Apparatus for a coating device for depositing functional materials - Patent Application 20070122997

Abstract

The present invention relates to a device (1) for a coating apparatus for depositing functional materials, comprising an electroplating bath (3) that can be filled with a liquid electrolyte (2) and at least one counter electrode (4) arranged in the electroplating bath (3), a substrate carrier (5) that is at least partially constructed as a hollow body with an outer shell that surrounds a cavity, and a drainage and / or suction device (6) arranged in the cavity for draining and / or suctioning the electrolyte (2), the outer shell being permeable and the outside (5B) being exposed to the substrate (7), and The device relates to a substrate carrier (5) that, in an operating state, at least partially projects into the electroplating bath (3), the substrate carrier (5) is configured as or includes a working electrode, and a voltage can be applied between the counter electrode (4) and the working electrode, and the discharge and / or suction device (6) and the electroplating bath (3) are connected by a piping system (11), which is configured to ensure the transport of electrolyte between the discharge and / or suction device (6) in the cavity of the substrate carrier (5) and the electroplating bath (3), thereby providing a device for metal deposition that allows efficient regeneration of the electrolyte, accelerating the deposition process and improving its quality.

Description

[Technical Field]

[0001] The present invention relates to a device for a coating apparatus for depositing functional materials. In particular, the present invention relates to a device for applying functional materials to a substrate. The method is used in the manufacture of components for electrochemical energy converters, such as fuel cells, electrolyzers, or batteries. For example, components such as electrolyte-electrode assemblies made of expanded metal, sintered materials, or perforated materials, or other media-permeable substrates, can be coated. [Background technology]

[0002] Traditionally, mass production of such parts required the use of batch, semi-continuous, or continuous processes. The coating process can be one of several process steps that are sequenced to form a production chain. Because these process steps are interconnected, the slowest step determines the maximum achievable process speed and can limit production rates. If the substrate to be coated is sufficiently flexible, a roll-to-roll process can generally be used. When coating less flexible substrates, movable substrate carriers with 2D or 3D geometries can be used, depending on the nature of the substrate.

[0003] The process is described below using the example of coating a flexible substrate in a roll-to-roll system. The substrate is unwound from a roll, processed stepwise in a production process to form an (intermediate) product, and then wound up for sale or further processing. The substrate to be coated is guided by a substrate carrier, e.g., a roll. The production process can include functionalization, cleaning, drying, and coating steps between the unwound and wound ends. In the coating step described here, the substrate is immersed in a liquid containing the functional material. During contact between the substrate and the liquid, the functional material is coated onto the substrate, allowing further downstream treatment (e.g., cleaning, chemical or physical changes). Coating the substrate with the functional material can be performed in various ways and is influenced to different degrees by migration, diffusion, or convection effects of the functional material in the liquid (electrolyte). This coating, also known as deposition, can be obtained by physical or chemical methods.

[0004] Electrolyte refers to any liquid containing functional materials in particulate, precursor, electrostatically charged, or ionic form. Deposition of functional materials refers to electrochemical deposition of ions, electrophoresis of electrostatically charged particles, and / or deposition of materials from a liquid onto a substrate.

[0005] In the case of catalytically active functional materials, catalyst deposition is typically performed directly on the substrate during the process. The substrate is immersed in an electrolyte containing catalyst ions, for example, in the form of dissolved catalyst salts, and is converted into a metal catalyst by the application of an electric current. The speed of this process step depends heavily on the transport of catalyst ions from the electrolyte volume to the deposition center on the substrate surface. During catalyst deposition, electrons are supplied to the substrate, electrochemically reducing catalyst ions from the electrolyte near the surface to the substrate, resulting in a metal material that will later function as a catalytic material. This deposition step reduces the concentration of catalyst ions in the electrolyte near the surface. Replenishing the electrolyte region with depleted ions (electrolyte regeneration) requires a certain time, known as the regeneration time. This process allows for slow deposition or pulsed deposition (e.g., on / off) with current pulses. Depending on the location of the catalyst ions in the electrolyte, the driving forces for ion migration are primarily convection due to electrolyte migration, diffusion due to concentration differences, or migration due to an applied electric field. Convection, in particular, can inhibit the process speed because it requires a long transport path within the electrolyte. This gradual ion transport continues until the concentration of the entire electrolyte is equilibrated, determining the regeneration time and thus the coating time of the electrochemical deposition (catalytic coating).

[0006] Typically, attempts are made to maintain a low ion concentration gradient, for example, by mechanical stirring, to accelerate the ion transport process and shorten the electrolyte regeneration time. However, the structure and scale of roll-to-roll plants make this process challenging. For example, vigorous stirring can cause vortex formation and inhomogeneity. Due to the remaining regeneration time, production processes using electrochemical catalyst deposition can only achieve slow process speeds, which hinders process upscaling and makes them less competitive compared to other methods, such as chemical catalyst deposition using catalyst powders.

[0007] To avoid the slow cycle rates of roll-to-roll systems, for example, the substrate can be repeatedly immersed in the electrolyte via several rollers and then removed again. This increases the substrate surface area in contact with fresh electrolyte, thereby improving process speed. However, the crucial drawbacks here are the high investment costs, increased space requirements, and high operating costs of such electrochemical setups. Furthermore, the use of large electroplating systems (several or long electroplating baths) requires large amounts of electrolyte, further increasing running costs due to the expensive metal-containing electrolyte. In addition, the need to technically monitor, adjust, and control large amounts of electrolyte complicates the process. Mechanical agitation increases the likelihood of errors due to deviations from ideal operating conditions, increases wear on multiple components, and reduces the quality of the deposited catalyst layer.

[0008] The complex process control involved in the extensive catalyst deposition, the non-uniform deposition of catalyst material, and the possible need for the use of auxiliary electrodes are also significant. Generally, the achievable process speed and layer quality are limited, despite the high cost, making the entire process unattractive for the large-scale industrial production of components for electrochemical energy converters.

[0009] Metal deposition devices known from the prior art do not yet offer a means for fast electrolyte regeneration that can be easily integrated into conventional roll-to-roll systems, as well as batch or semi-continuous operating systems. Summary of the Invention [Problem to be solved by the invention]

[0010] Based on this, it is an object of the present invention to provide a functional material coating device that allows for efficient regeneration of the electrolyte, thereby improving the process speed and the quality of the coating produced, and reducing investment and operating costs. [Means for solving the problem]

[0011] This object is solved by the subject matter of claim 1. Preferred further developments are set out in the dependent claims.

[0012] Therefore, the present invention provides a device for a coating apparatus for depositing a functional material, comprising: an electroplating tank that can be filled with a liquid electrolyte; at least one counter electrode disposed in the electroplating tank; a substrate carrier at least partially configured as a hollow body with an outer shell surrounding a cavity and having an inner side facing the cavity and an outer side away from the cavity; and a drainage and / or suction device disposed in the cavity for draining or suctioning the electrolyte, wherein the outer shell is configured to be permeable and the outer side can be exposed to the substrate; the substrate carrier at least partially protrudes into the electroplating tank in an active state; the substrate carrier is configured as or includes a working electrode, and a voltage can be applied between the counter electrode and the working electrode; the drainage and / or suction device and the electroplating tank are connected by a piping system, and the piping system is configured to ensure transport of the electrolyte between the drainage and / or suction device in the cavity of the substrate carrier and the electroplating tank. [Brief explanation of the drawings]

[0013] [Figure 1] 1 shows a schematic perspective view of a roll-to-roll electroplating apparatus equipped with a device according to a preferred embodiment of the present invention for flexible substrates. [Figure 2] 2 shows a schematic cross-sectional view of the electrolytic electroplating apparatus of FIG. 1. [Figure 3] 1 shows a perspective view of the space between an electrolytic electroplating bath and a substrate carrier according to a preferred embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0014] When referring to an electroplating tank, this means any structure suitable for electroplating that has a volume that can be filled with an electrolyte. For example, this can be an electroplating bath.

[0015] The term "substrate carrier" particularly refers to a three-dimensional hollow body that allows contact with the substrate in two or three dimensions. The substrate carrier is preferably configured to be movable, for example by a robot arm, and can be used for batch and / or (partially) continuous processes with 2D or 3D geometries.

[0016] The term "permeable" refers to a material that is permeable to a medium.

[0017] When referring to a piping system, this refers to any design of structure or formation that conducts a medium, such as a pipe, hose, nozzle, valve, permeable material, flow guide or channel, or simply an inlet.

[0018] When electrodes are required for separation, they are called the working electrode and the counter electrode. For the separation of positively charged metal ions, the counter electrode and working electrode are positioned so that the counter electrode acts as the anode or positive electrode, transferring the metal ions dissolved in the electrolyte to the working electrode. The working electrode then acts as the cathode, and a current flows between the anode and the working electrode. The metal ions dissolved in the electrolyte are deposited by electrochemical reduction on a substrate electrically connected to the working electrode or anode. If the metal ions are catalytic materials, the catalytically active material is applied to the substrate by reducing the ions, and the substrate is electroplated with a catalytic layer. During deposition, the positive and negative electrodes can be briefly reversed or pulsed, allowing for additional flexibility in deposition.

[0019] Additionally, auxiliary and reference electrodes can be used to improve process control. The working and counter electrodes can be located either inside or outside the liquid. The substrate itself may conduct current into the liquid, so that contact with the working electrode can occur outside the liquid. For example, deposition such as by electrophoresis can be achieved by generating an electromagnetic field, in which case one or both electrodes can be located outside or inside the liquid.

[0020] To transfer the metal ions to the substrate, the substrate must be in contact with the electrolyte, and for this purpose the substrate carrier is positioned so that it at least partially projects into the electroplating bath, i.e., is partially immersed in the electrolyte when the electroplating bath is filled with the electrolyte.

[0021] As used herein, the term "working electrode" refers to an electrical contact preferably located outside the electrolyte, which is electrically connected to a substrate immersed in the electrolyte so as to transfer metal ions toward the substrate.

[0022] In this context, the term "drainage and / or suction device" refers in particular to a device capable of draining and / or suctioning electrolyte by pressure differential. This refers to the flow direction of the electrolyte. When the electrolyte is drained, it is sucked from the electroplating bath through the substrate, through the permeable outer shell of the substrate carrier, into the cavity of the substrate carrier, and from there back into the electroplating bath. However, when the electrolyte is sucked, it is sucked from the electroplating bath, supplied to the cavity, and then through the permeable outer shell and the substrate back into the electroplating bath. The suction and / or discharge device is therefore configured to transport the electrolyte in either or both of the two flow directions. During operation of the coating device, it is desirable to be able to select one or both flow directions and / or alternate between them, and / or to temporarily stop the electrolyte flow.

[0023] Therefore, a key feature of the present invention is that immediately after and / or during the deposition of functional or catalytic materials on the substrate surface, depleted electrolyte is replaced with the initial concentration of electrolyte by continuous or intermittent removal of electrolyte through the substrate and substrate carrier. As a result, deposition can continue immediately after the previous deposition pulse, and the substrate can be subjected to a new deposition pulse immediately after the previous deposition pulse is completed. This reduces or eliminates regeneration time, resulting in continuous deposition, the fastest deposition method possible. Furthermore, this approach allows for control of the penetration depth of catalytic materials into the substrate and tailoring of the concentration profile of functional materials across the substrate layer depth. By-products that may interfere with uniform deposition (e.g., air bubbles remaining on the substrate surface) can also be easily removed. Furthermore, the selection of pulse removal and / or electrolyte flow rate allows for precise control of the regeneration process in the depleted electrolyte layer, which also positively impacts deposition results.

[0024] According to a further preferred embodiment of the present invention, the substrate carrier comprises a hollow cylindrical roller. More preferably, the substrate carrier is mounted so as to be rotatable about its longitudinal axis. The longitudinal direction of the substrate carrier refers to the length of the cylindrical shape. The substrate can be arranged on the outer surface of the cylindrical surface. The substrate carrier rotates about the longitudinal axis of the cylinder. This has the advantage that the substrate can be wrapped around the substrate carrier along a wide surface, making efficient use of the carrier surface in one rotation.

[0025] According to a preferred further development of the invention, the outer shell comprises a plurality of openings, which may in particular be configured as slots or holes. In the present invention, slot-like openings are understood to be elongated, narrow openings through which the electrolyte can diffuse. The length of the slots is preferably several centimeters. The holes may have different sizes and distances from one another. Furthermore, the substrate carrier may be made of a permeable material (e.g., sintered material, expanded metal, perforated material, fleece).

[0026] According to a preferred further development of the invention, the substrate carrier is arranged on a movement device, via which the substrate carrier is movable, in particular the movement device comprises a robot arm, a rod or a rope.

[0027] According to a preferred further development of the invention, the electroplating bath comprises a base plate, in which at least one inlet is arranged, for example via a piping system, so that the electrolyte can be supplied or sucked from below, i.e. from the bottom or another position in the electroplating bath, and the electrolyte can flow through the entire volume of the electroplating bath and no dead volumes can occur.

[0028] In principle, it is possible to ensure that the electrolyte moves within the volume of the electroplating bath by a freely generated pressure difference. The electrolyte flow can be caused, for example, by a geodesic difference in height, thermal forces, or by the rotation of the substrate carrier. Preferably, the suction and / or evacuation device comprises multiple suction nozzles arranged inside the outer shell, or a single suction nozzle coupled to a suction device such as a pump. The suction device thus actively sucks or pushes out the electrolyte.

[0029] According to a preferred further development of the present invention, it is provided that the suction direction can be changed. Preferably, during operation of the coating device, one or both flow directions can be selected and / or alternated between them, and / or the electrolyte flow can be temporarily stopped. A variable and adjustable suction force is also preferably provided. By changing the suction direction and / or the suction force, the flow profile can be adjusted, preferably set as turbulent, laminar, or a mixture of both, to achieve the desired mixing during electrolyte regeneration and deposition, respectively. A temporary change in the electrolyte transport direction can also cause the removal of by-products, such as hydrogen generation, which can hinder or reduce uniform and efficient catalyst separation.

[0030] Preferably, the length of the drainage and / or suction device corresponds to the length of the outer surface exposed to the substrate, so that the drainage and / or suction device extends over the entire length of the substrate, allowing the electrolyte to be drawn uniformly across the substrate and resulting in a homogenous flow profile within the electroplating bath.

[0031] According to a preferred further development of the invention, the external working electrode comprises a chain consisting of several links, such as an armored chain. An armored chain is a chain in which each link is twisted by 90 degrees and can be laid flat. This chain can therefore be laid flat on the outer surface of the substrate carrier, establishing electrical contact between the electrolyte, the chain, and the substrate and allowing the electrolyte to pass through a larger area of ​​the substrate. This increases the contact area between the electrolyte and the substrate, accelerating the deposition process. Furthermore, the choice of a 2D or 3D geometry allows for a more uniform electric field, potentially resulting in a higher layer quality.

[0032] Alternatively, according to a preferred further development of the invention, the substrate carrier has contacts for electrical contact with the substrate, which itself is configured as the working electrode, so that the current for deposition can be conducted either via the substrate carrier, via the external working electrode in the form of an armored chain, or via the substrate itself.

[0033] According to a preferred further development of the invention, the substrate carrier is configured to be inert. The inert properties of a material are characterized by a very limited tendency to undergo chemical reactions. This prevents the deposition of functional material on the substrate carrier itself. This prevents loss of functional material and allows functional deposition only at the desired locations on the substrate. This ensures the most efficient deposition possible.

[0034] The above-described devices may also be preferably used to deposit functional materials for the fabrication of electrolyte electrode assemblies for electrochemical energy converters in continuous and / or semi-continuous processes, such as roll-to-roll processes, and / or batch processes.

[0035] The present invention will be described in detail below using preferred embodiments with reference to the drawings.

[0036] Figure 1 shows a schematic diagram of an electroplating apparatus 1 equipped with a metal deposition device. The device includes an electroplating tank 3 and a roller-shaped substrate carrier 5 that rotates about its longitudinal axis L. The electroplating tank is filled with a liquid electrolyte 2, and the substrate carrier 5 is immersed in the electrolyte so that the substrate passes through the electrolyte. A counter electrode 4 is located around the periphery of the electroplating tank 3. The substrate carrier 5 itself serves as the working electrode, or an electrical contact attached to the substrate carrier 5 is connected to the substrate. This allows current to flow from the counter electrode 4 in the electroplating tank 3 through the electrolyte to the working electrode or the substrate to be electroplated. A reference electrode can also be used, located in the electrolyte close to the substrate. Metal ions must be dissolved in the electrolyte so they can be transferred to the substrate. If the metal ions are catalytic ions, the substrate is exposed to the catalytically active material by reduction. Reduction occurs in the electrolyte layer close to the substrate surface, resulting in a shortage of metal ions at this point. This creates an imbalance in the metal ion concentration in the electrolyte. To compensate for this imbalance and allow for the influx of additional metal ions or regeneration of the electrolyte, a drainage and / or suction device 6 removes the electrolyte from the surface and returns it to the electrolyte volume in the deeper region of the electroplating bath 3, completing a circuit. The drainage and / or suction device 6 is shown in FIG. 2.

[0037] FIG. 2 shows a cross section of the electrolytic bath 3 along its longitudinal axis and along the substrate carrier 5. Arrows 2A represent two possible directions of electrolyte 2 flow. The electrolyte 2 is pumped from the electroplating bath 3 through the substrate 7 and substrate carrier 5 to the drainage and / or suction device 6, and then returned to the electroplating bath through two inlets 10 at the bottom of the electroplating bath 3 via the piping system of the electroplating bath. Alternatively, the electrolyte 2 can be sucked from the electroplating bath 3 through the inlets 10 to the suction and / or discharge device 6 and pumped back through the substrate carrier 5 and substrate 7 to the vicinity of the surface of the electroplating bath 3. The latter is provided with several slit-like openings 8 to allow the electrolyte 2 to diffuse through the substrate carrier 5. Both options (dashed arrows) allow continuous electrolyte transport within the circuit, which homogenizes the metal ion concentration and ensures as efficient metal deposition on the substrate 7 as possible without delays due to long regeneration times. The openings 8 represent the permeability of the substrate carrier through which the electrolyte can be transported.

[0038] FIG. 3 shows in detail the space between the substrate carrier 5 and the electroplating tank 3. The illustrated region of the electroplating tank 3 is filled with electrolyte and equipped with an inlet and an outlet, which are connected to a piping system 11. This allows the electrolyte to be directly discharged from the substrate 7, which is placed inside the substrate carrier 5A and on its exterior 5B, and then supplied to the electroplating tank via the inlet or outlet 10. The piping system is preferably configured to enable uniform electrolyte exchange across the entire substrate surface that comes into contact with the electrolyte. To this end, the piping system 11 itself, like the substrate carrier itself, is configured to be permeable, for example, via incorporated slots, holes, or other media passages. The pressure difference required for electrolyte transfer 2A is achieved, for example, by a pump (not shown). The suction direction and capacity can be changed and controlled during operation, allowing the electrolyte flow profile to be altered at any time and adapted to specific conditions, as indicated by arrow 2A. [Explanation of symbols]

[0039] 1 Coating equipment 2 Electrolytes 2A Electrolyte movement direction 3. Electroplating tank 4 Counter electrode 5 Substrate carrier 5A inside 5B Outside 6. Exhaust and / or suction devices 7 Base material 8 Openings 9 Base Plate 10 Inlet / Exit 11 Piping System L Longitudinal axis

Claims

1. A device (1) for a coating apparatus for depositing functional materials, comprising: an electroplating bath (3) that can be filled with a liquid electrolyte (2) and at least one counter electrode (4) disposed in the electroplating bath (3); a substrate carrier (5) at least partially constructed as a hollow body with an outer shell surrounding a cavity and having an inner side (5A) facing said cavity and an outer side (5B) facing away from said cavity; a drainage and / or suction device (6) arranged in the cavity for draining or suctioning the electrolyte (2); The outer shell is configured to be permeable, and the outer side (5B) can be exposed to the substrate (7); The substrate carrier (5) projects at least partially into the electroplating bath (3) in an operating state; the substrate carrier (5) is configured as or includes a working electrode, and a voltage can be applied between the counter electrode (4) and the working electrode; The device, wherein the discharge and / or suction device (6) and the electroplating bath (3) are connected by a piping system (11), the piping system (11) being configured to ensure the transport of electrolyte between the discharge and / or suction device (6) and the electroplating bath (3) in the cavity of the substrate carrier (5).

2. 2. The device of claim 1, wherein the substrate carrier (5) comprises a hollow cylindrical roller.

3. 3. The device according to claim 1 or 2, wherein the substrate carrier (5) is rotatable about its longitudinal axis (L).

4. 10. A device according to any one of the preceding claims, wherein the outer shell comprises a plurality of openings (8) or the outer shell is configured to be permeable.

5. 10. A device according to any of the preceding claims, wherein the substrate carrier (5) is arranged on a moving device.

6. 10. The device according to any one of the preceding claims, wherein the electroplating bath (3) comprises a base plate (9), and the piping system (11) is connected to at least one inlet (10) arranged on the base plate (9).

7. 10. A device according to any one of the preceding claims, wherein the evacuation and / or suction device (6) is configured to change the direction of the electrolyte transport.

8. 10. A device according to any one of the preceding claims, wherein the working electrode is arranged on the outside (5B) and comprises an armored chain type chain having several links.

9. 8. The device according to any one of claims 1 to 7, wherein the substrate carrier (5) comprises contacts for making electrical contact with the substrate, the substrate being configured as a working electrode.

10. 10. The device according to any one of the preceding claims, wherein the substrate carrier (5) is configured to be inert.

11. 10. Use of a device according to any one of the preceding claims for depositing functional materials for the manufacture of electrolyte electrode assemblies for electrochemical energy converters in a continuous and / or semi-continuous and / or batch process.

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