Patent Application
20250075350
This disclosure relates to electrochemical devices that may incorporate metallic components and methods of operation.
Electrolyzers are known electrochemical devices that may be configured to convert electricity and water into hydrogen and oxygen. Metallic parts exposed to the environment of the electrolyzer may corrode at the highly acidic conditions, may form stable oxides that may reduce conductivity, or may hydrogen embrittle. Some arrangements may include a coating on the metallic parts with a precious metal such as gold, a stable “valve” metal such as titanium (Ti) or nobium (Nb), and/or their nitrides/carbides. The coating may need to be defect-free to protect the metallic part. Other arrangements may utilize a solid carbon flow field plate to establish a cathode flow field half of a bipolar plate assembly.
An assembly for an electrochemical device may include a conductive metallic plate. At least one carbon layer may extend along the metallic plate. The at least one carbon layer may include a plurality of carbon fibers that may establish a porous construct. A plastic film may extend between the metallic plate and the at least one carbon layer. The plastic film may impregnate the porous construct such that the at least one carbon layer may be substantially impermeable to fluid. At least some of the carbon fibers may extend through the plastic film to establish a conductive path between the at least one carbon layer and the metallic plate.
An electrochemical device may include a proton exchange membrane between an anode and a cathode. A conductive metallic plate may be adjacent to a fluid stream of the cathode. A protective barrier may be disposed along the plate. The protective barrier may include one or more carbon layers that each may have a porous construct that may be established by a plurality of carbon fibers. A plastic film may extend between the metallic plate and the one or more carbon layers. The plastic film may impregnate the porous construct such that the one or more carbon layers may be substantially impermeable to fluid through the fluid stream. At least some of the carbon fibers may extend through the plastic film to establish a conductive path between the one or more carbon layers and the metallic plate.
A method of forming an electrochemical device may include disposing a plastic film between a metallic separator plate and a carbon layer. The carbon layer may have a porous construct that may be established by a plurality of carbon fibers. The method may include establishing a protective barrier in response to compressing the carbon layer to cause the plastic film to impregnate the porous construct such that the carbon layer may be substantially impermeable to hydrogen fluid.
The present disclosure may include any one or more of the individual features disclosed above and/or below alone or in any combination thereof.
Various features and advantages of at least one disclosed example embodiment will become apparent to those skilled in the art from the following detailed description. The drawing that accompanies the detailed description can be briefly described as follows.
Like reference numbers and designations in the various drawings indicate like elements.
Assemblies for electrochemical devices such as a proton exchange membrane (PEM) electrolyzer or fuel cell may include one or more conductive metallic plates or other components. A protective barrier may be established along the metallic components.
In implementations, one or more relatively thin, porous conductive carbon paper sheets may be impregnated substantially or fully across a face of the respective sheet and partially through a thickness of the sheet with a substantially fluid (e.g., gas) impermeable material for establishing a protective barrier. The impermeable material may be conductive or non-conductive. The non-conductive material may be a thermoplastic or other non-conductive material. The thermoplastic may be suitable for use in a high-pressure hydrogen environment. In other implementations, the impermeable material may be a conductive material such as a graphite paste. In implementations, impregnation can be performed by laminating two or more carbon paper sheets together and placing them against a metallic plate, or by laminating one or more carbon paper sheets directly onto the metallic plate or other component. The sheets and thermoplastic may be hot-pressed such that the electrically conductive carbon fibers may push through the hot plastic film and establish sufficient contact with the surface of the metallic component to which they may be bonded to. The carbon sheet(s) and plastic film may be secured to the metallic plate once the plastic is cooled. The plastic may substantially fill the pore structure of the carbon paper in-plane, resulting in a substantially gas-impermeable barrier. An appropriate starting thickness of the plastic film may be selected based on a thickness of the carbon paper sheet and porosity such that a conductive path may be established across the barrier subsequent to fabrication. The resultant protective barrier may be gas impermeable thru-plane and may be electrically conductive both thru-plane and in-plane, and may still be relatively thin (e.g., 0.003-0.006 inches). The protective barrier may be suitable to withstand relatively high cross-pressures, but it may be as conductive as the bare carbon paper.
An assembly for an electrochemical device may include a conductive metallic plate. At least one carbon layer may extend along the metallic plate. The at least one carbon layer may include a plurality of carbon fibers that may establish a porous construct. A protective film may extend between the metallic plate and the at least one carbon layer. The protective film may impregnate the porous construct such that the at least one carbon layer may be substantially impermeable to fluid. At least some of the carbon fibers may extend through the protective film to establish a conductive path between the at least one carbon layer and the metallic plate.
In any implementations, the carbon fibers may be randomly distributed in the at least one carbon layer.
In any implementations, the metallic plate may comprise titanium.
In any implementations, the protective film may be a solid protective layer.
In any implementations, the protective layer may comprise a thermoplastic.
In any implementations, the protective film may be a spray-on material.
In any implementations, the at least one carbon layer may include one or more carbon paper sheets.
In any implementations, the at least one carbon layer may be bonded directly to the metallic plate.
In any implementations, the at least one carbon layer may include a first carbon layer and a second carbon layer. The protective film may be sandwiched between the first and second carbon layers such that the fibers of the first carbon layer and the fibers of the second carbon layer may contact each other in the protective film to establish a portion of the conductive path.
In any implementations, the metallic plate may be a separator plate and/or a bipolar plate for a proton exchange membrane (PEM) electrolyzer.
An electrochemical device may include a proton exchange membrane between an anode and a cathode. A conductive metallic plate may be adjacent to a fluid stream of the cathode. A protective barrier may be disposed along the plate. The protective barrier may include one or more carbon layers that each may have a porous construct that may be established by a plurality of carbon fibers. A protective film may extend between the metallic plate and the one or more carbon layers. The protective film may impregnate the porous construct such that the one or more carbon layers may be substantially impermeable to fluid through the fluid stream. At least some of the carbon fibers may extend through the protective film to establish a conductive path between the one or more carbon layers and the metallic plate.
In any implementations, the carbon layer may establish a boundary of the fluid stream.
In any implementations, the one or more carbon layers may include a first carbon layer and a second carbon layer. The protective film may be sandwiched between the first and second carbon layers.
In any implementations, the protective film may include a non-conductive material. The carbon fibers of the first carbon layer and the carbon fibers of the second carbon layer may contact each other in the protective film to establish the conductive path.
In any implementations, the metallic plate may be a separator plate and/or a bipolar plate.
A method of forming an electrochemical device may include disposing a protective film between a metallic separator plate and a carbon layer. The carbon layer may have a porous construct that may be established by a plurality of carbon fibers. The method may include establishing a protective barrier in response to compressing the carbon layer to cause the protective film to impregnate the porous construct such that the carbon layer may be substantially impermeable to hydrogen fluid.
In any implementations, the protective film comprises a non-conductive material. The compressing step may occur such that at least some of the carbon fibers may extend through the protective film to establish a conductive path between the carbon layer and the metallic plate.
In any implementations, the compressing step may include applying a compressive force that may be between approximately 420 pounds per square inch (PSI) and approximately 500 PSI.
In any implementations, the disposing step may include spraying a plastic material on the separator plate and/or the carbon layer to establish the protective layer.
In any implementations, the method may include arranging the protective barrier adjacent to a fluid stream of a cathode.
A plurality of cells 22 may be arranged in a stack. In the implementation of
Each of the cells 22 may include a matrix 24 containing an electrolyte, such as a solid polymer electrolyte (SPE). The matrix 24 may serve as a membrane.
A cathode 26 may be situated on one side of the matrix 24. A cathode flow field 28 adjacent to the cathode 26 may include a plurality of ribs 29 and channels 30 that may establish flow passages for collecting hydrogen (H2) generated by the electrochemical reaction and carrying the hydrogen away from the cell 22. In implementations, water (H2O) may be utilized to sweep hydrogen away from the cell 22. The flow passages of the cathode flow field 28 may be arranged into or out of the page in the illustration. The cathode 26 may include a catalyst adjacent to the matrix 24 and a gas diffusion layer (GDL) adjacent to the cathode flow field 28.
An anode 34 may be situated on an opposite side of the matrix 24 from the cathode 26. The matrix 24 may be situated between the anode 34 and cathode 26. An anode flow field 36 may include flow channels (not illustrated) that may supply reactant, such as water, to the anode 34. The flow passages may carry oxygen (O2) generated from the electrochemical reaction and/or remaining water away from the cell 22. In
The individual cells 22 may be separated by a separator 38 as schematically shown by the broken lines. In implementations, the cathode flow field 28 and anode flow field 36 of adjacent cells 22 may be established by a single, bipolar plate that may also serve as the separator 38 between the adjacent cells 22. The bipolar plates may be coupled to a (e.g., direct current) power source PS for inducing a current across the cell 22.
Referring to
At least one conductive fiber layer 48 may extend along the metallic plate 46. In implementations, the fiber layer(s) 48 may substantially follow a contour of the plate 46. Each fiber layer 48 may include one or more fibers F that may establish a porous construct C (
A protective barrier (e.g., layer or covering) 50 may be disposed along, or otherwise adjacent to, the metallic plate 46. The protective barrier 50 may be an electrically conductive, gas impermeable protective barrier. The protective barrier 50 may establish a barrier to hydrogen gas and/or other fluid along the fluid stream S. In implementations, the protective barrier 50 may establish a coating that substantially or completely blocks permeation of fluid such as hydrogen gas through the conductive layer(s) 48 to the metal plate 46. For the purposes of this disclosure, the terms “approximately” and “substantially” mean ±5% of the stated value or relationship unless otherwise indicated. Protecting the metallic plate 46 from the fluid stream S may reduce a likelihood of corrosion and embrittlement. The protective barrier 50 may be gas impermeable in a thickness direction T (e.g., through plane) and may be electrically conductive in a thickness direction T and lengthwise/widthwise directions L/W (e.g., in-plane).
Various techniques may be utilized to establish the protective barrier 50. The protective barrier 50 may be established by a non-metallic material such as plastic or may be a conductive material such as graphite. The graphite may be in the form of a graphite paste. In implementations, the protective barrier 50 may be established by a relatively thin plastic film 51. The plastic film 51 may extend between the metallic plate 46 and the fiber layer(s) 48. The plastic film 51 may include a thermoplastic or other plastic material. Plastic materials may include high density polyethylenes (HDPE) and polytetrefluoroethylenes (PTFE). The plastic film 51 may be a solid plastic layer. In implementations, the plastic film 51 may be established by a spray-on material. The plastic material may be curable and may serve as an adhesive. The plastic material may be suitable adhering directly to surface of the metallic plate 46.
Referring to
Referring to
A protective barrier 150 may be established between the adjacent portions of the first and second fiber layers 148-1, 148-2. The protective barrier 150 may be established by a substantially impermeable protective film 151. The protective film 151 may be a solid plastic layer that may be arranged between the fiber layers 148-1, 148-2.
Referring to
Referring to
At step 80A, a conductive component (e.g., plate) 46 may be arranged. The plate 46 may be positioned on a fixture or other component suitable for fabricating the device. In implementations, the plate 46 may be a metallic bipolar and/or separator plate. The plate 46 may incorporate any of the materials disclosed herein, such as titanium.
At step 80B, a substantially impermeable protective layer (e.g., film) 51 may be disposed on or otherwise adjacent to the plate 46. The film 51 may include any of the materials disclosed herein, including non-conductive materials such as plastic and conductive materials such as graphite (e.g., paste). Step 80B may include arranging a solid plastic layer or a graphite paste along the plate 46 and/or conductive layer(s) 48. In other implementations, step 80B may include spraying a plastic material on the plate 46 and/or conductive layer(s) 48 to establish the film 51.
At step 80C, one or more conductive layers 48 may be arranged relative to the plate 46 and/or protective film 51. Each conductive layer 48 may include any of the arrangements disclosed herein, such as a carbon layer including one or more fibers F that may establish a porous construct C. In implementations, step 80C may include arranging conductive layers 148-1, 148-2 in abutment to establish an interface 152. In implementations, steps 80B and 80C may occur such that the film 51 may be disposed between the conductive plate 46 and the conductive layer(s) 48.
At step 80D, a protective barrier 50 may be established. Various techniques may be utilized to establish the protective barrier 50, including any of the techniques disclosed herein. The protective barrier 50 may serve to protect the conductive plate 46 from fluid in the fluid stream S, such as hydrogen gas and/or other fluid. In implementations, the protective barrier 50 may be established in response to compressing the conductive layer(s) 48 against the conductive plate 46 to cause the protective film 51 to impregnate the porous construct C such that the conductive layer(s) 48 is substantially impermeable to the fluid. The plastic material may substantially or completely fill the pores of the porous construct C and may secure all of the layers 48, 50 together. The protective barrier 150 may be substantially impermeable to fluid along the interface 152 between the conductive layers 148-1, 148-2. Step 80D may occur such that the conductive layer(s) 48 and protective film 51 may establish a laminate in response to applying the compression and curing the plastic material. Step 80D may occur such that the conductive layer(s) 48 may be secured to surfaces of the conductive plate 46.
Compressing the conductive layer(s) 48 may occur such that at least some of the fibers F may extend through the protective film 51 and contact the plate 46 to establish an electrically conductive path C between the conductive layer(s) 48 and the conductive plate 46. One or more fibers F may be exposed on an opposite side of the conductive layer 48 such that electrically conductive contact can be established between the conductive plate 46 and another component situated against the conductive layer 48 (see, e.g., conductive layers 148-1, 148-2). Step 80D may include applying a compressive force. The compressive force may an amount adequate to establish conductivity that may substantially match unbonded carbon paper. In implementations, the compressive force may be between approximately 420 pounds per square inch (PSI) and approximately 500 PSI that may be applied for a suitable duration.
Each conductive layer 48 may include one or more carbon paper sheets. The carbon paper sheet may have a thickness between approximately 4/1000 inches and approximately 15/1000 inches. The protective film 51 may have a total thickness of less than a thickness of the adjacent conductive layer(s) 48 such that at least some of the fibers F may extend through both sides of the protective film 51.
At step 80E, the assembly 44 incorporating the protective barrier 50 may be arranged to establish a portion of an electrochemical device, such as the electrochemical system 20 of
The disclosed techniques may be utilized to establish a protective barrier that may serve to protect conductive metallic components adjacent to relatively corrosive fluid stream, substantially maintain conductivity and may reduce a likelihood of embrittlement. The protective barrier may be substantially gas-impermeable and may be electrically conductive. The disclosed techniques may be relatively less expensive to fabricate than precious metal coatings. Plastic film and carbon paper may be relatively inexpensive. The disclosed arrangements may have improved reliability over other thin film coatings and may be much thinner and less inexpensive than a carbon flow field plate.
The preceding description is illustrative rather than limiting in nature. Variations and modifications to the disclosed examples may become apparent to those skilled in the art that do not necessarily depart from the essence of this invention.
