Preparation and application of graphene-copper composite powder

Abstract

Systems, methods, and apparatus for forming and implementing graphene-copper composite powders are disclosed. The graphene-copper composite powder may be prepared by providing an inert environment, introducing the first mist into the inert environment, introducing the second mist into the inert environment, and mixing the first mist and the second mist in the inert environment. The first mist is negatively charged atomized copper, and the second mist comprises positively charged graphene flakes. The graphene-copper composite powder may be used to form parts via additive manufacturing or traditional powder metallurgy processes.

Description

Technical Field

[0001] The present disclosure relates to the field of composite powders, and more particularly, to systems and methods for producing and implementing composite graphene-copper powders for additive manufacturing or traditional powder metallurgy processes. Background Art

[0002] Graphene-copper composites can be used as conductors in various applications (e.g., in battery electric vehicles). Graphene-copper powders formed by mechanical mixing (e.g., ball milling) may damage the graphene and cause copper oxidation. This can reduce the desired properties of graphene and its coupling effect with copper. Therefore, there is a need in the art to mix graphene-copper powders to avoid possible damage to the powders. Summary of the invention

[0003] It is desirable to mix copper particles and graphene flakes without irreversibly altering the graphene flakes. It is also desirable to inhibit oxidation of the copper particles during formation of the composite powder and use of the composite powder to form a composite component. It is further desirable to optimize the contact between the copper particles and the planes of the graphene flakes.

[0004] The systems, methods and devices according to the present disclosure optimize the formation of graphene-copper composite powders by mixing a first mist including copper particles and a second mist including pristine graphene flakes in an inert environment. The first mist and the second mist have opposite charges so that when mixed, the copper particles in the first mist are attracted to the plane of the graphene flakes in the second mist. Advantageously, this contact optimizes the electrical properties of the graphene-copper composite powders. In addition, because the charges imparted and the process avoid irreversibly damaging the graphene flakes, the material and electrical properties of the graphene-copper composite powders and the behavior of the materials are more predictable, with narrower tolerances and variations.

[0005] The graphene-copper composite powder can be classified into multiple fractions with known particle size distribution, where the area fraction or volume fraction of graphene flakes and copper particles is known. Each fraction can then be used for further processes, such as additive manufacturing processes. Advantageously, the optimized contact between the planes of the graphene flakes and the copper particles reduces the gaps formed by the copper particles that only contact the edges of the graphene flakes, which optimizes the material and electrical properties of the resulting graphene-copper composite parts.

[0006] According to various aspects of the present disclosure, a method includes providing an inert environment, introducing a first mist into the inert environment, introducing a second mist into the inert environment, and mixing the first mist and the second mist in the inert environment to prepare a graphene-copper composite powder. The first mist is negatively charged atomized copper, and the second mist includes positively charged graphene flakes.

[0007] According to other aspects of the present disclosure, the method further includes separating the graphene-copper composite powder into a plurality of fractions in an inert environment using at least one mesh screen.

[0008] According to other aspects of the present disclosure, the method further includes sending a first fraction of the plurality of fractions into an additive manufacturing device connected to an inert environment.

[0009] According to other aspects of the present disclosure, the first mist is formed from a copper melt fed into an inert environment through a high pressure nozzle.

[0010] According to other aspects of the present disclosure, the process pressure of the inert environment includes a vacuum.

[0011] According to other aspects of the present disclosure, the copper particles of the graphene-copper composite powder are composed of copper nanoparticles.

[0012] According to other aspects of the present disclosure, graphene flakes are formed via electrochemical exfoliation.

[0013] According to other aspects of the present disclosure, the method further includes forming a graphene-copper composite busbar from the composite powder via additive manufacturing or conventional powder metallurgy processes.

[0014] According to other aspects of the present disclosure, the method further includes forming a graphene-copper composite heat sink from the composite powder via additive manufacturing or conventional powder metallurgy processes.

[0015] According to aspects of the present disclosure, a system includes a chamber containing an inert environment, a first nozzle configured to introduce a first mist into a mixing portion of the inert environment, a second nozzle configured to introduce a second mist into the mixing portion of the inert environment, and an output portion configured to deliver a graphene-copper composite powder from the inert environment. The graphene-copper composite powder is formed by mixing a first mist of negatively charged atomized copper and a second mist of positively charged graphene flakes. The first mist is negatively charged atomized copper, and the second mist includes positively charged graphene flakes.

[0016] According to other aspects of the present disclosure, the system further includes at least one mesh screen configured to separate the graphene-copper composite powder into a plurality of fractions in an inert environment.

[0017] According to other aspects of the present disclosure, the first nozzle is a high pressure nozzle.

[0018] According to other aspects of the present disclosure, the copper particles of the graphene-copper composite powder are composed of copper nanoparticles.

[0019] According to other aspects of the present disclosure, the system further includes a forming device configured to form a graphene-copper composite heat sink from a graphene-copper composite powder via additive manufacturing or a conventional powder metallurgy process.

[0020] According to other aspects of the present disclosure, the system further includes a forming device configured to form a graphene-copper composite busbar from a graphene-copper composite powder via additive manufacturing or a conventional powder metallurgy process.

[0021] According to various aspects of the present disclosure, a graphene-copper composite powder is formed by providing an inert environment, introducing a first mist into the inert environment, introducing a second mist into the inert environment, and mixing the first mist and the second mist in the inert environment, thereby preparing the graphene-copper composite powder. The first mist is negatively charged atomized copper, and the second mist includes positively charged graphene flakes.

[0022] According to other aspects of the present disclosure, the graphene-copper composite powder is a fraction among a plurality of fractions separated using at least one mesh screen in an inert environment.

[0023] According to other aspects of the present disclosure, the first mist is formed from a copper melt fed into an inert environment through a high pressure nozzle.

[0024] According to other aspects of the present disclosure, the copper particles of the graphene-copper composite powder are composed of copper nanoparticles.

[0025] According to other aspects of the present disclosure, graphene flakes are formed via electrochemical exfoliation.

[0026] The above features and advantages and other features and advantages of the present disclosure are readily apparent from the following detailed description of the best modes for carrying out the disclosure when taken in connection with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The drawings are illustrative and are not intended to limit the subject matter defined by the claims. Exemplary aspects are discussed in the following detailed description and are shown in the accompanying drawings, in which:

[0028] Figure 1 An exemplary system for preparing graphene-copper composite powder is shown;

[0029] Figure 2 An exemplary graphene-copper composite powder is shown;

[0030] Figure 3 A method for preparing graphene-copper composite powder is shown;

[0031] Figure 4 An exemplary additive manufacturing apparatus is shown;

[0032] Figure 5 A schematic process for preparing a graphene-copper composite component from a graphene-copper composite powder is shown;

[0033] Fig. 6A shows a schematic first view of a graphene-copper composite heat sink;

[0034] Figure 6B Shows Fig. 6A A schematic second view of a composite heat sink;

[0035] Figure 7 A battery cell using a graphene-copper composite current collector is shown; and

[0036] Figure 8 A graphene-copper composite busbar is shown for use with an electric motor. DETAILED DESCRIPTION

[0037] Figure 1 An exemplary system for preparing a graphene-copper composite powder 101 is shown. The system includes a chamber 102, a copper raw material 104, a graphene raw material (not shown), a mixing portion 105, a separation portion 106, and a graphene-copper composite powder output portion 108. The chamber 102 includes an inert environment that can be adjusted using a vacuum source 110, an inert gas inlet 112 and an inert gas outlet 114, and a temperature adjustment device (not shown).

[0038] The vacuum source 110 is configured to evacuate air from the inert environment during startup.The vacuum source 110 or another vacuum source may also be configured to maintain the inert environment at a desired process pressure alone or in combination with other devices.

[0039] An inert gas flows through the system 100 to inhibit oxidation of the powder and its particles. The inert gas enters the chamber 102 via the inert gas inlet 112 and leaves the chamber 102 via the inert gas outlet 114. The flow of the inert gas can also be configured to affect or produce a desired gas flow pattern within the system. For example, the inert gas inlet 112 can be located below the separation portion 106, and the inert gas outlet 114 can be located above the separation portion 106, so that the flow of the inert gas promotes agitation of the graphene-copper composite powder 101 to help separate the graphene-copper composite powder 101 by size (e.g., by promoting fluidization of the graphene-copper composite powder 101).

[0040] The temperature regulating device is configured to heat and / or cool the inert environment to a desired temperature profile. The temperature profile can be a uniform temperature, multiple zones with different temperatures, a temperature gradient, a combination thereof, etc. In some aspects, the temperature profile is generated by controlling the temperature of the feedstock, the spacing of the components, and the insulation or thermal conductivity of the system chamber 102.

[0041] Copper and graphene are fed into the mixing portion 105 of the system through respective nozzles 116. Copper and graphene are oppositely charged. Advantageously, while not being bound by theory, it is believed that providing the feed as oppositely charged particles enhances contact between the copper particles and the graphene flakes and the stacking of the resulting graphene-copper composite powder 101. In some aspects, the nozzle 116 may include one or more high pressure nozzles. Additionally or alternatively, the nozzle 116 may include one or more electric nozzles.

[0042] In addition, the amount of charge imparted to the particles is selected to reduce voids in the resulting powder and parts formed therefrom. For example, only a portion of the copper particles may be charged so that the charged particles are attracted to the graphene flakes, while the uncharged particles reduce repulsive forces that may leave voids in the resulting powder or additive manufacturing process. Additionally or alternatively, any residual charge may be removed by grounding after mixing (e.g., by grounding the mesh screen 124).

[0043] The first nozzle 116A is connected to a copper raw material 104, such as a deoxidized copper melt 118. The first nozzle 116A is configured to produce a negatively charged atomized copper mist 120 having a desired particle size distribution. For example, the copper particles in the atomized copper mist 120 can be nanoparticles. In some aspects, the diameter of the copper particles is approximately the lateral sheet size of the graphene particles. Although not bound by theory, it is believed that this provides an enhanced copper-copper interface. In alternative aspects, the diameter of the copper particles is one order of magnitude smaller than the lateral sheet size of the graphene particles. Although not bound by theory, it is believed that this provides enhanced copper-copper and graphene-copper interfaces. In other aspects, the diameter of the copper particles is two orders of magnitude smaller than the lateral sheet size of the graphene particles. Although not bound by theory, it is believed that this provides an enhanced graphene-copper interface.

[0044] The second nozzle 116B is connected to the graphene raw material. The second nozzle 116B is configured to produce a positively charged graphene mist 122. The graphene raw material includes raw graphene flakes in a solvent. The size of the graphene flakes is designed to provide the desired mechanical properties, electrical conductivity and / or thermal conductivity of the resulting graphene-copper composite component. The graphene flakes can be single-layer graphene flakes and / or few-layer graphene flakes. In some aspects, the graphene flakes are formed via an electrochemical exfoliation technique. In some examples, the average lateral diameter of the graphene flakes is between 10nm and 10μm.

[0045] The solvent is selected to avoid negative interactions with the copper mist 120. For example, the solvent is selected to avoid oxidation of the copper particles, flocculation of the copper particles, or undesirable shapes of the copper particles. The solvent is also selected so that the solvent is not present in the resulting powder under the process conditions. The solvent can be or include a polar solvent such as an alcohol (e.g., methanol or ethanol) and / or a non-polar solvent such as a medium-chain to long-chain hydrocarbon (e.g., gasoline or kerosene).

[0046] Copper mist 120 and graphene mist 122 are combined in a mixing section 105 of an inert environment. The mixing section 105 is designed to produce a uniform mixture of the two mists. For example, the nozzles 116 can be distributed around the mixing section 105 so that the turbulence from the spray mist provides a uniform mixing of the copper particles and the graphene flakes. Additionally or alternatively, the flow of the inert gas can be controlled to enhance the mixing of the mist. For example, the mixing can be enhanced by selecting the inert gas inlet 112 and the inert gas outlet 114, the flow rate of the inert gas, the positioning of the flow control features (e.g., baffles, shapers and turbulators), their combination, etc.

[0047] After the two mists are uniformly mixed, the graphene-copper composite powder 101 settles to the separation portion 106 of the inert environment. The separation portion 106 may include, for example, a plurality of meshes 124. The meshes 124 are arranged so that the graphene-copper composite powder 101 is filtered through a first mesh 124A, and the first mesh 124A has a larger pore size than the subsequent mesh 124B, so that the graphene-copper composite powder 101 is separated into a plurality of fractions 126 having a known and unique particle size distribution. The plurality of fractions 126 can be selected for respective uses. For example, one of the fractions 126C can be selected for use in an additive manufacturing process, another of the fractions 126B can be further processed for another use, and another of the fractions 126A can be processed to remove contaminants and recycled into the copper melt 118.

[0048] In some examples, the graphene content of the graphene-copper composite powder 101 and / or the specific one or more fractions 126 is between 1wt% and 40wt%. In other examples, the graphene content of the graphene-copper composite powder 101 and / or the specific one or more fractions 126 is between 5wt% and 30wt%. In other examples, the graphene content of the graphene-copper composite powder 101 and / or the specific one or more fractions 126 is between 10wt% and 20wt%. Advantageously, the composite graphene-copper composite powder with graphene flakes can obtain optimized tensile strength and electrical properties, wherein the average transverse flake diameter of the graphene flakes is 2μm and the loading is 10wt%, the average transverse flake diameter is 5μm and the loading is 15wt%, or the average transverse flake diameter is 7μm and the loading is 20wt%. Advantageously, reducing the average transverse flake diameter generally reduces the desired graphene content in the resulting powder.

[0049] In some aspects, the system is coupled to an additive manufacturing device, such as Figure 4The graphene-copper composite powder output 108 can connect these devices so that they include a shared inert environment for one or more desired fractions 126 of the powder to be transferred directly from the system to the additive manufacturing device. Additionally or alternatively, the fractions 126 can be transferred to a container within the inert environment, which can then be sealed, removed from the inert environment, moved to the additive manufacturing device, and opened / accessed for use within the inert environment of the additive manufacturing device.

[0050] Figure 2 An exemplary graphene-copper composite powder 101 produced by the system is shown. As can be seen, graphene flakes 202 are distributed throughout the copper particles 204. While not being bound by theory, it is believed that the static or imparted charge enhances contact between the planes of the copper particles 204 and the graphene flakes 202, which reduces or eliminates interstitial voids of the powder that would otherwise cause the copper particles 204 to contact only the edges of one or more graphene flakes 202.

[0051] The avoidance of interstitial voids and the optimized contact between the copper particles 204 and the graphene flakes 202 enhance the electrical, thermal, and mechanical properties of components made from the graphene-copper composite powder 101. In addition, while not being bound by theory, it is believed that the charge can be selected to balance the different electronic properties of the planar and edge portions of the graphene flakes 202, thereby further optimizing the packing and other physical properties of the powder, as well as the properties of the components formed from the powder. Advantageously, the mixing of charged particles also increases the graphene loading of the composite graphene-copper powder 101. For example, a composite graphene-copper powder formed from mixed charged particles can result in a graphene loading of between 30 vol% and 40 vol%, which is higher than the expected loading of between 20 vol% and 25 vol% for mixing the same particles without charge.

[0052] Figure 3 A method 300 for preparing a graphene-copper composite powder 101 is shown. At step 302, the method includes providing an inert environment. At step 304, a first mist (e.g., atomized copper particles 204) and a second mist (e.g., graphene flakes 202 in a solvent) are introduced into the environment. The first mist and the second mist are oppositely charged so that when mixed, the copper particles 204 in the first mist are attracted to the plane of the graphene flakes 202 in the second mist. The method 300 also includes mixing the first mist and the second mist at step 306 to prepare the graphene-copper composite powder 101. The method 300 may also include an optional step 308 of filtering the prepared powder into a plurality of fractions 126 having a known particle size distribution, wherein the area fraction or volume fraction of the graphene flakes 202 and the copper particles 204 is known. It is contemplated that the area fraction or volume fraction of each of the plurality of fractions may be different.

[0053] Figure 4 An exemplary additive manufacturing apparatus 400 is shown. The additive manufacturing apparatus 400 is configured to form a component using the graphene-copper composite powder 101 through a lamination process. The additive manufacturing apparatus 400 includes a sintering apparatus 402, a chamber 404, a powder supply source 406, and a powder bed 408. The chamber 404 includes an inert environment therein.

[0054] The sintering device 402 is configured to selectively form a coherent portion within the graphene-copper composite powder 101 when the graphene-copper composite powder 101 is exposed to the sintering device 402. The selective formation of the coherent portion produces a resulting graphene-copper composite component 410, such that in the resulting graphene-copper composite component 410, enhanced contact is maintained between the graphene flakes 202 and the copper particles 204 of the graphene-copper composite powder 101.

[0055] In the illustrated figure, the sintering device 402 is an electron gun 412 that emits an electron beam 414. The electron beam 414 is shaped and aimed at a focal point corresponding to an upper surface 416 of the powder bed 408 so that the electron beam 414 melts a volume of the graphene-copper composite powder 101 to produce a layer of the resulting graphene-copper composite component 410.

[0056] The inert environment may use the same inert gas as the system or may use a different inert gas. Additionally or alternatively, the inert environment may be an ultra-low pressure environment. In addition, the chamber 404 includes a powder supply source 406 and a powder bed 408 within the inert environment.

[0057] The powder supply source 406 is configured to maintain the graphene-copper composite powder 101 in an inert environment and deliver it to the additive manufacturing apparatus 400 for use in the powder bed 408. Although the powder supply source 406 is shown as a container in the inert environment of the chamber 404, it is contemplated that the container or other delivery mechanism may be connected to the outside of the chamber 404 without exposing the graphene-copper composite powder 101 to a non-inert environment.

[0058] The powder bed 408 includes a platform 418 that is movable relative to the sintering device 402. In the illustrated embodiment, the platform 418 is configured to move in three dimensions using a Cartesian coordinate system. It is contemplated that other systems may be used. The powder bed 408 is configured to contain a quantity of the graphene-copper composite powder 101 that moves therewith.

[0059] Figure 5An illustrative process 500 for preparing a graphene-copper composite component 410 from a graphene-copper composite powder 101 is shown. The process 500 begins at step 502, where a certain amount of graphene-copper composite powder 101 is fed onto a substrate. Next, in step 504, a certain amount of graphene-copper composite powder 101 is prepared for sintering. The preparation may include, for example, drying a certain amount of graphene-copper composite powder 101, subjecting a certain amount of graphene-copper composite powder 101 to a predetermined temperature or temperature distribution, and / or treating a surface 416 of the graphene-copper composite powder 101 to enhance sintering or exposure to a sintering device 402. Surface treatment may include, for example, chemical or mechanical treatment.

[0060] Step 506 of process 500 includes exposing surface 416 of powder bed 408 to sintering device 402 while translating powder bed 408. Powder bed 408 is translated in one or more dimensions and at one or more speeds such that the portion of graphene-copper composite powder 101 exposed to sintering device 402 forms one or more features of a cross-sectional layer of a resulting component.

[0061] After forming the desired features of the layer, step 508 of process 500 includes determining whether the part is complete. If the part is not complete, the platform 418 is moved so that additional layers of the resulting part can be formed and connected to the previous layers. Then, the process 500 repeats steps 502, 504, and 506, feeding another quantitative amount of graphene-copper composite powder 101 onto the substrate on top of the previous layer, preparing the graphene-copper composite powder 101 for sintering, and exposing the corresponding layer to the sintering device 402 while translating the powder bed 408 to form one or more features of the corresponding cross-sectional layer. This process is repeated until all the desired features of all the desired layers of the part are formed.

[0062] Optionally, step 510 of process 500 may include further processing or treating the formed component to produce a finished graphene-copper composite body having desired mechanical, thermal and / or electronic properties. For example, hot pressing or annealing may be employed to optimize interlayer bonding and / or optimize grain boundaries and other material properties of the formed component. Additionally or alternatively, the substrate may be a sacrificial substrate that is removed from the formed component by mechanical processing, chemical treatment, heat or light exposure, combinations thereof, and the like.

[0063] Fig. 6A and Figure 6B Shows the use of Figure 5The graphene-copper composite heat sink 600 produced by the process of the invention. The graphene-copper composite heat sink 600 includes a base 602 and a plurality of heat sinks 604, and the heat sink 604 is configured to increase the heat flux from the heat-generating object. The base 602 is configured to contact the heat-generating object and conduct heat from the heat-generating object to the plurality of heat sinks 604. The heat sink 604 is configured to increase the surface area of ​​the graphene-copper composite heat sink 600 exposed to the cooling fluid (e.g., air or liquid). The heat sink 604 can be formed during additive manufacturing or can be formed into a shaped block of the graphene-copper composite material by a subtractive process (e.g., grinding) without negatively affecting the target properties of the graphene-copper composite heat sink 600 provided by the graphene-copper composite powder 101. Advantageously, the graphene-copper composite heat sink 600 optimizes the cooling of the heat-generating component by optimizing the grain characteristics (e.g., by suppressing grain growth caused by high temperature operation and / or electromagnetic field interaction) and thermal conductivity of the graphene-copper composite heat sink 600.

[0064] Figure 7 A battery cell 700 is shown that employs a graphene-copper composite current collector 702. The battery cell 700 includes a separator 704 disposed between a first electrode 706 and a second electrode 708. The separator 704 allows ion transfer and inhibits electron transfer therethrough.

[0065] The first electrode 706 is configured to intercalate ions when the battery cell 700 is charged and to deintercalate ions when the battery cell 700 is discharged. The first electrode 706 is disposed on the first graphene-copper composite current collector 702. The first graphene-copper composite current collector 702 is configured to collect and move free electrons between the first electrode 706 and the second electrode 708 via an external circuit. The external circuit may include an external device, which may be a load that consumes power from the battery cell 700 and / or a power source that provides power to the battery cell 700.

[0066] The second electrode 708 is configured to intercalate ions received from the first electrode 706 when the battery cell 700 is discharging, and to deintercalate ions to be transferred to the first electrode 706 when the battery cell 700 is charging. The second electrode 708 includes a second electroactive material (not shown) and is disposed on the second graphene-copper composite current collector 702. The second electroactive material is formed of a material that cooperates with the first electroactive material to facilitate ion flow and electron flow between the first electrode 706 and the second electrode 708.

[0067] The second graphene-copper composite current collector 702 is configured to collect and move free electrons between the first electrode 706 and the second electrode 708 via an external circuit. The second electrode 708 may also include a binder (not shown). In some aspects, the binder of the second electrode 708 is an adhesive.

[0068] Each of the first electrode 706, the second electrode 708, and the separator 704 may also include an electrolyte. The electrolyte is configured to facilitate ion movement between the first electrode 706 and the second electrode 708 during charging and discharging of the lithium-ion battery. The electrolyte may be a liquid, solid, or gel electrolyte.

[0069] Figure 8 A graphene-copper composite busbar 802 is shown for use with an electric motor. Each graphene-copper composite busbar 802 includes a coupler 804 configured to be electrically connected to a power source. The graphene-copper composite busbar 802 is attached to the windings (not shown) of the electric motor so that current is transmitted between the power source (not shown) and the windings via the graphene-copper composite busbar 802. Advantageously, the enhanced mechanical properties of the graphene-copper composite busbar 802 optimize the performance of the graphene-copper composite busbar 802 by avoiding the impact on the material properties of ordinary copper busbars due to resistive heating generated during use. Advantageously, the enhanced thermal conduction of the graphene-copper composite busbar 802 also optimizes the transfer of heat generated in the windings away from the motor, which improves operating efficiency, maintains the desired material properties of the copper windings, and extends the service life of the motor. For example, the electric motor may generate an electromagnetic field with a temperature range of 50°C to 100°C. This may occur in short cycles, long-term operation, and combinations thereof. The graphene-copper composite busbar 802 optimizes the material's microstructure and inhibits grain growth and / or softening of the busbar that may occur with other materials. Advantageously, these optimized mechanical properties and enhanced durability also allow the graphene-copper composite busbar 802 to include heat transfer channels to further enhance the operation of the motor.

[0070] Although the present disclosure discusses additive manufacturing using the graphene-copper composite powder 101 , it is contemplated that other powder metallurgy forming apparatus and techniques may be used to produce graphene-copper composite parts using the graphene-copper composite powder 101 .

[0071] The foregoing detailed description is merely exemplary in nature and is not intended to limit the present application and uses. Furthermore, there is no intention to be bound by any expressed or implied theory presented in the preceding section or the foregoing detailed description.

[0072] As will be appreciated by those skilled in the art, the present disclosure is susceptible to various modifications and alternative forms, and some representative embodiments have been illustrated by way of example in the accompanying drawings and described in detail above. However, it should be understood that the novel aspects of the present disclosure are not limited to the specific forms shown in the accompanying drawings. On the contrary, the present disclosure encompasses modifications, equivalents, combinations, sub-combinations, permutations, groupings, and substitutions that fall within the scope and spirit of the present disclosure and are defined by the appended claims.

[0073] As used herein, unless the context clearly dictates otherwise: the words “and” and “or” shall be regarded as both conjunctions and disjunctions, unless the context clearly dictates otherwise; the word “all” means “any and all”; the word “any” means “any and all”; the word “include” means “including but not limited to”; the singular forms “a”, “an” and “the” include plural referents and vice versa.

[0074] The numerical values ​​of parameters (such as quantities or conditions) in this specification, unless otherwise explicitly or clearly indicated by the context (including the appended claims), should be understood as being modified by the term "about", whether or not "about" actually appears before the numerical value. The numerical parameters set forth herein and in the appended claims are approximate values, which may vary depending on the desired properties sought to be obtained by the present disclosure. At the very least, and without attempting to limit the application of the doctrine of equivalents to the scope of the claims, each numerical parameter should at least be interpreted in light of the number of reported significant digits and by applying ordinary rounding techniques.

[0075] For example, approximate words such as "approximately," "about," "substantially," and the like may be used herein to mean "at, close to, or nearly at," "within 0-10% of," or "within an acceptable manufacturing tolerance," or logical combinations thereof.

[0076] Although the scope and limits of the term "about" are readily understood by those of ordinary skill in the art, the term "about" indicates that the numerical value or property described allows for imprecision. If the imprecision provided by "about" is not understood in this ordinary sense in the art, then "about" at least indicates the variation that may result from ordinary methods of measuring and using such parameters. For example, if not otherwise understood in the art, the term "about" means within 10% (e.g., ±10%) of the stated value.

[0077] Although the scope and limits of the term "substantially" are readily understood by those of ordinary skill in the art, the term "substantially" indicates that the numerical value or property described allows for some imprecision. If the imprecision provided by "substantially" is not understood in this ordinary sense in the art, "substantially" at least indicates variations that may be caused by manufacturing processes and measurements of these parameters. For example, if not otherwise understood in the art, the term "substantially" means within 5% (e.g., ±5%) of the stated value.

[0078] Although the scope and limits of the term "substantially" are readily understood by those of ordinary skill in the art, the term "substantially" indicates that the numerical value or property described allows for some slight imprecision. If the imprecision provided by "substantially" is not understood in this ordinary sense in the art, "substantially" indicates at least negligible changes in the desired parameter that may not be overcome. For example, if not otherwise understood in the art, the term "substantially" means within 1% (e.g., ±1%) of the stated value.

[0079] Although the scope and limits of the term are readily understood by those of ordinary skill in the art, the term "pure" indicates that the compound may include very small amounts of other materials. If the imprecision provided by "pure" is not understood in this ordinary sense in the art, "pure" at least indicates the variations that may be caused by the separation process and measurement of these parameters. For example, if the art does not understand otherwise, the term "pure" means greater than 99.9% of the material.

[0080] While the best modes for carrying out the disclosure have been described in detail, those familiar with the art to which this disclosure relates will recognize various alternative designs and embodiments for practicing the disclosure within the scope of the appended claims.

Claims

1. A method comprising: Provide an inert environment; introducing a first mist into the inert environment, the first mist being negatively charged atomized copper; introducing a second mist into the inert environment, the second mist comprising positively charged graphene flakes; and The first mist and the second mist are mixed in the inert environment to prepare a graphene-copper composite powder. 2 . The method according to claim 1 , further comprising separating the graphene-copper composite powder into a plurality of fractions in the inert environment using at least one mesh screen.

3. The method of claim 2, further comprising feeding a first fraction of the plurality of fractions into an additive manufacturing device connected to the inert environment.

4. The method of claim 1, wherein the first mist is formed by copper melt fed into the inert environment through a high pressure nozzle. The method of claim 1 , wherein the process pressure of the inert environment comprises a vacuum. 6 . The method according to claim 1 , wherein the copper particles of the graphene-copper composite powder are composed of copper nanoparticles.

7. The method of claim 1, further comprising forming a graphene-copper composite busbar from the composite powder via additive manufacturing or conventional powder metallurgy processes.

8. The method of claim 1, further comprising forming a graphene-copper composite heat sink from the composite powder via additive manufacturing or conventional powder metallurgy processes.

9. A system comprising: a chamber comprising an inert environment and a mixing section, the mixing section being located within the inert environment; a first nozzle and a second nozzle, wherein the first nozzle is configured to introduce a first mist into the mixing portion of the inert environment, the first mist is atomized copper, the first mist has a negative charge, and wherein the second nozzle is configured to introduce a second mist into the mixing portion of the inert environment, the second mist includes graphene flakes, the second mist has a positive charge; as well as An output part is configured to transport graphene-copper composite powder from the inert environment, wherein the graphene-copper composite powder is formed by mixing a first mist of negatively charged atomized copper and a second mist of positively charged graphene flakes.

10. A graphene-copper composite powder is formed by the following steps: Provide an inert environment; introducing a first mist into the inert environment, the first mist being negatively charged atomized copper; introducing a second mist into the inert environment, the second mist comprising positively charged graphene flakes; and The first mist and the second mist are mixed in the inert environment to prepare a graphene-copper composite powder.

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