Scalable electrolytic cells and stacks and method for manufacturing them at high speed

Abstract

The electrolyzer stack is configured for rapid manufacturing and assembly of multiple scalable electrolysis cells. Each cell includes multiple water windows configured to maintain pressure drop, temperature rise, and / or oxygen outlet volume fraction below a predetermined threshold. The repeating members of the cells are configured based on a desired roll web width for manufacturing, and the stack compression system is configured to allow for variable amounts and areas of repeating cells in a single stack. The rapid manufacturing system is configured to manufacture the scalable cells and assemble the scalable stacks at a rate exceeding 1,000 MW class stacks per year.

Description

Technical Field

[0001] Incorporation by reference to related patent applications This application claims the benefit of priority under 35 U.S.C. 119(e) based on U.S. Provisional Patent Application No. 63 / 218,446, filed on Jul. 5, 2021, and U.S. Provisional Patent Application No. 63 / 311,773, filed on Feb. 18, 2022, the entire contents of which are hereby incorporated by reference in their entirety.

[0002] Field of the invention The present disclosure relates to an electrochemical cell, and more particularly, Scalable to an electrochemical cell and stack designed for high-speed manufacturing.

Background Art

[0003] An electrochemical cell is a device for inducing a chemical reaction using electricity or generating electricity using a chemical reaction. When electricity is the output, the cell can be considered a fuel cell or an expander cell, depending on the chemical product. When electricity is the input, the cell can be considered an electrolytic cell, a compressor cell, or a purification cell, depending on the chemical product. For example, an electrolytic cell takes in electrical energy and stores the electrical energy in a fuel such as hydrogen by decomposing water into its components. In contrast, a fuel cell can essentially be thought of as an electrolytic cell operating in the reverse direction, where hydrogen and oxygen are provided to the cell, which then combines these molecules to form water and releases electrical energy in the process. The basic elements of these devices are two electrodes, an ion-conductive electrolyte, and an ion-permeable layer separating the two electrodes, although it is also possible to operate an electrolytic cell or a fuel cell in a membrane-less configuration. An electrochemical cell can also include a separator between the electrodes to prevent the products from mixing inside the cell. In the case of a solid electrolyte cell, the membrane and the separator may be combined into an integrated solid ion-conductive layer. A complete electrochemical cell can also include a flow field for delivering reactants to the electrodes, a seal for separating the reactants from each other and from the environment, and one or more impermeable separator plates, also called bipolar plates, which are for isolating one cell from adjacent cells in a stack and, in some embodiments, for containing a separate cooling fluid for thermal management of the cell.

[0004] A variety of electrolytes, including proton exchange membranes, anion exchange membranes, solid oxide ceramic membranes, and liquid alkali solutions such as potassium hydroxide and sodium hydroxide, can be used in electrochemical cells. Different electrolytes require different operating conditions, each having its own advantages and limitations. Advantages of proton and anion exchange membrane electrolytes include a relatively low operating temperature and cells that can be constructed using unitized planar electrolyte / membranes. Electrolyzers using such membranes have distinct advantages compared to other electrolyzer cells that can operate using pure liquid water as a feedstock rather than caustic solutions or steam, thereby substantially simplifying the actual system balance. Such electrolyzers can also operate without liquid water on the cathode, enabling the production of hydrogen gas with a low vapor-phase water content.

[0005] The impact of carbon dioxide on global climate change is well-documented. As society's efforts to address global climate change accelerate, the need to deeply decarbonize most or all of human energy use has become clear and urgent. Using hydrogen as a carbon-free energy carrier is essential to reach certain segments of human industry that are difficult or impossible to directly decarbonize with electricity. Examples of such segments include steel production, fertilizer manufacturing, construction, and weight transportation such as trucking, maritime shipping, and air transportation. In addition to these segments, hydrogen's high energy density and stable storage characteristics make it one of the most promising candidates for seasonal-scale energy storage, leading to the establishment of a resilient power grid using only renewable electricity. This will be necessary to fully convert energy use to carbon-free sources. These and other advantages have drawn high levels of interest in the production of "green hydrogen."

[0006] When hydrogen is produced by electrolysis from renewable electricity (such as wind, solar, and hydro), it is given the label "green". In the future global energy system, the scale required to meet the potential demand for green hydrogen is enormous. The production capacity of electrolyzers needs to increase by several orders of magnitude in the next decade to meet such demand, and their costs need to be reduced by more than a factor of 10. So far, the manufacture of hydrogen electrolyzers has been a niche industry with limited deployment based on small systems and cells and stacks designed for research and development. Little consideration has been given to the manufacturing speeds required to produce and assemble cells and stacks at a rate commensurate with society's ultimate needs.

Summary of the Invention

[0007] Recognizing the urgent need for innovative electrolyzer technology, the inventors of the present application Scalable along with a stack compression system, Scalable developed electrolytic cells and stacks, as well as high-speed manufacturing methods. Embodiments of the present application minimize the capital costs for manufacturing a wide range of electrochemical cell stack sizes and enable the rapid manufacture of electrochemical cells, including water electrolyzers.

[0008] The basic process of water electrolysis involves supplying water to a positively charged anode and conducting ions between the anode and a negatively charged cathode. Oxygen gas is generated at the anode, and hydrogen gas is generated at the cathode at room temperature at sea level (0M). The specific ions conducted between the anode and cathode depend on the electrolyte used. In acidic cells, positively charged hydronium ions are conducted from the anode to the cathode. In alkaline cells, negatively charged hydroxide ions are conducted from the cathode to the anode. In both systems, the overall reaction is the same: (2)H2O(l) → (2)H2(g)+O2(g). Electricity must be supplied to drive the reaction. The open circuit or thermoneutral voltage for the basic reaction of hydrogen to liquid water is 1.481, and thus, a voltage higher than 1.481 must be applied to a hydrogen electrolysis cell supplied with liquid water to drive the reaction (as discussed below, an overvoltage is usually required for the reaction to proceed at an acceptable rate). The size of the cell (i.e., the active area) determines the rate of hydrogen / oxygen production from one cell at a given applied voltage. The total current required at a specific applied voltage can be proportional to the size of the cell (i.e., the active area). In practical systems, multiple cells can be "stacked" on top of each other to increase production capacity. This stacking of cells results in the need to apply a higher voltage (an integer multiple of the number of cells) to drive the reaction. For example, a single cell of 1000 cm 2 can produce the same hydrogen flow as two stacked cells of 500 cm 2 , but the 500 cm 2 stack requires twice the voltage and half the current. The flexibility in choosing the required voltage and current can be an important consideration in the design and cost of the overall electrolysis system. For example, a power supply for high current and low voltage can be more expensive than a power supply for high voltage and low current due to the size of the required conductors and the additional materials required for their construction.

[0009] As the reaction proceeds, water is consumed and hydrogen + oxygen gas is produced, so water must be continuously supplied to the cell to feed the reaction. Stoichiometry is the term for the "balance" of a chemical reaction. In an electrochemical cell, the term "stoichiometry" or "stoich" refers to the ratio of reactants supplied to the cell relative to the amounts necessary to exactly balance the overall reaction. For example, an electrolysis cell operating at a water stoichiometry of 2 has an input of twice the amount of water required to produce the hydrogen and oxygen exiting the cell. Conserving the mass of the system at 1 stoichiometry indicates that 1 kg of hydrogen production per hour is associated with approximately 8 kg of oxygen production per hour and approximately 9 kg of water consumption per hour. Electrolyzers can typically be operated at a minimum water stoichiometry greater than 1 to ensure appropriate reactants everywhere within the cell. For example, when the water flow stoichiometry is 1, all of the water provided to the cell is converted to oxygen on the anode and the oxygen fraction at the cell exit is 100% (i.e., there is no water exiting the cell). This condition can be unstable and can result in damage due to anode starvation in the cell near the exit. Also, since everything exiting the cell is in the gas phase, it can result in high fluid velocities and pressure losses at the exit. Thus, the process conditions can be selected to maintain the oxygen vapor fraction at the cell exit below a given threshold. For example, with an exit oxygen fraction of less than 40%, the flow field velocity from the water inlet to the exit can increase by less than a factor of 2. To maintain an oxygen fraction of less than 40%, a water stoichiometry of 100 or more may be required.

[0010] The electrolysis process is not 100% efficient, and as a result, a portion of the input electricity is converted to heat within the cell rather than chemical energy stored as hydrogen. This results in a voltage greater than the thermoneutral voltage (1.481) required for a practical hydrogen output flow rate. The energy efficiency of this system is [1 - (1.481 / V), where the fraction of the power supplied to the hot cell (voltage × current) cell)]It can be shown that it can be equal to. A practical electrolytic cell can operate at 1.8V. As a result, [1-(1.481 / 1.8)] =~18% of the power is sent to the cell and converted to heat rather than hydrogen. Therefore, an actual electrolytic cell requires cooling during operation, and an efficient way to achieve this cooling could be to utilize the process water itself to cool the cell. Depending on the operating conditions of the cell, a relatively high flow rate of water may be required to ensure that the peak temperature of the cell is maintained below an acceptable threshold and that the temperature gradient within the cell is also acceptable. This flow rate can also represent a water stoichiometry much greater than 1. For example, for a cell operating at 1.8V, releasing 18% of the input energy as heat, and operating at 2.7W / cm 2 In a cell operating at, approximately 160 water stoichiometry may be required to maintain a temperature rise of less than 10°C across the cell. From the above-described design considerations, the flow rate of water to the cell is determined by the higher of either the need for appropriate reactants or the need for appropriate temperature control.

[0011] Managing the water provided to a hydrogen electrolysis cell / stack can be a major consideration for the overall hydrogen production system. Flow rate, pressure, temperature, and composition must all be adjusted to meet the requirements of the cell / stack. A typical system includes a liquid-gas separator, heat exchanger, pump, and deionization system connected in a loop to the anode side of the cell / stack and can recirculate water at the required flow rate. As the system produces hydrogen and oxygen, 1 "stoichiometric" of water is consumed. The consumed water can be replenished by injecting 1 stoichiometric of fresh water into the system loop from a source of acceptable quality (e.g., demineralized water, desalinated water, or municipal water). Considering the scale of the electrolysis plant, the required water flow consumed by the cell / stack can be proportional to the plant capacity. Regardless of scale, it may be desirable to keep other process parameters (pressure, temperature, composition) uniform, as this can significantly simplify the selection of system components, overall system control, and the cost of engineering, procurement, and construction (EPC) at the deployment site. For example, water pumps are generally commercially available in a wide range of flow rates for a given pressure capacity. Therefore, it can be advantageous to have a basic cell / stack where the water flow resistance does not depend on the size of the cell or stack. Larger systems can then be constructed modularly from more cells and / or more stacks without the need to change the water pump technology and basic pressure ratings for the system and plant.

[0012] The elements of a hydrogen electrolyzer stack can include a stack of repeating members and a system of non-repeating members. As the name implies, the repeating members are those whose quantity increases with stack height and can typically include a membrane / electrolyte, anode and cathode electrodes, water and hydrogen flow fields, water and hydrogen seals, and bipolar cell separator plates. The non-repeating members can typically include end units and mechanical systems for maintaining stack compression. The end units can also include power terminals, electrical isolators, fluid distribution and / or drain / purge manifolds, and structural end plates. The stack compression system can include tension elements, spring elements, and adjustable elements used to transmit mechanical forces (compression) within the stack core of the repeating members to mechanical forces (tension) within the tension and spring elements. This compression of the stack core can be essential to ensure both electrical contact and fluid sealing between the individual cells and the end units. For convenience, a Cartesian coordinate system with perpendicular x-y-z axes can be defined, where "x" is parallel to the general direction of water flow through the stack, "y" is perpendicular to x and lies within the same plane defined by a single cell, and "z" is generally parallel to the stacking direction of the cells. In this text, the compression system generally functions to apply a compressive load along the z-axis.

[0013] To function properly over the expected range of operating conditions for the electrolyzer stack, the compression system can maintain appropriate compression on the stack over a range of temperatures, taking into account thermal expansion and contraction. The system can also apply a compressive load high enough to prevent the cells from separating over the expected range of operating pressures within the cell. As the pressure increases and separation occurs, performance can degrade due to loss of contact between cells, fluid leakage, or both. The electrolytic cells and stack can be designed for a maximum allowable working pressure (MAWP) on both the hydrogen and water sides of the cells. The MAWP, desired inter-cell contact pressure, mechanical rigidity of the core, overall operating temperature range, and expected variations in the thickness of the repeating members can be the main driving forces for the design of the stack compression system.

[0014] Typical electrolytic cells can have other shapes, but generally may be circular or rectangular in shape. Historically, circular cells have been selected, allowing for a circular cell pressure boundary when establishing the MAWP of the cell. In recent years, rectangular cells have been introduced for the major advantage in reducing material waste during manufacturing. Rectangular cells can maintain a cell pressure boundary that depends on the friction and / or bonding between the self-frame and the bipolar plates. In both cases, a typical compression system used can include two thick end plates (one at each end of the stack core) and a number of spring-loaded tie rods that extend between the plates and are generally evenly distributed around the perimeter of the x-y plane of the stack to minimize deformation of the end plates. The tie rods can act as both the tensile and adjustable elements of the compression system. As the tensile load increases in the adjustable rod, the end plates can function like a diaphragm and bend to transmit a compressive load to the stack core. In basic structural mechanics, as the load increases (the MAWP increases and more preload is required for contact or sealing), the thickness or material stiffness of the end plates also increases to prevent excessive bending and loss of contact in the vicinity of the central region of the cell. Also, in basic structural mechanics, as the area of the cell increases within the x-y plane, the thickness or material stiffness of the end plates also increases to prevent excessive bending and loss of contact in the vicinity of the central region of the cell. As the area increases, the total number of rods / springs also increases, and the spacing between the rods, as well as the peripheral bending and contact / sealing problems, can be minimized. These changes may require redesign, reassembly, and re-verification of the stack and system from a basic level when larger cells are desired. As a result, manufacturing difficulties may arise due to multi-dimensional variations in the components, changes in requirements for handling, and other inconsistencies and changes in the assembly procedures.

[0015] As described above, the basic elements of an electrolytic cell include two electrodes, a unitized solid ion-conductive separator membrane, a flow field for delivering reactants to the electrodes, seals for isolating the reactants from each other and from the environment, and impermeable bipolar plates. The cell design may also include features to facilitate sealing between cell stacks and stacked cells. These can include seals for water and / or hydrogen, windows and ports in the cell periphery for distributing and collecting water, oxygen, and hydrogen, and various other detailed features to ensure that the load from compression of the stack core is directed in appropriate proportions to the active areas and peripheral seals of the individual cells. As the cells are stacked, the windows in the cell periphery can be aligned to form a continuous plenum through which water, oxygen, and hydrogen can be directed into / out of the cells and towards the ends of the stack. In a typical electrolysis stack, because the available area around the x-y boundary is limited, these plenums can be aligned with holes provided in one or both of the end plates, thereby facilitating external process fluid connections from the system to the stack. The through-hole features in the end plates may require that their structure be weakened and the end plates be made thicker or more rigid. Pipes exiting the stack along the z-axis may require additional z-direction height in the end units to distribute and collect fluid from plenums arranged around the x-y plane. This space can also be added to the thickness of the end plates. If sufficient space is not allocated, insufficient distribution of fluid to the stack or high pressure losses through the stack can occur, which can affect performance or durability. Pipes exiting the stack along the z-axis can also cause inconvenient installation and alignment problems for piping connections to the system. It can be advantageous to manifold the plenums together within one or both of the end units and make the process connections to the stack perpendicular to z in the x and / or y directions.However, for tensile elements surrounding the entire x-y plane, it may be difficult for the process connection portion to exit the stack boundary other than along the z-axis without interfering with the tensile member.

[0016] Accordingly, one embodiment of the present disclosure provides an electrolytic cell having substantially equal resistance to water flow, equal temperature rise, and equal outlet oxygen fraction for a given operating voltage, regardless of the selected active region. Scalable In some embodiments, the cell may be substantially rectangular and characterized by a dimension along the x-axis selected according to the roll web width (w) of the membrane, electrode, and / or flow field material used in its manufacture. In some embodiments, the desired roll web width (w) may be selected based on maintaining process parameters for the operating cell within target thresholds. For example, it may be desirable to keep the water pressure drop of the cell below the pumping pressure limit of the system in which the cell can be installed. Alternatively, it may be desirable to keep the water flow temperature below the stack temperature gradient limit to ensure acceptable performance and life. Alternatively, it may be desirable to maintain the cell outlet oxygen volume fraction below the limit to ensure stable performance and life of the cell. Alternatively, the desired roll web width (w) may be selected based on the available source materials for constructing the cell. For example, it may be desirable to select a roll web width that minimizes scrap material when converting the roll into parts during assembly. In this case, the desired roll web widths for the membrane, electrode, and flow field may be the same or different. If they are different, the selected roll web width may be based on the most expensive of the membrane, electrode, and flow field, and the other material rolls may be selected with a web width (w) that matches the others, where matching means a roll web width (w) that optimizes the manufacturing speed and / or overall cost.

[0017] In some embodiments, by adjusting the length of the cell along the y-axis, ScalableA variable cell area can be achieved from the cell. Along the leading edge of the anode flow field, water distribution windows may be arranged parallel to the y-axis, and each window may be associated with the unit length of the anode flow field. The leading edge of the anode flow field can be defined as the edge where water flows into the anode flow field. The area or effective diameter (diameter of a circle having an area equal to the area of the window) of each water distribution window is selected with a stoichiometry of water flow such that one or more of the temperature rise of the cell or the oxygen outlet volume fraction is maintained below a target threshold, and the water velocity along the z-axis through the window is selected to be maintained below a predetermined threshold. The unit length associated with each water distribution window may be selected to keep the water velocity along the x-axis at the leading edge of the anode flow field below a predetermined threshold. Then, the number of water distribution windows can be selected to achieve the overall target hydrogen production rate of the cell while maintaining the water flow pressure loss, the water temperature rise, and the oxygen outlet volume fraction below the target thresholds.

[0018] In another embodiment, a bipolar plate assembly for a scalable electrolysis cell is provided that includes a bipolar plate, a hydrogen seal, a water seal, and a fluid distribution frame. The fluid distribution frame may be configured to arrange, bond, and house a cathode flow field, a cathode electrode, a membrane, an anode electrode, and an anode flow field between two adjacent bipolar plates. The fluid distribution frame may also be configured to uniformly distribute the water flow from one or more water delivery windows to the leading edge of the anode flow field. The fluid distribution frame may be further configured to uniformly collect the flow of water and oxygen from the trailing edge of the anode flow field and distribute this flow to one or more oxygen collection windows. The trailing edge can be defined as the edge of the anode flow field where water and / or oxygen flows out of the flow field. UniformNo distribution or collection can be defined as a velocity change of less than ±50% at the leading edge and / or trailing edge of the flow field. The fluid distribution frame may be further configured such that a hydrogen seal fits between the frame and the bipolar plate adjacent to the cathode flow field. The fluid distribution frame may be further configured to receive a water seal between the frame and the bipolar plate adjacent to the anode flow field. The fluid distribution frame may be further configured to enable curing of at least one of the hydrogen or water seals by ultraviolet light, microwaves, magnetic curing, thermal curing, solvent curing, two-component epoxy curing and / or moisture curing. To achieve this, the frame can be made of a UV-transparent material or a microwave-transparent material, whereby ultraviolet light can access the hydrogen seal disposed between the frame and the bipolar plate. The advantage of curing seals by ultraviolet light and microwaves is the possibility of very fast curing and short cycle times, which results in high-speed and low-cost manufacturing of the bipolar plate assembly. Alternatively, the fluid distribution frame may be made of a material that functions as a seal, thereby eliminating the need for curing. For example, the frame itself may be made of silicone rubber or polyurethane, or any of various other polymers having properties and geometries suitable for deforming under compression to form a hydrogen seal, a water seal or both. For example, the frame may be manufactured by combining a two-shot injection molding process as a single integral component with a rigid base frame having an overmolded elastomeric pattern for the hydrogen seal, the water seal or both. In another example, the fluid distribution frame may be constructed by screen printing hydrogen and / or water seals on one or both sides of a plastic film in a roll-to-roll process. The fluid distribution frame may be further configured to collect the flow of hydrogen from one or more trailing edges of the cathode flow field and deliver this flow to one or more hydrogen collection windows.The fluid distribution frame can be further configured to fit into an internal seal between the anode flow field and the cathode flow field, and the seal is applied to at least one of the membrane, the catalyst-coated membrane, the electrode, the sub-gasket boundary of the membrane-electrode assembly, or the frame itself. The anode flow field may be further configured to be larger than the cathode flow field so as to facilitate the application of a compressive load to the internal seal when the cell stack is compressed. The fluid distribution frame, the water seal, and the hydrogen seal may further be arranged to minimize unsealed areas in a projection view along the z-axis, where the unsealed area is defined as any area where a compressive load cannot be transmitted between members along the z-axis. For example, ensuring that less than 50% of the projected seal along the z-axis remains unsupported may be advantageous for seal performance and reliability.

[0019] In some embodiments, ScalableA method for manufacturing a bipolar plate assembly for an electrolytic cell is described. In some embodiments, the method includes a series of manufacturing steps in a continuous production line designed for high-speed assembly. First, the materials for the bipolar plate, hydrogen seal, water seal, and fluid distribution frame can be selected from suitable candidate materials that meet the expectations for the production, operation, performance, and lifespan of the electrolytic cell to be manufactured. Second, the bipolar plate can be manufactured from a coil of the selected material by stamping, laser cutting, waterjet cutting, or other suitable metal forming techniques. If required for performance or durability, the bipolar plate can be coated with a layer of a suitable material. For example, a thin layer of gold is required for a PEM electrolytic cell, and a thin layer of nickel is required for an AEM electrolytic cell. Alternatively, a coating may not be required, and the resulting bipolar plate may only need to be passivated and / or washed after formation to eliminate contaminants and promote adhesion of the applied hydrogen seal. Various standard passivation and washing methods can be used to ensure that free metals and hydrophobic contaminants on the bipolar plate surface are minimized. Third, the hydrogen seal may be applied to the bipolar plate in an uncured state. Methods include screen printing, rotary screen printing, stencil printing, robotic dispensing, injection molding, compression molding, or stamp printing, and can be selected based on factors such as process speed, cycle time, material waste, and machine costs, among others. For example, screen printing can be a very fast method but may not be suitable for seals that are too thick or not planar by design. In another example, multiple screen prints can be performed to build up the required thickness of the seal. Fourth, a fluid distribution frame manufactured in a separate process can be aligned with the bipolar plate and hydrogen seal in the x-y plane and pressed onto the uncured hydrogen seal, applying an appropriate force to ensure that an unbroken seal is created between the cathode flow field of the cell and both the water distribution window and the outer perimeter of the cell. The fluid distribution frame may also be pressed onto the hydrogen seal to achieve a specific target thickness for the bipolar plate assembly.By this method, the final thickness of the hydrogen seal can be varied, thereby reducing tolerance stack-up and overall bipolar plate thickness variations due to variations in either the bipolar plate thickness, the fluid distribution frame thickness, or both. At this point, the hydrogen seal can be cured by an appropriate process (as discussed herein) or can remain uncured. Fifthly, a water seal can be applied to the fluid distribution frame in an uncured state. Methods include screen printing, rotary screen printing, stencil printing, robotic dispensing, injection molding, compression molding, or stamp printing, and can be selected based on factors such as process speed, cycle time, material waste, and machine cost, among others. Sixthly, if not pre-cured, the water seal and hydrogen seal can be cured using an appropriate treatment such as ultraviolet curing, microwave curing, thermal curing, solvent curing, two-component epoxy curing, or moisture curing, based on factors including process speed, cycle time, and machine cost. For example, ultraviolet curing can be a very fast method but requires a light source with a line of sight to the uncured seal material. Ultraviolet light curing may not function for curing the hydrogen seal between the bipolar plate and the fluid distribution frame consisting of members that are opaque to light. If the fluid distribution frame or the bipolar plate is transparent to ultraviolet light, rapid curing using this technique may be possible. The advantage of selecting a transparent material for the fluid distribution frame can be that both the hydrogen seal and the water seal can be cured simultaneously, eliminating the cost and process time associated with separate curing steps.

[0020] In another embodiment, a plurality of Scalable electrolytic cell assemblies having a generally fixed dimension along the x-axis and a variable dimension along the y-axis are received and adapted to compress ScalableAn electrolytic cell stack compression system is described. The compression system can include tension members along two opposing sides of a generally rectangular cell stack, and those sides can be parallel to the y-axis such that the stress region of the tension members increases proportionally to the variable y-axis dimension (e.g., y-axis length) of the cell. The two sides adjacent to the tension members may remain open to facilitate high-speed stack assembly and efficient process connection to the stack, or optionally may include additional tension members. In some embodiments, the tension members may be further characterized as being constructed from a generally flat material sheet wrapped around a frame structure that surrounds the ends and two variable-length sides of the stack. The wrap may be formed in a semi-cylindrical shape at each end of the stack and, when viewed along the y-axis, generates a generally oval racetrack shape. This shape may have the advantage that the wrap material can be configured such that the mechanical stress within the wrap can be substantially tensile stress and the bending of the semi-cylindrical end units can be minimized. The wrap may be configured to allow a slip surface between the associated semi-cylindrical end unit of the cell stack and the wrap. This wrap has a dimension that is generally fixed along the x-axis and dimensions along both the y-axis (cell area) and z-axis (number of cells), and the same material and thickness can be used regardless of the active area of the cell or stack height. As the cell area increases with increasing length along the y-axis, the wrap depth along the y-axis can grow arbitrarily proportionally. Since an added active area may require an additional compression load for assembly, the material that is naturally added to increase the wrap depth along the y-axis can provide a structure that carries this load in direct proportion with the same wrap thickness. This geometric Scalable feature has dimensions such that the same material and thickness can be used regardless of the active area of the cell or stack height. As the cell area increases with increasing length along the y-axis, the wrap depth along the y-axis can grow arbitrarily proportionally. Since an added active area may require an additional compression load for assembly, the material that is naturally added to increase the wrap depth along the y-axis can provide a structure that carries this load in direct proportion with the same wrap thickness. This geometric ScalableThe property can provide advantages in the simplified and consistent manufacture of wraps for different stacks and in the economies of scale for raw material procurement. In that case, the thickness of the wrap can only be a function of the fixed x-axis dimension of the cell, the desired preload applied to the stack core during assembly, and / or the rated maximum allowable operating pressure of the electrolytic cell. The thickness of the wrap can be made greater than or equal to the dimension of the cathode flow field along the x-axis multiplied by the ratio of the maximum allowable operating pressure of the electrolytic cell to the tensile strength of the selected wrap material.

[0021] In another embodiment, the wrap may be constructed from a single piece of material connected by a single seam, or more than one piece of material connected by several seams. For example, it may be advantageous to construct the wrap from two opposing halves connected by a joint such as a hinge pin to the flat side of an oval race track shape. This structure facilitates high-speed direct stack assembly within one half of the wrap through one or both of the open faces of the wrap. Also, it thereby enables the use of the second half of the wrap when efficiently pre-compressing the stack of cells after the stack is completed. Also, it thereby enables the two wrap halves to be efficiently connected to a continuous structural boundary by inserting a hinge pin along the y-axis into the aligned hinge loops formed in each wrap half. The connection method may be formed using alternative connection designs such as butt welding, butt bolting, flange welding, flange bolting, hem hooks and / or hem hooks with fasteners. The wrap may be designed to be generally continuous along the y-axis, or may be designed to have strips along the flat sides. The width and length of the strips can be selected to facilitate the formation of the selected connection design. The width and length of the strips can be selected to achieve the desired strength and / or desired elasticity under load. The strips may extend partially around one or both of the wrap halves, or may completely divide the two halves into separate bands. The strips may have a uniform y-axis dimension along the z-axis, or may vary. The variation in the strip shape in the y-z plane can be selected to achieve the desired strength, desired elasticity, or both.

[0022] In another embodiment, the semi-cylindrical end unit may be configured to accommodate adjustable elements of the compression system. The adjustable elements may be fully contained within one or both of the cylindrical end units, thereby reducing the overall volume as compared to a stack having adjustable elements outside the tensile element boundary. Examples of adjustable elements include screws, nuts, springs, pads, shoes, and other structural members necessary to transfer tensile stress from the wrap to compressive stress within the stack core. The members of the adjustable element may be configured to facilitate the separation of two or more members aligned along the z-axis with the cell stack from within the wrap boundary, thereby stretching the wrap while the cell stack is being compressed. The adjustable element may be configured with a longer adjustable length when a greater number of cells of the cell stack are compressed. The adjustable element may also have features that allow an external system to compress the cell stack during initial assembly. For example, holes and contact pads can be provided to allow a hydraulic or pneumatic cylinder, as part of a high-speed manufacturing machine, to compress the cell stack to a desired exact load during assembly. The adjustable element can then be fitted to transfer the load from the manufacturing system to the wrap and achieve the desired final and exact load on the cell stack. One or multiple adjustable elements may be attached within the cylindrical end unit. The number of adjustable elements may be designed to scale proportionally to the y-axis dimension of the cell stack and / or the number of fluid distribution windows selected for the Scalable cells being compressed.

[0023] In another embodiment, the wrap may have features that facilitate cell stack alignment and fitting with the compression fixture. For example, the wrap can have holes or slots along one or both of its flat sides, which allows one or more edges of the cell to contact the alignment rails when the cell is placed on the stack during assembly. It should be understood that the holes or slots do not necessarily have to be rectangular or circular. These features can be designed to establish accurate reference points along the z-axis, thereby ensuring that all cells within the cell stack are accurately aligned with respect to each other and with respect to the cell stack compression system. The wrap may also have features that allow access to adjustable elements within one or both of the semi-cylindrical end units to facilitate compression. For example, holes can be provided in the wrap to allow a hydraulically driven post to compress the cell stack to a desired first load. Additional holes may be provided to allow access to an adjustable screw or nut for the purpose of transmitting the load from the compressor to the wrap. It should also be understood that the holes do not necessarily have to be rectangular or circular.

[0024] In another embodiment, Scalable a cell stack of electrolytic cells, Scalable a cell stack end unit, and Scalable a cell stack compression system are provided, Scalable and an electrolytic cell stack is described. The electrolytic cell stack includes a number of individual cells arranged along the z-axis. When aligning these cells into a cell stack, the water distribution window and the hydrogen distribution window present in each cell are aligned along the z-axis, forming a water plenum and a hydrogen plenum for distributing and collecting process fluid to and from the individual cells within the cell stack.

[0025] The electrolyzer stack can also include process ports that enter and / or exit the stack compression system boundary on a plane defined by the x-z plane through a freely accessible side of the compression system. The stack may comprise a process manifold at one end unit of the stack and a drain / purge manifold at the opposite end unit. These manifolds can be configured to fluidly connect the stack process ports to appropriate fluid plenums within the cell stack. In this way, a single water stream is delivered to the water inlet port of the stack, subdivided among a number of water inlet plenums, further subdivided and delivered to individual water distribution windows, and associated with the length of the leading edge of the anode flow field. Each associated length of the leading edge of the anode flow field can ensure that the water stream is delivered to the anode electrode in terms of mass flow rate and velocity such that the pressure loss, temperature rise, and increase in oxygen volume fraction are below the target threshold values for each parameter over the length of the flow along the x-axis of the anode flow field. At the trailing edge of the anode flow field, the trailing edge of the associated length delivers the water / oxygen flow to associated water collection windows, which combine to form a water collection plenum, which can deliver water and oxygen to a common manifold and ultimately to a single water outlet port for connection to the electrolysis system.

[0026] Power terminals may be provided at both end units, one being the positive electrode and one being the negative electrode, to supply electricity to the stack. Access to the individual cells of the cell stack can be provided on one or both of the freely accessible sides of the cell stack to probe the individual cell voltages. In some cases, when the z-axis is substantially aligned with the gravitational vector, it may be advantageous for the positive electrode of the stack to be at the top and the negative electrode to be at the bottom. In this configuration, bubbles formed on the anode side of the cell can be motivated to move away from the electrode by gravity, thereby liberating access for further reaction of water and potentially improving the performance of the cell stack. Even in other configurations where the z-axis is not substantially aligned with the gravitational vector, for similar reasons, it may still be advantageous for the positive electrode of the stack to be at a higher position relative to the negative electrode.

[0027] In some cases, it may be advantageous for process connections such as water inflow, water / oxygen outflow, and hydrogen outflow to be at the upper end unit. In this configuration, since oxygen bubbles occupy a significant volume percentage of the outlet fluid on the anode side, they tend to rise due to gravity within the water outlet plenum. If there is a process manifold at the upper end, the rising oxygen bubbles can flow in the desired general direction, helping to prevent liquid slugging, gas phase locking, and / or other flow instabilities potentially caused by flowing the bubbles against gravity. In some cases, it may be advantageous for the drain / purge manifold to be within the lower end unit. During start-up and service of the electrolyzer stack, it may be necessary to drain stagnant water from the electrolyzer stack before connecting or disconnecting the stack to the system. During operation or actuation, it may be necessary to purge the condensate hydrogen collection plenum. A drain / purge manifold located at the lowest point relative to gravity can most easily facilitate complete drainage of water from the stack. During use, it may also be necessary to purge the cathode with an inert gas such as nitrogen before hydrogen is first generated on the cathode. The drain / purge manifold may also be configured to receive a process connection for inert gas purging on the cathode side of the stack.

[0028] In another embodiment, it comprises a stack assembly station arranged at the end of the cell assembly line. ScalableA method of manufacturing an electrolyzer stack is described. The stack station can be configured to allow multiple operators to perform operations simultaneously, thereby accelerating the throughput of the completed stack and enabling high-speed manufacturing of both cells and stacks. For example, a full-scale stack can include 300 cells, and a manufacturing facility configured to produce 1,000 megawatts of electrolyzer stacks per year may need to process up to 1,000 such stacks and 300,000 corresponding cells per year. In the case of one production shift with 1,750 labor hours of operation per year, this production capacity requires a takt time of approximately 20 seconds per cell. Using 300 cells per stack, each stack station may require up to 1.8 hours. In some embodiments, the stations can include: 1) preparation and loading of non-repetitive stack members in an assembly fixture; 2) placement and alignment of cells; 3) compression, leak check, and locking of the cell stack; and 4) finishing and unloading of the stack. These stations can be conveniently arranged on a rotating table at the end of the cell manufacturing line. These stations may be at a 90-degree angle to each other, such that the non-repetitive station may be first, the cell placement station may be second, the cell stack compression and leak station may be third, and the stack finishing and unloading station may be last. Each station can include specific tools, fixtures, and devices to facilitate the tasks. For example, the cell placement and alignment station can include one or more cell alignment rails that can place individual cells to ensure straight and accurate alignment along the z-axis. The function of this rail can be facilitated by features such as holes and / or slots in the stack compression wrap. The table may be controlled to rotate 90 degrees every 1.8 hours after the final cell in the stack is placed and aligned at the second station. One station may require more labor hours than other stations, and a single worker may perform duties at two or more stations.

[0029] As described above, based on the fixed roll web width (w) along the x-axis, the Scalable system can facilitate the assembly of cells and stacks. The cell assembly line can carry members generally in a direction along the y-axis. Such a conveyor can handle cells of various fields flexibly because changing cell dimensions for larger or smaller cells are in the conveying direction and a wider cell assembly belt, machines, and handling devices are not required. At the end of the cell assembly line, a rotating stack assembly station can be arranged so that a stack compression system configured for cells of different sizes can receive the cells. Also based on the same fixed roll web width (w) Scalable The compression system enables handling the assembly of stacks of cells of different areas by changing only the distance along the y-axis for the pick-and-place operation.

[0030] Also, this system enables a production rate of over 1,000 stacks per year. For example, an operator of a rotary table may only need 30 minutes to complete the work. As a result, the cell production rate can increase by a factor of 4, and thus a tack time of about 5 seconds per cell can be obtained. High-speed curing techniques such as ultraviolet curing can facilitate such cycle times, whereby a single stack manufacturing line can manufacture up to 4,000 megawatt-class stacks per year in a single shift. Scalable The flexibility of the cell, stack, and manufacturing process design improves the technology, and different sizes of stacks may be required by sales, so the investment in such a line can be protected from early obsolescence.

[0031] The described manufacturing system can also be flexible from an electrolysis technology perspective. This system can manufacture PEM electrolyzers as long as PEM components and materials are used in the cell assembly line. This system can manufacture AEM electrolyzers as long as AEM components and materials are used in the cell assembly line.

[0032] In another embodiment, Scalable A method for the high-speed manufacture of internal seals for electrolytic cells is described. A film or catalytic coating film of a desired roll web width along the x-axis can be selected. The material from the roll may be directed through a seal applicator along the y-axis, and the uncured internal seal may be applied to one side of the material using one of screen printing, rotary screen printing, stencil printing, or robotic dispensing methods. The choice of method can be made based on the required production speed (i.e., process cycle and / or tact time), and multiple application cycles can be used to build up the thickness required to function on the seal. The applied internal seal can be cured using a high-speed curing system such as ultraviolet curing, microwave curing, thermal curing, solvent curing, two-component epoxy curing, or moisture curing. The film-gasket assembly or catalytic coating film-gasket assembly roll can then be cut into individual component pieces using a flat knife die, rolling knife die, laser, or any other common cutting method. The resulting individual component pieces can be transported to a cell assembler for Scalable integration into the electrolytic cell.

[0033] In another embodiment, ScalableA method for manufacturing a unitized electrode flow field for an electrolysis cell is described. The electrode substrate of a desired roll web width along the x-axis can be selected from one of foam, felt, woven screen, expanded metal, or sintered metal frit. The flow field substrate of a desired roll web width along the x-axis can be selected from one of foam, felt, woven screen, expanded metal, or sintered metal frit. The electrode substrate material from the roll may be directed along the y-axis through calendar rollers configured to achieve the desired thickness and surface characteristics at each edge of the electrode substrate. For example, the rolling rollers disposed at either edge of the substrate web may have the same diameter or different diameters, and may be of the same material or different materials. It may be advantageous to use harder and / or smaller rollers at the edges of the electrode substrate to be converted into the active electrode to achieve a denser and / or smoother surface for the conversion. Also, it may be advantageous to use softer and / or larger rollers at the edges of the electrode substrate to be laminated to the flow field substrate to maintain a more porous and / or rougher surface for the lamination.

[0034] The electrode substrate may be converted into the active electrode by appropriate treatment. For example, the electrode material can be laminated onto the appropriate surface of the electrode substrate using spray coating, screen printing, rotary screen printing, doctor blade coating, slot die coating, curtain coating, squeegee coating, or heat and / or pressure. The electrode conversion process may also include a post-coating step. For example, the coating may be dried, heat treated, annealed, or physically or chemically treated to promote bonding to the substrate and / or the functional performance of the cell. The flow field substrate material from the roll may be directed along the y-axis and disposed adjacent to the active electrode web, and the electrode and the flow field web may be adhered together through a lamination process. The lamination process can include roller rolling, and the mating surface of the electrode web and the flow field web is mechanically compressed so that the solid fibers of the substrate and / or Intermembranebecome intertwined and locked together. The laminated electrode flow field rolls can then be cut into separate component pieces, which are transported to a cell assembly machine for integration into a complete Scalable electrolytic cell.

[0035] It should be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the disclosure as set forth in the claims. Further objects, features, and advantages of this application will become apparent from the detailed description of the preferred embodiments described below when considered in conjunction with the drawings.

Brief Description of the Drawings

[0036] The accompanying drawings, which are incorporated herein and constitute a part of this specification, illustrate specific embodiments of the disclosure and, together with the foregoing and following descriptions, serve to explain the principles of the disclosure. As far as possible, the same reference numbers are used throughout the different figures to indicate common or similar components.

[0037]

Figure 1

[0038]

Figure 2ab

[0039]

Figure 3

[0040]

Figure 4

[0041]

Figure 5a

[0042]

Figure 5b

[0043]

Figure 5c

[0044]

Figure 5d

[0045]

Figure 5e

[0046]

Figure 6

[0047]

Figure 7a

[0048]

Figure 7b

[0049]

Figure 7c-e

[0050]

Figure 8

[0051]

Figure 9

[0052]

Figure 10

[0053]

Figure 11

[0054]

Figure 12

[0055]

Figure 13

[0056]

Figure 14a

[0057]

Figure 14b

[0058]

Figure 15

[0059]

Figure 16

[0060]

Figure 17a

[0061]

Figure 17b

[0062]

Figure 18a

[0063]

Figure 18b

[0064]

Figure 19

[0065]

Figure 20

[0066]

Figure 21

[0067]

Figure 22

[0068]

Figure 23a-d

[0069]

Figure 24

[0070]

Figure 25

[0071] Here, a detailed description of several preferred embodiments is given with reference to the accompanying drawings. Although the specification relates to electrolysis, it is understood that the features, members and methods described herein are applicable and adaptable by those skilled in the art to other electrochemical technologies including hydrogen compressors and hydrogen purifiers.

[0072] FIG. 1 includes the main members, namely, the lower wrap (103), the upper wrap (104), the cell stack (105), the lower end unit (106), the upper end unit (107), and the defined Cartesian coordinate system (102). ScalableAn isometric view of an embodiment of the electrolytic cell stack (101) is shown. The stack (101) can be characterized as having variable dimensions along the y-axis and z-axis and a relatively fixed dimension along the x-axis of FIG. 1. Changes in the active area of the cells within the cell stack (105) can increase or decrease the dimensions of the stack along the y-axis. Changes in the number of cells used in the cell stack can increase or decrease the dimensions of the cell stack along the z-axis. For manufacturing convenience (details will be described later), the compression system of the stack assembly may include two pieces connected by joints (109), namely, a lower wrap (103) and an upper wrap (104), to form a continuous tension boundary around the cell stack (105) and the end units (106) and (107) when viewed along the y-axis. This wrap configuration can also provide free access to two opposing sides of the stack aligned with the x-z plane (102). The lower wrap (103) and / or the upper wrap (104) may also include holes, slots, or other gap features (108) to facilitate high-speed stack assembly, as described in the following process (1801). The lower end unit (106) and the upper end unit (107) may each include several members including end blocks, gaskets, manifolds, electrical insulation, and / or power terminals. Additionally, one or both of the end units may be configured to include adjustable elements for compressing the cell stack.

[0073] Figures 2a and 2b show an exemplary prior art electrolyzer stack that includes features that may limit the scalability of the main members and their design, as well as a reference coordinate system (202). In the prior art electrolyzer stack, the cell shape can be circular (201a) or rectangular (201b). Both shapes can embody common elements including end plates (203a / b) and (204a / b), tension elements - tie rods (206), adjustable elements - screws, nuts, springs (205), cell stacks (208a / b), and ports (207a / b) for carrying process fluid in and out of the stack. An essential element of the electrolyzer stack can be to maintain a compressive load on the cell stack (208a / b). As shown, historically, this has been achieved by using tie rods (206) to connect the structural plates (203a / b) and (204a / b) at both ends of the cell stack. The tie rods can be threaded to allow adjustment for changing the height of the cell stack and to generate tension in the rods that are used as a source of compressive force for the cell stack core. The overall compressive load can be a function of the pressure required by the cell active area, the pressure required by the seals between each cell, and the operating pressure in the process fluid of the cells that acts to separate the cells from each other. As the active area of the cell stack becomes larger (e.g., in the case of a higher capacity system), the total pressure required by the entire cell can remain fixed, thereby increasing the total force required for the compression system in proportion to that area. Thus, as the cells within the stack (201a / b) grow in the x - y plane, the end plates (203a / b) and (204a / b) can become very heavy and thick. Also, the number of tie rods (206) may increase to minimize the structural bending of the end plates. Since the tie rods (206) can surround the entire perimeter of the cell stack (208a / b), the space available for connecting the process fluid ports (207a / b) can only pass through the end plates (203a / b) and / or (204a / b).The overall variation in the size, weight, and amount of tensile elements of conventional electrolytic cell stacks can limit the ability to expand the design and manufacturing systems for cells and stacks designed in this way.

[0074] Figure 3 shows a cross-section of an exemplary core electrolysis cell member (301) in the active area of a cell, showing typical ion, electron, and fluid flows for proton (312) and anion (313) exchange membrane electrolysis technology. Here, (308) is an impermeable separator, i.e., a bipolar plate, (305) is a cathode flow field, (307) is a cathode electrode, (304) is an ion-conducting membrane, (306) is an anode electrode, and (303) is an anode flow field. When a power source is attached to the cell having a negative electrode (309) at the bottom and a positive electrode (310) at the upper end, electrons (311) can flow upward through the cell. If the cell is of the acidic proton-conducting type (312), the resulting electric field can direct the positively charged hydronium ions to move downward through the membrane (304). If the cell is of the alkaline hydroxide-conducting type (313), the resulting electric field can direct the negatively charged hydroxide ions to move upward through the membrane (304). In both types, hydrogen is formed on the cathode (307) and can flow into the cathode flow field (305), while oxygen is formed on the anode (306) and can flow into the anode flow field (303). In a dry cathode system, water may be provided only to the anode flow field (303) as a reactant for forming hydrogen and oxygen. Stoichiometry is a term related to the "balance" of a chemical reaction. In an electrochemical cell, the term "stoichiometry" or "stoichiometric" refers to the ratio of reactants supplied to the cell to the amounts necessary to accurately balance the overall reaction. As previously described herein, the water stoichiometry supplied to the anode flow field (303) may be much higher than 1. Also, since the fluid within the anode flow field (303) can be mostly liquid, this compartment can represent a significant flow resistance compared to the cathode flow field. The thickness (314) of the cathode flow field and the thickness (315) of the anode flow field can affect the flow rate, temperature distribution, and pressure loss within the cell. The overall cell pitch (316) of the cell can be determined by the thickness of each of the members (303)-(308) that make up the complete cell.A small cell pitch (316) may be desirable to produce an electrolyzer stack having a high power density and a small size for a given hydrogen production rate [kg / hr]. Thus, optimizing the length of the water flow direction along the x-axis, the width along the y-axis, and the thickness along the z-axis, and the geometric shape of the anode flow field can be an important design goal for the electrolyzer. For example, the anode flow field (303) and / or the cathode flow field (305) may be configured with a thickness of 0.1 to 5.0 mm, 0.2 to 3.0 mm, 0.3 to 2 mm, 0.5 to 2 mm, or 0.6 to 2 mm. Although they are shown in FIG. 3 as having relatively equal thicknesses, the flow fields (303) and (305) can be selected to have the same or different thicknesses based on factors for optimizing the cell process conditions, performance, and manufacturing.

[0075] FIG. 4 shows an isometric view (401) of an embodiment of a stack core (301), and further illustrates exemplary cross-flow orientations (408) and (409) of the process fluid, and the repetition of cell members (410) along the z-axis for generating a stack of cells. Here, it can be seen that the bipolar plate (308) separates one cell of thickness (316) from an adjacent cell 410 (below). The bipolar plate (308) of another adjacent cell can be seen above the cell (401). Water and oxygen (408) can flow along the x-axis within the composite anode electrode flow field (403) of thickness (404). Hydrogen (409) can flow along the y-axis within the composite cathode electrode flow field (405) of thickness (406). Assuming that the cell is oriented such that the gravitational vector is downward and parallel to the z-axis, by placing the anode above the membrane as shown, buoyancy can assist the movement of oxygen bubbles formed on the anode electrode into the water flowing through the anode flow field on the anode electrode, which can be advantageous.

[0076] Figure 5a shows an isometric view (501) of an embodiment of an anode flow field member (506) that illustrates the trade-offs that can exist when expanding the cell area. The base unit of the anode flow field can include a width "w" (505) along the x-axis, a length "l" (504) along the y-axis, and a thickness "t" (503) along the z-axis. The width "w" (505) of the base unit along the x-axis can be 5 - 1000 cm, 5 - 500 cm, 5 - 100 cm, or 10 - 50 cm. The length "l" (504) of the base unit along the y-axis can be 0.5 - 100 cm, 1 - 50 cm, 2 - 25 cm, or 2 - 10 cm. The area (507) of this base unit can be determined by multiplying the width "w" (505) by the length "l" (504). The water flow area at the leading edge (508) of this base unit can be determined by multiplying the thickness "t" (503) by the length "l" (504). The water flow for the fixed stoichiometry and efficiency (509) into this water flow region (508) can be determined by the region (507). To achieve higher hydrogen production [kg / hr] with a certain efficiency and water stoichiometry, additional area "dA" (511a) and / or (511b) may be required. When "dw" (510b) is added to "w" (505) to create "dA" (511b), additional water (513b) may be required to flow into the fixed leading edge flow region (508). The additional water flow may thereby increase the water flow rate through the cell, which may result in an increase in the pressure drop (514). When "dl" (510a) is added to "l" (504) to create "dA" (511a), the additional water (513a) can result in an increase proportional to the fixed leading edge flow area (512a). The additional water can flow through the incremental proportional flow rate region (512a) without increasing the pressure drop (514). Thus, the expansion region along the y-axis can keep all process conditions (pressure, temperature, and oxygen volume fraction) within the cell constant. The total water flow rate can necessarily be proportional to the hydrogen / oxygen production rate, but other system parameters may remain invariant with the expansion of the cell only along the y-axis.This can significantly simplify the resulting electrolyzer system made from cells and cell stacks designed in this way. For example, the specifications of an electrolyzer manufacturing plant, including pressure ratings, temperature ratings, and / or fluid composition ratings, may be consistent for plants with different water flows and hydrogen / oxygen capacities. This, in turn, can simplify engineering procurement and construction activities, expand the available supply of system components, and reduce overall hydrogen production costs.

[0077] Figure 5b shows the results (531) of a mathematical model for the pressure loss per unit flow length (514) [mbar / cm] as a function of the flow rates (509) [cm / s] of hydrogen gas (532) and liquid water (533) flowing through a typical porous medium that can be used in the flow fields of the anode and / or cathode. Also shown is an exemplary target pressure loss threshold (534) that can be selected based on the overall electrolyzer stack and system design. The threshold (534) represents the upper limit of the water pressure loss, and thereby can define the target threshold for the water velocity in the anode flow field (535). As is apparent from the results (531), the pressure loss per unit length for hydrogen can be less than a fraction of the pressure loss for water at a given velocity. Thus, when increasing the cell area, it can be advantageous to prioritize cell expansion based on the water velocity and flow length. For example, a water pump for supplying water to the electrolytic cell can have a pressure capacity of up to 10 bar. The anode flow field (501) can advantageously be configured to stay within the range of the capabilities of commonly available and / or economically useful system water pumps where the water velocity (509) is less than 100 cm / s, less than 50 cm / s, less than 20 cm / s, less than 10 cm / s, or less than 5 cm / s.

[0078] Figure 5c shows the results (541) of a mathematical model for the water temperature rise (515) [°C] as a function of the stoichiometric value of the supplied water. The heat released during the operation of the electrolyzer may be a function of efficiency, which in turn may be a function of the operating cell voltage. Saving energy for the cell can result in an equation for the water temperature rise as specified in Equation 5c-1 below. Here, V is the operating cell voltage, V0 is the thermoneutral cell voltage [1.481 V], HHV is the higher heating value of hydrogen [141.79 MJ / kg], c p is the specific heat capacity of water [4.182 kJ / kg °C], and St is the stoichiometry of the water delivered to the cell. Plots (542) and (543) show the results of this model at two possible operating voltages representing exemplary values at the beginning of life [BoL] and end of life [EoL] of the electrolyzer cell. Also shown is an exemplary water temperature rise target threshold (544), above which the electrolyzer cell cannot operate stably or durably, or above which the electrolysis system cannot operate efficiently. The temperature rise threshold can be used with the EoL voltage limit to define a lower threshold for the water stoichiometry (545). To maintain stable and durable operation of the electrolyzer cell, it may be advantageous to select a water stoichiometry that keeps the water temperature rise at the end of the useful life below 100 °C, below 50 °C, below 25 °C, below 15 °C, or below 10 °C.

[0079]

Number

[0080] Figure 5d shows the result (551) of a mathematical model for the oxygen volume fraction at the anode flow field outlet (552) as a function of the stoichiometric value of the delivered water. The process of electrolysis splits water into hydrogen on the cathode side and oxygen on the anode side. When oxygen is formed on the anode, the oxygen can mix with the delivered liquid water and gas, resulting in a two-phase flow in the anode flow field. The volume fraction of oxygen at the anode outlet can indicate the operating stability, performance, and / or durability of the electrolysis cell, and the target threshold value for this parameter can be set by the designer. Conserving mass for the cell can result in an equation for the oxygen outlet volume fraction as specified in Equation 5d-1. Here, r O2 is the density of the oxygen gas at the anode outlet, and r H2O is the density of the liquid water at the anode outlet, and St is the stoichiometry of the water delivered to the cell. The plot (552) shows the results of this model at a pressure of 10 bara for the anode of the electrolysis cell, along with an exemplary oxygen volume fraction threshold (554). Above this threshold, the cell may not operate stably or durably, or above it, the electrolysis system may not operate efficiently. The oxygen volume fraction threshold can be used to specify a lower limit threshold (555) for the water stoichiometry. To maintain stable and durable operation of the electrolysis cell, it may be advantageous to select a water stoichiometry that maintains the oxygen volume fraction below 80%, below 60%, below 50%, below 40%, or below 30%.

[0081]

Number

[0082] Figure 5e shows the test results (561) for the pressure loss per unit flow length (514) [mbar / cm] as a function of the liquid water flow velocity (509) [cm / s] through several porous media candidates that can be used in the flow field of the anode and / or cathode. The mathematical model results from Figure 5b (533) are referred to again with respect to an exemplary target pressure loss threshold (534) that can be selected based on the overall electrolyzer stack and system design. The threshold (534) can represent an upper limit of the water pressure loss, thereby defining a target threshold for the water velocity in the anode flow field (535) for these actual potential flow field candidates (Samples 1 - 8).

[0083] Figure 6 shows a plan view of an exemplary cell (601) showing features including a water delivery window (603) and a water collection window (604), the scalability of the cell active area by replication of the water window, and a related unit anode flow field length (608) generally fixed along the x-axis and along the y-axis based on a desired roll web width (w) (609). The area or effective diameter (diameter of a circle having an area equal to the area of the window) of each water distribution window (603) is selected in a water stoichiometry selected to maintain one or more of the cell temperature rise or oxygen outlet volume fraction below a target threshold, and to maintain the water velocity along the z-axis through the window below a predetermined threshold. For example, to minimize pressure loss, the water velocity along the z-axis through each window (603) can be maintained below 10 m / s, below 4 m / s, or below 2 m / s. By selection of the unit length (504) associated with each water distribution window, the water flow region (508) (shown in FIG. 5a) at the leading edge of the anode flow field can be formed such that the water velocity along the x-axis at the leading edge (509) is kept below a predetermined threshold. The number of water distribution windows can then be selected to achieve the overall target hydrogen production rate of the cell while maintaining the water flow pressure loss (514) (shown in FIG. 5a), the water temperature rise (515) (shown in FIG. 5a), and an oxygen outlet volume fraction below the target threshold. The cell (601) can comprise an active region (611) and a contour region (610). The contour region can define several fluid flow windows for water delivery (603), water and oxygen collection (604), and hydrogen collection (606). As described, the number of water windows (603) can scale with the active area, while the number of hydrogen windows (606) cannot scale, resulting in a cell having more water windows than hydrogen windows as any single configuration of one cell. The water delivery window and / or the water collection window may be circular, rectangular or another shape that enables low-cost and high-speed manufacturing of the cell (601). For window shapes other than circular, the "effective diameter" can be found by determining the diameter of a circular hole having an area equivalent to the window.Each water window (603) may be associated with a unit length along the y-axis of the anode flow field (504). The effective diameter of the window (603) can be configured to be 1% - 110%, 5% - 75%, 10% - 50%, or 25% - 50% of the unit length (504). The water flow can proceed from the delivery window (603) across the associated section of the active region (611) to the collection window (604) along the path (605). When operating the cell, hydrogen can be generated on the cathode side along the path (605), which can flow to one or more hydrogen collection windows (606) along the streamlines (607). These collection windows (606) may be at one or both ends of the cell and may consist of one or more windows (606) at each end. Since additional hydrogen / oxygen capacity is required, an incremental water window and the associated flow field length (608) can be added along the y-axis to increase the generation of hydrogen / oxygen while maintaining certain operating conditions - pressure, temperature, and fluid composition - within the cell. The total number of windows selected for a particular cell (601) can determine the active region of the entire cell and can be a number from 1 to 100, 2 to 50, 2 to 25, or 2 to 20. An increase in the length of the cell along the y-axis can result in an increase in the length of the flow of the streamlines (607) for hydrogen collection, but the flow resistance to hydrogen gas in the cathode flow field is much smaller (as shown in Figure 5b) than that for liquid water in the anode flow field, such that the impact on the conditions and performance of the cell, stack, or system can be made negligible. Thus, even if the cell size is expanded, no additional hydrogen windows are required. The cell may also include features (612) at one or more positions along the contour region (610) to facilitate equipment connections for measuring and / or controlling cell performance.The scalable electrolytic cell can include a membrane, an anode electrode, a cathode electrode, an anode flow field, a cathode flow field, and a bipolar plate assembly. The bipolar plate assembly can define one or more water delivery windows disposed along one edge of the anode flow field aligned with the y-axis. Each water delivery window can be associated with a length along the y-axis of the anode flow field. The number, effective diameter, and / or associated length of the water delivery windows of the anode flow field can be selected to maintain the water flow resistance, or the water temperature rise, or the cell outlet oxygen volume fraction below the target threshold of the electrolytic cell. The combined number of the water delivery windows and the oxygen collection windows can be equal to or greater than the number of the hydrogen collection windows of the electrolytic cell. The effective diameter of each water delivery window can be 5% to 110% of the associated length along the y-axis of the anode flow field of the electrolytic cell. The dimension of the anode flow field along the x-axis can be the same as that of each water delivery window of the electrolytic cell. The length along the y-axis associated with each water delivery window can be selected based on the thickness of the anode flow field to keep the average velocity of water at the leading edge of the anode flow field below 100 cm / s for the electrolytic cell. The water stoichiometry can be selected to maintain the cell temperature rise at the end of life below 50 °C, or to maintain the oxygen volume fraction at the trailing edge of the anode flow field in the electrolytic cell below 80%. The hydrogen flow velocity vector in the cathode flow field can be generally parallel to the y-axis of the electrolytic cell.As discussed herein, in some embodiments, a scalable electrolyzer stack can include a number of scalable electrolysis cells aligned along the z-axis in a stacked configuration, each cell can include a membrane, an anode electrode, a cathode electrode, an anode flow field, a cathode flow field, and a bipolar plate assembly, the stack bipolar plate assembly can define one or more water delivery plenums disposed along one edge of the anode flow field, each water delivery plenum can be sized to maintain the water velocity through the plenum along the z-axis below a target threshold, each water delivery plenum can be associated with the length of the anode flow field along the y-axis, and the number and / or size of the water delivery plenums can be selected to maintain one of the water flow resistance, the water temperature rise, or the cell outlet oxygen volume fraction below a target threshold of the electrolyzer stack. The combined number of the water delivery plenums and the oxygen collection plenums may be greater than or equal to the number of the hydrogen collection plenums. The stack can further include an end unit at either end of the cell stack, a scalable structural wrap compression system, and at least one fluid manifold included in one of the end units, the manifold can facilitate the delivery of water to the stack along the y-axis through a freely accessible face of the compression system. The fluid manifold may be disposed at the upper end of the stack with respect to the gravitational vector along the z-axis. The stack can further include a drain and / or a purge manifold disposed at the lower end of the stack with respect to the gravitational vector along the z-axis. The sizes of the water flow ports and the manifolds connecting the individual cell stack plenums are to be selected as provided. Flow distribution with a variation of less than ±25% to individual plenums Can be selected as provided.

[0084] Figure 7a shows an exploded view (701) of an exemplary member of a bipolar plate assembly (BPA) designed to enable high-speed manufacturing. The BPA (701) comprises a bipolar plate (308), a hydrogen seal (705), a fluid distribution frame (704), and a water seal (703). The bipolar plate (308) can be composed of a substrate suitable for the environment of the electrolytic cell. For example, if the cell is an acidic proton-conducting type, (308) may include an alloy of titanium, stainless steel, inconel, nickel-chromium, or combinations thereof. Such bipolar plates for acidic cells may also be coated with a suitable corrosion-resistant coating such as platinum, gold, tin, carbon, titanium nitride, or combinations thereof. If the cell is an alkaline hydroxide-conducting type, (308) may include an alloy of iron, steel, stainless steel, nickel, nickel-chromium, inconel, ferraloy, or combinations thereof. Such bipolar plates for alkaline cells may also be coated with a suitable coating such as platinum, gold, tin, nickel, carbon, or combinations thereof. The hydrogen seal (705) can be configured to be applied to the bipolar plate (308) using a high-speed manufacturing process. Suitable fast methods include screen printing, rotary screen printing, stencil printing, robotic dispensing, compression molding, injection molding, stamp printing, or punching and laminating of hot melt adhesive films made from polyester, urethane, nylon, ethylene, or other chemically and mechanically suitable polymer compounds. The thickness of the seal (705) can be manufactured in one or more application steps. It may be advantageous to apply the gasket (705) in an uncured state to facilitate the bonding between the frame (704) and the plate (308). It may also be advantageous that the seal (705) can be cured by a high-speed curing method such as ultraviolet curing, microwave curing, thermal curing, solvent curing, two-component epoxy curing, or moisture curing, or a combination of these methods. If the seal (705) is made in multiple application steps, curing may or may not be required during the above steps.The seal (705) may include a compatible elastomer or polymer material such as silicone, polyurethane, polyolefin, urethane, acrylate, vinyl, butyl, EPDM, nitrile, SBR, SEBS, SIBS or EVA. The seal (705) may be constructed of a reinforcing material embedded in the seal, such as wire mesh, continuous foam, expanded metal, or sintered metal frit. This reinforcement can provide functional advantages when sealing high-pressure fluids by strengthening the polymer / elastomer seal material. It can also provide assembly advantages when setting the exact thickness of the BPA by providing a hard stop when assembling, compressing, and curing the plate (308) / seal (705) / frame (704). The hardness or durometer of the cured seal material may be relatively soft or medium durometer. For example, it can be advantageous if the seal (705) exhibits a relatively compressible modulus of elasticity compared to the bipolar plate (308) and / or frame (704), so that when the cell stack is compressed, elasticity can be provided to the cell contour region (610). For example, the cured hydrogen seal (705) can be configured in a range of modulus of elasticity of 0.01 MPa to 100 MPa, 0.1 to 50 MPa, 1.0 to 25 MPa, or 5 to 20 MPa. Alternatively, the geometric shape of the seal (705) can be adjusted to achieve the desired elasticity. The thickness of the seal (705) can be increased or decreased. For example, the thickness of the seal (705) can be in the range of 10 to 500, 20 to 250, 25 to 250, or 25 to 100 μm. The width of the seal (705) can also be increased or decreased. For example, the width of the seal (705) can be in the range of 0.5 to 15 mm, 1 to 10 mm, or 2 to 5 mm. The materials and properties selected for the seal (705) may vary for the design of acidic or alkaline cells. The fluid distribution frame (704) can be constructed from a relatively rigid plastic material.For example, it can be made by injection molding, compression molding, extrusion molding, casting or slip casting of polymers or elastomers such as polycarbonate, urethane, polysulfone, polyamide, polyamideimide, acrylonitrile-butadiene-styrene, high density polyethylene, polyphenylene sulfide, polyetherimide, silicone, polyurethane, polyolefin, urethane, acrylic, polyvinyl chloride, polystyrene, polypropylene, polyether ether ketone, polyimide or acrylate or other suitable mechanical, electrical, chemical and thermal property polymers or elastomers. The frame (704) is made from a continuous film of material and is then shaped by die, knife die, rotary die, laser or water jet cutting. The frame (704) can be configured in the range of elastic modulus of 1.0 MPa to 100,000 MPa, 10 to 50,000 MPa, 100 to 10,000 MPa, or 1,000 to 10,000 MPa. Making the frame (704) from a visible, ultraviolet transmissive or microwave transmissive material is advantageous as it facilitates the ultraviolet or microwave curing of the hydrogen seal (705) after bonding the hydrogen seal to the bipolar plate 308 using an adhesive. The frame (704) can be provided with specific geometric features for positioning the cell's flow field, electrodes, and membrane. The frame (704) can also include geometric shapes required to uniformly distribute the process fluid to the cell and collect the process fluid from the cell, as well as features for fitting and compressing the internal seal between the anode flow field and the cathode flow field of the cell. The frame (704) may also be provided with features (612) (shown in Figure 6) intended to facilitate cell voltage measurement after assembly into a cell stack. The water seal (703) can be configured to be applied to the fluid distribution frame (704) using a high-speed manufacturing process. Suitable rapid methods include screen printing, rotary screen printing, stencil printing, robotic dispensing, compression molding, injection molding, stamp printing, or punching and laminating. The thickness of the seal (703) can be manufactured in one or more application steps.The seal (703) may also advantageously be curable by a fast curing method such as ultraviolet curing, microwave curing, thermal curing, solvent curing, two-component epoxy curing or moisture curing or a combination of these methods. If the seal (703) is made in multiple application steps, curing may or may not be required during the above steps. The seal (703) may include an elastomeric or polymeric material such as silicone, polyurethane, polyolefin, urethane, acrylate, vinyl, butyl, EPDM, nitrile, SBR, SEBS, SIBS or EVA. The hardness or durometer of the cured seal material may be relatively soft or medium durometer. For example, by the seal (703) exhibiting a relatively compressible modulus of elasticity compared to the bipolar plate (308) and / or the frame (704), it can provide elasticity to the cell contour region (610) when the cell stack is compressed, which may be advantageous. For example, the cured water seal (703) can be configured in a range of modulus of elasticity of 0.01 MPa to 100 MPa, 0.1 to 50 MPa, 1.0 to 25 MPa, or 5 to 20 MPa. Alternatively, the geometry of the seal (703) can be adjusted to achieve the desired elasticity. The thickness of the seal (703) can be increased or decreased. For example, the thickness of the seal (703) can be in the range of 10 to 500, 20 to 250, 25 to 250, or 25 to 100 μm. The width of the seal (703) can also be increased or decreased. For example, the width of the seal (703) can be in the range of 0.5 to 15 mm, 1 to 10 mm, or 2 to 5 mm. The material and properties selected for the seal (703) may be different for the design of acidic or alkaline cells. The seal (703) may also be incorporated into the geometry of the frame (704) by appropriate selection of material and geometry, thereby eliminating the need to apply the seal (703) in a separate process. For example, the frame (704) can be configured to have the geometry of the seal (703) and be manufactured from a material with an appropriate modulus of elasticity to provide a water seal function in a single member.Alternatively, the frame (704) may be manufactured in a two-step process, whereby the seal (703) can be injection molded or compression molded directly onto a pre-injection molded rigid plastic substrate. In another example, the seal (703) may be applied to the fluid distribution frame (704) by screen printing on one side of a plastic film in a roll-to-roll process. The bipolar plate (308), although shown as a flat plate, can have features formed in a central region (706) that are intended to function as flow fields for the cathode and anode or as both sides of the cell. These features can comprise channels, dimples, or other geometries that project along the z-axis, which gives the bipolar plate (308) a three-dimensional shape, creates a structural support for the flow field, electrodes, and / or membrane, and at the same time creates a flow guiding path for hydrogen, water / oxygen, or both fluids.

[0085] FIG. 7b shows a cross-sectional view (711) of an embodiment of the bipolar plate assembly (701) of FIG. 7a, showing the positions and internal seal features for the membrane (304), electrode / and flow field members (403) and (405), and when added to the bipolar plate assembly, according to a preferred embodiment of the present invention ScalableAn electrolytic cell (601) is configured. The cross-section of the frame (704) can be arranged to have a step (714) into which an internal seal (713) can be fitted to separate the anode electrode flow field (403) from the cathode electrode flow field (405). The step (714) can be configured to surround the cathode electrode flow field (405) and fully support the outer edges of the anode electrode flow field (403) and the membrane (304). In this way, the anode flow field (403) can be larger than the cathode flow field (405) in the x-y plane (712). During compression, the electrode flow fields (403) and (405) can be configured to deform, allowing the internal seal (713) to compress between the membrane (304) and the step (714) of the frame (704). Advantageously, the cathode electrode flow field (405) can be elastic so as to contact the membrane (304) over the range of thermal expansion, internal gas pressure, and member thickness variations expected in the fabricated cell (601). Similarly, the thickness, width, and modulus of elasticity of the seals (703), (705), and (713) can be adjusted to achieve the necessary elasticity to provide a sealing function over the range of thermal expansion, internal gas pressure, and member thickness variations expected in the fabrication and operation of the cell (601).

[0086] Figure 7c shows a cross-sectional view and an embodiment of Figure 7b showing an alternative geometric shape of the bipolar plate (308), whereby the cathode electrode flow field (405) can be replaced with features (723) formed directly on the plate (308). These features (723) can comprise channels, dimples or other geometric shapes protruding along the z-axis, which gives the bipolar plate (308) a three-dimensional shape, creates structural support for the flow field, electrodes and / or membrane, and at the same time creates a flow-inducing path for hydrogen, water / oxygen or both fluids. These features can be created by mechanical stamping, machining, hydroforming or other suitable manufacturing methods. The anode flow field and / or the cathode flow field can be selected from and formed of one or more of foam, felt, fabric screen, expanded metal, or sintered metal frit. The anode flow field and / or the cathode flow field can be formed on the bipolar plate by a stamping or hydroforming process.

[0087] Figure 7d shows an isometric view of an alternative embodiment where the bipolar plate assembly includes a porous sheet (732) in which a hydrogen seal (705) can be embedded using screen printing, liquid dispensing, injection or compression molding or other suitable processes. In this configuration, the porous sheet (732) can provide the function of the cathode electrode flow field (405) from Figure 7b, providing both mechanical reinforcement for the hydrogen seal (705) and an open space for hydrogen gas flow from the active area of the cell to the hydrogen gas window (606). The porous sheet (732) can also provide precise thickness control of the bipolar plate assembly during pressing and curing of the hydrogen seal (705) and the frame (704).

[0088] Figure 7e illustrates an embodiment of the cross-sectional view of FIG. 7d with the cathode electrode (722), the membrane (304), the anode electrode flow field (403), and the internal seal (714) added. After assembly and curing, the hydrogen seal (705) is fully embedded within the porous structure of the porous sheet (732) to form an airtight seal of hydrogen gas within the cathode, while at the same time physically adhering the bipolar plate (308) to the porous sheet (732) and the frame (704). The porous sheet (732) can be selected from one or more of foam, felt, woven screen, expanded metal, or sintered metal frit. The porous sheet can include alloys of iron, steel, stainless steel, nickel, nickel-chromium, inconel, ferraloy, or combinations thereof, and can be coated with a suitable coating such as platinum, gold, tin, nickel, carbon, or combinations thereof.

[0089] FIG. 8 shows a plan view of an embodiment of the bipolar plate assembly (701) of FIG. 7a as viewed downward along the z-axis (802), showing the projected alignment of the water seal (703) and the hydrogen seal (705). In order to minimize local bending of the fluid distribution frame and potential losses of the seals, it may be important that the water seal (703) is uniformly supported by the frame (704) and the hydrogen seal (705). Any gap in the total material thickness for the frame (704) and / or the hydrogen seal (705) can cause bending of the frame when the water seal (703) is compressed by adjacent cells within the cell stack. Excessive bending can then lead to improper compression of the water seal (703) and subsequent leakage. For example, a gap exceeding twice the thickness of the frame in a section can cause excessive bending. Uniform support can be determined by evaluating the percentage of the total projected area of the water seal (703) that is not supported by the total thickness section of the frame (704) and the hydrogen seal (705). To provide adequate support, the percentage of the unsupported projected area may be less than 10%, less than 20%, less than 30% or less than 50%. Also shown is the step (714) of the frame (704), which completely surrounds and defines the boundary of the open active area (611) of the cell (601). The step (714) can be configured to have a width such that while allowing the internal seal (713) to fall outside the cathode flow field (405), it provides a pocket in which the anode flow field (403) can be placed. Also, the reference dimension "w" (609) representing the desired roll web width as described above in accordance with the properties of the cell (601) is also shown. The detailed view (803) is explained in FIG. 9. Scalable The reference dimension "w" (609) representing the desired roll web width as described above in accordance with the properties of the cell (601) is also shown. The detailed view (803) is explained in FIG. 9.

[0090] FIG. 9 shows an isometric view of an embodiment of a typical water distribution window (803), showing the features of the distribution (905) and seal (713) included in the frame (704) to provide a uniform water flow (908) over the relevant length of the anode electrode flow field (403). A portion of one water delivery window (603) is shown, with the water velocity vector (907) entering the window (603) generally along the z-axis and turning and spreading in the x-y plane towards the leading edge of the anode flow field (403). The delivery window (603) can be constituted by one or more distribution features (905), and can facilitate the diffusion of the flow (907) in the x-y plane so as to enter the leading edge of (403) in a uniform manner along the y-axis, as indicated by the vector (908). The distribution mechanism (905) may be integrated into the frame (704) or may be formed as part of the geometric features of the water seal (703) (shown in FIGS. 7a - e and 8). The frame may also be configured with a mechanical support mechanism (906) to ensure that sufficient compressive load is transmitted to the hydrogen seal (705) between the frame (704) and the bipolar plate (308), as shown in FIG. 7b. The mechanical support mechanism (906) may also be formed as part of the geometric features of the water seal (703). The cathode electrode flow field (405) is shown disposed inside a step (714) of the frame (704) having a membrane (304) separating the cathode flow field (405) and the anode flow field (403). An internal seal (713) is shown between the membrane (304) and the step (714) of the frame (704), with an overlap with the anode electrode flow field (403) visible. In this configuration, the anode electrode flow field (403) may be larger than the cathode electrode flow field such that it overlaps the seal step (714) all around the active area. The step (714) can act to ensure that the cathode electrode flow field (405) and the anode electrode flow field (403) remain properly positioned and that the internal seal (713) is properly positioned on the step (714). Assurance of these features may be essential for reliable high-speed assembly of the cells and stacks.

[0091] FIG. 10 shows a plan view of an embodiment of the bipolar plate assembly (701) of FIG. 7a as viewed upward along the z-axis (1002), showing the projected alignment of the water seal (703) and the hydrogen seal (705). The view from below shows more clearly how the elements of the hydrogen seal (705) are included for the purpose of supporting the water seal (703). For example, the seal (705) may have features as shown at (1004) to conform to the corresponding geometric shape of the water seal (703). The seal (705) may also have features such as those shown at (1005) to support steps (714) (shown in FIGS. 7b, 7c, 7e, 8, and 9) along the hydrogen trailing edge of the cathode electrode flow field. The bridge mechanisms (1105) and (1106) can be included within the frame (705) as detailed in FIG. 11 at (1003) to allow hydrogen gas to exit into the collection window (606).

[0092] FIG. 11 shows an isometric view of one embodiment of a typical hydrogen collection window (606), which shows the bridges (1105) and (1106) and the features of the internal seal (713) contained within the frame, uniformly collecting the hydrogen (1108) generated by the cell and delivering it (1107) to one or more collection windows (606). A section of one hydrogen collection window (606) is shown with the hydrogen velocity vector (1107), which generally exits the window (606) along the z-axis while rotating from the x-y plane emerging from the trailing edge of the cathode electrode flow field (405). The collection window (606) may be configured using one or more bridge features (1105) and (1106) to facilitate uniform collection of the flow (1108) from the x-y plane and to provide mechanical support to both the internal seal (713) and the water seal (705). The bridge mechanism (1105, 1106) may be integrated into the frame (704) or may be formed as part of the geometric features of the hydrogen seal (705) (shown in FIGS. 7a-e, 8, 10). As part of the geometric shape of the hydrogen seal (705), the bridge features can be made using a porous reinforcing material such as wire mesh, continuous bubble foam, expanded metal, or sintered metal frit. This porous reinforcement can be formed as an extension of all or part of the cathode electrode flow field (405), as a porous sheet (732), as shown in FIGS. 7d and 7e. The cathode electrode flow field (405) is shown disposed inside the step (714) of the frame (704) having a membrane (304) separating the cathode flow field (405) and the anode flow field (403) flow fields. The internal seal (713) is shown between the membrane (304) and the step (714) of the frame (704), with an overlap with the anode flow field (403) visible. The bipolar plate assembly can include a fluid distribution frame configured to dispose and accommodate at least one of a cathode flow field, a cathode electrode, a membrane, an internal seal, an anode electrode, or an anode flow field between two adjacent bipolar plates.The fluid distribution frame can be configured to allow the diffusion of water flow in the x-y plane from one or more water delivery windows to the leading edge of the anode flow field, providing a leading edge velocity distribution within plus or minus 50% of the average velocity of the flow field. The fluid distribution frame can be configured to collect the flow of water and oxygen from the trailing edge of the anode flow field, imposing a change of plus or minus 50% or less on the trailing edge velocity distribution. The hydrogen seal may be disposed between the frame and the bipolar plate adjacent to the cathode flow field, while the water seal may be disposed between the frame and the bipolar plate adjacent to the anode flow field. The fluid distribution frame can include a visible light or ultraviolet light transparent material or a microwave transparent material. The bipolar plate assembly can be configured to collect the hydrogen flow from one or more trailing edges of the cathode flow field and deliver that flow to one or more hydrogen collection windows. The fluid distribution frame can be configured to mate with an internal seal between the anode flow field and the cathode flow field, and the seal is applied to at least one of a membrane, a catalytic coating membrane, an electrode, a sub-gasket boundary of a membrane-electrode assembly, or the frame itself. The fluid distribution frame, the water seal, and the hydrogen seal can be arranged such that the unsealed area is less than 50% in a projection view along the z-axis. The anode flow field may be larger than the cathode flow field within the fluid distribution frame, and the anode flow field can facilitate the application of a compressive load to the internal seal. The bipolar plate assembly can include a bipolar plate material selected from one or more of stainless steel, titanium, nickel, carbon, chromium, iron, or alloys thereof. The bipolar plate assembly can include a bipolar plate that can be coated with one or more of platinum, gold, tin, palladium, rhodium, titanium nitride, nickel, carbon, or chromium. An electrolytic cell using the described fluid distribution frame can have a compression cell pitch of 2.5 mm or less.

[0093] Figure 12 shows an embodiment of the basic steps in a high-speed manufacturing process (1201) for a bipolar plate assembly. The bipolar plate (308) can be loaded onto an assembly line. Next, the hydrogen seal (705) can be applied to the bipolar plate (308) in an uncured state (1203) using a suitable high-speed application method such as screen printing, rotary screen printing, stencil printing, or robotic dispensing. Next, the fluid distribution frame (704) can be positioned relative to the bipolar plate (308) and pressed onto the seal (705) (1204). In the case of a bipolar plate (308) with formed flow field features (723), it may be advantageous to apply the seal (705) to the frame (704) rather than the bipolar plate prior to process step (1204). For example, a screen or stencil printing process (1203) can be performed better on a flat member. Thus, if the bipolar plate (308) is not flat, applying the seal (705) to the frame (704) and then pressing it together with the bipolar plate (308) can be a preferred order of operations. The material properties, geometry, and thickness of the uncured seal (705) can be selected to ensure proper adhesion to both the bipolar plate (308) and the frame (704). The thickness and geometry can be further selected to ensure that the resulting uncured seal forms a continuous gasket between the bipolar plate (308) and the frame (704) after pressing (1204). The pressing step (1204) can include assembling the members with a fixed compressive load using a mechanical, pneumatic, or hydraulic press and flat tooling, or by applying a uniform vacuum pressure to the assembly through a sealed bag or membrane using a vacuum system. The pressing step (1204) can include assembling the members to achieve a certain thickness in the uncured state. After pressing, the hydrogen seal (705) can be cured using a suitable high-speed curing method such as ultraviolet curing, microwave curing, thermal curing, solvent curing, two-part epoxy curing, or moisture curing. Alternatively, the hydrogen seal may remain uncured at this stage.Next, the water seal (703) can be applied to the top of the frame (704) in the uncured state (1205) using a suitable high-speed application method such as screen printing, rotary screen printing, stencil printing, or robotic dispensing. The material properties, geometry, and thickness of the uncured seal (703) can be selected to ensure proper adhesion to the frame (704). As described with respect to FIG. 7a, the thickness and geometry of the seal (703) can be further selected to ensure proper elastic compliance to form a reliable water seal over the range of expected thickness tolerances of the cell members in high-speed manufacturing. For example, a thicker water seal (703) provides a wider range of seals and can accommodate a larger thickness tolerance for the electrode flow field. A narrower water seal (703) provides a lower overall load in the contour region (610) for a given compression, thereby minimizing the percentage of the stack compression load occupied by the seal and ensuring proper contact pressure in the active part of the cell. The final step (1206) may be to cure the seal(s) (703) and (705) using one or more of ultraviolet curing, microwave curing, thermal curing, solvent curing, two-part epoxy curing, or moisture curing if not pre-cured. In certain embodiments, it may be advantageous to apply the water seal (703) to the frame (704) before pressing step (1204) either in the uncured or cured state, or to design the frame (704) with the water seal (703) integrated during its manufacture. The final bipolar plate assembly (1207) may be tested to ensure quality after the curing step (1206). For example, following the curing step (1206), fixtures and machinery for pressure testing and for verifying that the cured seal is leak-tight can be used in accordance with the manufacture of the bipolar plate assembly. ScalableA method of manufacturing a bipolar plate assembly for an electrolytic cell can include selecting materials for the bipolar plate, hydrogen seal, water seal, and fluid distribution frame; applying a hydrogen seal to one of the bipolar plate or fluid distribution frame in an uncured state; aligning the fluid distribution frame with the bipolar plate; compressing to fit the uncured hydrogen seal between the plate and the frame; and applying a water seal to the fluid distribution frame. At least one of the hydrogen seal or the water seal can be cured using an ultraviolet curing method, microwave curing method, thermal curing method, solvent curing method, two-component epoxy curing method, or moisture curing method. The hydrogen seal and the water seal may be cured simultaneously. The water seal may be formed during the manufacture of the fluid distribution frame before fitting with the uncured hydrogen seal. The fluid distribution frame can be pressed with the bipolar plate with sufficient force to ensure that a continuous and unbroken seal is formed between the bipolar plate and the fluid distribution frame, and / or achieve a target thickness of the bipolar plate assembly with a variation of ±25% or less. The seal of hydrogen and / or water can be applied using a screen or stencil printing process. One or both of the hydrogen seal or the water seal can be applied in an uncured state having a thickness of 10 to 1000 μm and a width of 0.5 to 15 mm.

[0094] FIG. 13 shows an embodiment of a basic process (1301) in a high-speed manufacturing process for applying a cell internal seal (713) to a membrane (1305). The membrane or catalyst-coated membrane “CCM” (1304) is selected from a desired roll web width (w) (609). The membrane may be acidic, proton-conducting or alkaline, hydroxide-conducting. The membrane may be bare or may have an electrode catalyst applied to one or both sides. The catalyst coating on one or both sides may be continuous or may be coated with patches having a bare membrane exposed at the edges of each patch. A roll of web width (w) (609) may be loaded onto an unwind station designed to hold the web (1305) flat under known surface tension and be movable along the y-axis (1302). Then, an appropriate high-speed application method (1307), such as screen printing, rotary screen printing, stencil printing, or robotic dispensing, can be used to apply the internal seal (713) directly to the membrane or CCM. The internal seal (713) can then be cured using one or more of ultraviolet curing, microwave curing, thermal curing, solvent curing, two-component epoxy curing, or moisture curing (1307). The web can then be advanced, where discrete membrane-gasket assembly pieces (1309) can be cut from the roll (1308) using an appropriate method, such as punching, rotary blade cutting, or laser cutting, and provided to a separate cell assembly process (1501) (shown in FIG. 15). Waste from the membrane or CCM roll may be collected at the end of the line (1310) for recycling and / or reuse. ScalableA method for manufacturing an internal seal for an electrolytic cell can include selecting one of a film or a catalyst-coated film having a desired roll web width along the x-axis, directing the roll web through a seal applicator along the y-axis, applying an uncured internal seal to one side of the web using one of a screen printing method, a stencil printing method, or a robot dispensing method, curing the applied internal seal using one of ultraviolet curing, microwave curing, thermal curing, solvent curing, two-part epoxy curing, or moisture curing, cutting the roll of the membrane gasket assembly or the catalyst-coated membrane gasket assembly into separate part pieces, and transporting the obtained individual part pieces to a cell assembly machine. The membrane material can be acidic, proton-conducting, or alkaline, hydroxide-conducting, and can be coated on one or both sides as a CCM, either uncoated, continuously coated, or patch-coated. The internal seal can be applied to the anode side and / or the cathode side of the web.

[0095] Figure 14a shows an embodiment of the basic steps in a high-speed manufacturing process (1401) for fabricating an integrated electrode flow field member (1413). One or more rolls of a porous substrate (1403a) can be selected based on the desired roll web width (w) (609) as described above. The substrate can include foams, felts, woven screens, expanded metals, sintered frits, or fiber cloths or papers. The selected substrate can have a porosity of up to 98%, where porosity is defined as the volume percentage of the substrate available for fluid perfusion. For example, the porosity can be 98% - 40%, 95% - 50%, 90% - 60%, or 95% - 80%. The composition of the substrate can include iron, nickel, chromium, steel, stainless steel, inconel, aluminum, titanium, carbon, or combinations thereof. The substrate can be plated or coated with other materials, such as platinum, gold, tin, carbon, titanium nitride or PTFE, or another corrosion-inhibiting layer including a processed layer of a polymer material or an oxide material having conductive metal or carbon paths. The roll (1403a) may be loaded onto an unwind station designed to hold the web flat under known surface tensions and be movable along the y-axis (1402). The roll (1403a) is calendered through a set of rollers (1404) and (1405) to laminate two or more layers together, reduce the porosity of the web, reduce or increase its thickness, increase its strength, increase its stiffness, and / or create desired surface characteristics on one or both sides of the web (1406). For example, it may be advantageous for one side of the substrate to be relatively smooth and the other side to be rough to facilitate subsequent steps in the process. It may also be advantageous to achieve a porosity gradient through the thickness of the substrate. For example, it may be beneficial for downstream processes that one side of the calendered substrate (1406) has a relatively low porosity to receive conversion to an electrode, while the opposite side of (1406) has a relatively high porosity to facilitate bonding with a second substrate.To achieve different properties on each side of the web (1406), the rollers (1404) and (1405) may have the same or different diameters, and / or may be made of the same or different materials, and / or may be constructed with different surface finishes or coatings, and / or may be embossed on one or both sides of the roll web (1403a). Specific surfaceA pattern may be provided. The calendared substrate (1406) can then be converted into an electrode (1408) in step (1407). For example, the electrode material can be coated on a suitable surface of the electrode substrate (1406) using heat and / or pressure by spray coating, screen printing, rotary screen printing, doctor blade coating, slot die coating, curtain coating, squeegee coating, or can be laminated as a film, transfer paper, or solid layer. The electrode applied in step (1407) may include a suitable catalyst material, a conductive support material, an ion-conductive binder material, and an inert binder material, together with a suitable solvent, to facilitate electrode application. By selecting multiple binder materials such as primary, secondary, tertiary, etc. for the ink, proper adhesion of the electrode to the substrate (1406) and proper structural integrity of the final electrode layer itself can be ensured to prevent delamination and / or washing away of the electrode layers during the operation of the electrolytic cell. The binder used can be composed of an ion-conductive polymer alone to optimize the adhesive and ion-conductive functions of the electrode, or can also be composed of a combination of both ion-conductive and non-conductive polymers. The ion-conductive binder can be selected from an ionomer completely dissolved in a suitable solvent (liquid ionomer solution) or a dispersion of an insoluble ionomer in a suitable fluid carrier (ionomer dispersion). In a preferred embodiment, it may be advantageous to use a liquid ionomer solution as the electrode binder to be able to form a continuous ion-conductive film within the structure of the final electrode after coating and during the operation of the electrolytic cell. In another preferred embodiment, it may be advantageous to use a primary inert binder in combination with a secondary ion-conductive binder to achieve optimal resistance to washout and low ion resistance. In another preferred embodiment, it may be advantageous to combine both a liquid ionomer solution and an ionomer dispersion within the electrode to achieve optimal resistance to washout and low ion resistance. The electrode conversion step (1407) may also include post-coating steps.For example, the coating can be dried, heat-treated, annealed, and / or physically or chemically treated to promote bonding to the substrate and / or enhance the electrochemical performance of the cell. The conversion step (1407) may also include a chemical or physical vapor deposition process for conversion to the active electrode (1408). The conversion step (1407) can also include a plasma or flame spray method for depositing the electrode material on the substrate (1406) or for chemically reacting and / or converting the substrate (1406) to the active electrode. Following step (1407), the electrode web (1408) may be disposed adjacent to the second roll of the porous substrate (1403b). This substrate may be the same as or different from (1403a) and may be selected based on a similar range of possible materials and properties as (1403a), but is selected to meet the functional requirements for the fluid flow field rather than for the electrode. For example, making (1403b) the same as (1403a) may result in the highest purchase volume and the lowest supply cost. Selecting (1403b) from a substrate different from (1403a) may be advantageous for battery performance (electrical resistance, flow resistance, thermal conductivity, mechanical elasticity or mechanical strength). In process step (1410), the electrode web (1408) may be laminated to the flow field web (1409) by an appropriate lamination process. The lamination process (1410) is for the simultaneous penetration of solid fibers from web (1408) to web (1409). Intermembrane Or to promote the simultaneous penetration of wires, it may include mechanical rolling or calendaring through rollers similar to (1404) and (1405). To achieve this mechanical bonding, the similar rollers (1404) and (1405) may have the same or different diameters and / or may be made of the same or different materials and / or may be configured with different surface finishes or coatings and / or Specific surfaceIt may be provided with a pattern. Select (1403a) and (1403b) from the same supply material, but it may be advantageous to perform the pre-calender (1403b) slightly before the lamination step (1410). The pre-calendering step may include embossing a pattern on the side (1409) co-penetrated with (1408) to promote mechanical bonding. The lamination step (1410) may include other steps including the application to one or more of the webs (1408) and (1409). Heat treatment or bonding promoters such as adhesives, polymer suspensions, liquid ionomer solutions or ionomer dispersions The order of steps (1407) and (1410) may be reversed so that the conversion of the web (1406) to the electrode (1408) can be carried out after lamination to the web (1409). Certain electrode materials and / or methods may advantageously be formed only after calendering and lamination to ensure sufficient adhesion is maintained within the final web (1411). In some cases, the electrode may be coated on the film, in which case the conversion step (1407) may be omitted in the process (1401). Following the lamination step (1410), the unitized electrode flow field web (1411) can be processed (1412) to produce individual component pieces (1413) of the appropriate size for integration into the electrolytic cell (601). For example, the web (1411) can be processed in step (1412) by punching with a knife or other cutting die to ensure the exact sizing of the component pieces. The exact size of the component (1413) may depend on whether an anode electrode flow field or a cathode electrode flow field is to be generated. The size may also depend on the design tolerances required for reliable high-speed integration with the bipolar plate assembly (1201). The overall process (1401) may be adapted, as required, to generate either the flow field of the anode electrode or the cathode electrode, and the specific materials, coatings, steps and settings of the line may be the same or different for each. In manufacturing, to enable the high-speed production of complete electrolytic cells, two independent lines can be used to simultaneously manufacture one anode electrode flow field and one cathode electrode flow field. ScalableA method for manufacturing an integrated electrode flow field for an electrolysis cell includes selecting an electrode substrate of a desired roll web width along the x-axis from one of a foam, felt, woven screening, expanded metal, or sintered metal frit; selecting a flow field substrate of a desired roll web width along the x-axis from one of a foam, felt, woven screening, expanded metal, or sintered metal frit; directing an electrode substrate web along the y-axis through a calendar roller configured to achieve a desired thickness and surface characteristics on each side of the electrode substrate; converting the electrode substrate into an active electrode; aligning a flow field substrate web adjacent to the electrode substrate web and directing it along the y-axis while passing through a lamination process to bond the electrode and the flow field together; cutting the laminated electrode flow field roll into individual component pieces; and transporting the resulting individual component pieces to a cell assembly machine. The base materials of the electrode and the flow field can include at least one of carbon, nickel, titanium, iron, chromium, stainless steel, or inconel. One or more of the electrode web and the flow field web can have a rough, patterned, or embossed surface to facilitate lamination. The lamination process may include a binding promoter selected from one of an adhesive, a polymer dispersion, a liquid ionomer solution, or an ionomer dispersion. The electrode flow field web may comprise a foam electrode and a woven screen flow field after lamination. The conversion of the electrode can be performed before or after lamination.

[0096] Figure 14b shows some exemplary embodiments of patterning or embossing of the electrode and / or flow field substrate to promote enhanced bonding during the lamination process (1410). The patterns can be linear along the y-axis as shown in (1421) and (1422), along the x-axis (not shown), or along both the x-axis and y-axis in a cross-hatch style (1423) and (1424). The depth and spacing of the contour shapes (triangle (1421), rectangle (1422), or other shapes (not shown)) can be optimized based on the material and other characteristics of the substrate to be laminated.

[0097] Figure 15 shows an embodiment of the basic process (1501) in a high-speed manufacturing process for assembling the unitized electrolysis cell (601). The bipolar plate assembly (1207) can be loaded onto an assembly line that moves along the y-axis (1502). The cathode electrode flow field (1413a) can be placed within the cavity of the bipolar plate assembly (1207) using an appropriate handling method (1503). The resulting subassembly can be advanced along the y-axis using an appropriate handling method (1504), where the membrane gasket assembly (1309) can be placed within the cavity of the bipolar plate (1207). The resulting subassembly can be advanced along the y-axis using an appropriate handling method (1505), where the anode electrode flow field (1413b) can be placed within the cavity of the bipolar plate (1207). For example, the appropriate handling methods (1503), (1504), and (1505) can include robotic handlers and / or automated linear motion machines and can include vision or other measurement systems to ensure the accuracy of the positioning members. The design features of the bipolar plate assembly (1207) can assist in the accurate placement of the members (1413a), (1309), and (1413b). For example, the stepped pockets (714) of the frame (704) can assist the self-positioning members (1413a), (1309), and (1413b). The resulting unitized cell assembly (601) can be further processed to ensure that the members (1413a), (1309), and (1413b) are properly placed within the bipolar plate assembly (1206). For example, a pressing process may be performed after step (1505), whereby a generally flat platen may be used to apply a generally uniform pressure along the z-axis to the component (1413b). The pressure applied in this manner can act to flatten the members (1413a), (1309), and (1413b) and ensure that they are firmly positioned and seated within the bipolar plate assembly (1207).Such a pressing process may be integrated into the handling method (1505) and executed simultaneously with the placement process (1505). The pressing process may also include a leak check to ensure that the members (1413a), (1309), and (1413b) are properly placed and sealed within the bipolar plate (1207).

[0098] Figure 16 shows a y-axis view of an exemplary embodiment of a stack compression system (1601), illustrating a tension wrap (1603) surrounding a core cell stack (1604) and end units (1605) and (1606), whereby the mechanical tension within the wrap (1609) can be balanced by the mechanical compression forces within the cell stacks (1607) and (1608). A slip surface (1610) between the wrap (1603) and the end units (1605) and (1606) is also shown. The slip surface (1610) can ensure that the stress within the wrap (1609) can be maintained primarily as tensile stress, while the load from the wrap (1603) to the end units (1605) and (1606) is generally directed perpendicular to the slip surface and can be directed radially inwards through the end units. This force arrangement can ensure minimal bending in the end units and the application of uniform pressure to the cell stack (1604) by the end units (1605) and (1606). The semi-cylindrical cross-sectional shape of the end units can assist with this force arrangement. The wrap (1603) may be composed of a material with sufficient strength and elasticity to properly maintain the compression load on the core cell stack. For example, the wrap may be made from various alloys of steel, stainless steel, aluminum, or titanium, or may also include suitably strong plastics or reinforced plastics, or composite materials such as carbon, glass, and aramid fibers. The thickness of the wrap "h" (1705) can be selected such that the stress (1609) is below the fracture threshold based on the material selected for the wrap (1603) and ensures the maximum tension (1609) to which the wrap (1603) can be exposed. The thickness "h" (1705) can also be selected to achieve the desired stretch, expansion, or spring constant of the wrap during the assembly and / or use of the compression system (1601). For example, the wrap (1603) advantageously may have a spring constant [N / m] lower than that of the cell stack (1604) [N / m] to accommodate the thermal expansion and contraction of the stack without substantially changing the load applied to the cell stack (1604).For example, the wrap spring constant can be selected to be between 0.1% and 25%, 0.5% and 10%, 1% and 5%, or 2% and 5% of the cell stack spring constant.

[0099] FIG. 17a shows the cell (601) along the y-axis (1702) of the compression system wrap (1603). ScalableFIG. 1701 is an exemplary x-y plane cross-sectional view showing an embodiment of stack 101 indicating the association of properties. Strip 1703 can be characteristic of wrap 1603 as shown in FIGS. 1(103) and (104), and these strips 1703 can carry the tension 1609 of compression system 1601 as a whole. The total compression forces 1607 and 1608 within cell stack 1604 may be equal to the total maximum tensile force 1609 within wrap 1603, or may be divided among the numerous strips 1703 that make up complete wrap 1603. The tensile stress in any one strip may be equal to the tensile force in the strip divided by the cross-sectional area of the strip. When cell 601 is expanded within the active region, a water window and associated anode flow field length 608 are added, and the dimensions of cell 601 increase along the y-axis. This increase in the y-axis dimension of the cell may be accompanied by a proportional increase in the dimension of wrap 1603 along the y-axis. New strips 1704 may be added and / or the strip length "m" 1706 may be adjusted to ensure proportionality between the increased cell 601 length and the length of wrap 1603 along the y-axis. In this way, the additional total compression force required by the incremental cell region 608 can be transmitted at the same tensile stress in the added strip 1704 without requiring a change in the wrap thickness "h" 1705. It may be advantageous to keep the thickness "h" 1705 the same for wraps configured for cells of different sizes. For example, a manufacturing method developed to manufacture a wrap for a relatively large cell may be used directly to manufacture a wrap for a smaller cell, and vice versa. It can also be shown that the required thickness "h" 1705 of the wrap is only a function of the stack compression requirements and not the active region of cell 601. It can be shown that the thickness "h" 1705 can be selected to ensure that the tensile stress within the wrap does not exceed a predetermined fracture threshold "Su" 1707 of the wrap material. This threshold may be the yield strength or tensile strength of the material from which strip 1703 is manufactured.In some embodiments, the thickness “h” (1705) and / or the material of the wrap can be selected to ensure that the tensile stress in the wrap does not exceed 10%, 20%, 30%, 50%, 75%, 80%, or 90% of the yield strength or the tensile strength. To ensure that the tensile stress in the wrap does not exceed “Su” (1707), the dimension “h” (1705) can also be shown to be greater than or equal to the ratio of the selected maximum allowable working pressure “MAWP” (1709) for hydrogen gas in the cathode flow field of the cell to the fracture threshold “Su” (1707) of the wrap material, multiplied by the dimension “wc” (1708) of the cathode flow field along the x-axis, as described by Equation 17a-1 below.

[0100]

Number

[0101] Figure 17b shows an exemplary x-y plane cross-sectional view (1710) of an embodiment of the stack (101) of FIG. 1, showing the fitting of stack alignment fixtures (1713) and (1715) through gaps provided in a wrap (108) configured for this purpose and the fitting of a fixture (1712) on one freely accessible surface of the stack. Also shown is the fitting of movable cell positioning actuators (1716) and (1717) along both sides of the cell. The accurate alignment of the cells with respect to each other and with respect to the stack compression system during lamination and compression can be important for the reliable sealing, performance, and durability of the electrolyzer stack. Precise mechanical restraint is an assembly process in which the six basic degrees of freedom (three translations and three rotations) of the cell (601) are restrained by a system of positioning reference points. In practice, this involves placing the cell (601) on a flat surface (i.e., a previously laminated cell or end unit) and bringing two adjacent edges of the cell into contact with three fixed points, i.e., two on one side (1713) and (1715) and one on an adjacent side (1712). This positioning method fully constrains the cell without overconstraining it. The wrap (1603) extends along two opposing sides of the cell (601). To facilitate the precise restraint assembly process, a gap (108) can be provided through the wrap wall to allow the alignment fixtures (1713) and (1715) to pass through the wrap and establish the aforementioned positioning reference points. The third reference (1712) can be established on a freely accessible surface of the stack without being obstructed by the wrap structure. To ensure that the cell (601) contacts the three established reference points (1712), (1713), and (1714), the cell (601) can be brought into contact with the reference points by a cell handling system used to move the cell from the manufacturing line into the wrap. For example, a robotic arm can be used to ensure contact when placing the cell on the stack.Alternatively, during the placement of the cell (601), the movable actuators (1716) and (1717) can be provided separately, which, after being placed on the stack, push the cell (601) long along the x-axis and y-axis, thereby acting to ensure that the cell (601) contacts the designated reference points (1712), (1713) and (1714). The wrap (1603) may further be configured with features that allow the necessary movable actuator (1716) to pass through the wrap and push the cell into place.

[0102] Figure 18a shows a y-axis view of an exemplary stack compression system in three stages during the compression process (1801), ending with a fully compressed and locked electrolytic cell stack (1820). In stage 1 (leftmost figure), the cell stack (1504) is not compressed and has a free height along the z-axis that can be determined by the weight of the cells and the upper end unit, as indicated by the dimension (1809). The lower wrap element (1803) can include a lower end unit consisting of a semi-cylinder (1505) and a block (1807). The block (1807) can comprise a drain manifold, gasket, spacer, electrical insulation, and power terminal elements. The upper wrap element (1804) can include an upper end unit consisting of a semi-cylinder (1506) and a block (1808). The block (1808) can comprise a process manifold, gasket, spacer, electrical insulation, and power terminal elements. The block (1808) may be further configured to fit into the upper wrap (1805) and hold the members of the upper end unit by separating from the upper wrap (1804) by gravity along the z-axis. The lower (1803) and upper (1804) wrap sections can further include connection elements (1805) and (1806) that can enable the lower and upper wrap sections to be connected when aligned. In stage 2 (middle figure), the upper wrap (1804) and end unit assemblies (1506) and (1808) are lowered along the z-axis (1810) to compress the cell stack (1504) to a pre-compressed height indicated by the dimension (1811). This movement can be achieved using a press powered by hydraulic, pneumatic, mechanical screw, or any other means of force capable of compressing the cell stack to the dimension (1811). The upper wrap and end units can be lowered until the connection elements (1805) and (1806) are aligned, enabling a fixed connection (1812) to be completed between the wrap sections. At this stage, the wrap can act as a continuous integral structure capable of maintaining the designed tensile load.In stage 3 (rightmost figure), the adjustable elements (1815), (1816), and (1817) can be fitted together to compress the cell stack (1504) to its final dimension (1814). This final stage can be achieved in multiple sub-steps. The adjustable element (1816) can be driven upward along the z-axis by temporarily using a hydraulic, pneumatic, or other mechanical system to achieve the desired cell stack load. This temporary load can be advantageous for applying an accurate load by incorporating a load or pressure measuring device into the temporary system. The temporary system can also be advantageous in that a fixed or variable load profile can be applied during compression. For example, the cell stack may be compressed beyond the final load planned for lapping to minimize the contact resistance between cells and cell members. Then, the load within the cell stack can be lowered to the final load planned for lapping, thereby minimizing the structural requirements for the compression system. The temporary load can cycle up and down several times and / or vibrate when the cell stack is compressed in stage 3 to ensure that all members are in close contact and / or the seals are well-fitted. After the temporary load profile is completed, the adjustable elements (1815) and (1817) can be fitted together to transfer the reaction load of the cell stack (1504) from the temporary system to the integral wrap (1603). For example, the screw (1817) can be rotated to separate the pad (1816) from the shoe (1815) within the lower semi-cylinder (1505) and further extend the integral wrap (1603) (1818). As the screw (1817) is rotated, the reaction load carried by the temporary system can decrease while the tensile load within the wrap (1818) can increase as the wrap (1603) extends. When the load within the temporary system drops to zero, the stack assembly can reach its final compressed state. Leakage and other quality control tests of the compression stack (1820) may be incorporated into the process (1801).For example, leak tests on the anode, cathode, or both sides of the stack for an appropriate pressure are carried out during the application of a temporary load before fitting the screw (1817), which can ensure that the stack quality is acceptable before fitting the screw (1817). The leak test may be carried out after the screw (1817) is fitted, or may be carried out before and after the screw (1817) is fitted. Other metrics can be introduced, such as measuring the dimensions of the compressed stack height (1814), the pre-compression height (1811), the free stack height (1809), or all of these heights. The stretch (1818) of the wrap (1803) may be measured before, during, and / or after the third stage to ensure proper fitting of the adjustable elements (1815), (1816), and (1817). For example, the stretch (1818) can be measured using a linear variable displacement transducer or a displacement dial indicator or a strain gauge attached to the wrap (1803). These measurements can be used to determine the spring constants of the wraps (1803) and (1804) using the laws of the housing, to convert the stretch (1818) into force, and to determine the final load on the cell stack (1504).

[0103] Figure 18b shows embodiments of various potential connections (1812) for connecting the lower and upper sections of the wrap. Hinge pin A comprises a lower wrap (1803) and an upper wrap (1804) configured as a series of alternating strips, such that when the strips are aligned, a pin (1820) can pass through a common hole formed along the y-axis (1802). The centerlines of the thicknesses of the lower and upper wraps (1821) can be configured to be aligned along the z-axis and along the centerline of the pin (1820) with respect to each other by the geometry of the hinge. This configuration can be advantageous in minimizing bending and local stress of the strips around the pin when the integrated wrap is tensioned. The bent flanges of each strip (1803) and (1804) may be joined by welding or other means at point (1822) or elsewhere to increase connection strength. The pin can be made from any suitable material of appropriate strength, such as iron, steel, aluminum, titanium, plastic, reinforced plastic, or combinations or alloys of these materials. Hinge pin B is an alternative geometry to hinge pin A and may be advantageous in minimizing the material thickness of the upper and lower wraps. The radius of bending in strips (1803) and (1805) for hinge pin B may be larger, thereby reducing local stress around the connection. The hem hook comprises opposing hem bends formed in the lower wrap (1803) and the upper wrap (1804) that interlock. This style of connection can serve to connect the lower and upper wraps configured as a continuous sheet along the y-axis rather than a series of alternating strips. The hem hook with fastener comprises an improved hem hook connection that can encapsulate the connection to counteract the natural tendency for the connection to rotate under load due to moments that may be caused by misalignment of the centerlines of the wraps (1803) and (1804). The encapsulation may be incorporated into the design of the end block (1808).

[0104] Figure 19 shows an exemplary configuration embodiment of an adjustable element of a compression system (1901) packaged within a lower semi-cylindrical end unit (1505), showing internal separating forces (1909) and (1910) generated by locking the system, which result in compression within the cell stack and tension within the wrap. The cell stack (105) can be abutted by a power terminal plate (1905) that can be set on a drain manifold (1904) having a drain port (1906). The compression plate (1903) may be below the drain manifold (1904) and may be located on one or more compression pads (1816) that can be distributed along the y-axis (1902) in proportion to the number of water windows provided in the cell. The compression pads (1816) can act along the z-axis (1902) to apply an upward force to the plate (1903). The shoe (1815) may be set within the lower semi-cylinder (1505) and may be configured to apply a substantially radial distribution of force (1910) to the semi-cylinder when loaded. The screw (1817) may be passed through the shoe (1815) and the abutting pad (1816). When the screw (1817) is rotated, it acts to separate the pad (1816) from the shoe (1815) and increases the forces (1909) and (1910). The lower wrap (1803) includes the lower semi-cylinder (1505) and may be arranged under tension by the action of the adjustable elements as described above. Also shown is a through-hole (1907), which can enable the stack assembly mechanism to directly compress the pad (1816) in order to achieve the aforementioned temporary compression means. The temporary force (1908) can be achieved using a strut or rod connected to a hydraulic or other type of mechanical loading machine to achieve the third stage of the process (1801). The compression plate (1903), the pad (1816), and the shoe (1815) can be constructed from any suitable structural material based on the design load of the system and the resulting stresses.For example, the plate, pad, and / or shoe can each be selected from iron, steel, aluminum and stainless steel alloys, plastics (of various structural grades), fiber or bead-reinforced plastics or composite materials (such as carbon fiber, glass fiber or aramid fiber). The lower semi-cylinder 1505 can be made from any of the aforementioned materials, as well as some typically low-strength plastics, such as polycarbonate, high-density polyethylene, acrylonitrile-butadiene-styrene, polyamide, polyethylene terephthalate, polypropylene, ultra-high molecular weight polyethylene, or materials similar in terms of the relatively uniform stress expected in this member. The semi-cylinder (1505) can be selected from materials that promote low friction at the boundary (1610) between it and the wrap (1803). The semi-cylinder (1505) may be coated on the outside to further promote low friction at the boundary (1610). To promote low friction, a layer of a thin film such as polytetrafluoroethylene can be disposed between the wrap (1803) and the semi-cylinder (1505). The wrap (1803) may be provided with holes or other features to facilitate the temporary compression means (1907) and (1908) as well as the screw (1817). All or most of the adjustable elements of the compression system (1901) are packaged within the lower end unit (106), thereby saving space and providing resistance tamperability for the installation of the electrolyzer stack (101). For the electrolyzer stack. ScalableA compression system can comprise a cell stack, end units, and a structural wrap configured to include one or more adjustable elements. The wrap may be configured to allow free access to two opposing sides of the cell stack. The wrap may be configured to function as a tension element of the compression system. The wrap may generally be formed from a generally flat sheet of material having a generally uniform thickness. The thickness of the wrap may be determined by the x-axis dimension of the cell stack and the maximum allowable operating pressure of the electrolyzer stack. The wrap thickness may be greater than or equal to the dimension of the cathode flow field along the x-axis multiplied by the ratio of the maximum allowable operating pressure of the electrolyzer to the tensile strength of the wrap material. The wrap may generally have an oval racetrack shape when viewed along the y-axis and may be configured to connect to a semi-cylindrical cell stack end unit. The wrap and the semi-cylindrical end unit may be configured to slide relative to each other when the compression system is loaded. The diameter of the semi-cylindrical end unit may be in the range of 100% to 150% of the electrolytic cell dimension along the x-axis. The adjustable elements of the compression system may be at least partially included within one or both of the semi-cylindrical end units. The adjustable elements may be configured to achieve a final dimension of the cell stack along the z-axis within ±25%. The wrap and the semi-cylindrical end unit may be configured to allow direct compression of the cell stack by a temporary stack assembly system that is mechanically parallel to the adjustable elements. The wrap and the semi-cylindrical end unit may be configured to allow access to and operation of the adjustable elements. The adjustable elements may comprise one or more of screws, nuts, springs, hydraulic cylinders, pneumatic cylinders, pressure pads, or pressure shoes. The total amount of adjustable elements within the stack may be proportional to the number of water delivery windows provided within the cells that make up the cell stack. The wrap may be composed of two connected parts as one of a hinge pin connection, a hem hook connection, or a hem hook connection with a fastener on each of the two flat sides of the wrap.This connection may be configured to allow two wrap components to be fitted along the z-axis while pre-compressing the cell stack, and to complete the assembly of the wrap connection in the pre-compressed cell stack. The wrap can be configured to allow one or more cell stack alignment fixtures to penetrate the wrap boundary and contact one or more edges of the cell stack during assembly. The wrap may be configured to extend along the z-axis by no more than 2% of the final length of the cell stack at the final cell stack compression load. The wrap may be configured to provide a spring constant along the z-axis that is between 0.1% and 25% of the spring constant of the cell stack at the target cell stack compression load.

[0105] FIG. 20 shows an embodiment of the basic steps in a high-speed manufacturing process (2001) for placing individual electrolytic cells (601) on a cell stack (1801) through a freely accessible surface aligned as shown in process (1701) and provided by target stack compression systems (2008) and (2009). The unitized electrolytic cell assembly (601) can be conveyed along the y-axis from the cell assembly process (1501). The cell (601) can be picked up by a robot and placed at the position (2007) of the lower stack wrap assembly (2008) at the end of the belt (2005). Alternatively, the cell (601) may be directly moved along the y-axis to the position (2007) by the conveyor belt (2005) without the need to pick and place each cell. It may be advantageous to align the z-axis of the stack wrap assembly (2008) at an angle to the gravity vector to enable gravity to assist the cell (601) that contacts the positioning reference points described in process (1701) throughout the stacking process. It may be advantageous to move the stack wrap assembly (2008) downward along the z-axis to facilitate the placement of the cell (601) either by the robot or the conveyor at the position (2007) from the fixed z-axis height of the belt (2005). The stack conveyor and assembly system (2001) is flexible as described herein to accept cells in the active area such that the belt (2005) does not need to change its width (1303) to accept cells of such different sizes. Scalable cells that can be

[0106] Figure 21 shows an embodiment of a rotary table stack assembly station (2104) showing the arrangement at the end of a high - speed line (2001). The stack station (2104) can be configured to allow multiple operators to perform operations simultaneously, thereby accelerating the throughput of the completed stacks and enabling high - speed manufacturing of both cells and stacks. For example, a full - scale stack can contain more than 300 cells, and a manufacturing facility configured to manufacture 1,000 megawatt electrolyzer stacks per year may need to process up to 1,000 such stacks and more than 300,000 corresponding cells per year. In the case of one production shift with 1750 labor - hours of operation per year, at this production capacity, a takt time of approximately 20 seconds per cell is required, which can define the required conveyance speed of the cells (601) on the belt (2005). When using 300 cells per stack, each of the stack stations 1 - 4 on the rotary table 2104 may require up to 1.8 hours to complete its task. The stations 1 - 4 of the rotary table (2104) can include: 1) preparing and loading non - repeating stack members such as bottom wraps and end units (1803 / 1505 / 1807) and top wraps and end units (1804 / 1506 / 1808) in the assembly fixtures provided on the table (2104); 2) cell placement and alignment as specified in the stack process (2001); 3) cell stack compression, leak check, and locking as specified in the processes (1801 / 1901); and 4) stack finishing and unloading from the table (2104). These stations can be conveniently arranged on the rotary table at the end of the cell manufacturing line. These stations may be at 90 - degree angles to each other, whereby the non - repeating station may be first, the cell placement station may be second, the cell stack compression and leak station may be third, and the stack finishing and unloading station may be last. Each station can include specific tools, fixtures, and devices to facilitate the tasks.For example, the cell placement and alignment station can include one or more cell alignment rails that can place individual cells to ensure straight and accurate alignment along the z-axis, as specified in process (1710). The function of this rail can be facilitated by features such as holes and / or slots in the stack compression wrap (1603). This table may be controlled to rotate 90 degrees each time after the final cell in the stack is placed and aligned in the second station. One station may require more labor time than other stations, and a single worker may perform duties at two or more stations, or stations may be combined. For example, depending on the periods required at stations 1 and 4, it may be possible to perform these activities in series, reducing the number of stations arranged at 120 degrees to 3 stations instead of 4 stations arranged at 90 degrees in the rotating table (2104). The cell assembly line (2001) can carry the cells (601) generally in a direction along the y-axis (2103). Such a conveyor can flexibly handle cells in various fields because the changing cell dimensions for larger or smaller cells are in the conveying direction (y-axis), eliminating the need for a wider cell assembly belt, machinery, and handling devices. At the end of the cell assembly line (2001), the rotating stack assembly station (2104) may be arranged to allow the stack compression system configured for different sizes of cells to accept different amounts of cells, such that the system can manufacture electrolytic cell stacks with variable active areas and variable numbers of cells on the same line. It is also based on the fixed roll web width "w" (1303). ScalableThe compression system (1801) enables the handling of the assembly of stacks of cells of different areas by varying only the distance along the y-axis for the pick-and-place operation in step 2 on the table (2104). Also, this system (2101) enables a production rate of over 1,000 stacks per year. For example, an operator of the rotary table (2104) may only need 30 minutes to complete tasks at stations 1 to 4. This can potentially increase the cell production rate by four times, resulting in a takt time of approximately 5 seconds per cell and a corresponding increase in the speed along the y-axis of the belt (2005). High-speed curing techniques such as ultraviolet curing can accelerate such cycle times in the manufacture of bipolar plate assemblies (1206) and membrane gasket assemblies (1309), thereby enabling a single stack manufacturing line to produce up to 4,000 megawatt-class stacks per year in a single shift. Scalable The integrated design and flexibility of the cells, stacks, and manufacturing process improve the technology, and since stacks of different sizes may be required by sales, investment in such a line can be protected from premature obsolescence. The described manufacturing system is also flexible with respect to electrolysis technology and can be configured to manufacture PEM or AEM type cells and stacks. Scalable A method of manufacturing an electrolytic cell stack includes placing a lower wrap element and an end unit assembly on a stack fixture, placing an upper wrap element and an end unit assembly on the stack fixture, ScalableIn a manufacturing line for producing electrolytic cells, it can include aligning the freely accessible surface of the lower wrap in the direction of the component piece flow, placing individual cells on the lower wrap through the freely accessible surface, lowering the upper wrap and end unit assembly along the z-axis to pre-compress the cell stack, fitting the connecting elements of the wrap style compression system to connect the lower wrap and the upper wrap into an integral structure, further compressing the cell stack according to a desired compression profile, and locking the stack under a compression load using the adjustable elements of the compression system. The stack assembly can be achieved using a rotating table at the end of the cell manufacturing line. The rotating table can be equipped with stations for loading non-repeating members, placing, aligning cells, compressing the assembly, performing quality checks, and unloading the final stack. The cell alignment fixture can be provided at at least two adjacent edges of the cell stack. The cells can be automatically moved from the end of the cell manufacturing line to the inside of the lower wrap using one of a robotic placement, a linear motion actuator, or gravity. The cells can be directly moved through the freely accessible surface of the lower wrap by the conveyor system of the cell manufacturing line. The lower wrap and the end unit assembly can be moved downward along the z-axis after each cell has been moved to a predetermined position. The z-axis of the stack assembly can be angled with respect to the gravity vector such that the cells placed inside the lower wrap are directed by gravity towards the cell alignment fixtures on one or more edges of the cell stack. The movable cell alignment actuator can be involved on one or more edges of the cell stack such that the cells placed inside the lower wrap are directed towards the cell alignment fixtures on one or more opposing edges of the cell stack.

[0107] Figure 22 shows a bipolar plate assembly (1201), a membrane gasket assembly (1301), a cathode electrode flow field assembly (1401h), an anode electrode flow field assembly (1401x), Scalable an electrolytic cell assembly (1501), and ScalableAn embodiment of a high-speed manufacturing system that combines the above-described processes for an electrolyzer stack assembly (1801) is shown. The system can be configured to synchronize the speeds of each process to achieve a continuous flow of cells (601) into the process (2104). The rate-limiting step at any point within the system may define the maximum speed at which cells (601) and stacks (1801) can be produced. For example, the curing of the hydrogen seal (705) and the water seal (703) in process (1201) may be the longest cycle time in the system (2201), taking 30 seconds. At this cycle time, only 210,000 cells can be produced in one production shift operating 1750 labor hours per year. Instead, if a curing method that shortens the cycle time to 5 seconds is used, assuming that seal curing remains the rate-limiting process in the system (2201), over 1.2 million cells can be manufactured in the same single shift. For example, the simultaneous ultraviolet curing of both the hydrogen (705) and water (703) seals, as shown in step (1206) of process (1201), can constitute cycle times of 30 seconds, 20 seconds, 10 seconds, 5 seconds, or less. If process (1201) constitutes a 30-second cycle time instead of a 5-second cycle time, six parallel lines of process (1201) may be required to achieve the same single-shift capacity, which requires six times the cost for equipment and production space and may significantly impact the cost of the electrolyzer stack (101). This system (2201) can manufacture PEM electrolyzers as long as PEM members and materials are introduced into processes (1201), (1301), and (1401). This system can manufacture AEM electrolyzers as long as AEM members and materials are introduced into processes (1201), (1301), and (1401).

[0108] Figures 23a, 23b, 23c, and 23d illustrate alternative embodiments of compression system 1901. Compression system (2401) includes one semi-cylindrical end unit (2404) and one end block (2405), and as shown in detail in Figure 23d, a cross pin (2409) through a hole (2408) can be used to connect the wrap element (2403). Multiple sets of holes (2408) can be provided within the wrap (2403) to facilitate compression of stacks of cells of various heights or various numbers using the same compression hardware. Slots (2406) and (2407) are provided within the wrap (2403) to facilitate alignment of the internal stack members during assembly and compression using shoulder bolts (2406) or similar means (either temporary or permanent). Internal members similar to those shown in Figure 19 are labeled with the same identification numbers on Figure 23b for clarity. As shown in Figure 23c, the wrap (2403) may comprise one or more independent layers of material wound around the semi-cylindrical end unit (2404). These layers can be formed by plastically bending the layers prior to assembly or by elastically bending the layers during assembly. Elastic bending of the layers during assembly can have a manufacturing advantage of simplifying the structure and reducing costs by allowing each layer of the wrap (2403) to be manufactured from a single two-dimensional cut pattern without considering bending tolerances. Additionally, plastically deformed materials may exhibit different stress / strain relationships compared to elastically deformed materials, which can affect the forces applied to the cell stack. For cell stacks (105) with larger active areas, the wrap (2403) can be extended along the y-axis without the need to change the thickness or number of layers. Similarly, the end unit (2404) is as described herein ScalableAccording to the cell, it can be extended along the y-axis to accommodate a large-area cell. The end unit (2405) may be extended along the y-axis or may be made from modular units whose quantity varies along the y-axis to accommodate larger area cells. Other design and fabrication features of the wrap (2403), end unit (2404), and end unit (2405) remain unchanged for such large-area cells, thereby simplifying design and manufacturing and reducing costs by reusing components for multiple stack products.

[0109] FIG. 24 shows measured strength data (2561) for several samples of candidate flow field materials showing the permanent change in thickness (2509) as a function of mechanical exposure stress (2514). Representative samples were exposed to various levels of mechanical stress and the unloaded thickness was measured after each level, resulting in the curve shown in FIG. 24. This curve then represents the material yield strength as a function of the calendared thickness. During assembly of the electrolytic stack, a compressive load is applied to the active area to maintain sufficient contact and low contact resistance between the layers within the cell and between the individual cells within the stack. The compressive load applied during assembly can be made greater than the expected internal fluid pressure of the stack to ensure that the cell or cell member does not separate during operation. To ensure that this contact is maintained, it is desirable to maintain the elastic behavior of the cells and cell members during assembly and operation. As indicated by limits (2534) and (2535), it may then be advantageous to calendar the flow field material to a value less than X% of its initial thickness (e.g., during calendaring and / or lamination) during manufacture of the flow field to ensure that the material remains elastic during stack assembly and operation. For the candidate materials tested, x = 40%, but depending on the specific properties and material physical properties of the candidate, including porosity, basis weight (defined as the mass per unit area in the x-y plane), structural material, and porous shape (e.g., foam, mesh, expanded metal, felt or others), the specific value for any candidate flow field material may be greater than or less than 40%.

[0110] FIG. 25 shows a preferred embodiment of a complete megawatt-class electrolytic stack (2601) including the elements of the invention disclosed herein. Scalable The stack of cells (105) is ScalableIt includes a membrane, electrodes, flow fields, seals, frames, and bipolar plates, designed and fabricated as previously disclosed, and is housed and compressed within the wrap (2403) and end blocks (2605a and 2605b) by a cross pin (2409) for holding the wrap and end blocks together. In the illustrated megawatt-class stack, as shown, up to 400 such cells, including 8 water flow windows, may be preferred to achieve a cell pitch of 1.6 mm with a water flow velocity of less than 20 cm / s, a pressure drop of less than 2 bar, and a temperature rise of less than 20 °C. It is preferably possible to construct the cathode flow field from stainless steel wire mesh and the anode flow field from a plurality (2 or 3) of nickel foam layers laminated and calendared according to thickness. It may be preferred to reinforce the electrodes with calendared nickel foam. The stack can include one or more end blocks (2605b) depending on the selected cell length along the y-axis. In the illustrated megawatt-class stack, 2 end blocks (2605a) and 4 end blocks (2605b) may be preferred. Each end block (2605b) can include adjustable elements as described in FIGS. 19 and 23 for applying final compression to the stack unit after assembly, as described in the process (1801) of FIG. 18a. The wrap (2403) may be composed of one or more layers, and more layers are preferred as the width of the selected cell along the x-axis increases, as described for FIGS. 17a (variable "h") and 23. For the illustrated megawatt-class stack, the total number of layers can be 3 or 4, depending on the strength of the material used for each layer, the x-axis dimension of the cell stack, and the maximum allowable operating pressure of the electrolyzer stack.In the illustrated megawatt-class stack operating at a maximum hydrogen MAWP of 30 barg, three layers of fully hardened 304 stainless steel having a yield strength of 140 ksi and a thickness of 0.5 mm for each layer may be preferred, which can meet the requirement that the total thickness "h" is greater than or equal to the x-axis dimension of the cathode flow field of the cell multiplied by the ratio of the MAWP to the yield strength of the wrap material. The total number of cross pins (2409) may be proportional to the total number of end blocks (2605a and 2605b). Slots (2406 and 2407) are shown to facilitate alignment, guidance, and attachment of the manifolds (1904 and 2604) during assembly. Slot (2407) can also facilitate accurate constrained assembly and perform the function of the "gap (108)" described in Figure 17b. Also shown is an exemplary lifting system (2603) integrated into the wrap (2403) and crown (2404) to facilitate lifting and moving of the stack after final assembly. This system may be composed of a cross bar located at the top of the crown (2404) within the wrap (2403) having screw holes for receiving standard lifting eyes or swivels (2603) as shown. Two such swivels may be preferred for the megawatt-class stack shown in Figure 25.

[0111] Further embodiments:

[0112] A-1. An electrolytic cell comprising a membrane, an anode electrode, a cathode electrode, an anode flow field, a cathode flow field, and a bipolar plate assembly: wherein the bipolar plate assembly comprises a plurality of repeating water delivery windows disposed adjacent to the leading edge of the anode flow field aligned with the y-axis, each water delivery window being associated with the window length along the y-axis of the anode flow field, and the electrolytic cell is configured such that the number, effective diameter, or window length of the water delivery windows is selected to maintain a water flow resistance, water temperature rise, or cell outlet oxygen volume fraction below a target threshold of the electrolytic cell.

[0113] A-2. The bipolar plate assembly includes one or more oxygen collection windows and hydrogen collection windows, and the total number of water delivery windows and oxygen collection windows is equal to or greater than the number of hydrogen collection windows, the electrolytic cell according to A-1.

[0114] A-3. The electrolytic cell according to A-1, wherein the effective diameter of each water delivery window is 5% to 110% of its associated window length.

[0115] A-4. The electrolytic cell according to A-1, wherein the dimensions of the anode flow field along the x-axis perpendicular to the leading edge of the anode flow field are the same for each water delivery window.

[0116] A-5. The electrolytic cell according to A-1, wherein the window length associated with each water delivery window is selected based on the thickness of the anode flow field to (a) maintain an average water velocity at the leading edge of the anode flow field of less than 100 cm / s at rated hydrogen production output, or (b) maintain a water pressure drop of less than 5 bar at rated hydrogen production output.

[0117] A-6. The electrolytic cell according to A-1, configured to use a selected water stoichiometry to maintain a cell temperature rise of less than 50°C at the end of life, or to maintain an oxygen volume fraction of less than 95% at the trailing edge of the anode flow field.

[0118] A-7. The electrolytic cell according to A-1, wherein the cathode flow field is arranged such that the hydrogen flow velocity vector within the cathode flow field is generally parallel to the leading edge of the anode flow field.

[0119] A-8. The bipolar plate assembly comprises a bipolar plate and a fluid distribution frame, wherein the central region of the bipolar plate assembly is at least partially bounded by the fluid distribution frame and two bipolar plates, and the electrolytic cell according to A-1, comprising at least one of a cathode flow field, a cathode electrode, the membrane, an anode electrode or an anode flow field.

[0120] A-9. The electrolytic cell according to A-8, further comprising a water seal disposed between the frame and the bipolar plate adjacent to the anode flow field.

[0121] A-10. The electrolytic cell according to A-9, wherein at least one of the fluid distribution frame or the water seal is configured to allow the spread of water flow in the x-y plane from one or more water delivery windows to the leading edge of the anode flow field, thereby providing a leading edge water velocity distribution within ±50% of the average velocity of the anode flow field.

[0122] A-11. The electrolytic cell according to A-9, wherein at least one of the fluid distribution frame or the water seal is configured to collect the flow of water and oxygen from the trailing edge of the anode flow field and impose a change of ±50% or less on the trailing edge velocity distribution for the anode flow field.

[0123] A-12. The electrolytic cell according to A-8, further comprising a hydrogen seal disposed between the fluid distribution frame and the bipolar plate adjacent to the cathode flow field.

[0124] A-13. The electrolytic cell according to A-8, wherein the fluid distribution frame comprises a visible light or ultraviolet light transparent material.

[0125] A-14. The electrolytic cell according to A-8, wherein the bipolar plate assembly is configured to collect the hydrogen flow from one or more trailing edges of the cathode flow field and deliver the flow to one or more hydrogen collection windows.

[0126] A-15. The fluid distribution frame is configured to mate with an internal seal between the anode flow field and the cathode flow field, and the internal seal is applied to at least one of a membrane, a catalyst-coated membrane, an electrode, a sub-gasket boundary of a membrane-electrode assembly, or the fluid distribution frame itself. The electrolytic cell according to A-8.

[0127] A-16. The electrolytic cell according to A-8, further comprising a water seal disposed between the frame and a bipolar plate adjacent to the anode flow field, a fluid distribution frame, and a hydrogen seal disposed between the fluid distribution frame and a bipolar plate adjacent to the cathode flow field, wherein the fluid distribution frame, the water seal, and the hydrogen seal are arranged such that the unsealed area is less than 50% from a projection viewpoint along the z-axis.

[0128] A-17. The electrolytic cell according to A-1, wherein the anode flow field is larger than the cathode flow field, and the anode flow field facilitates the application of a compressive load to the internal seal.

[0129] A-18. The electrolytic cell according to A-1, wherein the bipolar plate assembly includes a bipolar plate, and the bipolar plate includes a material selected from the group consisting of stainless steel, titanium, nickel, carbon, chromium, iron, and alloys thereof.

[0130] A-19. The electrolytic cell according to A-5, having a compression cell pitch of 5.0 mm or less, 3.0 mm or less, or 2.0 mm or less.

[0131] A-20. The electrolytic cell according to A-1, wherein at least one of the anode flow field or the cathode flow field includes at least one of a foam, a felt, a woven screen, an expanded metal, or a sintered metal frit.

[0132] A-21. The electrolytic cell according to A-1, wherein the cathode flow field has geometric features protruding along the z-axis perpendicular to the y-axis and the x-axis within the bipolar plate.

[0133] B-1. A method for manufacturing a bipolar plate assembly for an electrolytic cell, comprising: selecting materials for the bipolar plate, hydrogen seal, water seal, and fluid distribution frame; applying a hydrogen seal to the bipolar plate or the fluid distribution frame; aligning the fluid distribution frame with the bipolar plate and pressing the fluid distribution frame to fit the hydrogen seal therebetween; applying a water seal to the fluid distribution frame; and curing at least one of the hydrogen seal or the water seal using an ultraviolet curing method, a microwave curing method, a thermal curing method, a solvent curing method, a two-component epoxy curing method, or a moisture curing method; wherein: the bipolar plate, hydrogen seal, water seal, and fluid distribution frame include two-dimensional patterns suitable for manufacturing using punching, laser cutting, waterjet cutting, robotic dispensing, and / or screen printing methods.

[0134] B-2. The method according to B-1, wherein both the hydrogen seal and the water seal are cured simultaneously.

[0135] B-3. The method according to B-1, wherein the water seal is formed during the manufacture of the fluid distribution frame before fitting with the hydrogen seal.

[0136] B-4. The method according to B-1, wherein the fluid distribution frame is pressed together with the bipolar plate with a force sufficient to ensure that a continuous and unbroken seal is formed between the bipolar plate and the fluid distribution frame.

[0137] B-5. The method according to B-1, wherein the fluid distribution frame is pressed together with the bipolar plate to achieve a target thickness of the bipolar plate assembly with a variation of ±25% or less.

[0138] B-6. The method according to B-5, wherein the hydrogen seal is reinforced with one of a wire mesh, a continuous bubble foam, an expanded metal sheet, or a sintered metal frit.

[0139] B-7. The method according to B-1, wherein the hydrogen seal or the water seal is applied using a screen or stencil printing process, and at least one of the hydrogen seal or the water seal is applied in an uncured state having a thickness of 10 to 1000 μm and a width of 0.5 to 15 mm.

[0140] C-1. A compression system for an electrolytic cell stack, comprising: A structural wrap including one or more wrap layers that circumferentially surround at least a portion of an electrolytic cell stack including a plurality of cells; End units at opposite ends of the electrolytic cell stack; One or more adjustable elements proximate to the one or more end units; A compression system including: wherein The structural wrap allows free access to opposite sides of the cell stack; The structural wrap functions as a tensile element of the compression system; The one or more wrap layers are substantially flat sheets of a material having an essentially uniform thickness; The total thickness of the one or more wrap layers is determined by the x-axis dimension of the cell stack and the maximum allowable operating pressure of the electrolytic cell stack.

[0141] C-2. The compression system according to C-1, wherein the total wrap thickness is greater than or equal to the dimension along the x-axis of the cathode flow field of the cells in the cell stack multiplied by the ratio of the maximum allowable operating pressure of the electrolytic cell to the tensile strength of the wrap material.

[0142] C-3. The wrap has a substantially elliptical racetrack shape when viewed along the y-axis, is configured to connect to the end unit, and one or more end units have a semi-cylindrical shape when viewed along the y-axis, the compression system according to C-1.

[0143] C-4. The wrap is configured to slide relative to one or more semi-cylindrical end units when the compression system is loaded, the compression system according to C-3.

[0144] C-5. The diameter of one or more semi-cylindrical end units is a dimension of 100% to 150% of the electrolytic cell dimension along the x-axis, the compression system according to C-3.

[0145] C-6. The adjustable element of the compression system is at least partially included in one or both of the end units, the compression system according to C-3.

[0146] C-7. The adjustable element is configured to achieve a final dimension of the cell stack along the z-axis within ±25%, the compression system according to C-6.

[0147] C-8. At least one of the wrap and the semi-cylindrical end unit is configured to enable direct compression of the cell stack by a temporary stacking assembly system mechanically parallel to the adjustable element, the compression system according to C-6.

[0148] C-9. At least one wrap or end unit is configured to enable access to the adjustable element and operation of the adjustable element, the compression system according to C-6.

[0149] C-10. The adjustable element comprises one or more of a screw, a nut, a spring, a hydraulic cylinder, a pneumatic cylinder, a pressure pad or a pressure shoe, the compression system according to C-6.

[0150] C-11. The total amount of adjustable elements in the stack is proportional to the number of water delivery windows provided in the cells constituting the cell stack, the compression system according to C-3.

[0151] C-12. The wrap comprises one or more components connected such that the wrap continuously surrounds the cell stack using one or more of a cross pin connection, a hinge pin connection, a hem hook connection or a hem hook connection with a fastener on each of the two flat sides of the wrap, or The wrap comprises one or more layers of flexible sheet material that includes one semi-cylindrical end unit and is configured to fit and connect with a second end unit using one or more cross pins, or When one or more layers of the wrap include one or more end units, the compression system according to C-1, wherein the one or more layers of the wrap are composed of a material having a yield strength and thickness sufficient to maintain elasticity.

[0152] C-13. The above connection is configured to allow the wrap to be fitted along the z-axis while pre-compressing the cell stack and to complete the assembly of the wrap connection in the pre-compressed cell stack, the compression system according to C-12.

[0153] C-14a. The cell stack comprises cells having a hexagonal shape that allows for fully constrained alignment fixation from the open end of the wrap, the compression system according to C-1.

[0154] C-14b. The wrap is configured such that one or more cell stack alignment fixtures penetrate the wrap boundary and are able to contact one or more edges of the cell stack during assembly, the compression system according to C-1.

[0155] C-15. The compression system according to C-1, wherein the wrap is configured to extend along the z-axis and have a length of 2% or less of the final length of the cell stack at the final cell stack compression load.

[0156] C-16. The compression system according to C-1, wherein the wrap is configured to provide a spring constant along the z-axis that is 0.1% to 25% of the spring constant of the cell stack at the target cell stack compression load.

[0157] D-1. An electrolytic cell stack comprising a plurality of electrolytic cells aligned along the z-axis in a stacked configuration: where each cell comprises a membrane, an anode electrode, a cathode electrode, an anode flow field, a cathode flow field, and a bipolar plate assembly, adjacent bipolar plate assemblies at least partially Boundary setting 、 each water delivery plenum is sized to maintain the water velocity through the plenum along the z-axis below a target threshold, each water delivery plenum is associated with the length of the anode flow field along the y-axis, the number or size of the water delivery plenums is configured to maintain one of the water flow resistance, the water temperature rise, or the cell outlet oxygen volume fraction below a target threshold of the electrolytic cell stack.

[0158] D-2. The stack according to D-1, further comprising an oxygen delivery plenum and a hydrogen collection plenum, wherein the total number of the water delivery plenum and the oxygen collection plenum is greater than or equal to the number of the hydrogen collection plenum.

[0159] D-3. Of the electrolytic cell LaminationAn end unit at opposite ends of the structure, a scalable structural wrap compression system, and at least one fluid manifold included in one of the end units, wherein the fluid manifold facilitates the delivery of water to the stack through a freely accessible surface of the compression system along the y-axis. The stack according to D-2.

[0160] D-4. A stack according to D-3, wherein the fluid manifold is disposed at the upper end of the stacked configuration of the electrolytic cells with respect to the gravitational vector along the z-axis.

[0161] D-5. A stack according to D-3, further comprising a drain or purge manifold disposed at the lower end of the stacked configuration of the electrolytic cells with respect to the gravitational vector along the z-axis.

[0162] D-6. The water flow connecting the individual cell stack plenums Port inside and the size of the manifold are Flow distribution with a variation of less than ±25% to individual plenums selected to provide. The stack according to D-3.

[0163] E-1. Placing the lower wrap element and end unit assembly onto the stack fixture, Placing the upper wrap element and end unit assembly onto the stack fixture, Scalable Aligning the freely accessible surface of the lower wrap in the direction of the component piece flow in the manufacturing line for manufacturing the electrolytic cells, Placing the individual cells onto the lower wrap through the freely accessible surface, Lowering the upper wrap and end unit assembly along the z-axis to pre-compress the cell stack, Fitting the connecting elements of the wrap-style compression system to connect the lower wrap and the upper wrap into an integral structure, Further compressing the cell stack according to the desired compression profile, and Using adjustable elements of the compression system to lock the stack under a compression load, A method for manufacturing an electrolytic cell stack including.

[0164] E-2. The method according to E-1, wherein the stack assembly is achieved using a rotary table at the end of the cell manufacturing line.

[0165] E-3. The method according to E-2, wherein the rotary table comprises stations for loading non-repetitive members, placing cells, aligning them, compressing the assembly, performing quality checks, and unloading the final stack.

[0166] E-4. The method according to E-1, wherein the cell alignment fixture is provided at at least two adjacent edges of the cell stack.

[0167] E-5. The method according to E-1, wherein the cell automatically moves from the end of the cell manufacturing line to the inside of the lower wrap using one of robot placement, a linear motion actuator, or gravity.

[0168] E-6. The method according to E-1, wherein the cell moves directly through the freely accessible surface of the lower wrap by means of a conveyor system of the cell manufacturing line.

[0169] E-7. The method according to E-1, wherein the lower wrap and the end unit assembly move downward along the z-axis after each cell has been moved to a predetermined position.

[0170] E-8. The method according to E-1, wherein the z-axis of the stack assembly is angled with respect to the gravity vector such that the cells disposed within the lower wrap are directed by gravity towards the cell alignment fixture on one or more edges of the cell stack.

[0171] E-9. The method according to E-1, wherein a movable cell alignment actuator is involved on one or more edges of the cell stack such that cells disposed within the lower wrap are directed towards cell alignment fixtures on one or more opposing edges of the cell stack.

[0172] F-1. Selecting a roll of material of a desired roll web width along the x-axis for use as a membrane or a catalytic coating membrane, Directing the web of the roll through a seal applicator along the y-axis, Applying an uncured internal seal to one side of the web using one of screen printing, stencil printing or robotic dispensing methods, Curing the applied internal seal using any of ultraviolet curing, microwave curing, thermal curing, solvent curing, two-component epoxy curing or moisture curing, Cutting the roll of the membrane gasket assembly or the catalytic coating membrane gasket assembly into separate part pieces, and Conveying the obtained individual part pieces to a cell assembly machine, A method for manufacturing an internal seal for an electrolytic cell, comprising:

[0173] F-2. The method according to F-1, wherein the web material is an acidic proton-conducting membrane.

[0174] F-3. The method according to F-1, wherein the web material is an alkaline hydroxide-conducting membrane.

[0175] F-4. The method according to F-1, wherein the web material is selected from one of a CCM continuously coated on one side or a CCM patch-coated on one side.

[0176] F-5. The method according to F-4, wherein the internal seal is applied to the cathode side of the web.

[0177] G-1. Selecting an electrode substrate of a desired roll web width along the x-axis from one of foam, felt, textile screening, expanded metal or sintered metal frit; Selecting one or more flow field substrates of a desired roll web width along the x-axis from one of foam, felt, textile screening, expanded metal or sintered metal frit; Directing the electrode substrate web along the y-axis through a calendar roller configured to achieve a desired thickness and surface characteristics on each side of the electrode substrate; Converting the electrode substrate into an active electrode; Adjacent to the electrode substrate web, directing one or more flow field substrate webs along the y-axis while passing through a lamination process to bond the electrodes and flow fields together; Cutting the laminated electrode flow field roll into individual component pieces; and Transporting the obtained individual component pieces to a cell assembly machine, A method for manufacturing an integrated electrode flow field for an electrolytic cell, comprising:

[0178] G-2. The method according to G-1, wherein the electrode substrate and the flow field substrate each independently comprise at least one of carbon, nickel, titanium, iron, chromium, stainless steel or inconel, or a mixture or alloy thereof.

[0179] G-3. The method according to G-1, wherein one or more of the electrode web and the flow field web have a rough, patterned or embossed surface to facilitate lamination.

[0180] G-4. The method according to G-1, wherein the lamination step comprises a binding promoter selected from one of an adhesive, a polymer dispersion, a liquid ionomer solution, or an ionomer dispersion.

[0181] G-5. The method according to G-1, wherein the electrode flow field web comprises a foam electrode and a textile screen flow field after lamination.

[0182] G-6. The method according to G-1, wherein the electrode conversion is performed before lamination.

[0183] G-7. The method according to G-1, wherein the electrode conversion is performed after lamination.

[0184] G-8. The method according to G-1, wherein the porosity, basis weight, number of layers, and final lamination thickness of the flow field are selected to prevent cell assembly, compression, and yielding during operation.

[0185] G-9. The method according to G-1, wherein the active electrode comprises one or more binders selected from a liquid ionomer solution, an ionomer dispersion, and an inert polymer.

Explanation of Signs

[0186] 101 Electrolytic cell stack 103 Lower wrap 104 Upper wrap 105 Cell stack 107 Upper end unit 106 Lower end unit 109 Joint 301 Core electrolytic cell member 303 Anode flow field 304 Ion conductive membrane 305 Cathode flow field 306 Anode electrode 307 Cathode electrode 308 Bipolar plate 403 Anode flow field 405 Cathode flow field 601 Cell 603 Water delivery window 604 Water collection window 606 Hydrogen collection window 610 Contour region 611 Active region 701 Bipolar Plate Assembly 703 Water Seal 704 Fluid Distribution Frame 705 Hydrogen Seal 713 Internal Seal 714 Step 732 Porous Sheet

Claims

1. An electrolytic cell comprising a membrane, an anode electrode, a cathode electrode, an anode flow field, a cathode flow field, and a bipolar plate assembly comprising the cathode flow field and a fluid distribution frame: wherein the cathode flow field is a porous sheet comprising an embedded hydrogen seal, the porous sheet providing both mechanical reinforcement for the embedded hydrogen seal and an open space for hydrogen gas flow from the active region of the electrolytic cell to one or more hydrogen collection windows, the embedded hydrogen seal is coupled to the cathode flow field, the bipolar plate, and the fluid distribution frame such that the cathode flow field, the bipolar plate, and the fluid distribution frame are physically coupled together, and the cathode flow field is sealed against the environment, the embedded hydrogen seal and the cathode flow field have the same thickness.

2. The electrolytic cell according to claim 1, wherein the cathode flow field is arranged such that a hydrogen flow velocity vector within the cathode flow field is generally parallel to a leading edge of the anode flow field.

3. The electrolytic cell according to claim 1, further comprising a water seal disposed between the fluid distribution frame and the bipolar plate adjacent to the anode flow field.

4. The electrolytic cell according to claim 3, wherein at least one of the fluid distribution frame or the water seal is configured to allow for the spread of water flow in the x-y plane from one or more water delivery windows to the leading edge of the anode flow field, thereby providing a leading edge water velocity distribution within ±50% of the average velocity of the anode flow field.

5. The electrolytic cell according to claim 3, wherein at least one of the fluid distribution frame or the water seal is configured to collect the flow of water and oxygen from the trailing edge of the anode flow field and impose a change of ±50% or less on the trailing edge velocity distribution for the anode flow field.

6. The electrolytic cell according to claim 1, wherein the fluid distribution frame comprises a visible light or ultraviolet light transparent material.

7. The electrolytic cell according to claim 1, wherein the bipolar plate assembly is configured to collect a hydrogen flow from one or more trailing edges of the cathode flow field and deliver the flow to one or more hydrogen collection windows.

8. The fluid distribution frame is configured to fit with an internal seal between the anode flow field and the cathode flow field, The electrolytic cell according to claim 1, wherein the internal seal is applied to at least one of a membrane, a catalyst-coated membrane, an electrode, a sub-gasket boundary of a membrane-electrode assembly, or the fluid distribution frame itself.

9. Further comprising a water seal disposed between the fluid distribution frame and a bipolar plate adjacent to the anode flow field, An embedded hydrogen seal is disposed between the fluid distribution frame and a bipolar plate adjacent to the cathode flow field, The electrolytic cell according to claim 1, wherein the fluid distribution frame, the water seal, and the hydrogen seal are arranged such that the unsealed area is less than 50% in a projection view along the z-axis.

10. The electrolytic cell according to claim 1, wherein the anode flow field is larger than the cathode flow field, and the anode flow field facilitates the application of a compressive load to the internal seal.

11. The electrolytic cell according to claim 1, wherein the bipolar plate assembly includes a bipolar plate, and the bipolar plate includes a material selected from the group consisting of stainless steel, titanium, nickel, carbon, chromium, iron, and alloys thereof.

12. The electrolytic cell according to claim 1, having a cell pitch of 2.0 mm or less.

13. The electrolytic cell according to claim 1, wherein at least one of the anode flow field or the cathode flow field includes at least one of a foam, a felt, a woven screen, an expanded metal, or a sintered metal frit.

14. The electrolytic cell according to claim 1, wherein the cathode flow field has geometric features protruding along the z-axis perpendicular to the y-axis and the x-axis within the bipolar plate assembly.

15. The electrolytic cell according to claim 1, wherein the porous sheet of the cathode flow field is selected from the group consisting of foams, felts, woven screens, expanded metals, and sintered metal frits.

16. The electrolytic cell according to claim 15, wherein the porous sheet contains an alloy of iron, steel, stainless steel, nickel, nickel-chromium, inconel, ferraloy, or a combination thereof.

17. The electrolytic cell according to claim 1, wherein the hydrogen seal contains a cured polymer compound.

18. The electrolytic cell according to claim 1, which does not have a substantially circular active region.

19. The electrolytic cell according to claim 1, wherein the anode flow field and the cathode flow field each have a thickness of 0.1 mm to 5.0 mm, and the anode flow field has a flow field length of 2 cm to 25 cm.

20. The electrolytic cell according to claim 1, wherein the embedded hydrogen seal is completely embedded in the cathode flow field.

21. The electrolytic cell according to claim 1, which has a compression cell pitch of 5.0 mm or less.

22. The electrolytic cell according to claim 1, wherein the bipolar plate assembly includes a plurality of repetitive water delivery windows disposed adjacent to the leading edge of the anode flow field aligned with the y-axis.

23. The bipolar plate assembly includes one or more oxygen collection windows, The electrolytic cell according to claim 22, wherein the total number of the water delivery windows and the oxygen collection windows is equal to or greater than the number of the hydrogen collection windows.

24. The electrolytic cell according to claim 22, wherein each water delivery window has a uniform end along the x-axis perpendicular to the leading edge of the anode flow field. **Claim 25** An electrolytic cell stack comprising a plurality of electrolytic cells aligned along the z-axis in a stacked configuration: wherein, each cell comprises a stack compression system having a tensile wrap, a membrane, an anode electrode, a cathode electrode, an anode flow field, a cathode flow field, a bipolar plate, and a bipolar plate assembly including the cathode flow field and a fluid distribution frame, adjacent bipolar plate assemblies at least partially bound one or more water delivery plenums disposed along the edge of the anode flow field, the bipolar plate assembly comprises a plurality of repeating water delivery windows disposed adjacent to the leading edge of the anode flow field aligned with the y-axis, each water delivery plenum is sized to maintain the water velocity through the plenum along the z-axis below a target threshold, the electrolytic cell stack has a cell pitch (distance between the centers of two adjacent electrolytic cells) of 5.0 mm or less, the cathode flow field is a porous sheet including an embedded hydrogen seal, the porous sheet providing both mechanical reinforcement for the embedded hydrogen seal and an open space for hydrogen gas flow from the active region of the electrolytic cell to one or more hydrogen collection windows, the embedded hydrogen seal couples to the cathode flow field, the bipolar plate, and the fluid distribution frame such that the cathode flow field, the bipolar plate, and the fluid distribution frame are physically joined together, and the cathode flow field is sealed against the environment, the embedded hydrogen seal and the cathode flow field have the same thickness. **Claim 26** The electrolytic cell stack according to claim 25, wherein the porous sheet of the cathode flow field is selected from the group consisting of a foam, a felt, a woven screen, an expanded metal, and a sintered metal frit. **Claim 27** The electrolytic cell stack according to claim 26, wherein the porous sheet comprises an alloy of iron, steel, stainless steel, nickel, nickel-chromium, inconel, ferraloy, or a combination thereof.

28. The electrolytic cell stack according to claim 25, wherein the hydrogen seal comprises a cured polymer compound.

29. The electrolytic cell stack according to claim 25, wherein the plurality of cells do not have a substantially circular active region.

30. The electrolytic cell stack according to claim 25, wherein the anode flow field and the cathode flow field each have a thickness of 0.1 mm to 5.0 mm, and the anode flow field has a flow field length of 2 cm to 25 cm.

31. The electrolytic cell stack according to claim 25, wherein the embedded hydrogen seal is completely embedded in the cathode flow field.

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