WO2020065334A1

WO2020065334A1 - Method of processing substrate for an energy storage device

Info

Publication number: WO2020065334A1
Application number: PCT/GB2019/052730
Authority: WO
Inventors: Alexander John Topping
Original assignee: Power Roll Limited
Priority date: 2018-09-28
Filing date: 2019-09-27
Publication date: 2020-04-02
Also published as: GB2591378A; GB201815842D0; JP2022502853A; GB202103274D0; GB2591378B

Abstract

The present invention relates to a method of processing a substrate for an energy storage device comprising providing a drum arranged to transport a moving substrate, the drum having an electromagnetic charge. A substrate to be moved is provided and a plurality of curing stations are provided around the circumference of the drum. Each curing station performs the steps of depositing a precursor on the surface of the moving substrate, generating a plasma and directing the plasma onto the surface of the moving substrate such that the precursor is reacted to form a material layer on the substrate without substantially raising the temperature of the substrate.

Description

METHOD OF PROCESSING SUBSTRATE FOR AN ENERGY STORAGE DEVICE

[0001] This present invention relates to a substrate for an energy storage device and a method of processing same.

BACKGROUND

[0002] Ceramic-based and film-based capacitors are useful for a number of applications including control measurement and power applications. Film capacitors are often produced in a roll-to-roll process where the polymer or flexible substrate becomes the dielectric material sandwiched between conductors that are often vacuum coated onto the film. Ceramic capacitor coatings can be applied to any suitable substrate and applications to flexible substrates using roll-to-roll processing lowers the cost and increases the production speed. Other materials can also be used to generate capacitors for commercial applications and the application of these to flexible substrates can generate capacitor structures that can be easily transformed into wound or layered commercial products.

[0003] A number of methods for producing suitable capacitor coatings are known, for example, High Speed Physical Vapour Deposition (PVD). This method is relatively high speed and low cost, but can produce relatively thin and sometimes porous or defective coatings, where pin holes that when sandwiched between conductors may promote short circuiting. Improved coating properties can be achieved through a number of known techniques including but not limited to reactive sputtering, Chemical Vapour Deposition and Atomic Layer Deposition. However, all of these techniques are low speed and therefore high cost, particularly when used in roll-to-roll processing.

[0004] Plasma Enhanced Chemical Vapour Deposition (PECVD) is also a known technique for producing coatings. However, in PECVD the deposition rate is limited as the coating will only be deposited in a generated plasma zone. Increasing the amount of precursor materials applied has an effect of quenching the plasma (due to increasing process pressure and thus makes maintaining a plasma require increased voltages) which stops the deposition of the coating. Therefore, although high quality coatings can be produced with this technique, it is a low speed technique, which results in low line speed when the technique is used in roll-to-roll processing.

[0005] The speed of coating can be increased in principle by using many coating areas and using the same PECVD process at each stage. Such an approach would result in longer web paths so that each station can be passed and thus coat the substrate. The deposition rate at each station in order to get the required coating quality is related to the material flow, applied power and the local vacuum level, etc. As such, this would require a large and complex control system with several instabilities when the kinetics of stabilisation in a vacuum are considered, such as vacuum pumping speed variations, gas conductance variations and local area history adding to uncontrolled gas load, etc.

[0006] Multiple individual racetracks, powered from a single power source have been used to increase line speed. However, there are a number of disadvantages associated with such an arrangement. Specifically, it can be very difficult to ensure that the racetracks are stable and equal. Any differences and variance in the gas pressures and precursor delivery around the circumference of the plasma roller can result in uneven powering of individual racetracks. Such an arrangement therefore requires very high engineering tolerances and tight control and consistency of the magnets and process pressures when multiple individual racetracks are generated from a single power source.

[0007] It is an object of the invention to alleviate or mitigate at least one or more of the aforementioned problems.

BRIEF SUMMARY OF THE DISCLOSURE

[0008] In accordance with the present invention there is provided a method of processing a substrate for an energy storage device according to appended claims 1 to 17, a substrate for an energy storage device according to appended claims 18 to 33 and an energy storage substrate according to appended claims 34 to 36.

[0009] According to a first aspect of the present invention, there is provided a method of processing a substrate for an energy storage device comprising:

providing a drum arranged to transport a moving substrate, the drum having an electromagnetic charge;

providing a substrate to be moved; and

providing a plurality of curing stations around the circumference of the drum, wherein each curing station performs the steps of:

depositing a precursor on the surface of the moving substrate;

generating a plasma; and

directing the plasma onto the surface of the moving substrate such that the precursor is reacted to form a material layer on the substrate without substantially raising the temperature of the substrate.

[0010] The plasma preferably comprises a reactive gas. In this way, the plasma dissociates the precursor and the reactive gas reacts with the dissociated precursor to form the material layer.

[0011] By processing a substrate in this way, the reaction between a precursor and plasma can occur at multiple sites simultaneously to form material layers, improving the speed and uniformity of the process. By using plasma, the substrate can be processed without raising the temperature substantially and damaging the substrate. In certain embodiments, the substrate temperature can be maintained at less than 100°C. In this way, the method is suitable for producing an energy storage device in a low temperature, roll-to-roll process. Further still, material layers free from pin holes can be produced at low temperature and high speed.

[0012] In an alternative aspect of the present invention, there is provided a method of processing a substrate for an energy storage device comprising:

providing a substrate to be moved; and

providing a vapourised precursor of a material coating;

providing a plurality of curing stations spaced apart from one another around the circumference of the drum, each curing station performing the steps of:

generating a plasma comprising a reactive gas, the plasma being spatially defined by the electromagnetic charge of the drum; and

mixing the vapourised precursor with the plasma such that the precursor is dissociated by the plasma and the dissociated precursor is reacted with the reactive gas to form a material coating which is deposited on the substrate as a material layer without substantially raising the temperature of the substrate.

[0013] The following embodiments relate to the first and further aspects of the invention.

[0014] In certain embodiments, the method includes the step of providing a vacuum chamber in which the drum, plurality of curing stations and substrate are provided.

[0015] In certain embodiments, power is supplied to the drum by a high voltage supply of either alternating current (AC) or direct current (DC).

[0016] In certain embodiments, the material layer comprises a dielectric material. The dielectric material may be titanium dioxide.

[0017] In certain embodiments, the material layer comprises a dielectric material selected from one or more of the following: Titanium oxide, Tantalum oxide, Niobium oxide, Barium titanate, Strontium titanate and Calcium copper titanate.

[0018] In certain embodiments, the dielectric material is doped with one or more of iron, cerium, manganese and calcium.

[0019] In certain embodiments, the plasma contains a reactive gas. More specifically, the plasma contains a reactive gas or a reactive gas mixture. When used herein,“reactive gas” means a gas other than a noble gas and“reactive gas mixture” means a mixture of gases including a portion of a noble gas. Yet more specifically, the reactive gas or reactive gas mixture is or contains one or more of: oxygen, nitrogen or the like.

[0020] In certain embodiments, the substrate to be moved comprises a plurality of grooves each groove having a first face and a second face, the first face and the second face each having a coat of non-insulating material. In certain embodiments, the face and/or the second face of the groove may be partially or substantially wholly coated with the non-insulating material. Without wishing to be bound by theory, in certain embodiments it is preferred for the face and/or the second face of the groove to be partially coated with the non-insulating material. In this way, the material layers deposited in the groove extend further into the groove that the non-insulating materials on the faces of the grooves.

[0021] In certain embodiments, the method comprises providing a plurality of curing stations located around the circumference of the drum. Each curing station performs the steps of:

depositing a precursor in at least one groove of the plurality of grooves;

generating a plasma; and

directing the plasma onto the at least one groove such that the precursor in the groove is reacted to form a material layer in said groove.

In this way, the process can be used to provide multi-layered material within the grooves on a substrate.

[0022] In alternative embodiments, the method comprises providing a plurality of curing stations located around the circumference of the drum. Each curing station performs the steps of:

generating a plasma containing a reactive gas; mixing the plasma and the vapourised precursor in order to dissociate the precursor such that the dissociated precursor is reacted with the reactive gas to form a material coating;

and

directing the plasma onto the at least one groove such that the material coating is deposited to form a material layer in said groove.

[0023] The dissociated precursor is capable of reacting with the reactive gas in order to provide a material coating which forms a material layer when deposited in the groove.

[0024] In certain embodiments, the plurality of curing stations are configured to deposit or generate the same precursor. Thus, the thickness of material can be increased by forming multiple thin layers at the plurality of curing stations. [0025] In certain embodiments, the plurality of curing stations are configured to deposit or generate at least two different precursors. Thus, the material chosen for the precursor can be varied. Different precursors can be used at different stations depending on the material properties desired. For example, materials can be selected based on the electrical properties desired, or on the mechanical properties desired.

[0026] In certain embodiments, the plurality of curing stations are provided such that the at least two different precursors or, in alternative embodiments the material coatings formed from the at least two different precursors are deposited in the at least one groove in an alternating sequence. More specifically, the at least two different precursors or, in alternative embodiments the material coatings formed from the at least two different precursors are deposited in the at least one groove in such a way that the at least two precursors or, in alternative embodiments the material coatings formed from the at least two different precursors are stacked on top of one another in a repeated pattern. By providing a plurality of curing stations that can deposit at least two different precursors in an alternating pattern, or, in alternative embodiments that can generate at least two different precursors which are reacted with a plasma comprising a reactive gas to provide material coatings formed from the at least two different precursors, the arrangement of the precursors can be customised based on the desired electrical characteristics. More specifically, the arrangement can be customised to increase the amount of energy storable in the device. In this way, if voltage potential difference causes electrical breakdown the breakdown voltage of the capacitor formed in the groove or on the surface of the substrate will not depend on the thickness of the capacitor material between any two adjacent electrodes (with adjacent electrodes only having capacitor material between them).

[0027] In certain embodiments, the two different precursors are precursors of a dielectric material and an electrically conductive material. More specifically, the dielectric material and the electrically conductive material are deposited in an alternating sequence.

[0028] In certain embodiments wherein, when the groove is filled with material layers, the final curing station deposits or generates a precursor of either dielectric material or conductive material.

[0029] In certain embodiments wherein the groove is partially filled, and an air gap exists between the material layer(s) on the first face and the material layer(s) on the second face of the groove, the final curing station deposits or generates an electrically conductive material in the groove. In this way, no capacitor comprising air as the dielectric is formed in the gap which would otherwise dominate the capacitance characteristics of the groove.

[0030] In certain embodiments, the non-insulating material is a conductor material. [0031] In certain embodiments, the precursor is vaporised before it is deposited on the surface of the moving substrate. Alternatively, the precursor is vapourised before mixing with the plasma causing dissociation of the vapourised precursor.

[0032] In certain embodiments, each material layer is continuous between the first face and the second face of each groove. More specifically, each dielectric material layer is continuous between the first face and the second face of each groove.

[0033] In certain embodiments, when the precursor is of an electrically conductive material, the electrically conductive layer is discontinuous in the groove. More specifically, the electrically conductive material layer comprises first and second portions which are electrically separated from one another. In this way, electrical shorting across the groove is avoided. In certain embodiments, the precursor may be a precursor of one of: titanium, tantalum, niobium, barium, strontium or copper.

[0034] In certain embodiments, the method comprises the step of applying a non-insulating (e.g. electrically conductive) material layer onto the surface of the moving substrate using a coating process. The coating process may be an off-axis coating process for example when the non-insulating (e.g. electrically conductive) material layer is deposited in a groove in the substrate.

[0035] In certain embodiments, the non-insulating (e.g. electrically conductive) material layer is applied sequentially onto a dielectric material layer. In this way, alternating dielectric and non-insulating material layers are deposited on the surface of the moving substrate or, in certain embodiments, into the groove in the moving substrate.

[0036] In certain embodiments, the non-insulating material on the first face and the non insulating material on the second face are electrically separated from each other.

[0037] In certain embodiments, the drum is cooled by a coolant.

[0038] In certain embodiments, the precursor is a metal organic precursor.

[0039] In certain embodiments, the metal organic precursor is one or more of: Titanium(IV) isopropoxide, Titanium(IV) ethoxide, Titanium(IV) chloride, Tantalum(V) ethoxide, Tantalum(V) chloride, Niobium(V) ethoxide, Niobium(V) chloride, q5-cyclopentadienyl)- tetracarbonylniobium, Bisdipivaloylmethanate barium and Barium hexafluoroacetylacetonate pentaethyleneglycol ethyl butyl ether.

[0040] In certain embodiments the precursor is or comprises: Titanium isopropoxide, Titanium ethoxide, Iron isopropoxide, Ferrocene, Dimethylferrocene, Tris(2,2,6,6-tetramethyl-3,5-heptanedionato) iron(lll), Cerium isopropoxide, Tetrakis(2,2,6,6-tetramethyl-3,5-heptanedionato)cerium(IV), Bis(n- propyltetramethylcyclopentadienyl) barium, Bis(2,2,6,6-tetramethyl-3,5- heptanedionato)barium hydrate, Barium titanium(IV) 2-ethylhexanoate pentaisopropoxide, Titanium(IV) chloride, Tantalum(V) chloride, Niobium(V) ethoxide, Niobium(V) chloride, h5- cyclopentadienyl)-tetracarbonylniobium, Bisdipivaloylmethanate barium or Barium hexafluoroacetylacetonate pentaethyleneglycol ethyl butyl ether.

[0041] In certain embodiments, the precursor comprises a precursor of titanium dioxide.

[0042] In certain embodiments, the precursor comprises a precursor of one or more of the following: Titanium oxide, Tantalum oxide, Niobium oxide, Barium titanate, Strontium titanate and Calcium copper titanate.

[0043] According to a further aspect of the present invention, there is provided a substrate for an energy storage device processed by the method according to the first aspect of the present invention.

[0044] According to a yet further aspect of the present invention, there is provided a substrate for an energy storage device processed by the method of the further aspect of the present invention.

[0045] In certain embodiments, the substrate for an energy storage device comprises: a plurality of grooves, each groove having a first face and a second face, the first face and the second face each having a coat of non-insulating material; and

a plurality of material layers in each groove of the plurality of groove, each material layer formed by depositing a precursor into each groove and reacting the precursor with a plasma.

In this way, the substrate has an increased surface area for receiving the deposited precursor and a greater surface area for reacting the precursor with a plasma.

[0046] In certain embodiments, the substrate for an energy storage device comprises: a plurality of grooves, each groove having a first face and a second face, the first face and the second face each having a coat of non-insulating material; and

a plurality of material layers in each groove of the plurality of groove, each material layer formed by generating a vapourised precursor;

generating a plasma comprising a reactive gas; and

mixing the vapourised precursor with the plasma such that the precursor is dissociated by the plasma and the dissociated precursor is reacted with the reactive gas to form a material coating which is then deposited into each groove on the substrate as a material layer. [0047] In certain embodiments, the plurality of material layers comprise a dielectric material layer. The dielectric material may be titanium dioxide.

[0048] In certain embodiments, each of the plurality of material layers comprise the same material.

[0049] In certain embodiments, the plurality of material layers comprise at least two layers of different materials. Thus, the arrangement of the material layers can be customised based on the desired electrical characteristics. More specifically, the arrangement can be customised to increase the amount of energy storable in the device.

[0050] In certain embodiments, in the at least two layers of different materials, at least one layer comprises a dielectric material and at least one layer comprises a conductor material.

[0051] In certain embodiments, the at least two different material layers are arranged in an alternating sequence. More specifically, the at least two different material layers are arranged in such a way that the at least two material layers are stacked on top of one another in a repeated pattern.

[0052] In certain embodiments, at least one material layer comprises a capacitor material with a dielectric constant of above 10.

[0053] In certain embodiments, at least one material layer comprises a polymer material.

[0054] In certain embodiments, the polymer material is conjugated.

[0055] In certain embodiments, at least one layer comprises a conductive material.

[0056] In certain embodiments, at least one material layer comprises a radio-curable binder.

[0057] In certain embodiments, each material layer has a thickness of between 5nm and 300nm. Preferably, each material layer has a thickness of about 100nm.

[0058] In certain embodiments, the substrate for an energy storage device comprises at least two dielectric material layers in each groove.

[0059] In certain embodiments, the substrate for an energy storage device comprises at least two dielectric layers and a conductive layer positioned in between the dielectric layers.

[0060] According to a yet further aspect of the present invention, there is provided an energy storage substrate comprising a plurality of grooves, each groove having a first face and a second face. The first face and the second face each have a coat of non-insulating material. Each groove has a plurality of material layers each formed by depositing a precursor of the material layer into each groove and reacting the precursor with a plasma. [0061] According to a further aspect of the present invention, there is provided an energy storage substrate comprising a plurality of grooves, each groove having a first face and a second face. The first face and the second face each have a coat of non-insulating material. Each groove has a plurality of material layers each formed by depositing a material coating, formed by reacting a vapourised precursor and a plasma comprising and reactive gas, as a material layer into each groove.

[0062] In certain embodiments, the face and/or the second face of the groove may be partially or substantially wholly coated with the non-insulating material. Without wishing to be bound by theory, in certain embodiments it is preferred for the face and/or the second face of the groove to be partially coated with the non-insulating material. In this way, the material layers deposited in the groove extend further into the groove that the non-insulating materials on the faces of the grooves.

[0063] According to a still further aspect of the present invention, there is provided a planar energy storage substrate comprising a plurality of material layers. Each material layer is formed by depositing a precursor of the material layer and reacting the precursor with a plasma.

[0064] Alternatively, each material layer is formed by depositing a material coating, formed by reacting a vapourised precursor of the material layer and a plasma comprising and reactive gas, as a material layer.

BRIEF DESCRIPTION OF THE DRAWINGS

[0065] Embodiments of the invention are further described hereinafter with reference to the accompanying drawings, in which:

Figure 1 is a schematic diagram of an apparatus for curing or processing a substrate according to the prior art;

Figure 2 is a schematic diagram of a drum for use in a method according to embodiments of the invention having a serpentine racetrack;

Figure 3 is a schematic diagram of a magnet array for producing a racetrack as shown in Figure 2;

Figure 4 is a schematic representation of a method of providing multiple material layers in a groove-based capacitor according to an embodiment of the invention;

Figure 5 is a schematic diagram of a flat substrate according to an embodiment of the invention with multiple coated material layers and intermediate conductors; Figure 6 is a schematic diagram of a substrate according to an embodiment o the invention comprising a groove-based capacitor when filled during separate coating steps with intermediate conductor coatings so as to create an energy storage device;

Figure 7a is a schematic diagram of a substrate for an energy storage device comprising a filled groove with dielectric material layers and intermediate conductor layers;

Figure 7b is a resultant equivalent circuit diagram of the substrate of Figure 7a;

Figure 8 is a three-dimensional schematic representation of a portion of a grooved substrate showing the features required for external coating and defining the region of substrate that can be coated/filled so as to produce a capacitive structure with a single fill or multiple conductor capacitor alternating layers;

Figure 9 is a three-dimensional schematic diagram showing how a substrate for a groove-based energy storage device can be filled and then over coated with capacitor material and a top floating electrode included for increased capacitance also includes the effective capacitance circuit with indication of what conductor forms which connection within said circuit;

Figure 10 is a schematic diagram of an apparatus for curing or processing a substrate;

Figure 11 is a schematic diagram of an apparatus for curing or processing a substrate; and

Figure 12 is schematic diagram of an apparatus for curing or processing a substrate.

DETAILED DESCRIPTION

[0066] Figure 1 shows an apparatus 100 according to the prior art for processing or curing a substrate comprising a rotating drum 102, transporting a moving web substrate 104 over the surface of the drum 102. Located adjacent to the drum 102 there is provided a precursor inlet 106 arranged to apply a precursor 108 to the substrate as it passes underneath the precursor inlet 106. Adjacent to the drum 102 and subsequent to the precursor inlet 106 along the processing line is located a plasma generator 110 arranged to generate a plasma 112. Located inside the drum 102, or alternatively outside of it, there is provided a magnet array 1 14 arranged to spatially define the plasma 1 12. The apparatus is located inside a vacuum chamber (not shown). In the embodiment shown in Figure 1 , the web substrate is a polymeric film, for example PET. However, any suitable web-based substrate could be used.

[0067] As shown in Figure 2, the magnet array 114 is arranged to generate a serpentine shaped racetrack 202 around the surface of the drum 102. The racetrack 202 comprises a number of straight magnetic flux portions 204 linked together at alternate ends by curved end portions 206 to form a serpentine race track 202.

[0068] Figure 3 shows the magnet array 1 14 of Figure 2. The magnet array comprises a first elongate magnet 304 having a polarity such that the north pole of the magnet 304 faces in a direction pointing radially out of the drum 102 and the south pole of the magnet 304 faces in a direction pointing towards the centre of the drum 102.

[0069] A second elongate magnet 306 is located adjacent to the first elongate magnet 304. The second elongate magnet 306 is spaced from the first elongate magnet 304 and the longitudinal axis of the second elongate magnet 306 is aligned parallel to the longitudinal axis of the first elongate magnet 304. The second elongate magnet 306 has an opposite polarity to the first elongate magnet 304 such that the south pole of the second elongate magnet 306 faces in a direction pointing radially out of the drum 102 and the north pole of the magnet 306 faces in a direction pointing towards the centre of the drum 102.

[0070] A third elongate magnet 308 is located adjacent to the second elongate magnet 306. The third elongate magnet is spaced from the second elongate magnet 304 and the longitudinal axis of the third elongate magnet 308 is aligned parallel to the longitudinal axis of the first elongate magnet 304 and the second elongate magnet 306. The third elongate magnet has the same polarity as the first elongate magnet 304.

[0071] A fourth elongate magnet 310 is located adjacent to the third elongate magnet 308. The fourth elongate magnet is spaced from the third elongate magnet 304 and the longitudinal axis of the fourth elongate magnet 310 is aligned parallel to the longitudinal axis of the other elongate magnets 304, 306 and 308. The fourth elongate magnet has the same polarity as the second elongate magnet 304.

[0072] The transverse centres of the first and third elongate magnets (304 and 308 respectively) are aligned with each other. The transverse centres of the second and fourth elongate magnets (306 and 310 respectively) are also aligned with each other, but the transverse centres second and fourth magnets 306, 310 are offset with respect to the transverse centres of the first and third elongate magnets 304, 308. Thus, the magnet array 114 is arranged to such that each elongate magnet defines a passage region, where its first end terminates prematurely in comparison to flanking ends of adjacent elongate magnets to encourage flux flow around the first end, and a blocking region, where its second end projects beyond terminating magnet ends of the adjacent magnets to inhibit flux flow around the second end of the magnet.

[0073] Figure 4 shows a groove-based capacitor that is filled through multiple coatings to generate a filled capacitor volume. The section of the substrate 402 depicted in Figure 4 has three grooves 404 each having a first face 404a and a second face 404b. The first face 404a is coated with a conductor material 406a and the second face 404b is coated with a conductor material 406b. The conductor material 406a on the first face 404a and the conductor material 406b on the second face 406b are electrically separated from each other. As better seen in Figure 10 which illustrates a method for curing or processing the substrate, the substrate is processed by a plurality of curing stations located around the circumference of the drum 1002. Each curing station has a precursor depositing station 1008 that is arranged to deposit a precursor of titanium dioxide into the grooves 404 of the substrate 402 and directing a generated plasma 1010 onto the grooves 404. The precursor may first be vaporised before it is deposited.

[0074] Referring now back to Figure 4, directing the generated plasma onto the groove 404 reacts the precursor within the grooves 404 to form a material layertherein. This process is repeated so that a plurality of layers of titanium dioxide dielectric material are formed within the grooves 404 to fill the volume of the groove 404. The material layers are continuous between the first face 404a and the second face 404b of each groove 404b. In this embodiment, the plurality of curing stations are configured to deposit the same precursor, i.e. precursor of titanium dioxide. However, it will be appreciated that the plurality of curing stations can be configured to deposit a different precursor such as a conductor material and a metal organic precursor or a non-metal organic polymer precursor, or at least two different types of precursors arranged in a number of possible variations. For example, in an alternating sequence where the precursors are stacked (i.e. layered) on top of one another in a repeated pattern. In alternative embodiments, the vapourised precursor of titanium dioxide is delivered into the vacuum chamber (not shown) alongside plasma containing reactive, oxygen gas generated by the curing station. The plasma acts to dissociate the precursor and the dissociated precursor reacts with the oxygen in the plasma to form titanium dioxide material coating which is then deposited in the groove 404. The plasma is spatially defined by the magnetic array such that the material coating is deposited in the current position on the substrate.

[0075] Figure 5 shows a flat substrate for an energy storage device with multiple coated layers. The substrate has a base layer 501 , or PET or similar and a number of material layers 503. The dielectric layers 503 are separated from one another by intermediate conductor layers 502 such that an alternating sequence of dielectric layers 503 and conductors 502 is formed. This alternating sequence of dielectric layers 503 and conductors increases the operating voltage of the substrate.

[0076] Figure 6 shows a portion of a substrate for an energy storage device comprising a groove-based capacitor. The groove-based capacitor 602 is filled with multiple continuous dielectric layers 604 with intermediate discontinuous conductor layers 606. The discontinuous conductor layers 606 comprise two portions electrically separated from one another in the region of the bottom of the groove. In this way, electrical short circuits are avoided within the groove. The capacitor 602 has a conductor layer 608 arranged on top of the multiple dielectric layers 604. In this embodiment, the capacitor 602 has conductor layers 606, however, it will be appreciated that the capacitor 602 can be formed only of dielectric layers 604 such that the groove 610 is filled with dielectric material and the conductive coatings 612 on the first face 614a and second face 614b of the groove 610 are electrically connected through the dielectric material. By having multiple alternating dielectric 604 and conductor 606 layers arranged on top of one another, the voltage of the device is increased.

[0077] Figure 7a shows a part of a substrate for an energy storage device comprising a filled groove 702 with multiple dielectric layers 704 with intermediate conductor layers 710. The groove 702 has a final dielectric layer 708 which overfills the groove 702. The multiple coating layers 704, 710, 708 thereby forming capacitors in series across the grove between the conductive coatings 712 on the first face 714a and second face 714b of the groove 702. By having multiple coating layers 708 arranged on top of one another, the voltage of the capacitors across the groove are added to provide the total voltage across the groove.

[0078] Figure 7b shows the resultant equivalent circuit of the filled groove of Figure 7a. Arranging the multiple coating material layers 704, 710, 708 of alternating dielectric material and conductor material on top of each other forms a series circuit 750 of capacitors 752, which increases the voltage of the device.

[0079] Figure 8 shows a three-dimensional schematic representation for a substrate for an energy storage device comprising a grooved substrate for a capacitor construction. It shows the groove in a structured substrate 803, which comprises: 803a a non-conducting portion of the groove; 803c the portion of the groove where conductors have been coated onto the walls and associated flat portions of the structured substrate and 803b a non-conductor coated section of groove at the end. The charge extraction portions comprising a conductive coating 806a and 806b are provided at a depressed edge feature where the conductor can be contacted by an electrical load to form a circuit. 805a and 805b are indicated profiles allowing the coating 806 to be presented for contact even if multiple layers of capacitor substrate are rolled, laminated or otherwise stacked. 801 denotes a limiting line for the application of the capacitor coating, wherein the capacitor material coating does not cover the whole of the substrate as edges need to be provided for external connection. In the depicted embodiment, the depressed edge profile features 805a and 805b mean that the capacitor material coating can reach the edge of the flat section of the substrate. But for engineering reasons having a lower width limit indicated by 801 is preferred. [0080] Figure 9a shows a partially cut away section of a substrate comprising a single layer of capacitor dielectric material 902 derived from multiple coating stages of sufficient thickness to fill and overfill the groove 903. The groove is coated upon first and second vertical walls with conductors that are connected in turn to the flat portions 906a and 906b of the substrate adjacent each vertical wall. The top of the capacitor material is further coated with a conductor 904. The total electrical interconnections are shown in the circuit diagram in Figure 9b. Conductors 906a, 906b and 904 are the conducting elements that make the relevant electrical connections to the groove and the flat portions of the structured substrate generating the compound capacitor indicated in the electrical circuit. Edge exposure through restriction of capacitor coating or edge profiling as shown in Figure 8 are omitted for clarity purposes.

[0081] Figure 10 shows an apparatus for undertaking the process according to a further embodiment of the invention generally at 1000. The apparatus 1000 is arranged to deposit a titanium dioxide dielectric layer precursor onto a substrate. A moving web 1004 is transported around a water-cooled drum 1002 that is itself charged either positively or preferably negatively with respect to earth by an AC or pulsed DC power source (not shown). The web 1004 is guided on and off the drum 1002 by guide rollers 1006. These 1006 rollers may be driven or idle. Whilst it is transported around the drum the web 1004 is alternatingly dosed with precursor metal organic Titanium(IV) isopropoxide, from one of a plurality of precursor inlet points 1008 then plasma reacted to form the coating layer (titanium dioxide) and cured polymer systems dependent upon the type of monomer or precursor used for example by that element station) by discrete plasma race track portions 1010. The race track is formed by a permanent magnet array (not shown) that can be either external to the drum or held entirely within the drum, such as the magnet arrays shown in Figures 2 or 3, or a combination of the two.

[0082] The reactive gas, such as 0₂, N2O, NH3 etc., that can react with the precursor can be delivered into the chamber generically in which case the reaction primarily occurs within the plasma race track portions 1010, or where these interact with the surface of the web. Alternatively, the reactive gas can be delivered at the same position as the precursor is dosed 1008. In this case the reactive gas can either be controlled and dosed independently or mixed and dosed with the precursor material.

[0083] Figure 10 also indicates a method for curing or processing a substrate using the apparatus, the method including the steps of, firstly, at step 1003, the substrate is transported underneath a first precursor inlet 1008, which applies precursor to the surface of the moving substrate 1004. Secondly, a generated plasma 1010 is directed onto the surface of the substrate 1004 such that the precursor on the surface of the substrate 1004 is reacted to form a first layer at 1010. The substrate 1004 is then transported under a second precursor inlet 1018 which applies a second dose of precursor. In this embodiment, the second dose deposits the same precursor as the first dose. In alternative embodiments the first dose deposits a precursor of a dielectric material and the second dose deposits a precursor of an electrically conductive material. The substrate is then transported into a second plasma racetrack zone such that the second layer of precursor is reacted to form a second layer on top of the first layer. Optionally, the substrate may pass through additional element stations arranged to repeat the steps of dosing with precursor and plasma processing so that eventually a layer of required thickness (typically between 30 and 300 nm and more preferably between 100 and 300 nm) is built up.

[0084] Although the method and apparatus of Figures 10 to 12 use a precursor, the skilled person will appreciate that in other embodiments of the method and apparatus, other precursors could be used to obtain various coatings and material combinations.

[0085] Preferably the magnet array is housed within the deposition roller as displayed in Figure 12, rather than outside as shown in Figure 1 1 , as this allows more space for the precursor deposition equipment around the drum and enables the shape and position of the race track portions to be more easily controlled.

[0086] The discrete race track portions 1010 can be generated as a number of individual parallel racetracks on the deposition roller. Alternatively, they may be generated by a magnet array designed to produce a single racetrack which snakes around the drum with a number of discrete parallel or largely parallel (<5° off parallel) race track portions where the reaction of the precursor occurs.

[0087] Various modifications to the detailed designs are described above are envisaged. It will be clear to a person skilled in the art that features described in relation to any of the embodiments described above can be application interchangeably between the different embodiments. The embodiments described above are examples to illustrate various features of the invention.

[0088] Throughout the description and claims of this specification, the words“comprise” and“contain” and variations of them mean“including but not limited to”, and they are not intended to (and do not) exclude other moieties, additives, components, integers or steps. Through the description and claims of this specification, the singular encompasses the plural unless the context otherwise requires. In particular, where the indefinite article is used, the specification is to be understood as contemplating plurality as well as singularity, unless the context requires otherwise. [0089] Features, integers, characteristics, compounds, chemical moieties or groups described in conjunction with a particular aspect, embodiment or example of the invention are to be understood to be applicable to any other aspect embodiment, or example described herein unless incompatible therewith. All of the features disclosed in this specification (including any accompanying claims, abstract or drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive. The invention is not restricted to the details of any foregoing embodiments. The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.

[0090] The reader’s attention is directed to all papers and documents which are filed concurrently with or previous to this specification in connection with this application and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference.

Claims

1. A method of processing a substrate for an energy storage device comprising:

providing a drum arranged to transport a moving substrate, the drum having an electromagnetic charge and providing a substrate to be moved;

providing a plurality of curing stations located around the circumference of the drum, wherein each curing station performs the steps of:

depositing a precursor on the surface of the moving substrate;

generating a plasma; and

2. A method of processing a substrate for an energy storage device comprising:

providing a substrate to be moved; and

providing a vapourised precursor of a material coating;

providing a plurality of curing stations in the chamber and spaced apart from one another around the circumference of the drum, each curing station performing the steps of:

3. A method according to claim 1 or claim 2, wherein the material layer comprises a dielectric material.

4. A method according to any one of claims 1 to 3, wherein the substrate to be moved comprises a plurality of grooves, each groove having a first face and a second face, the first face and second face each having a coat of non-insulating material.

5. A method according claim 4 when dependent on claim 1 , wherein the method comprises: providing a plurality of curing stations located around the circumference of the drum, wherein each curing station performs the steps of:

depositing a precursor in at least one groove of the plurality of grooves;

generating a plasma; and

6. A method according claim 4 when dependent on claim 2, wherein the method comprises: providing a plurality of curing stations located around the circumference of the drum, wherein each curing station performs the steps of:

and

7. A method according to any one of claims 1 to 6, wherein the plurality of curing stations are configured to deposit or generate the same precursor.

8. A method according to any one of claims 1 to 6, wherein the plurality of the curing stations are configured to deposit or generate at least two different precursors.

9. A method according to claim 8, wherein the plurality of curing stations are provided such that the at least two different precursors are deposited in the at least one groove in an alternating sequence.

10. A method according to any one of claims 4 to 9, wherein the non-insulating material is a conductor material.

1 1. A method according to any one of the preceding claims, wherein the precursor is vaporised before it is deposited on the surface of the moving substrate.

12. A method according to any one claims 4 to 1 1 , wherein each material layer is continuous between the first face and second face of each groove.

13. A method according to any one of claims 4 to 12, wherein the non-insulating material on the first face and non-insulating material on the second face are electrically separated from each other.

14. A method according to any one of the preceding claims, wherein the drum is cooled by a coolant.

15. A method according to any one of the preceding claims, wherein the precursor is a metal organic precursor.

16. A method according to claim 15, wherein the metal organic precursor is one or more of: Titanium(IV) isopropoxide, Titanium(IV) ethoxide, Titanium(IV) chloride, Tantalum(V) ethoxide, Tantalum(V) chloride, Niobium(V) ethoxide, Niobium(V) chloride, h5- cyclopentadienyl)-tetracarbonylniobium, Bisdipivaloylmethanate barium and Barium hexafluoroacetylacetonate pentaethyleneglycol ethyl butyl ether.

17. A method according to any one of the preceding claims, wherein the precursor comprises a precursor of one or more of: titanium dioxide Titanium oxide, T antalum oxide, Niobium oxide, Barium titanate, Strontium titanate and Calcium copper titanate.

18. A substrate for an energy storage device processed by the method according to any one of the preceding claims.

19. A substrate for an energy storage device according to claim 18, comprising:

a plurality of grooves, each groove having a first face and a second face, the first face and the second face each having a coat of non-insulating material; and

a plurality of material layers in each groove of the plurality of grooves, each material layer formed by depositing a precursor into each groove and reacting the precursor with a plasma.

20. A substrate for an energy storage device according to claim 18, comprising a plurality of grooves, each groove having a first face and a second face, the first face and the second face each having a coat of non-insulating material; and

generating a plasma comprising a reactive gas; and

mixing the vapourised precursor with the plasma such that the precursor is dissociated by the plasma and the dissociated precursor is reacted with the reactive gas to form a material coating which is then deposited into each groove on the substrate as a material layer.

21. A substrate for an energy storage device according to any one of claims 19 to 20, wherein the plurality of material layers comprise a dielectric material layer.

22. A substrate for an energy storage device according to any one of claims 19 to 21 , wherein each of the plurality of material layers comprise the same material.

23. A substrate for an energy storage device according to any one of claims 19 to 21 , wherein the plurality of material layers comprise at least two layers of different materials.

24. A substrate for an energy storage device according to claim 23, wherein in the at least two layers of different materials, at least one layer comprises a dielectric material and at least one layer comprises a conductor material.

25. A substrate for an energy storage device according to claim 23 or claim 24, wherein the at least two different material layers are arranged in an alternating sequence.

26. A substrate for an energy storage device according to any one of claims 19 to 25, wherein at least one material layer of the plurality of material layers comprises a capacitor material with a dielectric constant of above 10.

27. A substrate for an energy storage device according to any one of claims 19 to 26, wherein at least one material layer of the plurality of material layers comprises a polymer material.

28. A substrate for an energy storage device according to claim 27, wherein the polymer material is conjugated.

29. A substrate for an energy storage device according to any one of claims 19 to 28, wherein at least one layer of the plurality of material layers comprises a conductive material.

30. A substrate for an energy storage device according to any one of claims 19 to 29, wherein at least one material layer of the plurality of material layers comprises a radio- curable binder.

31. A substrate for an energy storage device according to any one of claims 18 to 30, wherein each material layer has a thickness of between 5nm and 300nm, preferably 100nm.

32. A substrate for an energy storage device according to any one of claims 18 to 31 , comprising at least two dielectric material layers in each groove.

33. A substrate for an energy storage device according to claim 32, comprising at least two dielectric layers and a conductive layer positioned in between the dielectric layers.

34. An energy storage substrate comprising:

each groove having a plurality of material layers, each material layer formed by depositing a precursor of said material layer into each groove and reacting the precursor with a plasma.

35. An energy storage substrate being a planar substrate and comprising a plurality of material layers, each material layer formed by depositing a precursor of said material layer and reacting the precursor with a plasma.

36. An energy storage substrate according to claim 34 or claim 35 comprising a substrate according to any one of claims 18-33.