ELECTRICITY COLLECTING DEVICE AND METHOD

Abstract

A device for collecting electricity from the atmosphere comprises: a collecting element adapted to draw electricity from the atmosphere; an electrically conductive element electrically connected to the collecting element for transmitting electricity collected by the collecting element to an output; and a support member capable of holding the collecting element in an elevated position, wherein the electrically conductive element comprises a composite structure extending at least partially along its length, the composite structure comprising a first layer comprising graphene.

Claims

1-19. (canceled)

20. A device for collecting electricity from the atmosphere, comprising: a collecting element adapted to draw electricity from the atmosphere; a support member capable of holding the collecting element in an elevated position; and an electrically conductive element electrically connected to the collecting element for transmitting electricity collected by the collecting element to an output, wherein the electrically conductive element comprises a composite structure extending at least partially along its length, the composite structure comprising a first layer comprising graphene.

21. The device of claim 20, wherein the composite structure further comprises a second layer comprising an aerogel.

22. The device of claim 21, wherein the composite structure comprises between 2 and 250 first layers and 2 and 250 second layers.

23. The device of claim 20, wherein the composite structure comprises a plurality of alternating layers of graphene and aerogel.

24. The device of claim 23, wherein at least one of the graphene layers consists essentially of graphene.

25. The device of claim 23, wherein at least one of the graphene layers comprises graphene platelets.

26. The device composite structure of claim 22, wherein each first layer independently has a thickness of from 0.34 nm to 20 m.

27. The device composite structure of claim 22, wherein each second layer independently has a thickness of 20 m to 1000 m.

28. The device of claim 20, wherein the composite structure further comprises a support layer.

29. The device of claim 28, wherein the support layer has a tensile strength greater than the tensile strength of the other layers of the composite structure.

30. The device of claim 29, wherein the support layer comprises carbon nanotube (CNT) fibres.

31. The device of claim 20, wherein the device comprises a conductive member which comprises both the collecting element and the electrically conductive element.

32. The device of claim 20, wherein the electrically conductive element extends from the collecting element to the ground.

33. The device of claim 20, wherein the electrically conductive element comprises a terminal portion for connecting to the output and wherein the composite structure extends from the collecting element to the terminal portion.

34. The device of claim 20, further comprising an energy storage device, wherein the electrically conductive element is electrically connected to the energy storage device so as to transfer at least a portion of the electricity collected from the atmosphere to the energy storage device.

35. The device of claim 34, wherein the energy storage device is capacitor array or an ultra-capacitor array.

36. The device of claim 20, wherein the support member is a lift-providing support member.

37. The device of claim 36, wherein the lift-providing support member is an inflatable member.

38. A method of collecting electricity from the atmosphere, the method comprising: providing a device according to claim 20; drawing electricity from the atmosphere using the collecting element; and transmitting electricity collected by the collecting element along the electrically conductive element to an output.

39. The method of claim 38, further comprising providing a plurality of alternating layers of graphene and aerogel extending at least partially along the length of the electrically conductive element.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Embodiments of the invention will now be described with reference to the accompanying figures, in which:

[0040] FIG. 1 shows an embodiment of the device according to the invention;

[0041] FIGS. 2a and 2b show transverse cross-sections through a composite structure according to an embodiment of the invention;

[0042] FIG. 3 shows a radial cross-section through a composite structure according to an embodiment of the invention;

[0043] FIG. 4 shows another embodiment of a device according to the invention;

[0044] FIG. 5 shows a side view of a composite structure for use in a device according to the invention;

[0045] FIG. 6a shows an SEM image of a composite structure for use in a device according to the invention;

[0046] FIG. 7a shows a composite structure according to an embodiment of the invention;

[0047] FIG. 7b shows another composite structure according to an embodiment of the invention;

[0048] FIG. 7c shows another composite structure according to an embodiment of the invention;

[0049] FIGS. 8a and 8b show another embodiment of a composite structure according to the invention from side and side perspective views, respectively; and

[0050] FIG. 9 shows another embodiment of a composite structure according to the invention from a side view.

[0051] Like components are given like reference numerals. For example, a graphene layer may be referred to as 151a, 251 or 351. Further, in the figures where composite structures are shown, it should be appreciated that the thicknesses of the layers are purely representative (with the exception of those in which a photograph or SEM image is provided).

DETAILED DESCRIPTION OF THE INVENTION

[0052] A first embodiment of the invention is shown in FIG. 1 in the form of device 100 for collecting electricity from the atmosphere A. The device 100 comprises an electrically conductive member 101 in the form of a cable which comprises a collecting element 102 adapted to draw electricity from the atmosphere A and an electrically conductive element 103, which electrically connects the collecting element 102 to an output 108. The electrically conductive member 101, and specifically the collecting element 102, is held aloft in the atmosphere above the ground G (i.e. the Earth's surface) by a hydrogen-filled latex weather balloon 120 which is tethered to the conductive member 101 by a series of shroud lines 121, with the electrically conductive element 103 extending from the collecting element 102 located in the atmosphere A back to the ground G, where the output 108 is located. In this embodiment, the output 108 is the input terminal of ultra-capacitor array 110 (see EP2564404 for an example suitable ultra-capacitor array).

[0053] The conductive member 101 in this embodiment is a cable formed of a composite structure 150, which structure 150 extends along the length of the cable from a terminal for connecting to the output 108 located on the ground G to the opposing end of the conductive member 101 located in the atmosphere A. The composite structure 150 in this embodiment thus forms part of both the collecting element 102 and the conducting element 103.

[0054] The composite structure 150 can be seen in more detail in FIG. 2a, which shows a cross-section through the diameter of the collecting element 102. A radial cross-section through the composite structure 150 is also shown in FIG. 3. As can be seen, the composite structure 150 comprises a number of layers 151a-c, 152a-b 153a-b arranged as a series of concentric rings which repeat through the cross-section of the composite structure 150. The innermost layer in the structure 150 on this embodiment this is a support layer 153a in the form of carbon nanotube fibre layer (CNT). This provides a high-strength backbone through the composite structure 150. Immediately adjacent the central support layer 153a is a first layer 151a in the form of a graphene layer which is provided onto a surface a second layer 152a formed of a polyimide aerogel film. Onto the other side of the first aerogel layer 152a is provided another graphene layer 151b. The structure then continues (moving out from the graphene layer 151b) with a further CNT layer 153b, a further aerogel layer 152b and a final outer graphene layer 151b. Although not visible in FIG. 2a, the end of the cable 101 provides an exposed end surface whereby the inner graphene layers 151a, 151b, are exposed to the atmosphere such that current can pass along these layers 151a, 151b, as well as the outmost graphene layer 151c. This composite structure 150 is particularly advantageous as the materials used provide a flexible, lightweight and damage-resistant conducting member 101 which can extend over very long distances. In particular, the high-strength support layers 153a,b, the aerogel layers 152a,b and the graphene layers 151a-c all contribute to supporting the weight of the structure 150 along the length of the conductive member 101 and each are able to contribute to prevent damage as a result of shear forces (e.g. as a result of movement of the conductive member 101, for example when moving into position or under the action of wind) and impacts from debris, ice, etc.

[0055] This configuration of layers continues throughout the length of the composite structure 150 to provide a continuous set of graphene layers 151a-c which extend along the length of the conductive member 101. In addition to this, the composite structure 150 includes an additional layer in the form of an insulating layer 154 which surrounds the remaining layers of the composite structure 150 along the part of the conductive member 101 defining the conducting element 103. This insulating layer 154 reduces the risk of people or property coming into contact with the current flowing through the conductive member and thus acts as a protective shield. A cross-section of the conductive member 101 in the conducting element 103 region is shown in FIG. 2b, where the insulating layer 154 is visible.

[0056] In use, the weather balloon 120 is located at an altitude of approximately eight miles, such that the collecting element 102 is located approximately at cloud level. If resistive heat and electrical losses are ignored, the collecting element 102 is at substantially the same voltage level as the output 108 prior to use. Accordingly, when the collecting element 101 is not collecting electricity, the voltage level at the collecting element 102 and output 108 is substantially the same as the ground G to which the ultra-capacitor array 110 is connected. When the collecting element 101 is collecting electricity, the voltage level at the collecting element 101 and output 108 is substantially the same as the static electricity source. Accordingly, if the collecting element 102 is not collecting electricity there is no potential difference across the ultra-capacitor array 110, and no current flows into the array 110. When the collecting element 102 is collecting electricity, there is a potential difference across the ultra-capacitor array 110 and current flows into the array 110, thereby storing electrical energy in the array 110. In this embodiment, the exposed outermost graphene layer 151c and the ends of the inner graphene layers 151a, 151b provide highly conductive layers along which current can travel to the output 108 efficiently and it is these parts which harvest or collect the static electricity by providing a conductive surface across which there is the potential difference.

[0057] In this embodiment, to transfer energy to the electrical grid (not shown), the ultra-capacitor array 110 has its electrical connections (i.e. at input and output terminals) switched from the electrically conductive element 102 and the ground G (as it is connected when collecting electricity) to an electrical grid connection (not shown). When switching, the configuration of ultra-capacitors 110 can be adapted to provide the desired output voltage, for instance, a greater number of individual ultra-capacitors may be in parallel when transferring electricity to the grid than when collecting electricity, which would provide a step-down in voltage. The electrical grid connection comprises an inverter for converting from direct current to alternating current at a frequency suitable for the grid. In some scenarios, a potential difference between a static electricity source and the output 108 may be too great, and electrical damage by overcurrent or overvoltage may be prevented by shunting the electrical energy directly to ground G by the secondary conductive route providing an earthing point 106. It will be appreciated that the maximum energy flow along the conductive member 101 is limited by the take-up rate of the ultra-capacitors 110 and, therefore, the overflow would be transmitted into the earthing point 106 or dispersed as with existing lightning rods. In this embodiment, secondary conductive route to earthing point 106 is opened automatically in response to potential differences over a certain threshold.

[0058] Accordingly, the device 100 in this embodiment can be used to harvest the static electricity from the atmosphere and thereby provides a clean and renewable source of energy. Moreover, the electricity harvesting device 100 can also be used to harvest much higher levels of electricity by acting as a grounding rod for lightning. With the collecting element 102 located in highly charged clouds, the conductive member 101 provides a new path of least resistance for lightning, both within the clouds and between the clouds and the ground G. Moreover, the composite structure 150 is particularly effective for this function as the high voltage passing through the graphene layers 151a-c can be contained effectively within these layers by the surrounding aerogel layers 152a,b, which are effective insulators and thus reduce the risk of damage to other parts of the composite. Further, the presence of a secondary conductive route 106 helps to ensure that electrical components at the output 108 are protected during high voltage transmission.

[0059] As set out above, the composite structure 150 in this embodiment comprises a number of graphene layers 151a-c and a number of other layers 152a,b, 153a,b. This can be constructed by using atomic deposition to provide a layer of graphene (the layer having multiple graphene layers) on a flexible substrate, followed by applying this layer of graphene to the flexible polyimide aerogel and repeating on the other side of the aerogel. This sub-unit can then be rolled around the central CNT layer 153b and the process repeated for the other layers.

[0060] A second embodiment of the invention is shown in FIG. 4 in which there is an electricity collecting device 200. This device 200 comprises a support frame 220 formed of two upright support masts 221 from each of which a support arm 222 extends out towards the other mast 221. The support arms 222 both engage and hold a conductive member 201 in the atmosphere A between the two masts 220 so that electricity can be collected using the conductive member 201. In this embodiment, the support frame 220 is insulated from the ground G so that electricity does not pass through the support frame 220. The conductive member 201 comprises a composite material 250 which comprises an aerogel layer 252 onto which a graphene layer 251 is formed. This sheet of material (which is shown in FIG. 5) is then rolled over onto itself to form a spiraling circular conductive member 201. An SEM image of the composite material 250 in its unrolled configuration is shown in FIG. 6a and an SEM image of the composite material 250 in a partially rolled configuration is shown in FIG. 6b. This composite material runs throughout the whole length of the conductive member 201 and defines both a collecting element or portion 203 located at the top of the conductive member and a conducting element or portion 203. Thus, the collecting element 203 acts as a means for conducting and collecting electricity from the atmosphere A.

[0061] The device 200 in this embodiment is designed to be located at an elevated position, for example on top of a building or in a region with a high altitude (i.e. above sea level) so that the conductive member 201 can have a reduced length but so that the collecting element 202 is still located in an part of the atmosphere containing atmospheric electricity (or potentially, under particular conditions, containing atmospheric electricity, for example, once clouds begin to form). As with the embodiment of FIG. 1, this device 200 is arranged to create a potential difference across the conductive member 201 so that current can flow to an output 208 and subsequently be provided to an external circuit via wire 209. A secondary overflow earth 206 is also provided to avoid damage to the components of the device 200.

[0062] In this embodiment, the composite structure 250 is provided by forming a graphene layer 251 on a flexible polyimide aerogel layer 252. In this case, the graphene is disposed onto the aerogel substrate using graphene platelets or powder provided in the form of an ink. This is achieved by dispersing graphene platelets in a solvent, applying the ink to the surface of the aerogel and removing the solvent to leave a layer of graphene platelets on the surface. This allows for the simple and relatively inexpensive application of a highly-conductive layer of graphene to the aerogel. Moreover, no further additives are required in the layer (e.g. a matrix). Alternatively, a method of providing the graphene layer 251 on the aerogel layer 252 can include the use of mill rolling, such as applying the graphene powder or platelets using a three-roll mill. This can allow for layering of the graphene without the need for solvents and in a relatively high-throughput manner.

[0063] Alternative composite structures will now be described with reference to FIGS. 7a to c. Referring now to FIG. 7a, a cross-section of a conductive element 303 is shown, which comprises a composite structure 350 having multiple first layers 351 and multiple second layers 352, which alternate through the structure. The first layers 351 comprise graphene platelets formed into a uniform graphene layer using a graphene ink solution, which is dried onto a substrate. The second layers 352 are comprised of an aerogel. This structure is very lightweight due to the use of aerogel and graphene only and thus provides a composite 350 that can be used in conductive elements 303 over very large distances without requiring significant support. Rather than being provided as a circular cable, as with the previous embodiments, the composite structure 350 in this embodiment can be used as a square or rectangular conductive member and/or conducting element. An example of such a composite structure (labelled 350) is shown in FIGS. 8a and 8b. In FIG. 8b, it is clear that this structure is flexible.

[0064] Referring now to FIG. 7b, a cross-section of a conductive element 403 is shown, which comprises a composite structure 450 having multiple first layers 451, second layers 452, and support layers 453. The first layers 451 comprise graphene platelets formed into a graphene layer. The second layers 452 are flexible polyimide aerogel layers. The support layers 453 are formed from CNT. As can be seen, the first layers 451, second layers 452, and support layers 453 form a repeating structure wherein the support layer 453 of one repeat unit is adjacent to the first layer 451 of the next repeat unit. In this embodiment, the first layers 451 are bonded to the adjacent second layer 452, which are in turn bonded to the adjacent support layer 453. The support layers 453 of one repeat unit are bonded on one surface to the coincident surface of the first layers 451 of the next repeat unit.

[0065] A further embodiment is shown in FIG. 7. In this embodiment, the composite structure 550 of a conductive element 503 is shown. In this embodiment, the composite structure 550 comprises a first layer 551, second layer 552, and support layer 553 which have been rolled over so as to form a series of overlapping layers. The second layer 552 is an aerogel layer. The support layer 553 is formed of a carbon nanotube fibre layer (CNT). As can be seen in FIG. 7c, each of the first layer 551, second layer 552, and support layer 553, is therefore continuous. In this embodiment, the first layer 551 is bonded to the second layer 552, which is in turn bonded to the support layer 553. Where the layers are overlapped, the inner surface of support layer 553 is in proximity to the outer surface of first layer 551, such that an air gap exists between the surfaces. In this embodiment, no bonding occurs between the inner surface of support layer 553 and the outer surface of first layer 551. This arrangement is provides a composite structure that is easy to manufacture and which provides substantial strength due to the overlapping layers and the materials used. This also provides a large graphene surface area, which leads to a high capacity for current to pass through the composite structure 550.

[0066] Manufacture of the composite structure 550 can, in some embodiments, comprise 1) depositing, by Atomic Layer Deposition (ALD), Chemical Vapour Deposition (CVD), vacuum deposition, or Physical Vapour Deposition (PVD) including sputtering or slot die processes, at least one graphene layer onto an aerogel layer to form a graphene/aerogel composite, 2) bonding at least one carbon nanotube fibre layer to the graphene/aerogel composite, such that the fibres are oriented lengthwise along the composite, using processes that involve vacuum bonding, including use of heat and pressure (for instance, roll presses), and such as to form a graphene/aerogel/carbon nanotube composite, 3) rolling the graphene/aerogel/carbon nanotube composite along the width of the composite, such that the rolling axis is oriented lengthwise along the composite, and such that the graphene layer is the outermost layer of the rolled laminate structure, and 4) bonding the rolled composite such that it remains in a rolled state. In some embodiments, the fabrication process described above may additionally include the step of bonding a further aerogel layer to the carbon nanotube fibre layer.

[0067] Although in some of the embodiments described above, the graphene layers are provided in the form of graphene platelets formed into a layer or by building up graphene layers using a thin-film deposition method, other types of graphene or manufacturing methods can be used. In some embodiments, the graphene layer is a holey graphene layeri.e. graphene comprising pores or holes (from 1 nm to several hundred nm, e.g. 1 to 300 nm) therein. Such materials have been found to be high-conductive and their preparation is set out in U.S. Pat. No. 9,120,677, which is incorporated herein by reference. To form a layer of holey graphene that can be used in the composite structures of the invention, mill rolling can be used, such as dispersion using a three-roll mill. This can allow for dispersion of the graphene without the need for solvents and in a relatively high-throughput manner. In particular, one method of forming the layer is to form a holey graphene layer onto a polymer film substrate using a mill rolling technique. The materials disclosed in U.S. Pat. No. 9,120,677 also include holey graphene carbon nanotubes (CNT), which can also be used as the CNT of the support layer.

[0068] Although the composite structures described in respect of the above embodiments extends substantially along the entire length of the respective conductive members, with the only exception being a terminal portion for connecting to an output, the composite structures in some embodiments may only extend partially along the length. Preferably, the composite structure extends at least 30% of the length of the conductive member and/or conducting element, at least 50%, at least 75%, at least 90% or at least 95%. In some embodiments, the composite structure extends along substantially all of the length of the conductive member and/or conducting element. By substantially all, it is meant that the composite structure extends along all of the length of the conductive member and/or conducting element but there may be some additional components in the form of end terminals which form part of the length of the conductive member. Furthermore, the composite structure extending along the conductive member and/or conducting element may be a single, continuous structure or may be comprised of a series of individual composite structures which are in electrical connection (for example, bonded together or held together). The latter may facilitate manufacture.

[0069] A further embodiment is shown in FIG. 9, which illustrates why composites comprising both graphene and aerogel are particularly effective for providing long conductive members (e.g. cables or wires) for use in devices according to the invention. In this embodiment, there is a composite structure 650 in a transverse cross-section. The structure 650 comprises a number of aerogel layers 652 which alternate with graphene layers 652. This structure 650 provides a useful backbone for a cable as the aerogel and graphene present in the first 651 and second 652 layers provides the strength and resilience required to function where significant shear forces 670 (dissipated in the structure 650 by the mechanisms depicted by arrows 675) will be acting on the elongate designs. Similarly, vibrations are dampened and absorbed by the aerogel layers 652 in the structure so as to minimise vibration through the structure.

[0070] As set out above, manufacturing the above laminates can be carried out by a number of methods. For example, where the graphene is a planar layer, the graphene may be deposited using a thin-film deposition method or, alternatively, by using an exfoliation technique. In one embodiment, a roll-to-roll manufacturing process is used. In particular, a flexible aerogel layer (for example, a cross-linked aerogel) is provided on a flexible substrate (e.g. a polymeric substrate film) and a graphene layer is formed on the aerogel using a thin film deposition method. In another embodiment, graphene can be formed using an epitaxial formation of graphene on a flexible metal substrate, which can then be layered with a flexible aerogel. Thus, graphene can be grown on a metal (e.g. ruthenium) and placed on aerogel, before these are removed from the substrate and used to construct a composite structure comprising multiple layers of graphene and aerogel. In another embodiment, the graphene layer may be formed as an ink which is used to coat an aerogel layer or film. In this way, the graphene, in the form of platelets or a powder, for example, can be readily applied to a number of substrates in a relatively straightforward manufacturing process. The other components making up the ink may remain in the graphene layer or may be removed after the layer has been applied.

EXAMPLES

[0071] In addition to the examples above, further specific examples of composite structures for use in the components above are provided below:

Example 1

[0072] A 125 m flexible polyimide aerogel layer (AeroZero 125 micrometer polyimide aerogel film; BlueShift Inc (US)) was cut to size and coated with a 20 m layer of graphene (Elicarb graphene powder; Thomas Swan & Co Ltd UK Product No. PR0953) in a polyurethane matrix (PX30; Xencast UK Flexible Series PU Resin system. Manufacturer reported properties: Hardness of 30-35 (Shore A); Tensile strength 0.7-1.2 MPa; Elongation 100-155% at break; Tear Strength 3.5-3.8 kN/m) using a slot die process. After coating, the graphene/polyurethane layer was left to cure and subsequently cut to size.

[0073] The graphene/polyurethane layer comprised 5 wt % functionalised graphene (Elicarb graphene powder; Thomas Swan & Co Ltd UK Product No. PR0953), which was dispersed in the polyurethane prior to slot die processing. More specifically, prior to dispersion, the graphene was treated with a plasma treatment of oxygen functionalisation using the Hydale HDLPAS process, which is set out in WO 2010/142953 A1 (alternatively, plasma functionalised graphene nanoplatelets are commercially available from Hydale HDPLAS GNP e.g. HDPlas GNP-O.sub.2 or HDPLAS GNP-COOH). Following treatment, the graphene and polyurethane are premixed in a planetary centrifugal mixer and the resin was degassed under vacuum to remove air bubbles. The mixture was then passed through a dispersion stage using a Three Roll mill (at 40 C. with a <5 m gap) and with eight passes. The graphene/polyurethane mixture was then mixed with a hardener, followed by subsequent degassing using a planetary centrifugal mixer.

[0074] Once the graphene/polyurethane mixture was created it was layered down onto a polypropylene sheet with a 20 m drawdown wire rod (which regulates the thickness to 20 m). After the layering down has been completed, the layer was left to dry out. However, before the graphene/polyurethane layer fully cures, the aerogel is stuck onto the layer so as to bond the layers together. The combined layers making up the structure were then left to cure for 24 hours, and after which the combined layer of aerogel and the polyurethane/graphene resin mixture was cut into shape.

[0075] An ultra-high molecular weight polyethylene (UHMWPE) fabric (Spectra 1000; 200D; Honeywell; 80 gsm; Warp Yarn 24 Tex; Weft Yarn 25 Tex; EncsPicks/10 cm 177177; Plain Weave) was cut to the same size as the backing structure and was applied to the upper surface of the backing structure (i.e. the exposed surface of the polyurethane layer).

[0076] The composite structure was then further built up by adding additional, alternating layers of the graphene layers and aerogel layers, together with UHMWPE fabric between each pair of graphene and aerogel layers to form a multi-layered composite. This process was repeated to provide a multi-layered composite comprising 90 layers comprising 30 aerogel layers, 30 graphene/polyurethane layers and 30 UHMWPE layers with the repeating structure: UHMWPE/graphene layer/aerogel layer. The layers of the composite were bonded together.

[0077] This composite structure was both flexible and lightweight and therefore can be used as a cable. The composite structure also provided effective protection against damage.

Example 2

[0078] Using the techniques described in respect of Example 1, above, a composite structure comprising 26 layers of UHMWPE fibre (DOYENTRONTEX Bulletproof unidirectional sheet; WB-674; 160 g/m.sup.2; 0.21 mm thickness) alternating with 25 layers of backing structure was prepared. The backing structure comprised 125 m flexible polyimide aerogel (AeroZero 125 micrometer film from BlueShift Inc (US)) layered with a 20 m layer of a polyurethane (PX60; Xencast UK) (i.e. 25 layers of aerogel alternating with 25 layers of polyurethane). In this Example, the polyurethane was infused with 0.2% graphene (Elicarb graphene powder; Thomas Swan & Co Ltd UK Product No. PR0953) using the technique set out in respect of Example 2. Thus, the composite had the following repeating pattern arrangement of layers . . . UHMWPE layer/polyurethane+graphene layer/aerogel layer/UHMWPE layer/polyurethane+graphene layer/aerogel layer . . . .

Example 3

[0079] Using the techniques described in respect of Example 1, above, a composite structure comprising 26 layers of UHMWPE fabric (Spectra 1000; 200D; Honeywell; 80 gsm; Warp Yarn 24 Tex; Weft Yarn 25 Tex; EncsPicks/10 cm 177177; Plain Weave), 25 layers of 125 m flexible polyimide aerogel (AeroZero 125 micrometer film from BlueShift Inc (US)) and 25 layers of a 20 m layer of a polyurethane (PX60; Xencast UK) doped with 1% graphene (Elicarb graphene powder; Thomas Swan & Co Ltd UK Product No. PR0953). Thus, the laminate had the following repeating pattern arrangement of layers . . . UHMWPE layer/polyurethane+graphene layer/aerogel layer/UHMWPE layer/polyurethane+graphene layer/aerogel layer . . . .

Example 4

[0080] A composite structure 1101 is shown in FIGS. 14a (top view) and 14b (underside view). The composite structure 1101 comprises a repeating structure comprising an aerogel film (125 m flexible polyimide aerogel; AeroZero 125 micrometer film from BlueShift Inc (US)), a graphene particle infused epoxy (Elicarb graphene powder; Thomas Swan & Co Ltd UK Product No. PR0953) and a high-tensile polyoxymethylene (POM) layer (Delrin). Thus, the composite structure 1101 has a sub-unit of aerogel/graphene-infused epoxy/POM which repeats throughout the structure to form a composite having alternating graphene and aerogel containing layers.

[0081] The composite structure 1101 is manufactured by firstly functionalising the graphene nanoplatelets in a Haydale plasma reactor (using a carboxyl process) and subsequently dispersing the graphene nanoplatelets in a flexible epoxy. The graphene/epoxy mixture was subsequently slot die coated onto the Aerogel film and then layered with the POM layer (in the form of a fabric). This sub-unit is then vacuum-cured at room temperature. The structure was then built up by bonding multiple sub-units together on top of one another to form the composite structure 1101. In this way, an aerogel layer of one sub-unit was bonded to a POM layer of an adjacent sub-unit. Furthermore, the lowermost sub-unit of the composite structure 1101 was provided with a POM layer on its underside so that POM layers form the uppermost and lowermost layers.

[0082] The composite structure 1101 was flexible, strong and light and thus provides an excellent composite for use in aerospace and/or vehicle skin applications. The composite structure 1101 shown (dimensions 143 mm193 mm) had a weight of 61 g, whereas a comparative example of similarly-sized (with the exception of thickness) carbon-fibre aerospace composite having similar properties weighed 514 g. The comparative carbon-fibre aerospace composite panel was 4 thicker than the prototype panel; however, even scaling the composite structure 1101, the comparable weight of the composite structure would have been 244g, or less than half the weight of the carbon fibre aerospace composite, with improved properties.

Example Modifications

[0083] It will be appreciated that modifications can be made to the above examples to optimize the desired properties. For example, if it is desirable to increase the conductivity of the first (graphene-containing) layer(s) composite material, the amount of graphene relative to polymer could be increased. Alternatively, the polymer could be removed, and the graphene applied with no matrix (e.g. as platelets or particles in an ink or using any other suitable method) or as planar graphene layers (e.g. by thin-film deposition of any other suitable method).

[0084] Although the invention has been described with reference to specific embodiments and examples above, it will be appreciated that modifications can be made to the embodiments and examples without departing from the invention. For example:

[0085] the conductive member and the collecting member may be different portions of the same component, element or member or, alternatively, may be separate elements or members;

[0086] the collecting element may be any component able to draw electricity from the atmosphere, including, for example, antenna, exposed conductive surfaces of the composite (e.g. which may take the form of apertures through other layers), metal rods and other similar devices; and

[0087] additional layers (beyond those referred to above) may be provided.