical deposition, or a combination thereof.
  • the graphene sheets in the graphene dispersion occupy a weight fraction of 0.1% to 25% (preferably from 3% to 15%) based on the total weight of graphene sheets and liquid medium combined.
  • the graphene dispersion has greater than 3% by weight of graphene or graphene oxide sheets dispersed in the fluid medium to form a liquid crystal phase, which promotes alignment of graphene sheets during the sheet forming procedure.
  • FIG. 1 Schematic drawing illustrating the processes for producing conventional paper, mat, film, and membrane of simply aggregated graphite or NGP flakes/platelets. All processes begin with intercalation and/or oxidation treatment of graphitic materials (e.g. natural graphite particles).
  • graphitic materials e.g. natural graphite particles
  • FIG. 2 A SEM image of a cross-section of a conventional graphene paper (RGO) prepared from discrete graphene sheets/ platelets using a paper-making process (e.g. vacuum-assisted filtration).
  • RGO graphene paper
  • FIG. 3 A possible mechanism of chemical linking between graphene oxide sheets, which
  • FIG. 4 In-plane and through-plane electrical conductivity values of the GO-derived graphene foam sheets (prepared by Comma coating, heat treatment, and compression), with or without 10% Cu.
  • FIG. 5(A) Thermal conductivity values vs. specific gravity of the GO suspension-derived foam produced by the presently disclosed process, mesophase pitch-derived graphite foam, and Ni foam-template assisted CVD graphene foam;
  • FIG. 5(B) Thermal conductivity values of the GO suspension-derived foam, sacrificial plastic bead-templated GO foam, and the hydrothermally reduced GO graphene foam;
  • FIG. 5(C) Electrical conductivity data for the GO suspension-derived foam produced by the presently disclosed process and the hydrothermally reduced GO graphene foam.
  • FIG. 6(A) Thermal conductivity values (vs. specific gravity values up to 1.02 g/cm ) of the GO suspension-derived foam, mesophase pitch-derived graphite foam, and Ni foam-template assisted CVD graphene foam;
  • FIG. 6(B) Thermal conductivity values of the GO suspension-derived foam, sacrificial plastic bead-templated GO foam, and hydrothermally reduced GO graphene foam (vs. specific gravity values up to 1.02 g/cm );
  • FIG. 7 Thermal conductivity values of graphene foam samples derived from GO and GF
  • FIG. 8 Thermal conductivity values of graphene foam samples derived from GO and pristine graphene as a function of the final (maximum) heat treatment temperature.
  • FIG. 9(B) The oxygen content in the GO suspension-derived graphene foam.
  • FIG. 10 In-plane and through-plane electrical conductivity values of RGO foam sheets with or without bonding Cu.
  • FIG. 11 The through-plane electrical conductivity of graphene foam having, its Sn-bonded
  • FIG. 12 Through-plane thermal conductivity values of graphene fluoride paper bonded by Cu and those of nitrogenated graphene paper bonded by Zn.
  • FIG. 13 In-plane thermal conductivity values of graphene fluoride paper bonded by Cu.
  • graphene sheets means a material comprising one or more planar sheets of bonded carbon atoms that are densely packed in a hexagonal crystal lattice in which carbon atoms are bonded together through strong in-plane covalent bonds, and further containing an intact ring structure throughout a majority of the interior. Preferably at least 80% of the interior aromatic bonds are intact. In the c-axis (thickness) direction, these graphene planes may be weakly bonded together through van der Waals forces.
  • Graphene sheets may contain non-carbon atoms at their edges or surface, for example OH and COOH functionalities.
  • the term graphene sheets includes pristine graphene, graphene oxide, reduced graphene oxide, halogenated graphene including graphene fluoride and graphene chloride, nitrogenated graphene,
  • non-carbon elements comprise 0 to 25 weight % of graphene sheets.
  • Graphene oxide may comprise up to 53% oxygen by weight.
  • the term“doped graphene” encompasses graphene having less than 10% of a non-carbon element.
  • This non-carbon element can include hydrogen, oxygen, nitrogen, magnesium, iron, sulfur, fluorine, bromine, iodine, boron, phosphorus, sodium, and combinations thereof.
  • Graphene sheets may comprise single-layer graphene or few-layer graphene, wherein the few-layer graphene is defined as a graphene platelet formed of less than 10 graphene planes.
  • Graphene sheets may also comprise graphene nanoribbons.“Nanographene platelet” (NGP) refers to a graphene sheet having a thickness from less than 0.34 nm (single layer) to 100 nm (multi-layer).
  • NTP Networkene platelet
  • substantially and its variations are defined as being largely but not necessarily wholly what is specified as understood by one of ordinary skill in the art, and in one non-limiting embodiment substantially refers to ranges within 10%, within 5%, within 1%, or within 0.5% of a referenced range.
  • the term “essentially” and its variations are defined as being largely but not necessarily wholly what is specified as understood by one of ordinary skill in the art, and in one non-limiting embodiment substantially refers to ranges within 10%, within 5%, within 1%, or within 0.5% of a referenced range.
  • the present disclosure provides a metal-bonded graphene foam product, preferably in a sheet form or a roll of metal-bonded graphene foam.
  • the disclosed metal-bonded graphene foam product comprises: (a) a sheet or roll of solid graphene foam, having a sheet plane and a sheet thickness direction, composed of multiple pores (cells) and pore walls, wherein the pore walls contain a pristine graphene material having less than 0.01% by weight of non-carbon elements or a non-pristine graphene material having 0.01% to 20% by weight of non-carbon elements, wherein said non-pristine graphene is selected from graphene oxide, reduced graphene oxide, graphene fluoride, graphene chloride, graphene bromide, graphene iodide, hydrogenated graphene, nitrogenated graphene, boron-doped graphene, nitrogen-doped graphene, chemically functionalized graphene, or a combination thereof; and (b) a metal that fills in the
  • the bonding metal is preferably 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.
  • the metal preferably occupies a weight fraction of 0.l%-95% (more preferably from 1% to 50%) based on the total metal-bonded graphene foam product weight.
  • the solid graphene foam may contain a three-dimensional network of interconnected and ordered open cells.
  • the solid graphene foam when measured without the metal, has a density ranging from about 0.001 g/cm to about 1.7 g/cm , more preferably and typically from about 0.01 g/cm to about 1.5 g/cm , and most preferably from about 0.01 g/cm to about 0.8 g/cm .
  • the metal-bonded graphene foam product typically and preferably has a thickness- direction thermal conductivity from 10 to 800 W/mK or a thickness-direction electrical conductivity from 40 S/cm to 3,200 S/cm.
  • the disclosure also includes a process for producing the metal-bonded graphene foam product, the process comprising: (a) preparing a graphene dispersion having multiple graphene sheets dispersed in a liquid medium, wherein the graphene sheets are selected from a pristine graphene or a non-pristine graphene material, having a content of non-carbon elements greater than 2% by weight, selected from graphene oxide, reduced graphene oxide, graphene fluoride, graphene chloride, graphene bromide, graphene iodide, hydrogenated graphene, nitrogenated graphene, chemically functionalized graphene, or a combination thereof and wherein said graphene dispersion contains an optional blowing agent having a blowing agent-to-graphene material weight ratio from 0/1.0 to 1.0/1.0; (b) dispensing and depositing the graphene dispersion onto a surface of a supporting substrate to form a wet layer of graphene; (c) partially or completely removing the liquid medium from
  • the graphite intercalation compound (GIC) or graphite oxide may be obtained by immersing powders or filaments of a starting graphitic material in an
  • the starting graphitic material may be selected from natural graphite, artificial graphite, mesophase carbon, mesophase pitch, mesocarbon microbead, soft carbon, hard carbon, coke, carbon fiber, carbon nanofiber, carbon nanotube, or a combination thereof.
  • the resulting slurry is a heterogeneous suspension and appears dark and opaque.
  • the oxidation of graphite proceeds at a reaction temperature for a sufficient length of time (4-120 hours at room temperature, 20-25°C), the reacting mass can eventually become a suspension that appears slightly green and yellowish, but remain opaque. If the degree of oxidation is sufficiently high (e.g.
  • each oxidized graphene plane (now a graphene oxide sheet or molecule) is surrounded by the molecules of the liquid medium, one obtains a GO gel.
  • a graphite particle (e.g. 100) is typically composed of multiple graphite crystallites or grains.
  • a graphite crystallite is made up of layer planes of hexagonal networks of carbon atoms. These layer planes of hexagonally arranged carbon atoms are substantially flat and are oriented or ordered so as to be substantially parallel and equidistant to one another in a particular crystallite.
  • These layers of hexagonal- structured carbon atoms commonly referred to as graphene layers or basal planes, are weakly bonded together in their thickness direction (crystallographic c-axis direction) by weak van der Waals forces and groups of these graphene layers are arranged in crystallites.
  • the graphite crystallite structure is usually characterized in terms of two axes or directions: the c-axis direction and the a-axis (or h-axis) direction.
  • the c- axis is the direction perpendicular to the basal planes.
  • the a- or h-axes are the directions parallel to the basal planes (perpendicular to the c-axis direction).
  • a highly ordered graphite particle can consist of crystallites of a considerable size, having a length of L a along the crystallographic a-axis direction, a width of L b along the crystallographic h-axis direction, and a thickness L c along the crystallographic c-axis direction.
  • the constituent graphene planes of a crystallite are highly aligned or oriented with respect to each other and, hence, these anisotropic structures give rise to many properties that are highly directional.
  • the thermal and electrical conductivity of a crystallite are of great magnitude along the plane directions ⁇ a- or h-axis directions), but relatively low in the perpendicular direction (c-axis).
  • different crystallites in a graphite particle are typically oriented in different directions and, hence, a particular property of a multi-crystallite graphite particle is the directional average value of all the constituent crystallites.
  • natural graphite can be treated so that the spacing between the graphene layers can be appreciably opened up so as to provide a marked expansion in the c-axis direction, and thus form an expanded graphite structure in which the laminar character of the carbon layers is substantially retained.
  • the process for manufacturing flexible graphite is well-known in the art.
  • flakes of natural graphite e.g. 100 in FIG. 1 are intercalated in an acid solution to produce graphite intercalation compounds (GICs, 102).
  • GICs graphite intercalation compounds
  • the exfoliated graphite flakes are vermiform in appearance and, hence, are commonly referred to as worms 104.
  • These worms of graphite flakes which have been greatly expanded can be formed without the use of a binder into cohesive or integrated sheets of expanded graphite, e.g. webs, papers, strips, tapes, foils, mats or the like (typically referred to as "flexible graphite" 106) having a typical density of about 0.04-2.0 g/cm for most applications.
  • the exfoliated graphite (or mass of graphite worms) is re compressed by using a calendaring or roll-pressing technique to obtain flexible graphite foils (106 in FIG. 1), which are typically 100-300 pm thick.
  • the exfoliated graphite worm may be impregnated with a resin and then compressed and cured to form a flexible graphite composite, which is normally of low strength as well.
  • the exfoliated graphite may be subjected to high-intensity mechanical shearing/separation treatments using a high-intensity air jet mill, high-intensity ball mill, or ultrasonic device to produce separated nano graphene platelets (NGPs) with all the graphene platelets thinner than 100 nm, mostly thinner than 10 nm, and, in many cases, being single-layer graphene (also illustrated as 112 in FIG. 1).
  • NGPs nano graphene platelets
  • An NGP is composed of a graphene sheet or a plurality of graphene sheets with each sheet being a two-dimensional, hexagonal structure of carbon atoms.
  • graphite worms tend to be separated into the so-called expanded graphite flakes (108 in FIG. 1) having a thickness > 100 nm.
  • These flakes can be formed into graphite paper or mat 106 using a paper- or mat- making process.
  • This expanded graphite paper or mat 106 is just a simple aggregate or stack of discrete flakes having defects, interruptions, and mis-orientations between these discrete flakes.
  • the NGP is described as having a length (the largest dimension), a width (the second largest dimension), and a thickness.
  • the thickness is the smallest dimension, which is no greater than 100 nm, preferably smaller than 10 nm and most preferably 0.34 nm - 1.7 nm in the present application.
  • the length and width are referred to as diameter. In the presently defined NGPs, both the length and width can be smaller than 1 pm, but can be larger than 200 pm.
  • FIG. 2 shows a SEM image of a cross-section of a graphene paper prepared from discrete graphene sheets using a paper making process. The image shows the presence of many discrete graphene sheets being folded or interrupted (not integrated), most of platelet orientations being not parallel to the paper surface. The existence of many defects or imperfections leads to poor electrical and thermal conductivity in both the in-plane and the through-plane (thickness-) directions.
  • Fluorinated graphene or graphene fluoride is herein used as an example of the halogenated graphene material group.
  • fluorination of pre- synthesized graphene This approach entails treating graphene prepared by mechanical exfoliation or by CVD growth with fluorinating agent such as XeF 2 , or F-based plasmas;
  • Exfoliation of multilayered graphite fluorides Both mechanical exfoliation and liquid phase exfoliation of graphite fluoride can be readily accomplished [F. Karlicky, et al.“ Halogenated Graphenes: Rapidly Growing Family of Graphene Derivatives” ACS Nano, 2013, 7 (8), pp 6434-6464].
  • the process of liquid phase exfoliation includes ultra-sonic treatment of a graphite fluoride in a liquid medium to produce graphene fluoride sheets dispersed in the liquid medium.
  • the resulting dispersion can be directly made into a sheet of paper or a roll of paper.
  • the nitrogenation of graphene can be conducted by exposing a graphene material, such as graphene oxide, to ammonia at high temperatures (200-400°C). Nitrogenated graphene could also be formed at lower temperatures by a hydrothermal method; e.g. by sealing GO and ammonia in an autoclave and then increased the temperature to l50-250°C. Other methods to synthesize nitrogen doped graphene include nitrogen plasma treatment on graphene, arc- discharge between graphite electrodes in the presence of ammonia, ammonolysis of graphene oxide under CVD conditions, and hydrothermal treatment of graphene oxide and urea at different temperatures.
  • a graphene material such as graphene oxide
  • Nitrogenated graphene could also be formed at lower temperatures by a hydrothermal method; e.g. by sealing GO and ammonia in an autoclave and then increased the temperature to l50-250°C.
  • Other methods to synthesize nitrogen doped graphene include nitrogen plasma treatment on graph
  • NGPs or graphene materials include discrete sheets/platelets of single-layer and multi-layer (typically less than 10 layers, the few-layer graphene) pristine graphene, graphene oxide, reduced graphene oxide (RGO), graphene fluoride, graphene chloride, graphene bromide, graphene iodide, hydrogenated graphene, nitrogenated graphene, chemically functionalized graphene, doped graphene (e.g. doped by B or N).
  • Pristine graphene has essentially 0% oxygen.
  • RGO typically has an oxygen content of 0.00l%-5% by weight.
  • Graphene oxide (including RGO) can have 0.00l%-50% by weight of oxygen.
  • all the graphene materials have 0.00l%-50% by weight of non-carbon elements (e.g. O, H, N, B, F, Cl, Br, I, etc.). These materials are herein referred to as non-pristine graphene materials.
  • non-carbon elements e.g. O, H, N, B, F, Cl, Br, I, etc.
  • non-pristine graphene materials e.g. O, H, N, B, F, Cl, Br, I, etc.
  • the process for producing the disclosed graphene foam comprises the following steps:
  • this blowing agent is normally required if the graphene material is pristine graphene, typically having a blowing agent-to-pristine graphene weight ratio from 0.01/1.0 to 1.0/1.0);
  • a supporting substrate e.g. plastic film, rubber sheet, metal foil, glass sheet, paper sheet, etc.
  • a specific surface area from 50 to 3,000 m 2 /g (more typically from 200 to 2,000 m 2 /g, and most typically from 500 to 1,500 m 2 /g).
  • the pores in the graphene foam are formed slightly before, during, or after sheets of a graphene material are (1) chemically linked/merged together (edge-to-edge and/or face-to-face) typically at a temperature from 100 to l,500°C and/or (2) re-organized into larger graphite crystals or domains (herein referred to as re-graphitization) along the pore walls at a high temperature (typically > 2,l00°C and more typically > 2,500°C). Pores are formed due to the evolution of volatile gases (from a blowing agent and/or non-carbon elements, such as -OH, -F, etc.) during the heat treatment of the dried graphene layer.
  • the presently disclosed solid graphene foam can be prepared such that it exhibits not only a controllable porosity and density, but also excellent elasticity.
  • the solid graphene foam in accordance with the invention surprisingly can exhibit a low compression set value (for example less than 15%) when compressed 80% or more of its original volume, or a compression set less than 10% when compressed 50% or more of its original volume.
  • the ability of the pore walls to snap back upon release of a mechanical stress exerted on this type of graphene foam likely originates from the graphene sheets that are bonded and joint to form larger and stronger graphene planes during heat treatments. A plausible mechanism may be illustrated in FIG. 3.
  • a blowing agent or foaming agent is a substance which is capable of producing a cellular or foamed structure via a foaming process in a variety of materials that undergo hardening or phase transition, such as polymers (plastics and rubbers), glass, and metals. They are typically applied when the material being foamed is in a liquid state. It has not been previously known that a blowing agent can be used to create a foamed material while in a solid state. More
  • Blowing agents or related foaming mechanisms to create pores or cells (bubbles) in a matrix for producing a foamed or cellular material can be classified into the following groups:
  • Physical blowing agents e.g. hydrocarbons (e.g. pentane, isopentane, cyclopentane), chlorofluorocarbons (CFCs), hydrochlorofluorocarbons (HCFCs), and liquid C0 2 .
  • the bubble/foam-producing process is endothermic, i.e. it needs heat (e.g. from a melt process or the chemical exotherm due to cross-linking), to volatize a liquid blowing agent.
  • thermoplastic foams materials (for thermoplastic and elastomeric foams), sodium bicarbonate (e.g. baking soda, used in thermoplastic foams).
  • gaseous products and other by-products are formed by a chemical reaction, promoted by process or a reacting polymer's exothermic heat. Since the blowing reaction involves forming low molecular weight compounds that act as the blowing gas, additional exothermic heat is also released.
  • Powdered titanium hydride is used as a foaming agent in the production of metal foams, as it decomposes to form titanium and hydrogen gas at elevated temperatures.
  • Zirconium (II) hydride is used for the same purpose. Once formed the low molecular weight compounds will never revert to the original blowing agent(s), i.e. the reaction is irreversible.
  • Mechanically injected agents involve methods of introducing bubbles into liquid polymerizable matrices (e.g. an unvulcanized elastomer in the form of a liquid latex). Methods include whisking-in air or other gases or low boiling volatile liquids in low viscosity lattices, or the injection of a gas into an extruder barrel or a die, or into injection molding barrels or nozzles and allowing the shear/mix action of the screw to disperse the gas uniformly to form very fine bubbles or a solution of gas in the melt. When the melt is molded or extruded and the part is at atmospheric pressure, the gas comes out of solution expanding the polymer melt immediately before solidification.
  • liquid polymerizable matrices e.g. an unvulcanized elastomer in the form of a liquid latex.
  • Soluble and leachable agents Soluble fillers, e.g. solid sodium chloride crystals mixed into a liquid urethane system, which is then shaped into a solid polymer part, the sodium chloride is later washed out by immersing the solid molded part in water for some time, to leave small inter-connected holes in relatively high density polymer products.
  • Soluble fillers e.g. solid sodium chloride crystals mixed into a liquid urethane system, which is then shaped into a solid polymer part, the sodium chloride is later washed out by immersing the solid molded part in water for some time, to leave small inter-connected holes in relatively high density polymer products.
  • a bonding metal may be implemented into small gaps in the solid graphene foam to bond the un-connected graphene sheets in the graphitic layer at least in an end-to-end manner.
  • the metal may also fill into pores of the graphene foam to bridge the interruptions of electron and phonon transport pathways.
  • the bonding metal may be 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. Any transition metal can be used, but preferably, the bonding metal is selected from Cu, Al, Ti, Sn, Ag, Au, Fe, or an alloy thereof.
  • the step of impregnating a bonding metal onto graphene sheet surfaces in the pores of the solid graphene foam is preferably conducted chemically, electrochemically or
  • the step of impregnating the porous graphene foam with a metal or metal alloy can include an operation of electrochemical plating, pulse power deposition, solution
  • electrochemical deposition one may impose a DC current by connecting the porous graphitic film to one terminal (e.g. negative electrode) and a piece of the desired metal (e.g. Cu, Zn, or Ni) to the opposite terminal (e.g. positive electrode) in an electrochemical chamber (e.g. just a simple bath containing an electrolyte).
  • one terminal e.g. negative electrode
  • a piece of the desired metal e.g. Cu, Zn, or Ni
  • the plating solution may contain a chemical plating solution, an electrochemical plating solution, or an electrophoretic solution.
  • the plating solution contains a chemical plating solution comprising a metal salt dissolved in water or an organic solvent (e.g. CuS0 4 or N1NO3 dissolved in water for Cu plating or Ni plating).
  • a metal salt dissolved in water or an organic solvent (e.g. CuS0 4 or N1NO3 dissolved in water for Cu plating or Ni plating).
  • Example 1 Various blowing agents and pore-forming (bubble-producing) processes
  • any chemical blowing agent e.g. in a powder or pellet form
  • the chemical blowing agent may be dispersed in the liquid medium to become a second dispersed phase (sheets of graphene material being the first dispersed phase) in the suspension, which can be deposited onto the solid supporting substrate to form a wet layer.
  • This wet layer of graphene material may then be dried and heat treated to activate the chemical blowing agent.
  • Chemical foaming agents can be organic or inorganic compounds that release gasses upon thermal decomposition.
  • CFAs are typically used to obtain medium- to high-density foams, and are often used in conjunction with physical blowing agents to obtain low-density foams.
  • CFAs can be categorized as either endothermic or exothermic, which refers to the type of decomposition they undergo. Endothermic types absorb energy and typically release carbon dioxide and moisture upon decomposition, while the exothermic types release energy and usually generate nitrogen when decomposed. The overall gas yield and pressure of gas released by exothermic foaming agents is often higher than that of endothermic types.
  • Endothermic CFAs are generally known to decompose in the range from 130 to 230°C (266-446°F), while some of the more common exothermic foaming agents decompose around 200°C (392°F). However, the decomposition range of most exothermic CFAs can be reduced by addition of certain
  • CFAs The activation (decomposition) temperatures of CFAs fall into the range of our heat treatment temperatures.
  • suitable chemical blowing agents include sodium bi carbonate (baking soda), hydrazine, hydrazide, azodicarbonamide (exothermic chemical blowing agents), nitroso compounds (e.g. N, N-dinitroso pentamethylene tetramine), hydrazine derivatives (e.g. 4. 4’-Oxybis (benzenesulfonyl hydrazide) and hydrazo dicarbonamide), and hydrogen carbonate (e.g. sodium hydrogen carbonate).
  • baking soda hydrazine
  • hydrazide azodicarbonamide
  • nitroso compounds e.g. N, N-dinitroso pentamethylene tetramine
  • hydrazine derivatives e.g. 4. 4’-Oxybis (benzenesulfonyl hydrazide) and hydrazo dicarbonamide
  • blowing agents include carbon dioxide (C0 2 ), nitrogen (N 2 ), isobutane (C4H10), cyclopentane (C5H10), isopentane (C S H I2 ), CFC-l l (CFCI3), HCFC-22 (CHF 2 CI), HCFC-l42b (CF 2 CICH 3 ), and HCFC-l34a (CH 2 FCF 3 ).
  • C0 2 carbon dioxide
  • N 2 isobutane
  • C4H10 cyclopentane
  • C5H10 isopentane
  • C S H I2 CFC-l l
  • CFC-22 CHF 2 CI
  • HCFC-l42b HCFC-l42b
  • HCFC-l34a CH 2 FCF 3
  • chlorofluorocarbons are also not environmentally safe and therefore already forbidden in many countries.
  • the alternatives are hydrocarbons, such as isobutane and pentane, and the gases such as C0 2 and nitrogen.
  • blowing agent amount introduced into the suspension is defined as a blowing agent-to-graphene material weight ratio, which is typically from 0/1.0 to 1.0/1.0.
  • the compression set measurement was conducted according to ASTM D395.
  • the measured value of“compression set” is expressed as the percentage of the original deflection (i.e. a constant deflection test).
  • a test specimen of the solid graphene foam was compressed at a nominated % for one minute at 25°C. Compression set was taken as the % of the original deflection after the specimen was allowed to recover at standard conditions for 30 minutes.
  • the compression set value C can be calculated using the formula [(to-ti)/(to-t n )]xlOO, where to is the original specimen thickness, h the specimen thickness after testing, and t n is the spacer thickness which sets the % compression that the foam is to be subjected.
  • the specimens tested all had the same dimensions: diameter of about 12 mm and height of about 8 mm.
  • the solid graphene foam typically has a compression set (at 15% compression) of 15% or less and, in many cases, 8% or less. Many specimens have a compression set (at 50% compression) of 10% or less and, in many cases, 5% or less.
  • Example 2 Preparation of discrete nanographene platelets (NGPs) which are GO sheets
  • Chopped graphite fibers with an average diameter of 12 pm and natural graphite particles were separately used as a starting material, which was immersed in a mixture of concentrated sulfuric acid, nitric acid, and potassium permanganate (as the chemical intercalate and oxidizer) to prepare graphite intercalation compounds (GICs).
  • the starting material was first dried in a vacuum oven for 24 h at 80°C. Then, a mixture of concentrated sulfuric acid, fuming nitric acid, and potassium permanganate (at a weight ratio of 4: 1:0.05) was slowly added, under appropriate cooling and stirring, to a three-neck flask containing fiber segments.
  • the acid-treated graphite fibers or natural graphite particles were filtered and washed thoroughly with deionized water until the pH level of the solution reached 6. After being dried at l00°C overnight, the resulting graphite intercalation compound (GIC) or graphite oxide fiber was re-dispersed in water and/or alcohol to form a slurry.
  • GIC graphite intercalation compound
  • the resulting suspension was then cast onto a glass surface using a doctor’s blade to exert shear stresses, inducing GO sheet orientations.
  • the resulting GO coating films after removal of liquid, have a thickness that can be varied from approximately 5 to 500 pm (preferably and typically from 10 pm to 50 pm).
  • the GO coating film was then subjected to heat treatments that typically involve an initial thermal reduction temperature of 80-350°C for 1-8 hours, followed by heat-treating at a second temperature of 1, 500-2, 850°C for 0.5 to 5 hours. It may be noted that we have found it essential to apply a compressive stress to the coating film sample while being subjected to the first heat treatment. This compress stress seems to have helped maintain good contacts between the graphene sheets so that chemical merging and linking between graphene sheets can occur while pores are being formed. Without such a compressive stress, the heat-treated film is typically excessively porous with constituent graphene sheets in the pore walls being very poorly oriented and incapable of chemical merging and linking with one another. As a result, the thermal conductivity, electrical conductivity, and mechanical strength of the graphene foam are severely compromised.
  • FIG. 4 Shown in FIG. 4 are the in-plane and through-plane electrical conductivity values of the GO-derived graphene foam sheets (prepared by Comma coating, heat treatment, and compression), with or without 10% Cu. It is clear that the addition of 10% Cu has significantly increased both the in-plane and through-plane (thickness-direction) electrical conductivity.
  • Example 3 Preparation of single-layer graphene sheets from mesocarbon microbeads (MCMBs)
  • MCMBs Mesocarbon microbeads
  • MCMB 10 grams were intercalated with an acid solution (sulfuric acid, nitric acid, and potassium permanganate at a ratio of 4:1:0.05) for 48-96 hours. Upon completion of the reaction, the mixture was poured into deionized water and filtered. The intercalated MCMBs were repeatedly washed in a 5% solution of HC1 to remove most of the sulfate ions. The sample was then washed repeatedly with deionized water until the pH of the filtrate was no less than 4.5.
  • the slurry was then subjected ultrasonication for 10-100 minutes to produce GO suspensions.
  • TEM and atomic force microscopic studies indicate that most of the GO sheets were single-layer graphene when the oxidation treatment exceeded 72 hours, and 2- or 3-layer graphene when the oxidation time was from 48 to 72 hours.
  • the GO sheets contain oxygen proportion of approximately 35%-47% by weight for oxidation treatment times of 48-96 hours.
  • GO sheets were suspended in water. Baking soda (5- 20% by weight), as a chemical blowing agent, was added to the suspension just prior to casting. The suspension was then cast onto a glass surface using a doctor’s blade to exert shear stresses, inducing GO sheet orientations. Several samples were cast, some containing a blowing agent and some not. The resulting GO films, after removal of liquid, have a thickness that can be varied from approximately 10 to 500 pm.
  • This first heat treatment generated a graphene foam.
  • the graphene domains in the foam wall can be further perfected (re-graphitized to become more ordered or having a higher degree of crystallinity and larger lateral dimensions of graphene planes, longer than the original graphene sheet dimensions due to chemical merging) if the foam is followed by heat- treating at a second temperature of 1, 500-2, 850°C.
  • the graphene films were then subjected to heat treatments that involve an initial (first) thermal reduction temperature of 80-l,500°C for 1-5 hours. This first heat treatment led to the production of a graphene foam.
  • Some of the pristine foam samples were then subjected to a second temperature of 1, 500-2, 850°C to determine if the graphene domains in the foam wall could be further perfected (re-graphitized to become more ordered or having a higher degree of crystallinity).
  • the solid graphene foam without metal impregnation, typically has a compression set (at 15% compression) of 15% or less and, in many cases, 8% or less. Many specimens have a compression set (at 50% compression) of 10% or less and, in many cases, 5% or less.
  • Comparative Example 4-a CVD graphene foams on Ni foam templates
  • interconnected 3D scaffold of nickel was chosen as a template for the growth of graphene foam. Briefly, carbon was introduced into a nickel foam by decomposing CH 4 at l,000°C under ambient pressure, and graphene films were then deposited on the surface of the nickel foam. Due to the difference in the thermal expansion coefficients between nickel and graphene, ripples and wrinkles were formed on the graphene films. In order to recover (separate) graphene foam, Ni frame must be etched away.
  • PMMA poly(methyl methacrylate)
  • Comparative Example 4-b Conventional graphitic foam from pitch-based carbon foams
  • Pitch powder, granules, or pellets are placed in a aluminum mold with the desired final shape of the foam.
  • Mitsubishi ARA-24 mesophase pitch was utilized.
  • the sample is evacuated to less than 1 torr and then heated to a temperature approximately 300°C. At this point, the vacuum was released to a nitrogen blanket and then a pressure of up to 1,000 psi was applied.
  • the temperature of the system was then raised to 800°C. This was performed at a rate of 2 degree C/min. The temperature was held for at least 15 minutes to achieve a soak and then the furnace power was turned off and cooled to room temperature at a rate of approximately 1.5 degree C/min with release of pressure at a rate of approximately 2 psi/min.
  • Final foam temperatures were 630°C and 800°C.
  • the compression strength of the conventional graphitic foam samples having an average density of 0.51 g/cm was measured to be 3.6 MPa and the compression modulus was measured to be 74 MPa.
  • the compression strength and compressive modulus of the presently disclosed graphene foam samples derived from GO having a comparable physical density are 5.7 MPa and 103 MPa, respectively.
  • FIG. 5(A) and FIG. 6(A) Shown in FIG. 5(A) and FIG. 6(A) are the thermal conductivity values vs. specific gravity of the GO suspension-derived foam (Example 3), mesophase pitch-derived graphite foam (Comparative Example 4-b), and Ni foam template-assisted CVD graphene foam (Comparative Example 4-a). These data clearly demonstrate the following unexpected results:
  • CVD graphene is essentially pristine graphene that has never been exposed to oxidation and should have exhibited a much higher thermal conductivity compared to graphene oxide (GO).
  • GO is known to be highly defective (having a high defect population and, hence, low conductivity) even after the oxygen-containing functional groups are removed via conventional thermal or chemical reduction methods.
  • thermal conductivity values observed with the GO-derived graphene foams herein produced are much to our surprise.
  • a good thermal dissipation capability is essential to the prevention of thermal run-away and explosion, a most serious problem associated with rechargeable lithium-ion batteries.
  • FIG. 6(A) presents the thermal conductivity values over comparable ranges of specific gravity values to allow for calculation of specific conductivity (conductivity value
  • the specific conductivity values of the presently disclosed GO- and GF-derived foam exhibit values from 250 to 500 W/mK per unit of specific gravity; but those of the other two foam materials are typically lower than 250 W/mK per unit of specific gravity.
  • thermal conductivity data for a series of GO-derived graphene foams and a series of pristine graphene derived foams both plotted over the final (maximum) heat treatment temperatures.
  • These data indicate that the thermal conductivity of the GO foams is highly sensitive to the final heat treatment temperature (HTT). Even when the HTT is very low, clearly some type of graphene merging or crystal perfection reactions are already activated.
  • the thermal conductivity increases monotonically with the final HTT.
  • the thermal conductivity of pristine graphene foams remains relatively constant until a final HTT of approximately 2,500°C is reached, signaling the beginning of a re-crystallization and perfection of graphite crystals.
  • Graphite oxide was prepared by oxidation of graphite flakes with an oxidizer liquid consisting of sulfuric acid, sodium nitrate, and potassium permanganate at a ratio of 4:1:0.05 at 30°C.
  • an oxidizer liquid consisting of sulfuric acid, sodium nitrate, and potassium permanganate at a ratio of 4:1:0.05 at 30°C.
  • the reacting mass was rinsed with water 3 times to adjust the pH value to at least 3.0.
  • a final amount of water was then added to prepare a series of GO-water suspensions. We observed that GO sheets form a liquid crystal phase when GO sheets occupy a weight fraction > 3% and typically from 5% to 15%.
  • Comparative Example 5-a Graphene foams from hydrothermally reduced graphene oxide
  • a self-assembled graphene hydrogel (SGH) sample was prepared by a one-step hydrothermal method.
  • the SGH can be easily prepared by heating 2 mg/mL of homogeneous graphene oxide (GO) aqueous dispersion sealed in a Teflon- lined autoclave at l80°C for 12 h.
  • the SGH containing about 2.6% (by weight) graphene sheets and 97.4% water has an electrical conductivity of approximately 5 x 10 S/cm.
  • the resulting graphene foam Upon drying and heat treating at l,500°C, the resulting graphene foam exhibits an electrical conductivity of approximately 1.5 x 10 1 S/cm, which is 2 times lower than those of the presently disclosed graphene foams produced by heat treating at the same temperature.
  • a hard template-directed ordered assembly for a macro-porous bubbled graphene film was prepared.
  • Mono-disperse poly methyl methacrylate (PMMA) latex spheres were used as the hard templates.
  • the GO liquid crystal prepared in Example 5 was mixed with a PMMA spheres suspension.
  • Subsequent vacuum filtration was then conducted to prepare the assembly of PMMA spheres and GO sheets, with GO sheets wrapped around the PMMA beads.
  • a composite film was peeled off from the filter, air dried and calcinated at 800°C to remove the PMMA template and thermally reduce GO into RGO simultaneously.
  • the grey free-standing PMMA/GO film turned black after calcination, while the graphene film remained porous.
  • FIG. 5(B) and FIG. 6(B) show the thermal conductivity values of the presently disclosed GO suspension-derived foam, GO foam produced via sacrificial plastic bead template-assisted process, and hydrothermally reduced GO graphene foam.
  • the presently disclosed process produces the highest-performing graphene foams. Electrical conductivity data summarized in FIG. 4(C) are also consistent with this conclusion.
  • HEG highly exfoliated graphite
  • FHEG fluorinated highly exfoliated graphite
  • Pre-cooled Teflon reactor was filled with 20-30 mL of liquid pre-cooled ClF 3 , the reactor was closed and cooled to liquid nitrogen temperature. Then, no more than 1 g of HEG was put in a container with holes for ClF 3 gas to access and situated inside the reactor. In 7-10 days a gray-beige product with approximate formula C 2 F was formed.
  • FHEG FHEG
  • an organic solvent methanol, ethanol, 1 -propanol, 2-propanol, 1 -butanol, / ⁇ ? /7 -butanol, isoamyl alcohol
  • an ultrasound treatment 280 W
  • Five minutes of sonication was enough to obtain a relatively homogenous dispersion, but longer sonication times ensured better stability.
  • the dispersion Upon casting on a glass surface with the solvent removed, the dispersion became a brownish film formed on the glass surface.
  • FIG. 6 presents a comparison in thermal conductivity values of the graphene foam samples derived from GO and GF (graphene fluoride), respectively, as a function of the specific gravity. It appears that the GF foams, in comparison with GO foams, exhibit higher thermal conductivity values at comparable specific gravity values. Both deliver impressive heat- conducting capabilities, being the best among all known foamed materials.
  • Graphene oxide (GO), synthesized in Example 2 was finely ground with different proportions of urea and the pelletized mixture heated in a microwave reactor (900 W) for 30 s. The product was washed several times with deionized water and vacuum dried. In this method graphene oxide gets simultaneously reduced and doped with nitrogen.
  • the products obtained with graphene : urea mass ratios of 1 : 0.5, 1 : 1 and 1 : 2 are designated as NGO-l, NGO-2 and NGO-3 respectively and the nitrogen contents of these samples were 14.7, 18.2 and 17.5 wt% respectively as found by elemental analysis. These nitrogenated graphene sheets remain dispersible in water.
  • the resulting suspensions were then cast, dried, and heat-treated initially at 200-350°C as a first heat treatment temperature and subsequently treated at a second temperature of l,500°C.
  • the resulting nitrogenated graphene foams exhibit physical densities from 0.45 to 1.28 g/cm 3 .
  • Example 8 Chemical functionalization of pristine graphene foam and nitrogenated graphene foam
  • Specimens of pristine graphene foam and nitrogenated graphene foam prepared earlier were subjected to functionalization by bringing these specimens in chemical contact with chemical compounds such as carboxylic acids, azide compound (2-azidoethanol), alkyl silane, diethylenetriamine (DETA), and chemical species containing hydroxyl group, carboxyl group, amine group, and sulfonate group (— S0 3 H) in a liquid or solution form.
  • chemical compounds such as carboxylic acids, azide compound (2-azidoethanol), alkyl silane, diethylenetriamine (DETA), and chemical species containing hydroxyl group, carboxyl group, amine group, and sulfonate group (— S0 3 H) in a liquid or solution form.
  • the functionalized graphene foam were subjected to chemical nickel plating or chemical copper plating.
  • the functionalized graphene foam specimens were treated for 15 minutes in a chemical plating solution containing 1.2 M
  • the functionalized graphene foam specimens were dipped in an ammonia solution with 0.5 M CuS0 4.5 3 ⁇ 4() having a pH value of 9.5 and a temperature of 20°C for 30 seconds. These chemical functionalization treatments generally result in faster and more uniform and complete plating of metal in cell walls of the solid graphene foam.
  • the internal structures (crystal structure and orientation) of several dried GO layers, and the heat-treated films at different stages of heat treatments were investigated using X-ray diffraction.
  • the dried GO compact exhibits the formation of a hump centered at 22°, indicating that it has begun the process of decreasing the inter-graphene spacing due to the beginning of chemical linking and ordering processes.
  • the doo2 spacing has decreased to approximately 0.336, close to 0.3354 nm of a graphite single crystal.
  • the doo2 spacing is decreased to approximately to 0.3354 nm, identical to that of a graphite single crystal.
  • the (004) peak intensity relative to the (002) intensity on the same diffraction curve, or the /(004)//(002) ratio, is a good indication of the degree of crystal perfection and preferred orientation of graphene planes.
  • the (004) peak is either non-existing or relatively weak, with the 7(004 )//(002) ratio ⁇ 0.1, for all graphitic materials heat treated at a temperature lower than 2,800°C.
  • the 7(004 )//(002) ratio for the graphitic materials heat treated at 3,000-3,250°C is in the range from 0.2-0.5.
  • a graphene foam prepared with a final HTT of 2,750°C for one hour exhibits a 7(004)/7(002) ratio of 0.75 and a Mosaic spread value of 1.8, indicating a practically perfect graphene single crystal with a good degree of preferred orientation in the cell walls.
  • The“mosaic spread” value is obtained from the full width at half maximum of the (002) reflection in an X-ray diffraction intensity curve.
  • This index for the degree of ordering characterizes the graphite or graphene crystal size (or grain size), amounts of grain boundaries and other defects, and the degree of preferred grain orientation.
  • a nearly perfect single crystal of graphite is characterized by having a mosaic spread value of 0.2-0.4.
  • Some of our graphene foams have a mosaic spread value in this range of 0.2-0.4 when produced using a final heat treatment temperature no less than 2,500°C.
  • FIG. 9(A) The inter-graphene spacing values of both the GO suspension-derived foam samples obtained by heat treating at various temperatures over a wide temperature range are summarized in FIG. 9(A). Corresponding oxygen content values in the GO suspension-derived graphene foam layer are shown in FIG. 9(B).
  • purified zinc sulfate (ZnS0 4 ) is a precursor to Zn; zinc sulfate was impregnated into the pores of several solid foam products via solution impregnation and then converted into Zn via electrolysis.
  • zinc sulfate solution was used as electrolyte in a tank containing a lead anode and graphene foam cathode. Current was passed between the anode and cathode and metallic zinc was plated onto the cathodes (onto graphene surfaces of pore walls) by a reduction reaction.
  • Pure metallic Cu was synthesized (inside pores of graphene foam) by the reduction of cupric chloride with hydrazine in the aqueous CTAB solution.
  • the use of ammonia solution for the adjustment of solution pH up to 10 and the use of hydrazine as a reducing agent in a capped reaction chamber are crucial for the synthesis of pure Cu.
  • the reaction solution finally became wine-reddish and its UV/vis absorption spectrum exhibited an absorption band at 574 nm, revealing the formation of metallic Cu.
  • the precursor Cu complexes were carried out using a standard Schlenk technique under the Ar atmosphere.
  • precursor infiltration and chemical conversion could be used to obtain metal impregnation.
  • hydrogenolysis of nickelocene can occur through a self-catalyzed process at low temperature ( ⁇ 70°C) in
  • Nickelocene NiCp 2
  • H 2 was used as the reducing agent.
  • Coleman-grade C0 2 and high-purity H 2 were used without further purification. The experiment was carried out in a high-pressure reactor (autoclave).
  • the vessel was then further charged with fresh C0 2 using the high-pressure syringe pump to a pressure of 34.5 MPa.
  • This H 2 /SCC0 2 solution was kept stable at this condition for more than 2 h before being injected into the high-pressure reactor.
  • the pressure in the vessel dropped from 34.5 to 13 MPa, allowing the amount of H 2 fed into the reactor to be quantified.
  • the H 2 injection process was repeated to obtain a 50-100 molar excess of hydrogen relative to nickelocene in the reactor system.
  • the scC0 2 solution containing NiCp 2 maintained a green color and the reaction system was left undisturbed at 70°C, 17 MPa for 7-8 hours. After 7-8 h substantial Ni film deposition in the pores of graphene foam was obtained.
  • Example 11 Electric and Thermal Conductivities of Metal-Bonded Graphene Foam Products
  • FIG. 4 shows the in-plane and through-plane electrical conductivity values of the GO- derived graphene foam sheets with or without infiltrated 10% Cu, plotted as a function of the final heat treatment temperature (prepared by comma coating, heat treatment, and compression).
  • FIG. 11 shows the electrical conductivity values of the GO-derived graphene foam, similarly made graphene foam having graphene sheets bonded by 3% Sn (experimental values), and values based on rule-of-mixture law prediction, all plotted as a function of the final heat treatment temperature.
  • the experimental values are all significantly higher than the values based on the rule-of-mixture law prediction.
  • FIG. 12 Shown in FIG. 12 are through-plane thermal conductivity values of graphene fluoride foam bonded by Cu and those of nitrogenated graphene foam bonded by Zn. With some bonding metal (e.g. Cu), a thickness -direction thermal conductivity as high as 283 W/mK was readily achieved.
  • FIG. 13 shows that the in-plane thermal conductivity values of graphene fluoride foam bonded by Cu remain relatively high even though a high through-plane thermal conductivity has been achieved.

Abstract

La présente invention concerne un produit en mousse de graphène à liaison métallique (et son procédé de production). Ledit produit contient : (A) une feuille ou un rouleau de mousse de graphène solide présentant un plan de feuille et un sens de l'épaisseur de la feuille et composée de multiples pores (cellules) et parois de pores, lesdites parois de pores contenant un matériau de graphène vierge contenant moins de 0,01 % en poids d'éléments non carbonés ou un matériau de graphène non vierge contenant de 0,01 % à 20 % en poids d'éléments non carbonés et ledit graphène non vierge étant sélectionné parmi l'oxyde de graphène, l'oxyde de graphène réduit, le fluorure de graphène, le chlorure de graphène, le bromure de graphène, l'iodure de graphène, le graphène hydrogéné, le graphène azoté, le graphène dopé au bore, le graphène dopé à l'azote, le graphène chimiquement fonctionnalisé ou une combinaison de ceux-ci; et (B) un métal qui remplit les feuilles de graphène et y est lié. Le produit en mousse de graphène à liaison métallique a une conductivité thermique dans le sens de l'épaisseur de 10 W/mK à 800 W/mK ou une conductivité électrique dans le sens de l'épaisseur de 40 S/cm à 3200 S/cm.
PCT/US2019/025514 2018-04-03 2019-04-03 Mousse de graphène métallisée à forte conductivité à travers les plans WO2019195374A1 (fr)

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CN112993269A (zh) * 2019-12-18 2021-06-18 大连大学 一种非酶燃料电池阳极及其制备方法和应用
CN111117043A (zh) * 2020-03-04 2020-05-08 福州大学 一种热处理增强石墨烯微片/高密度聚乙烯复合材料及其制备方法
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