Coated sheet metal for producing graphene

Abstract

The invention relates to a process for producing graphene (3), wherein: a substrate is provided; graphene (3) is produced on the substrate by chemical vapor deposition; the graphene (3) is removed from the substrate, especially by way of a bubble transfer process, and is transferred onto a storage film (4) for storage. According to the invention, copper-coated (2) sheet metal (1) is provided as the substrate. The invention also relates to graphene (3) produced according to the process and to copper-coated sheet metal for use in this process.

Description

[0001] Coated metal sheet for the production of graphene

[0002] The invention relates to a method for producing graphene, graphene produced by this method and a copper-coated metal sheet for producing graphene.

[0003] Graphene is an allotrope of carbon consisting of a single layer of atoms arranged in a hexagonal lattice structure. Due to its material properties, it has been proposed for many applications. However, the practical use of graphene is currently very limited due to its high production costs. There are various methods for producing graphene:

[0004] Originally, graphene was extracted mechanically from graphite by exfoliation. The disadvantage of this method is that only small areas can be extracted, and it also contains a high proportion of graphene oxide.

[0005] The production of larger surfaces with better quality is possible through chemical vapor deposition (CVD). The production of graphene by CVD is described, for example, in P. Trinsoutrot et al., Surface and Coatings Technology, 2013, 230, 87-92. A device for continuous graphene production by CVD is known from US 2011 / 195207 A1.

[0006] Such a process for producing graphene was also described, for example, in WO 2013 154997 A1. Graphene is deposited on a copper foil using CVD. The copper foil is then dissolved, and the graphene is transferred to a titanium foil. A disadvantage of this process is that the structure of the graphene is partially disrupted by the different cooling of copper and graphene, resulting in poor graphene quality. Furthermore, production is very complex and expensive, particularly due to the high copper consumption.

[0007] A process that partially overcomes these disadvantages was described in DE 10 2013 220 158 A1. In this process, a copper ribbon is also first prepared. Graphene is deposited onto this copper ribbon using CVD. The hot graphene is then transferred to a transfer ribbon for cooling, and the copper ribbon is detached using a bubble transfer process. The bubble transfer process is described, for example, in L. Gao et al., Nature Communications, DOI: 10.1038 / NCQMMS1702. After cooling, the graphene is transferred from the transfer ribbon to another foil for storage. This allows for the production of higher-quality graphene. DE 10 2013 220 158 further describes that the copper ribbon and the transfer ribbon can be reused. However, repeated transfers also result in damage to the graphene in this process.Another disadvantage is that the copper tape has low tear strength, making reuse difficult and the process can only run at a low tape speed.

[0008] Another way to overcome the disadvantage of the different cooling times of copper and graphene was proposed in CN 1 10040726 A1. This discloses the production of graphene on a copper-nickel alloy. However, even unavoidable, minor fluctuations in the alloy composition lead to inhomogeneous graphene deposition. This is further exacerbated during cooling, as the different thermal expansion coefficients of the elements cause distortions in the graphene. Therefore, this process cannot produce larger, uniform surfaces of graphene.

[0009] The current production speed of graphene is extremely slow at 0.12 m / min. Graphene films, especially large-area, high-quality films, are therefore very expensive.

[0010] The object of the invention is therefore to enable a faster and more cost-effective production of graphene.

[0011] This object is achieved in a method for producing graphene, wherein a carrier material is provided, wherein graphene is produced on the carrier material by chemical vapor deposition, wherein the graphene is detached from the carrier material, in particular by a bubble transfer process, and transferred to a storage foil for storage, in that a copper-coated metal sheet is provided as the carrier material.

[0012] The metal sheet has a higher tensile strength, so that the process can be carried out at a higher speed and the carrier material can be reused more frequently. This results in significant cost savings. Copper-coated in the sense of the invention means that the proportion of copper in the copper layer is at least 90 wt.%, preferably at least 99 wt.%, with the remainder representing any impurities. Using the process according to the invention, graphene can be obtained that consists of only three to ten atomic layers, in particular three to five atomic layers. The graphene then has a thickness of less than 1 mm. At the same time, large areas of at least 10 cm 2 , in particular at least 100 cm 2The graphene is particularly preferably in the form of a continuous ribbon. This provides a process for producing large, homogeneous graphene surfaces. This gives the graphene high thermal and electrical conductivity.

[0013] In order to produce the graphene with particularly high quality, the provided metal sheet can be made of an alloy with a thermal expansion coefficient in the range of 20 - 400°C below 20 [10 A -6 m / (mx K)], especially below 15 [10 A -6 m / (mx K)], preferably below 12 [10 A-6 m / (mx K)], with the copper layer being planar or having a 11 1 orientation. The low thermal expansion coefficient and the uniform orientation of the copper prevent damage to the graphene structure when the graphene cools on the substrate. The resulting graphene is thus deposited particularly homogeneously and exhibits a consistent, homogeneous structure and constant layer thicknesses even after cooling.

[0014] To produce particularly large areas of graphene, it is advantageous to use the BIAS process for applying the copper layer. During the coating process, a voltage, particularly a negative one, is applied to the substrate as an electrical bias using the PVD plasma process. The resulting copper layer is particularly uniform and adheres particularly well.

[0015] A process in which the metal sheet provided consists of a steel alloy or an aluminum alloy is particularly suitable.

[0016] In order to carry out the process particularly cost-effectively, the metal sheet provided can contain an alloy with the following composition (in wt%):

[0017] 0.01 to 0.20 carbon (C),

[0018] 30 to 40 nickel (Ni)

[0019] 0.01 to 0.60 manganese (Mn),

[0020] 0.01 to 0.40 silicon (Si),

[0021] < 0.06 phosphorus (P),

[0022] < 0.04 sulfur (S), optionally containing:

[0023] 0 to 0.25 chromium (Cr),

[0024] 0 to 0.50 cobalt (Co)

[0025] 0 to 0.20 aluminum (AI),

[0026] 0 to 0.50 molybdenum (Mo)

[0027] 0 to 0.50 copper (Cu)

[0028] 0 to 0.30 vanadium (V)

[0029] 0 to 0.20 titanium (Ti)

[0030] 0 to 0.20 niobium (Nb)

[0031] 0 to 0.005 boron (B)

[0032] O to 0.015 nitrogen (N)

[0033] 0 to 0.01 calcium (Ca) and the remainder iron (Fe) and unavoidable impurities due to manufacturing.

[0034] This alloy is used for a wide variety of applications and is produced in larger quantities, allowing production costs for the metal sheet to be kept low. This alloy is also particularly well-suited for the process according to the invention because a very uniform copper layer can be produced when coated with copper. This enables the production of particularly high-quality graphene.

[0035] Steel material 1.3912 is particularly suitable for this purpose, as it has a particularly low coefficient of expansion. Steel material 1.4412 is also well suited.

[0036] Particularly high-quality graphene can be produced if the provided support material has a planar copper layer or a copper layer in a 1 11 orientation. This can prevent structural irregularities in the graphene.

[0037] For the production of particularly high-quality graphene, a process is particularly suitable in which the carrier material is produced by applying the copper layer to the metal sheet by vapor deposition, in particular physical vapor deposition. This method can provide a precisely defined copper layer with a uniform layer thickness and particularly regular alignment. For example, a planar copper layer or a copper layer with a 111 alignment can be obtained by vapor deposition. At the same time, the metal sheet for producing the carrier material can be coated with copper by vapor deposition at a high speed of 10 to 180 m / min.

[0038] The process for producing graphene is particularly resource-efficient and cost-effective if the support material is made available again for graphene production after the graphene has been removed. This enables a process cycle in which the support material can be directly reused. If the copper coating does become damaged after numerous runs, the copper can also be stripped from the metal sheet. The collected copper can be reused to coat a metal sheet, for example, in a PVD plasma process. Likewise, the cleaned metal sheet can be recoated with copper. A plasma etching process, for example, is suitable for cleaning the metal sheet.

[0039] Since the process described above can produce particularly uniform and high-quality graphene, a graphene produced according to the invention is also possible using the process described above. The graphene according to the invention consists of only three to ten atomic layers, in particular three to five atomic layers. The graphene thus has a thickness of less than 1 mm. At the same time, graphene areas of at least 10 cm 2 , in particular at least 100 cm 2 , can be produced. The graphene is particularly preferably in the form of a continuous ribbon. To prevent oxidation of the graphene, it can be stored under a protective atmosphere, for example, nitrogen or argon.

[0040] According to the invention, a copper-coated metal sheet, in particular metal strip, is further provided for use in a method according to one of claims 1 to 7, wherein the metal sheet has a coefficient of thermal expansion in the range of 20 - 400°C below 20 [10A -6 m / (mx K)], especially below 15 [10 A -6 m / (mx K)], preferably below 12 [10 A -6 m / (mx K)]. Due to the low thermal expansion coefficient, damage to the graphene structure can be avoided when the graphene cools on the support material.

[0041] The copper-coated metal sheet enables the cost-effective production of particularly high-quality graphene.

[0042] A copper-coated metal sheet made of a steel alloy or an aluminum alloy is particularly suitable for producing graphene. To achieve the most uniform graphene structure possible, even during cooling, a particularly suitable alloy is one with the following composition (in wt%):

[0043] 0.01 to 0.20 carbon (C),

[0044] 30 to 40 nickel (Ni)

[0045] 0.01 to 0.60 manganese (Mn),

[0046] 0.01 to 0.40 silicon (Si),

[0047] < 0.06 phosphorus (P),

[0048] < 0.04 sulfur (S), optionally containing:

[0049] 0 to 0.25 chromium (Cr),

[0050] 0 to 0.50 cobalt (Co)

[0051] 0 to 0.20 aluminum (AI),

[0052] 0 to 0.50 molybdenum (Mo)

[0053] 0 to 0.50 copper (Cu)

[0054] 0 to 0.30 vanadium (V)

[0055] 0 to 0.20 titanium (Ti)

[0056] 0 to 0.20 niobium (Nb)

[0057] 0 to 0.005 boron (B)

[0058] O to 0.015 nitrogen (N)

[0059] 0 to 0.01 calcium (Ca) and the remainder iron (Fe) and unavoidable impurities due to manufacturing.

[0060] Steel material 1.3912 is particularly suitable for this purpose because, on the one hand, it has a low coefficient of expansion, which prevents structural damage when the graphene cools, and, on the other hand, copper can be applied particularly evenly to this material. Steel material 1.4412 can also be used.

[0061] A copper-coated metal sheet, where the copper layer is planar or has an 111 orientation, can achieve particularly high graphene quality. To enable the copper-coated metal sheet to be reused repeatedly as a carrier material, the copper layer can have a thickness of 0.1 μm to 100 μm. It has been found that the layer thickness range of 1 μm to 75 μm can be particularly advantageous, as it improves adhesion with comparatively thin layer thicknesses and ensures scratch and abrasion resistance.

[0062] Since the copper-coated metal sheet described above is particularly suitable for producing graphene using the process described above, in particular the CVD process, the use of the copper-coated metal sheet as a support material in such a process is also in accordance with the invention. This allows high-quality graphene to be produced cost-effectively.

[0063] The invention is described by way of example with reference to the drawing without limiting the general inventive concept:

[0064] Fig. 1 shows the schematic flow of an exemplary method.

[0065] Fig. 1 shows that a metal sheet, in the illustrated embodiment, a metal strip 1, is first coated with copper. In the illustrated embodiment, the metal strip 1 is made of steel material 1.3912. The copper coating 2 is applied by physical vapor deposition (PVD). In the illustrated embodiment, the copper layer 2 has a layer thickness of 0.1 μm to 100 μm. Furthermore, in the illustrated embodiment, the copper layer 2 has a uniform orientation.

[0066] Graphene 3 is produced on the copper-coated metal strip as a carrier layer using chemical vapor deposition (CVD), which deposits it in high quality onto the copper layer 2. After cooling, the graphene 3 is transferred to a storage foil 4 for storage and detached from the carrier material using a bubble transfer process. The carrier material can then be reused, and graphene 3 can be deposited again onto the copper coating 2.

[0067] If the copper layer 2 has become worn after repeated use of the carrier material, the copper can be stripped off. The copper can be recovered from the solution and, after cleaning, reused to coat a metal strip 1. The metal strip 1 can also be cleaned after stripping and then recoated with copper.

[0068] This can provide a resource-saving, cost-effective process for producing high-quality graphene.

Claims

8 Patent claims 1. A method for producing graphene (3), wherein a carrier material is provided, wherein graphene (3) is produced on the carrier material by chemical vapor deposition, wherein the graphene (3), in particular by a bubble transfer process, is detached from the carrier material and transferred to a storage foil (4) for storage, characterized in that a copper-coated metal sheet is provided as the carrier material.

2. Method according to claim 1, wherein the provided metal sheet (1) is made of an alloy having a thermal expansion coefficient in the temperature range of 20 - 400°C below 20 [10 A -6 m / (mx K)], preferably below 15 [10 A -6 m / (mx K)], particularly preferably below 12 [10 A -6 m / (mx K)], exists.

3. Method according to one of claims 1 or 2, wherein the provided metal sheet (1) consists of a steel alloy or an aluminum alloy.

4. Method according to one of claims 1 to 3, wherein the provided metal sheet (1) contains an alloy having the following composition (in wt%): 0.01 to 0.20 carbon (C), 30 to 40 nickel (Ni), 0.01 to 0.60 manganese (Mn), 0.01 to 0.40 silicon (Si), < 0.06 phosphorus (P), < 0.04 sulfur (S), optionally containing: 0 to 0.25 chromium (Cr), 0 to 0.50 cobalt (Co), 0 to 0.20 aluminum (AI), 0 to 0.50 molybdenum (Mo), 0 to 0.50 copper (Cu), 0 to 0.30 vanadium (V), 0 to 0.20 titanium (Ti), 0 to 0.20 niobium (Nb), 9 0 to 0.005 boron (B), O to 0.015 nitrogen (N), 0 to 0.01 calcium (Ca), and the remainder iron (Fe) and unavoidable impurities due to production, wherein the metal sheet (1 ) consists in particular of the steel material 1.3912 or the steel material 1 .41 12.

5. The method according to any one of claims 1 to 4, wherein the carrier material provided comprises a planar copper layer (2) or a copper layer (2) in 1 11 orientation.

6. Method according to one of claims 1 to 5, wherein the carrier material is produced by applying the copper layer (2) to the metal sheet (1) by gas phase deposition, in particular physical gas phase deposition, in particular at a speed of 10 to 180 m / min.

7. The method according to any one of claims 1 to 6, wherein the carrier material is provided again for the production of graphene after the detachment of the graphene (3).

8. Graphene (3) consisting of three to ten atomic layers, in particular of three to five atomic layers, wherein the graphene has an area of ​​at least 10 cm 2 , in particular at least 100 cm 2 , and wherein the graphene is preferably present as an endless ribbon.

9. Copper-coated metal sheet, in particular metal strip, for use in a method according to one of claims 1 to 7, wherein the metal sheet (1) has a coefficient of thermal expansion in the temperature range of 20 - 400°C below 20 [10 A -6 m / (mx K)], preferably below 15 [10 A -6 m / (mx K)], particularly preferably below 12 [10 A -6 m / (mx K)], wherein the copper layer (2) is aligned planar or has a 1 11 alignment.

10. Copper-coated metal sheet according to claim 9, wherein the metal sheet (1) consists of a steel alloy or an aluminum alloy.

11. Copper-coated metal sheet according to claim 10, wherein the alloy has the following composition (in wt%): 0.01 to 0.20 carbon (C), 10 30 to 40 nickel (Ni), 0.01 to 0.60 manganese (Mn), 0.01 to 0.40 silicon (Si), < 0.06 phosphorus (P), < 0.04 sulfur (S), optionally containing: 0 to 0.25 chromium (Cr), 0 to 0.50 cobalt (Co), 0 to 0.20 aluminum (AI), 0 to 0.50 molybdenum (Mo), 0 to 0.50 copper (Cu), 0 to 0.30 vanadium (V), 0 to 0.20 titanium (Ti), 0 to 0.20 niobium (Nb), 0 to 0.005 boron (B), O to 0.015 nitrogen (N), 0 to 0.01 calcium (Ca), and the remainder iron (Fe) and unavoidable impurities due to production, wherein the metal sheet (1 ) consists in particular of the steel material 1.3912 or the steel material 1 .41 12.

12. Copper-coated metal sheet according to one of claims 9 to 11, wherein the copper layer (2) has a thickness of 0.1 pm to 100 pm, in particular of 1 pm to 75 pm.

13. Copper-coated metal sheet according to one of claims 9 to 12, wherein graphene (3), in particular graphene (3) according to claim 8, is arranged on the copper layer (2).

14. Use of a copper-coated metal sheet as a carrier material for the deposition of graphene (3) by chemical vapor deposition, in particular for use in a method according to one of claims 1 to 7.

15. Use according to claim 14, wherein the copper-coated metal sheet is formed according to one of claims 9 to 12.

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