Low impedance electrical connection device and method for electrochemical cells - Patents.com

Abstract

A low impedance electrical connection device for an electrochemical cell is provided. The membrane in the electrochemical cell is electrically and / or mechanically coupled to the flow field plate using a conductive adhesive. The use of a conductive adhesive increases the level of electrical contact between components that can be achieved for a given level of compressive force applied between the components in the electrochemical cell.

Description

Priority

[0001] This application claims priority to U.S. Provisional Application No. 62 / 294,492, filed December 29, 2021, having Attorney Docket No. 10378-21023A and entitled "LOW IMPEDANCE ELECTRICAL CONNECTIONS FOR ELECTROCHEMICAL CELLS," which is incorporated by reference in its entirety herein. [Technical field]

[0002] The following disclosure relates to low impedance electrical connections for electrochemical cells. [Background technology]

[0003] Electrolyzer systems use electrical energy to drive chemical reactions. For example, water is split into hydrogen and oxygen. The products may be used as chemical feedstocks and / or energy sources. In recent years, improvements in operational efficiency have made electrolyzer systems a competitive market solution for energy storage, generation, and / or transportation. For example, production costs can be less than $10 per kilogram of hydrogen in some cases. Lower costs, increased efficiency, and / or improved operation continue to drive the installation of electrolyzer systems.

[0004] Exemplary embodiments are described herein with reference to the following drawings: [Brief description of the drawings]

[0005] [Figure 1] 1 illustrates an exemplary electrochemical cell. [Diagram 2] 1 illustrates an exemplary method for forming electrical contact between a membrane and a flow-field plate. [Diagram 3] An example of a mask is shown. [Figure 4] 1 illustrates an exemplary flow field plate with selectively applied conductive adhesive. [Diagram 5]1 illustrates an exemplary electrochemical cell. [Figure 6] 1 illustrates an exemplary electrochemical cell with exemplary points for application of a conductive adhesive. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0006] The architectures and techniques described herein can support the implementation of electrical contacts between components in a variety of products. In some cases, the various discussed architectures and techniques can be implemented for membranes and / or electrodes in electrochemical cells, including those used in proton exchange membrane water electrolysis (PEMWE).

[0007] In some cases, it may be desirable to electrically couple the membrane (e.g., its surface) to an electrode of a flow field plate. Conventional wisdom dictates that electrical contact is achieved using a compressive force that may be applied via fasteners such as screws. Furthermore, conventional wisdom dictates that the level of electrical contact is proportional to the level of compressive force, since deformation of the various parts relative to one another mediates the electrical contact.

[0008] Furthermore, conventional wisdom discourages the use of forms of contact other than compressive force because selective contact with electrode portions of a component, but not with other portions of the component, can be achieved using raised electrodes. Thus, as conventional wisdom would understand, compressive force can achieve a level of spatial resolution for electrical contact that cannot be achieved through other techniques for electrically coupling dissimilar components in an electrochemical cell.

[0009] Furthermore, conventional wisdom discourages the use of forms of contact other than compressive forces because compressive forces have a high level of electrochemical stability, and the extreme conditions of electrochemical processing can degrade various other means of contact.

[0010] In some cases, the compressive forces used to achieve sufficient electrical contact between the membrane and / or flow field plates can result in damage to the membrane and / or other cell components, leading to reduced manufacturing yields. Conventional wisdom therefore dictates that it is important to expend significant design effort to balance compressive forces, electrical contact levels, and manufacturing yields.

[0011] As recognized herein, contrary to conventional wisdom, the electrical contact level may be decoupled from the compressive force used via the techniques and architectures described herein. Various of the techniques and architectures discussed herein use electrical contact with the electrochemical cell that is facilitated (at least in part) via a conductive adhesive. The conductive adhesive reduces the reliance on compressive force to form electrical contact.

[0012] In various embodiments, electrochemical cells can be assembled using conductive adhesives with or without the concurrent use of fasteners such as screws. Regardless of the use of fasteners, the level of electrical contact achieved for a given level of compressive force between components can be increased for cells incorporating conductive adhesives compared to cells that rely solely on compressive force. Furthermore, by selecting the type of conductive adhesive (including, for example, the type and concentration of conductive particles in the adhesive) and the area of ​​contact with the adhesive, the level of electrical contact can be controlled (e.g., reduced and / or increased) without changing the level of compressive force.

[0013] Various types of adhesives can be used, such as epoxies, butyl rubber, other rubbers, cross-linkable polymers, or other adhesives. The adhesive may be infiltrated with one or more types of conductive particles, including precious metal particles, graphite / graphene particles, or other particles of conductive materials. The adhesive may be selected for stability in electrolytic conditions over time scales corresponding to device operation (e.g., the particles may be stable over the time scale of one or more device operation cycles). In some cases, stability over multiple cycles may be desirable when a particular component or assembly is not practical to replace every cycle. Similarly, the conductive material in the adhesive may be selected for stability in electrolytic conditions over time scales corresponding to device operation.

[0014] In various embodiments, multiple different conductive adhesives can be used within a given cell or other assembly. For example, the conductive adhesives used for the cathode contact and / or the anode contact can be different from one another. The difference can be in the conductive particles that permeate the adhesive and / or the adhesive itself. In some cases, a conductive adhesive may be used on one side of the membrane (e.g., the cathode side or the anode side) but not necessarily on the other side. For example, a compression contact can be used on one side and an adhesive contact on the other side within a single electrochemical cell.

[0015] In some cases, the adhesive may be selected to allow the fluid phase of the adhesive (e.g., before curing) to diffuse through one or more porous layers of the electrochemical cell, such as a liquid / gas diffusion layer.

[0016] 1 illustrates an exemplary electrochemical cell 100. In the exemplary electrochemical cell 100, a flow-field plate 102 is bonded to a surface of a membrane 104. Electrical contact between the flow field plates may be made via a conductive adhesive 106 disposed between the flow field plate 102 and the membrane 104. In various implementations, the conductive adhesive 106 may be diffused (or otherwise spread) across one or more diffusion layers 108 between the membrane 104 and the flow field plate 102. In various implementations (not shown), a pair of flow field plates may be attached to the membrane 104 (e.g., one on each side).

[0017] With continued reference to FIG. 1, and with reference to FIG. 2, FIG. 2 illustrates an exemplary method 200 for forming electrical contact between a membrane and a flow field plate.

[0018] A conductive adhesive is applied to selected portions of the flow field plate, diffusion layer, membrane, and / or other selected components of the cell (step 202). In various implementations, the portions for selective application of the conductive adhesive may be physically distinct from other portions of the components. For example, the conductive adhesive 106 may be applied to the electrode contacts of the flow field plate 102. The electrode contacts themselves may be raised relative to other portions of the flow field plate 102, for example, at least in part to enable selective application, and / or may be otherwise physically separated.

[0019] In some embodiments, a mask may be used to control the selective application of the conductive adhesive 106. For example, a mask may be placed on the face of the flow field plate 102 prior to application of the conductive adhesive 106. The conductive adhesive 106 may be applied and the mask removed. The resulting placement of the conductive adhesive 106 may be targeted to the portions that are exposed when the mask is in place. For example, the mask may expose the face of the electrode contacts of the flow field plate 102. Using a mask in this example, the electrode contacts may be exclusively targeted for application of the conductive adhesive even if, for example, the contacts lack physical separation that may be used for selective application of the conductive adhesive 106 in other embodiments. In some cases, physical separation, such as raised contacts, may enable the creation of electrical and / or other contacts via compressive forces during assembly. Thus, physical separation of components may exist in embodiments whether or not a mask is used to enable selective application of the conductive adhesive.

[0020] The cell components are then assembled (step 204) to allow the adhesive to form a bond (and electrical contact) with the membrane. Because the conductive adhesive is electrically conductive, application of the conductive adhesive will cause selected portions where the conductive adhesive is applied to act as electrical contacts between the components. Thus, the selected portions can act as electrical contacts between the membrane, the diffusion layer, and / or the flow field plate. In some cases, the conductive adhesive may diffuse through the diffusion layer(s) 108, so that the conductive adhesive may create electrical contacts through these layers, similar to vias in a multi-layer integrated chip.

[0021] In various implementations, the conductive adhesive 106, once cured, can provide various levels of physical bonding between the components.

[0022] For example, the conductive adhesive 106 can provide a flexible bond between the components. For example, a flexible bond can include a bond in which the components can move relative to one another (e.g., over a deflection scale on the order of the thickness of the components) without degrading the bond created by the conductive adhesive. In some cases, a flexible bond can be associated with a lower bond strength than a semi-rigid or rigid bond.

[0023] For example, the conductive adhesive 106 can provide a semi-rigid bond between the components. For example, a semi-rigid bond can include a bond in which the components can move relative to one another (e.g., over a deflection scale less than the thickness of the components), potentially with some degradation of the bond created by the conductive adhesive. In some cases, a semi-rigid bond can relate to a bond strength between that of a flexible bond and that of a rigid bond.

[0024] For example, the conductive adhesive 106 can provide a rigid bond between the components. For example, a rigid bond can include a bond in which the components are contained with respect to movement relative to one another. In some cases, a rigid bond can be associated with a stronger bond strength than a flexible or semi-rigid bond.

[0025] In various embodiments, different conductive adhesives may be used on different components and / or different portions of the components to provide different levels of physical bonding and / or electrical contact between the joined components.

[0026] In some embodiments, fasteners, such as screws, rivets, clamps, and / or other fasteners, can be used to hold the bonded components together with the conductive adhesive 106. For example, the fasteners can be used to provide a desired level of compressive force. In one example, the fasteners can be used to provide a selected level of physical bond (e.g., a level of stiffness greater than the stiffness of the conductive adhesive), while the conductive adhesive provides a selected level of electrical contact that can be independent of the level of physical bond and / or compressive force provided by the fasteners.

[0027] In the following, exemplary embodiments are described.

[0028] Various exemplary examples are described below. The exemplary embodiment examples are illustrative of the general architectures and techniques described above and in the claims below. Designations of particular features, such as "key," "critical," "important," "essential," and / or other similar designations, are included to clarify the relationship of that particular feature to the particular exemplary scenario(s) in which the particular feature is discussed. The same degree of such relationship may not apply without an explicit description of such relationship to other embodiments. Nonetheless, such features described with respect to individual exemplary embodiments may be readily integrated with other embodiments with or without various other features present in the respective exemplary embodiments.

[0029] The highly resistive membrane may be connected to various interface components such as bipolar flow fields, porous transport layers, and gas diffusion layers. This electrical connection may be developed by using conductive adhesives that allow high interfacial contact and electronic pathways.

[0030] In various embodiments, the PEMWE components are aligned, stacked, and then fastened to create a compressive force. This force allows contact to the various parts and creates an electronic path. In some cases, high compressive forces can cause increased shorting and thinning of the membrane. In some cases, lowering the cell compressive force can reduce electrical contact between components and cause an increase in impedance.

[0031] To allow for electrical conductivity, the adhesive may have a fluid phase that allows for diffusion through one or more porous layers that may be included between the flow field plate and the membrane. In some cases, the conductive adhesive may be selected for stability in the PEMWE environment on both the anode and cathode sides. This may include, in some embodiments, being aggressive in the PEMWE environment.

[0032] Conductive adhesives can be used to increase the surface contact between components and also provide a more mechanically stable stack.

[0033] 3 shows an exemplary mask 300 for facilitating application of conductive adhesive to specific device regions. The mask may allow application of conductive adhesive to select regions of an electrochemical cell. In an illustrative example, conductive adhesive may be applied to the contact surface of a flow field plate through openings 302 in the mask.

[0034] FIG. 4 shows an exemplary flow field plate 400 with a conductive adhesive 402 applied to the electrode contact surfaces of the flow field plate.

[0035] 5 illustrates an exemplary electrochemical cell 500. In the exemplary electrochemical cell 500, each side of a membrane 502 is bonded to respective bipolar plates 504, 506 of the electrochemical cell 500 via a conductive adhesive 508.

[0036] FIG. 6 illustrates an exemplary electrochemical cell 600. The electrochemical cell includes an electrolytic membrane 602, a diffusion layer 604, polymer gaskets 606, 610, a flow field plate 608, and an end plate 612 for gas / liquid circulation. A conductive adhesive can be applied to exemplary points 650, such as electrode contacts of the flow field plate 608. In FIG. 6, the various components are sized for clarity and are not necessarily drawn to scale. Additionally, the various components of the electrochemical cell 600 are spaced apart for clarity of presentation. Nevertheless, upon assembly, the components of the electrochemical cell 600 are aligned and stacked.

[0037] Various examples are described below.

[0038] (1) A device comprising: A membrane, A flow field plate; a diffusion layer between the membrane and the flow field plate; an adhesive that is diffused through the diffusion layer and bonds the membrane and the flow field plate; conductive particles embedded in the adhesive, the conductive particles providing electrical contact between the membrane and the flow field plate; Optionally, the device is according to any of the other embodiments described herein.

[0039] (2) A device, A membrane, A flow field plate; an adhesive that bonds the membrane and the flow field plate; conductive particles embedded in the adhesive, the conductive particles providing electrical contact between the membrane and the flow field plate; Optionally, the device is according to any of the other embodiments.

[0040] (3) A device comprising: A pair of flow field plates; a membrane disposed between the pair of flow field plates; an adhesive bonding each side of the membrane to a respective one of the pair of flow field plates; conductive particles embedded within the adhesive, the conductive particles providing electrical contact for each side of the membrane with a respective one of the pair of flow field plates; Optionally, the device is according to any of the other embodiments.

[0041] (4) A method comprising the steps of: applying a conductive adhesive to selected portions of the electrochemical cell components; and assembling the electrochemical cell such that the conductive adhesive allows electrical contact to be made between various components within the electrochemical cell; Optionally, assembling the electrochemical cell includes placing the membrane in contact with an adhesive to bond the membrane to the flow field plate, and placing at least one side of the membrane in electrical contact with the flow field plate; Optionally, the method is according to any of the other embodiments.

[0042] (5) The device or method of any other embodiment described herein, wherein the adhesive spreads across a spreading layer between the flow field plate and the membrane.

[0043] (6) The device or method of any other embodiment described herein, wherein the flow field plate comprises one of a pair of plates coupled to either side of the membrane.

[0044] (7) The device or method of any of the other embodiments described herein, wherein the membrane comprises a membrane for proton exchange membrane electrolysis of water (PEMWE).

[0045] (8) The device or method of any of the other embodiments described herein, further comprising using a mask to apply the adhesive; Optionally, the mask directs the adhesive to the electrode contact surfaces on the field flow plate.

[0046] (9) The device or method of any of the other embodiments described herein, wherein the conductive particles comprise platinum particles, gold particles, other precious metal particles, other conductive metal particles, graphite particles, and / or other conductive materials; Optionally, the conductive material is stable (over one or more device operation cycles) under proton exchange membrane electrolysis of water (PEMWE) conditions.

[0047] (10) The device or method of any of the other embodiments described herein, wherein the adhesive comprises an epoxy, a butyl rubber compound, a cross-linkable polymer compound, or other adhesive; Optionally, the adhesive is stable (over one or more device operating cycles) under proton exchange membrane electrolysis of water (PEMWE) conditions.

[0048] (11) A device or method according to any of the other embodiments described herein, wherein the use of a conductive adhesive reduces the compressive force used to obtain sufficient electrical contact between the flow field plate and the membrane.

[0049] (12) The device or method of any of the other embodiments described herein, wherein a conductive adhesive is used in conjunction with one or more fasteners to secure the membrane to the flow field plate.

[0050] (13) The device or method of any of the other embodiments described herein, wherein a conductive adhesive secures the membrane to the flow field plate; Optionally, the membrane is coupled to the flow field plate via a flexible coupling; Optionally, the membrane is coupled to the flow field plate via a semi-rigid bond; Optionally, the membrane is coupled to the flow field plate via a rigid bond.

[0051] (14) A method comprising assembling a membrane electrode using a conductive adhesive.

[0052] (15) Membrane electrode assembly assembled using conductive adhesive.

[0053] One or more embodiments of the present disclosure may be referred to herein, individually and / or collectively, by the term "invention" merely for convenience, without any intention to spontaneously limit the scope of the present application to any particular invention or inventive concept. Furthermore, although specific embodiments have been illustrated and described herein, it should be understood that any subsequent configurations designed to achieve the same or similar purpose may be substituted for the specific embodiment shown. The present disclosure is intended to encompass any and all subsequent adaptations or variations of the various embodiments. Combinations of the above embodiments, as well as other embodiments not specifically described herein, will be apparent to those skilled in the art upon review of the description.

[0054] As used herein, the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise.

[0055] As used herein, "for example," "for instance," "such as," or "including" is meant to introduce examples that further clarify a more general subject matter. Unless otherwise expressly indicated, such examples are provided only as an aid to understanding the embodiments set forth in the present disclosure and are not meant to be limiting in any way. Additionally, these phrases do not imply any kind of preference for the disclosed embodiment.

[0056] The Abstract of the Disclosure is provided to comply with 37 CFR 1.72(b) and is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims. Moreover, in the foregoing Detailed Description, various features may be grouped together or described in a single embodiment for the purpose of streamlining the disclosure. This disclosure should not be interpreted as reflecting an intention that the claimed embodiments require more features than are expressly recited in each claim. Rather, as the following claims reflect, the inventive subject matter may be directed to less than all of the features of any of the disclosed embodiments. Thus, the following claims are hereby incorporated into the Detailed Description, with each claim standing on its own as defining separately claimed subject matter.

[0057] It is intended that the foregoing detailed description be considered illustrative rather than limiting, and that the following claims, including all equivalents, are within the scope of this disclosure. The claims should not be construed as limited to the described order or elements unless stated to that effect. Accordingly, all embodiments that come within the scope and spirit of the appended claims and equivalents thereto are included in this disclosure.

Claims

1. A device, comprising: An electrolytic membrane; A flow field plate; a diffusion layer between the electrolytic membrane and the bath field plate; an adhesive that is diffused through the diffusion layer and bonds the electrolytic membrane and the flow field plate; and conductive particles embedded within said adhesive for providing electrical contact between said electrolytic membrane and said flow field plate.

2. The device of claim 1 , wherein the flow field plate comprises one of a pair of plates coupled to either side of the electrolytic membrane.

3. 10. The device of claim 1, wherein the electrolytic membrane comprises a membrane for proton exchange membrane electrolysis of water (PEMWE).

4. The device of claim 1 , wherein the conductive particles comprise precious metal particles and / or graphite particles.

5. The device of claim 1 , wherein the adhesive comprises an epoxy, a butyl rubber compound, and / or a cross-linkable polymer compound.

6. The device of claim 1 further comprising a fastener, said fastener being used in conjunction with said adhesive to secure said electrolytic membrane to said flow field plate.

7. The device of claim 1 , wherein the conductive adhesive secures the electrolytic membrane to the flow field plate.

8. The device of claim 7 , wherein the electrolytic membrane is attached to the flow field plate via a flexible coupling.

9. The device of claim 7 , wherein the electrolytic membrane is attached to the flow field plate via a rigid bond.

10. 1. A method comprising: applying a conductive adhesive to electrode contacts disposed on a flow field plate; placing the flow field plate in contact with a diffusion layer and allowing the conductive adhesive to diffuse through the diffusion layer; and placing an electrolysis membrane in contact with the conductive adhesive diffused through the diffusion layer to electrically couple at least a first side of the electrolysis membrane to the electrode contacts disposed on the flow field plate.

11. The method of claim 10 , wherein applying the conductive adhesive comprises applying the conductive adhesive using a mask.

12. The method of claim 11 , wherein the mask is used to direct the conductive adhesive to the surface of the electrode contacts.

13. The method of claim 10 , further comprising electrically coupling a second side of the electrolytic membrane to another electrode contact of another flow field plate.

14. 11. The method of claim 10, wherein the electrolytic membrane comprises a membrane for proton exchange membrane electrolysis of water (PEMWE).

15. The method of claim 10 , wherein the conductive adhesive comprises conductive particles including precious metal particles and / or graphite particles.

16. The method of claim 10 , wherein the conductive adhesive comprises an epoxy, a butyl rubber compound, and / or a cross-linkable polymer compound.

17. The method of claim 10 , further comprising using fasteners to secure the electrolytic membrane to the flow field plate.

18. 20. The method of claim 17, further comprising adjusting the tightness of the fasteners to control a level of contact between the electrolytic membrane and the electrode contacts via the conductive adhesive.

19. The method of claim 10 , wherein the conductive adhesive securely fastens the electrolytic membrane to the flow field plate.

20. A device, comprising: An electrolytic membrane; A flow field plate; an adhesive for bonding the electrolytic membrane and the flow field plate; and conductive particles embedded within said adhesive for providing electrical contact between said electrolytic membrane and said flow field plate.

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