Multi-cell COX electrolyzer stack

Abstract

Various CO X Electrolyzer multi-cell architectures are provided, including various frame, flow area, gas diffusion layer, and repeat unit designs that may be particularly useful in the context of multi-cell COx electrolyzer cells.

Description

[Technical Field]

[0001] Incorporation by Reference The PCT application is filed concurrently herewith as part of the present application. Each application to which this application claims benefit or priority, as identified in the concurrently filed PCT application, is incorporated herein by reference in its entirety for all purposes. [Background technology]

[0002] CO X Electrolyzers use CO2 or CO X It provides a potential pathway for converting or reducing gases to one or more desirable carbon-based by-products, such as industrial chemicals or fuels, thereby reducing waste CO that would normally be released into the atmosphere. X The gases could instead be converted into industrially useful products.

[0003] The background and context discussion contained herein is provided solely for the purpose of generally providing a context for the present disclosure. Much of this disclosure represents work by the inventors, and this is merely because such work is described in the Background section or provided as context elsewhere herein, and does not mean that such work is admitted as prior art. Summary of the Invention

[0004] The details of one or more implementations of the subject matter described herein are set forth in the accompanying drawings and the description below. Other features, aspects, and advantages will become apparent from the description, drawings, and claims.

[0005] One or more embodiments may include CO X CO gas that can be converted or reduced to one or more desired by-products X An electrolysis device is provided.

[0006] One or more embodiments may include CO XA frame capable of promoting fluid flow within an electrolysis device is provided.

[0007] One or more embodiments may include CO x In the operating state of the electrolyzer, multiple CO x CO that can suppress the axial expansion of the electrolyzer cell x An electrolysis device is provided.

[0008] Additional aspects will be set forth in the detailed description which follows, and in part will be obvious from the disclosure, or may be learned by practice of the inventive concepts.

[0009] According to some embodiments, CO X The electrolysis device ("device") comprises a first end assembly, a second end assembly, a plurality of separator plates, and a plurality of CO X The electrolyzer includes a second end assembly connected to the first end assembly via a plurality of tension members. X The electrolyzer cells ("cells") are interposed between the first end assembly and the second end assembly and are arranged in an axial stack. Each of the cells includes an instance of a first component and an instance of a second component. The first component includes a membrane electrode assembly (MEA), a cathode frame, and a cathode field. The MEA has a cathode portion, an anode portion, and a separator between the cathode portion and the anode portion. The cathode frame is adjacent to the cathode portion. The cathode field is at least partially disposed within a first opening of the cathode frame. The second component includes an anode frame adjacent to the anode portion of the MEA and an anode field at least partially disposed within a second opening of the anode frame. The cathode frames and anode frames of adjacent cells of the cells are connected to each other via a corresponding plurality of frame fasteners, with any of the separator plates interposed therebetween. The frame fasteners are different from tension members.

[0010] In some embodiments, the first component may further include a cathode gas diffusion layer (GDL) adjacent to the cathode frame and covering the cathode flow field. The cathode GDL and cathode flow field allow gaseous CO 2 to pass through the first openings in a dispersive manner in a first direction transverse to the axial direction and in at least a second direction transverse to each of the axial direction and the first direction. X The second component may be configured to direct the flow of anolyte through the second openings in a third direction transverse to the axial direction and in a dispersive manner relative to at least the second direction. The second component may further include an anode porous transport layer (PTL) adjacent to the anode frame and covering the anode flow field. The anode PTL and anode flow field may be configured to direct the flow of anolyte through the second openings in a third direction transverse to the axial direction and in a dispersive manner relative to at least the second direction.

[0011] In some embodiments, the cathode frame may comprise a first opening disposed in a central portion of the cathode frame, at least one first fluid inlet passage fluidly connected to the anode portion of the cell, at least one first fluid outlet passage fluidly connected to the anode portion of the cell, at least one second fluid inlet passage fluidly connected to the first opening, and at least one second fluid outlet passage fluidly connected to the first opening.

[0012] In some embodiments, the anode frame may comprise a second opening disposed in a central portion of the anode frame, at least one third fluid inlet passage fluidly connected to the second opening, at least one third fluid outlet passage fluidly connected to the second opening, at least one fourth fluid inlet passage fluidly connected to the cathode portion of the cell, and at least one second fluid outlet passage fluidly connected to the cathode portion of the cell.

[0013] In some embodiments, each of the separator plates has a plurality of fastener holes through which a frame fastener respectively extends, at least one first hole through which an inlet anolyte flow path extends, at least one second hole through which an outlet anolyte flow path extends, an inlet gaseous CO X at least one third hole through which the flow path extends, and an outlet COX The reduced byproduct flow path may include at least one fourth hole extending therethrough.

[0014] In some embodiments, the cathode frame can include a first surface facing the MEA and a second surface facing away from the first surface. The second surface of the cathode frame can include at least one first protrusion through which the at least one first fluid inlet passage extends, at least one second protrusion through which the at least one first fluid outlet passage extends, at least one third protrusion through which the at least one second fluid inlet passage extends, and at least one fourth protrusion through which the at least one second fluid outlet passage extends.

[0015] In some embodiments, the at least one first protrusion of the cathode frame may be positioned and configured to extend through the at least one first hole in a first one of the separator plates and may abut the anode frame of a first adjacent one of the cells, such that the at least one first fluid inlet passage of the cathode frame is substantially axially aligned with the at least one third fluid inlet passage of the anode frame of the first adjacent cell. The at least one second protrusion of the cathode frame may be positioned and configured to extend through the at least one second hole in the first separator plate and may abut the anode frame of the first adjacent cell, such that the at least one first fluid outlet passage of the cathode frame is substantially axially aligned with the at least one third fluid outlet passage of the anode frame of the first adjacent cell. The at least one third protrusion of the cathode frame may be positioned and configured to extend through the at least one third hole in the first separator plate and may abut the anode frame of a first adjacent cell, such that the at least one second fluid inlet passage of the cathode frame is substantially axially aligned with the at least one fourth fluid inlet passage of the anode frame of the first adjacent cell. The at least one fourth protrusion of the cathode frame may be positioned and configured to extend through the at least one fourth hole in the first separator plate and may abut the anode frame of the first adjacent cell, such that the at least one second fluid outlet passage of the cathode frame is substantially axially aligned with the at least one fourth fluid outlet passage of the anode frame of the first adjacent cell.

[0016] In some embodiments, at least one of the first through fourth protrusions may be sized to form a clearance fit with a corresponding one of the first through fourth holes.

[0017] In some embodiments, the cathode frame may further include a plurality of first cathode fastening holes disposed about a peripheral region of the cathode frame. The peripheral region may surround the first opening of the cathode frame. The anode frame may further include a plurality of first anode fastening holes and a plurality of first swage nuts. The plurality of first anode fastening holes may be disposed about the peripheral region of the anode frame. The peripheral region of the anode frame may surround the second opening of the anode frame. The first cathode fastening holes may be substantially aligned with the first anode fastening holes in the axial direction. Each first swage nut of the first swage nuts may be disposed in one or the other of a corresponding one of the first anode fastening holes and a corresponding one of the first cathode fastening holes. The first swage nut may be configured to interface with a corresponding one of the frame fasteners.

[0018] In some embodiments, each of the cathode and anode fastener holes can be counterbore, and the counterbore portion of the cathode and / or anode fastener hole that does not include the first swage nut of the first swage nut can be configured to form a clearance fit with a respective one of the frame fasteners.

[0019] In some embodiments, the frame fasteners may be shoulder screws.

[0020] In some embodiments, the first component may further include a first support frame and a second support frame. The first support frame may be interposed between the cathode GDL and the cathode frame. The first support frame may include a first frame opening exposing a portion of the cathode GDL to the cathode flow field. A portion of the cathode GDL may abut the cathode flow field. The second support frame may be interposed between the MEA and the anode PTL. The second support frame may include a second frame opening exposing a portion of the MEA to the anode PTL. A portion of the MEA may abut the anode PTL. The first support frame, the cathode GDL, the MEA, and the second support frame may form an integrated MEA assembly.

[0021] In some embodiments, the first component may further include a first cathode gasket interposed between the first support frame and the cathode frame. The first cathode gasket may surround the first opening in the cathode frame, thereby forming a first fluid seal around the cathode flow field. The second component may further include a first anode gasket set. The first anode gasket set may include a first anode gasket, at least one second anode gasket, at least one third anode gasket, at least one fourth anode gasket, and at least one fifth anode gasket. The first anode gasket may be interposed between the second support frame and the anode frame. The first anode gasket may surround the second opening in the anode frame, thereby forming a first fluid seal around the anode flow field. At least one second anode gasket may be interposed between the cathode frame and the anode frame. At least one second anode gasket may surround at least one first fluid inlet passage of the cathode frame and at least one third fluid inlet passage of the anode, forming at least one fluid seal. At least one third anode gasket may be interposed between the cathode frame and the anode frame, and the at least one third anode gasket may surround at least one first fluid outlet passage of the cathode frame and at least one third fluid outlet passage of the anode frame, forming at least one fluid seal. At least one fourth anode gasket may be interposed between the cathode frame and the anode frame. At least one third anode gasket may surround at least one second fluid inlet passage of the cathode frame and at least one fourth fluid inlet passage of the anode frame, forming at least one fluid seal. At least one fifth anode gasket may be interposed between the cathode frame and the anode frame.At least one fifth anode gasket may surround the at least one second fluid outlet passage and the at least one fourth fluid outlet passage of the anode frame and form at least one fluid seal.

[0022] In some embodiments, the first component may further include a second cathode gasket interposed between a first one of the separator plates and the cathode frame. The second cathode gasket may surround a first opening in the cathode frame, thereby forming a second fluid seal around the cathode flow field. The second component may further include a second anode gasket set. The second anode gasket set may include a sixth anode gasket, at least one seventh anode gasket, at least one eighth anode gasket, at least one ninth anode gasket, and at least one tenth anode gasket. The sixth anode gasket may be interposed between the anode frame and a second one of the separator plates. The sixth anode gasket may surround a second opening in the anode frame, thereby forming a second fluid seal around the anode flow field. At least one seventh anode gasket may be interposed between the anode frame and the second separator plate. The at least one seventh anode gasket may surround at least one first hole in the second separator plate and at least one third fluid inlet passage of the anode frame to form at least one fluid seal. At least one eighth anode gasket may be interposed between the anode frame and the second separator plate. The at least one eighth anode gasket may surround at least one second hole in the second separator plate and at least one third fluid outlet passage of the anode frame to form at least one fluid seal. At least one ninth anode gasket may be interposed between the anode frame and the second separator plate. At least one ninth anode gasket may surround the at least one third hole in the second separator plate and the at least one fourth fluid inlet passage of the anode frame to form at least one fluid seal. At least one tenth anode gasket may be interposed between the anode frame and the second separator plate.At least one ninth anode gasket may surround the at least one fourth hole in the second separator plate and the at least one fourth fluid outlet passage of the anode frame to form at least one fluid seal.

[0023] In some embodiments, a cell may be formed of a plurality of repeat units, each of which may comprise an instance of a first component, an instance of a second component, and a separator plate that may be interposed between the cathode frame of that instance of the first component and the anode frame of that instance of the second component, and the separator plate may be interposed between the instance of the first component and the instance of the second component.

[0024] In some embodiments, the first end assembly may include a first end plate and a cathode interface assembly. The cathode interface assembly may include an instance of a first component and a cathode interface separator plate interposed between the first end plate and a first repeat unit of the repeat units. A first end cell may be formed between the cathode interface assembly and an instance of a second component of the first repeat unit. The first end cell may be interposed between the first end plate and the plurality of cells.

[0025] In some embodiments, the first end assembly may further comprise a first insulating plate, a manifold, and a first bus plate between the first end plate and the cathode interface assembly. The manifold has at least one first inlet fluidly connected to the anode portion of the cell via an inlet anolyte flow path, at least one first outlet fluidly connected to the anode portion of the cell via an outlet anolyte flow path, and an inlet gaseous CO X at least one second inlet fluidly connected to the cathode portion of the cell via a flow channel; and an outlet CO Xand at least one second outlet fluidly connected to the cathode portion of the cell via a reduced byproduct flow path. The first bus plate may be configured to receive a first electrical potential. The first insulating plate may be configured to electrically insulate the first end plate from the first bus plate.

[0026] In some embodiments, a first bus plate, a manifold, and a first insulating plate may be stacked sequentially on the cathode interface assembly.

[0027] In some embodiments, the inlet anolyte flow path, the outlet anolyte flow path, the inlet gaseous CO X flow path, and outlet CO X The reduced by-product flow path does not have to extend into the bus plate and the first insulating plate.

[0028] In some embodiments, the first bus plate, the insulating plate, and the manifold may be stacked sequentially on the cathode interface assembly.

[0029] In some embodiments, the first end assembly may further include a capping plate, an inlet runner, and an outlet runner. The inlet runner and the outlet runner may be coupled to the manifold so as to be axially stacked between the capping plate and the manifold.

[0030] In some embodiments, the inlet anolyte flow path, the outlet anolyte flow path, the inlet gaseous CO X flow path, and outlet CO X The reduced by-product flow path may extend through the first insulating plate.

[0031] In some embodiments, the first bus plate may be coupled to the manifold via tension members and a plurality of first fasteners distinct from the frame fasteners, and the first isolation plate may be coupled to the first end plate via tension members, frame fasteners, and a plurality of second fasteners distinct from the first fasteners.

[0032] In some embodiments, the first bus plate may be coupled to the first isolation plate via a plurality of first fasteners distinct from the tension members and the frame fasteners, hi some embodiments, the first isolation plate may be coupled to the manifold via the first fasteners.

[0033] In some embodiments, the second end assembly may include a second end plate and an anode interface assembly. The anode interface assembly may include an instance of a second component and an anode interface separator plate interposed between a second repeat unit of the repeat units and the second end plate. A second end cell may be formed between an instance of a first component of the second repeat unit and the anode interface assembly. The second end cell may be interposed between the plurality of cells and the second end plate.

[0034] In some embodiments, the second end assembly may further include a second bus plate and a second insulating plate axially stacked sequentially between the anode interface assembly and the second end plate. The second bus plate may be configured to receive a second electrical potential. The second insulating plate may be configured to electrically insulate the second end plate from the second bus plate.

[0035] In some embodiments, the second insulating plate may be coupled to the second end plate via a plurality of third fasteners that are different from the tension members and the frame fasteners.

[0036] In some embodiments, the second end assembly may further include a bladder gasket. The second insulating plate may include a first recess, a second recess, and a hole. The first recess may be formed in a central portion of the second insulating plate. The second recess may surround a central region of the central portion. The second recess may support the bladder gasket therein. The hole may be configured to receive one or more control fluids. The bus plate may be slidably disposed within the first recess and configured to axially abut a surface of the first recess facing the bladder gasket and / or the bus plate. An axial distance between the bus plate and a surface of the first recess facing the bus plate may be configured to increase in response to accumulation of one or more control fluids in a region between the bus plate and the insulating plate that is fluid-tightly sealed, at least via the bladder gasket.

[0037] In some embodiments, the second end plate may include a first body, a second end plate protrusion extending axially from the first body, and a second end plate opening extending in the opposite axial direction from a central portion of the second end plate protrusion and terminating in a concave surface facing the cell. The second end assembly may further include a piston interposed between the second insulating plate and the second end plate. The piston may include a second body and a piston protrusion extending in the opposite axial direction from the second body and terminating in a protrusion surface facing the concave surface. At least a portion of the piston protrusion may be slidably disposed within at least a portion of the second end plate opening.

[0038] In some embodiments, the second end assembly may further include a plurality of biasing members. The piston protrusion may include a plurality of piston protrusion openings extending axially into the protrusion surface. The second end plate may further include a plurality of support protrusions extending axially from the concave surface and may be arranged to correspond to the piston protrusion openings. The biasing members may each be supported within the second end plate openings via a corresponding one of the support protrusions, such that in a first compressed state of the second end assembly, the biasing members are compressed between the protrusion surface and the concave surface, and each portion of the support protrusion extends at least partially into a corresponding one of the piston protrusion openings.

[0039] In some embodiments, the second end plate may further include one or more holes fluidly connected to the second end plate opening. The one or more holes may be configured to receive one or more control fluids. The piston protrusion may include a plurality of piston gaskets surrounding the piston protrusion and axially offset from one another. The piston gaskets may have interfaces with one or more inner sidewalls of the second end plate opening, such that the second end plate opening, the piston protrusion, and the piston gaskets form a cavity within the second end assembly. The axial distance between the protruding surface and the recessed surface may be configured to increase in response to accumulation of one or more control fluids in the cavity.

[0040] In some embodiments, the cell is configured to receive an input gaseous CO X into one or more by-products, and X may be equivalent.

[0041] In some embodiments, the device comprises gaseous CO X The source may further comprise a source of gaseous CO at a substantially equivalent pressure. X may be configured to input into the cell and the second end assembly.

[0042] In some embodiments, the device comprises gaseous CO X The source may further comprise a source of gaseous CO X may be configured to enter the cell at a first pressure and enter the second end assembly at a second pressure, the first pressure and the second pressure being in equilibrium at steady state.

[0043] In some embodiments, the apparatus may further include a plurality of reference rods extending axially around a periphery of the cell, and the second insulating plate may include a plurality of openings each configured to support a corresponding one of the reference rods.

[0044] In some embodiments, the cathode frame and the anode frame may be formed from one or more polymers.

[0045] In some embodiments, the cathode frame and the anode frame may comprise at least one of polyethylene terephthalate (PET), polycarbonate (PC), polyimide (PI), polyamide (PA), poly(methyl methacrylate) (PMMA), polyethylene naphthalate (PEN), polyether ketone (PEK), polyether ether ketone (PEEK), polystyrene (PS), polyetherimide (PEI), polyphenylene sulfide (PPS), polyarylate (PAR), polyethersulfone (PES), cyclic olefin copolymer (COC), polyvinyl alcohol (PVA), ethylene chlorotrifluoroethylene (ECTFE), polytetrafluoroethylene (PTFE), polybutylene terephthalate (PBT), polychlorotrifluoroethylene (PCTFE), and polyethylene terephthalate glycol (PETG).

[0046] In some embodiments, the separator plates may be formed from one or more metals.

[0047] In some embodiments, the separator plate may include at least one of aluminum, aluminum alloy, copper, copper alloy, tin, tin alloy, titanium, titanium alloy, tungsten, tungsten alloy, zinc, zinc alloy, steel, and stainless steel.

[0048] In some embodiments, the tension members may surround the cells when viewed axially, thereby spacing the cells from the tension members.

[0049] According to some embodiments, CO X The electrolyzer frame ("frame") may comprise a body portion, an opening, a first fluid passage, a first recess, a second recess, and a first connecting riser. The body portion may have a first surface axially opposite a second surface. The opening may extend axially through a central region of the body portion. The first fluid passage may extend axially through the body portion. The first recess may be in the first surface. The first recess may be fluidly connected to the opening and may extend in a second direction transverse to the axial direction. The second recess may be in the second surface. The second recess may be fluidly connected to the first fluid passage and may extend in a third direction transverse to the axial direction. The first connecting riser may extend axially and may be fluidly interposed between the first recess and the second recess such that the opening is fluidly connected to the first fluid passage.

[0050] In some embodiments, the frame may further include a third recess in the first surface, the third recess surrounding the opening and the first recess.

[0051] In some embodiments, the second recess may pass below the third recess when viewed axially.

[0052] In some embodiments, the frame may further include a fourth recess in the first surface. The fourth recess may surround the first fluid passage.

[0053] In some embodiments, the second recess may pass below the fourth recess when viewed axially.

[0054] In some embodiments, the frame may further include a fifth recess in the second surface surrounding the opening, and the first recess may pass over the fifth recess when viewed axially.

[0055] In some embodiments, the first recess may include a proximal end, a distal end, and a plurality of sidewalls connecting the proximal end and the distal end. A first of the sidewalls may extend in a first diagonal direction relative to the second direction. A second of the sidewalls may extend in a second diagonal direction relative to the second direction. The second diagonal direction may be different from the first diagonal direction.

[0056] In some embodiments, the first connecting riser may extend to a proximal end of the first recess and a distal end of the first recess may extend to the opening.

[0057] In some embodiments, the frame may further include a plurality of protrusions extending axially from a surface of the first recess, the surface may be recessed relative to the first surface.

[0058] In some embodiments, at least one of the protrusions may have a different cross-sectional area than at least one other of the protrusions.

[0059] In some embodiments, the protrusions may include one or more first protrusions, one or more second protrusions, and at least one third protrusion. The one or more first protrusions may each have a first cross-sectional area in a plane perpendicular to the axial direction. The one or more second protrusions may each have a second cross-sectional area in a plane perpendicular to the axial direction. The second cross-sectional areas may each be smaller than the first cross-sectional area. The at least one third protrusion may have a third cross-sectional area in a plane perpendicular to the axial direction. The third cross-sectional area may be smaller than each of the second cross-sectional areas. The one or more second protrusions may be disposed closer to the proximal end of the first recess than each of the one or more first protrusions and the at least one third protrusion. A majority of the one or more first protrusions may be disposed closer to the opening than each of the one or more second protrusions and the at least one third protrusion. The at least one third protrusion may be disposed between a majority of the one or more second protrusions and a majority of the one or more first protrusions.

[0060] In some embodiments, the third recess can include first sides extending generally in the second direction and second sides extending between the first sides, each of the second sides including a first portion extending in a fourth direction transverse to the axial direction and the second direction, a second portion extending from the first side of the first portion in a third oblique direction forming a first angle with the fourth direction, a third portion extending in an arc between the second portion and the first sides and connecting the second portion to one of the first sides, a fourth portion extending in a fourth oblique direction forming the second angle from the second side of the first portion, and a fifth portion extending in an arc between the fourth portion and another of the first sides.

[0061] In some embodiments, the frame may further include a second fluid passageway extending axially through the body portion and a third fluid passageway extending axially through the body portion, wherein the second and third fluid passageways may be fluidly isolated from the first fluid passageway and the opening within the frame.

[0062] In some embodiments, the frame may further include a first protrusion extending axially from the second surface, and the first fluid passage, the second recess, and the first connecting riser may be formed in the first protrusion.

[0063] In some embodiments, the frame may further include a second protrusion extending axially from the second surface and a third protrusion extending axially from the second surface, the second fluid passageway may extend through the second protrusion, and the third fluid passageway may extend through the third protrusion.

[0064] In some embodiments, the second fluid passage may be disposed adjacent to a first side of the first fluid passage. The third fluid passage may be disposed adjacent to a second side of the first fluid passage. The second side of the first fluid passage may be opposed to the first side of the first fluid passage in a fourth direction that is axial and transverse to the second direction.

[0065] In some embodiments, the frame may further include a sixth recess in the first surface. The sixth recess may be fluidly connected to the first connecting riser and a proximal end of the first recess. The sixth recess may extend in a fourth direction that is transverse to the axial direction and the second direction.

[0066] In some embodiments, the frame may further include a second fluid passage, a seventh recess, and a second connecting riser. The second fluid passage may extend axially through the body portion. The seventh recess may be within the second surface. The seventh recess may be fluidly connected to the second fluid passage and may extend in a fifth direction transverse to the axial direction. The second connecting riser may extend axially and may be fluidly interposed between the seventh recess and the first recess such that the opening is fluidly connected to the second fluid passage. The first connecting riser may be fluidly connected to a first side of the sixth recess. The second connecting riser may be fluidly connected to a second side of the sixth recess opposite the first side of the sixth recess in the fourth direction.

[0067] In some embodiments, the first recess may be one of a plurality of first recesses in the first surface that extend parallel to one another in the second direction.

[0068] In some embodiments, the first recesses may include a first group of first recesses, a second group of first recesses, and a third group of first recesses. The first recesses of the first group may be spaced apart from one another according to a first pitch. The second group of first recesses may be disposed adjacent to a first side of the first group of first recesses. The first recesses of the second group may be spaced apart from one another according to a second pitch that is different from the first pitch. The third group of first recesses may be disposed adjacent to a second side of the first group of first recesses. The first recesses of the third group may be spaced apart from one another according to a third pitch that is different from the first pitch and the second pitch.

[0069] In some embodiments, the first pitch may be a constant pitch, the second pitch may be a first variable pitch, and the third pitch may be a second variable pitch.

[0070] In some embodiments, the first variable pitch and the second variable pitch may increase in size as the distance from the first group of first recesses increases.

[0071] In some embodiments, the second recess may be one of a plurality of second recesses in the second surface that extend parallel to one another in a third direction.

[0072] In some embodiments, the seventh recess is one of a plurality of seventh recesses in the second surface that extend parallel to one another in the fifth direction, and the third direction and the fifth direction may extend obliquely relative to the second direction.

[0073] In some embodiments, the frame may further include a third fluid passage, a fourth fluid passage, an eighth recess, and a ninth recess. The third fluid passage may extend axially through the body portion and be separated from the first fluid passage by a first partition. The fourth fluid passage may extend axially through the body portion and be separated from the second fluid passage by a second partition. The eighth recess may be in the second surface and extend parallel to each other in the sixth direction. The eighth recess may be fluidly interposed between the third fluid passage and the first connecting riser, thereby fluidly connecting the third fluid passage to the opening. The ninth recess may be in the second surface and extend parallel to each other in the seventh direction. The ninth recess may be fluidly interposed between the fourth fluid passage and the second connecting riser, thereby fluidly connecting the fourth fluid passage to the opening.

[0074] In some embodiments, the third direction may form a first oblique angle with respect to the second direction, the fifth direction may form a second oblique angle with respect to the second direction, which may be different from the first oblique angle, the sixth direction may form a third oblique direction with respect to the second direction, which may be different from the first and second oblique angles, and the ninth direction may form a fourth oblique direction with respect to the second direction, which may be different from the first through third oblique angles.

[0075] In some embodiments, the first oblique angle may be greater than the third oblique angle, the second oblique angle may be greater than the fourth oblique angle, the absolute values ​​of the first and second oblique angles may be substantially equal, and the absolute values ​​of the third and fourth oblique angles may be substantially equal.

[0076] In some embodiments, the frame may further include a tenth recess on the second surface, an eleventh recess on the second surface, and a twelfth recess on the first surface. The fourth recess may surround the first fluid passage and the third fluid passage. The tenth recess may surround the first fluid passage, the third fluid passage, the second recess, the eighth recess, and the first connecting riser. The eleventh recess may surround the second fluid passage, the fourth fluid passage, the seventh recess, the ninth recess, and the second connecting riser. The twelfth recess may surround the second fluid passage and the fourth fluid passage. When viewed axially, the second recess and the eighth recess may pass below the fourth recess, and the seventh recess and the ninth recess may pass below the twelfth recess.

[0077] In some embodiments, the frame may further include a fifth fluid passageway extending axially through the body portion, and within the frame, the fifth fluid passageway may be fluidly isolated from the first fluid passageway, the second fluid passageway, and the opening.

[0078] In some embodiments, the first fluid passage may be disposed adjacent to a first side of the fifth fluid passage, the second fluid passage may be disposed adjacent to a second side of the fifth fluid passage, and the second side of the fifth fluid passage may be opposite the first side of the fifth fluid passage in the fourth direction.

[0079] In some embodiments, the frame may further include a plurality of first fastening holes disposed in a peripheral region of the body portion and surrounding the opening.

[0080] In some embodiments, the frame may further include a plurality of second fastening holes disposed in an intermediate region interposed between the first opening and the peripheral region, and a pitch between adjacent second fastening holes among the second fastening holes may be smaller than a pitch between adjacent first fastening holes among the first fastening holes.

[0081] In some embodiments, the first and second fastening holes may be counterbore.

[0082] In some embodiments, the frame may be formed from one or more polymers.

[0083] In some embodiments, the frame may include at least one of polyethylene terephthalate (PET), polycarbonate (PC), polyimide (PI), polyamide (PA), poly(methyl methacrylate) (PMMA), polyethylene naphthalate (PEN), polyether ketone (PEK), polyether ether ketone (PEEK), polystyrene (PS), polyetherimide (PEI), polyphenylene sulfide (PPS), polyarylate (PAR), polyethersulfone (PES), cyclic olefin copolymer (COC), polyvinyl alcohol (PVA), ethylene chlorotrifluoroethylene (ECTFE), polytetrafluoroethylene (PTFE), polybutylene terephthalate (PBT), polychlorotrifluoroethylene (PCTFE), and polyethylene terephthalate glycol (PETG).

[0084] According to some embodiments, CO X The electrolysis apparatus ("apparatus") comprises a first end assembly, a second end assembly, and a plurality of CO X The electrolyzer includes a second end assembly connected to the first end assembly. X The electrolyzer cells ("cells") are interposed between the first and second end assemblies and arranged in an axial stack. Each of the cells is adapted to receive input gaseous CO 2 . X The cell is configured to reduce input gaseous CO X CO reduction to one or more byproducts XIn an operating state of the electrolyzer, the second end assembly is configured to expand axially in response to accumulation of one or more control fluids within the interior cavity of the second end assembly. The expansion of the second end assembly is configured to constrain axial expansion of the cell. The one or more control fluid flow paths are configured to accommodate input gaseous CO 2 . X The fluid is fluidly connected to the flow path of the

[0085] In some embodiments, each of the cells may include a membrane electrode assembly ("MEA"), a cathode frame, a cathode flow area, a cathode gas diffusion layer (GDL), an anode frame, an anode flow area, and an anode porous transport layer (PTL). The MEA may have a cathode portion, an anode portion, and a separator between the cathode portion and the anode portion. The cathode frame may be adjacent to the cathode portion. The cathode flow area may be at least partially disposed within a first opening of the cathode frame. The cathode GDL may be adjacent to the cathode frame and may cover the cathode flow area. The anode frame may be adjacent to the anode portion of the MEA. The anode flow area may be at least partially disposed within a second opening of the anode frame. The anode PTL may be adjacent to the anode frame and may cover the anode flow area.

[0086] In some embodiments, the second end assembly may include a first plate, a first gasket, and a second plate. The first plate may include a recess in a central portion of the first plate, a second recess surrounding a central region of the central portion, and a first hole configured to receive one or more control fluids. The first gasket may be at least partially disposed within the second recess. The second plate may be slidably disposed within the first recess and configured to abut a concave surface of the first recess facing the first gasket and / or the second plate in an axial direction, such that the first recess, the first gasket, and the second plate define a cavity within the second end assembly. The axial distance between the second plate and the concave surface of the first recess may be configured to increase in response to accumulation of one or more control fluids in the cavity.

[0087] In some embodiments, the second plate may be a first bus plate configured to receive a first electrical potential, and the first plate may be an insulating plate configured to electrically isolate the first bus plate from at least one other component of the first and / or second end assembly.

[0088] In some embodiments, the second end assembly may further include a second end plate, and the first plate may be interposed between the second plate and the second end plate.

[0089] In some embodiments, the first insulating plate may be coupled to the second end plate via a plurality of first fasteners.

[0090] In some embodiments, the first hole may be formed in the concave surface and may extend axially through the first plate.

[0091] In some embodiments, the second end plate may include a second hole having a proximal end fluidly connected to the first hole in the first plate and a distal end fluidly connected to the fluid inlet coupling.

[0092] In some embodiments, the first and second holes may be substantially axially aligned.

[0093] In some embodiments, the apparatus may further include a gasket interposed between the first plate and the second end plate, the gasket surrounding the first hole and the second hole to form a fluid seal.

[0094] In some embodiments, the second end assembly may include a first plate, a piston, and one or more gaskets. The first plate may include a first body, a first protrusion extending axially from the first body, a first blind opening extending in a central portion of the first protrusion in a second direction opposite the axial direction, and at least one first hole fluidly connected to the first blind opening and configured to receive one or more control fluids. The piston may include a second body and a second protrusion extending in the second direction from the second body, at least a portion of the second protrusion being slidably received in at least a portion of the first blind opening of the first protrusion. The one or more gaskets may surround the second protrusion and be configured to interface with one or more outer sidewalls of the second protrusion and one or more inner sidewalls of the first blind opening, such that the first opening, the second protrusion, and the at least one gasket define an internal cavity of the second end assembly. The first blind opening may terminate in a first concave surface. The second protrusion may terminate in a first protruding surface facing the first concave surface in the second direction. An axial distance between the first protruding surface and the first concave surface may be configured to increase in response to accumulation of one or more control fluids in the cavity.

[0095] In some embodiments, the one or more gaskets may be multiple gaskets, and the gaskets may be axially offset from one another.

[0096] In some embodiments, the second projection may include one or more recesses extending in one or more outer walls of the second projection in one or more directions transverse to the axial direction, and one or more gaskets may each be supported in a corresponding one of the one or more recesses.

[0097] In some embodiments, the second end assembly may further include a plurality of biasing members, the second protrusion may further include a plurality of second blind openings extending axially into the first protrusion surface, and the first plate may further include a plurality of third protrusions extending axially from the first concave surface. The biasing members may each be supported in the first blind opening via a corresponding one of the third protrusions, such that in a first compressed state of the second end assembly, the biasing members may be compressed between the first protrusion surface and the first concave surface, and each portion of the third protrusion may extend at least partially into a corresponding one of the second blind openings.

[0098] In some embodiments, the width of each of the second blind openings in a direction perpendicular to the axial direction may be greater than the width of each of the third protrusions in a direction perpendicular to the axial direction.

[0099] In some embodiments, the height of each of the third protrusions from the first concave surface in the axial direction may be greater than the depth of each of the second blind openings from the first protruding surface in the axial direction.

[0100] In some embodiments, the first plate may be a second end plate of the device configured to be coupled to the first end plate via a plurality of axially extending tension members.

[0101] In some embodiments, the second end assembly may further include an insulating plate and a first bus plate stacked axially from the piston, such that the first bus plate and the insulating plate are interposed between the cell and the piston. The first bus plate may be configured to receive a first electrical potential. The insulating plate may be configured to electrically insulate the first bus plate from at least one other component of the second end assembly and / or the first end plate.

[0102] In some embodiments, the first bus plate and the isolation plate may be coupled to the piston via a plurality of fasteners.

[0103] In some embodiments, the at least one first aperture may be a plurality of first apertures configured to receive one or more control fluids.

[0104] In some embodiments, in the operating state of the device, the cavity may be in a dead head state.

[0105] In some embodiments, the first plate may further include at least one second hole fluidly connected to the first blind opening, and the at least one second hole may be configured to drain excess accumulation of the one or more control fluids in the cavity in response to the accumulation of the one or more control fluids exceeding a predetermined threshold.

[0106] In some embodiments, one or more control fluids and input gaseous CO X may be substantially equivalent.

[0107] In some embodiments, the device comprises a gaseous CO 2 gas supply at a first pressure. X and at least one source configured to input one or more control fluids to the second end assembly at a first pressure and a second pressure, respectively. The first pressure and the second pressure may be substantially equal.

[0108] In some embodiments, the device comprises a gaseous CO 2 gas supply at a first pressure. X and at least one source configured to input one or more control fluids to the second end assembly at a second pressure. At steady state, the first pressure and the second pressure may be in equilibrium.

[0109] In some embodiments, at least one source is gaseous CO X into the cell and one or more control fluids into the second end assembly substantially simultaneously.

[0110] In some embodiments, at least one source is gaseous CO X The control fluid may be configured to delay the injection of one or more control fluids relative to the injection of the other fluid.

[0111] In some embodiments, at least one source may be configured to delay the introduction of one or more control fluids until cell expansion reaches a defined threshold.

[0112] In some embodiments, the flow path of one or more control fluids may not be through a cell.

[0113] The foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the claimed subject matter.

[0114] Various embodiments disclosed herein are illustrated by way of example, and not by way of limitation, in the figures of the accompanying drawings, in which like reference numerals refer to similar elements and in which: [Brief explanation of the drawings]

[0115] [Figure 1] FIG. 1 shows a diagram of an example MEA for use in COX reduction. [Figure 2]1 shows a CO2 electrolysis device configured to receive water and CO2 as reactants at the cathode and output CO as a by-product. [Figure 3] 1 shows an example structure of a CO2-reducing MEA having a cathode catalyst layer, an anode catalyst layer, and an anion-conducting PEM. [Figure 4] 1 shows an example of the structure of a CO-reducing MEA having a cathode catalyst layer, an anode catalyst layer, and an anion-conducting PEM. [Figure 5] FIG. 1 shows an exploded view of an example multi-cell COX electrolyzer stack. [Figure 6] FIG. 6 shows a perspective view of the exemplary multi-cell COX electrolysis device of FIG. [Figure 7] FIG. 7 illustrates a side view of the exemplary multi-cell COX electrolysis device of FIG. [Figure 8] FIG. 7 illustrates a side view of the exemplary multi-cell COX electrolysis device of FIG. [Figure 9] 9 shows a cross-sectional view of the example multi-cell COX electrolyzer of FIG. 7 taken along section line 9-9. [Figure 10] 10 shows a cross-sectional view of the example multi-cell COX electrolyzer of FIG. 8 taken along section line 10-10. [Figure 11A] FIG. 7 illustrates an exploded view of an exemplary repeat unit of the exemplary multi-cell COX electrolyzer stack of FIG. 6. [Figure 11B] FIG. 7 illustrates an exploded view of some cathode components of another exemplary repeat unit of the exemplary multi-cell COX electrolyzer stack of FIG. 6. [Figure 11C] FIG. 11C shows a cross-sectional view of the cathode component of the exemplary repeat unit of FIG. 11B. [Figure 11D] FIG. 7 illustrates an exploded view of the anode components of an exemplary repeat unit of the exemplary multi-cell COX electrolyzer stack of FIG. 6. [Figure 11E] FIG. 11D shows a cross-sectional view of an anode component of the exemplary repeat unit of FIG. [Figure 12] FIG. 7 illustrates a top view of an exemplary manifold block of the exemplary multi-cell COX electrolysis device of FIG. [Figure 13]13 illustrates a side view of the example manifold block of FIG. 12. [Figure 14] 13 illustrates a side view of the example manifold block of FIG. 12. [Figure 15] 13 illustrates a side view of the example manifold block of FIG. 12. [Figure 16] 13 illustrates a side view of the example manifold block of FIG. 12. [Figure 17] FIG. 7 illustrates an exploded view of an exemplary cathode interface assembly of the exemplary multi-cell COX electrolyzer stack of FIG. 6. [Figure 18] 18 shows an example of the cathode interface assembly of FIG. 17 in an undisassembled state. [Figure 19] 7 illustrates an exploded view of an exemplary COX electrolyzer cell of the exemplary multi-cell COX electrolyzer stack of FIG. 6. [Figure 20] FIG. 7 shows a bottom view of a representative repeat unit of the exemplary multi-cell COX electrolyzer stack of FIG. [Figure 21] 21 shows a cross-sectional view of the representative repeat unit of FIG. 20 taken along section line 21-21. [Figure 22] 22 shows a cross-sectional view of the representative repeat unit of FIG. 20 taken along section line 22-22. [Figure 23] 23 shows an enlarged portion of the cross-sectional view of FIG. 22. [Figure 24] 23 shows an enlarged portion of the cross-sectional view of FIG. 22. [Figure 25] FIG. 7 shows a perspective view of an exemplary integrated MEA assembly of the exemplary multi-cell COX electrolyzer stack of FIG. 6. [Figure 26] FIG. 26 shows a top view of the exemplary integrated MEA assembly of FIG. 25. [Figure 27] 27 shows a cross-sectional view of the exemplary integrated MEA assembly of FIG. 26 taken along section line 27-27. [Figure 28] 1 illustrates a first perspective view of an exemplary cathode frame. [Figure 29] 29 shows a bottom view of the exemplary cathode frame of FIG. 28. [Figure 30]29 illustrates an enlarged portion of the exemplary cathode frame of FIG. 28. [Figure 31] 29 illustrates an enlarged portion of the exemplary cathode frame of FIG. 28. [Figure 32] 29 shows a second perspective view of the exemplary cathode frame of FIG. 28. [Figure 33] 33 shows a top view of the exemplary cathode frame of FIG. 32. [Figure 34] 34 shows a cross-sectional view of the exemplary cathode frame of FIG. 33 taken along section line 34-34. [Figure 35] 34 shows an enlarged portion of the exemplary cathode frame of FIG. 33. [Figure 36] 36 shows a cross-sectional view of the exemplary cathode frame of FIG. 35 taken along section line 36-36. [Figure 37] FIG. 1 illustrates a first perspective view of an exemplary anode frame. [Figure 38] 38 shows a top view of the exemplary cathode frame of FIG. 37. [Figure 39] FIG. 38 shows a second perspective view of the exemplary anode frame of FIG. 37. [Figure 40] FIG. 40 shows a bottom view of the exemplary anode frame of FIG. 39. [Figure 41] 39 illustrates an enlarged portion of the exemplary anode frame of FIG. 38. [Figure 42] 41 shows an enlarged portion of the exemplary anode frame of FIG. 40. [Figure 43] 11B shows a plan view of an example separator plate of the representative repeat unit of FIG. 11A. [Figure 44] 48 illustrates the exemplary anode interfacial separator of FIG. 47. [Figure 45] 19A-19C illustrate top and bottom views of an exemplary cathode interfacial separator of the exemplary cathode interfacial assembly of FIG. 18. [Figure 46] 19A-19C illustrate top and bottom views of an exemplary cathode interfacial separator of the exemplary cathode interfacial assembly of FIG. 18. [Figure 47] FIG. 7 illustrates an exploded view of an exemplary anode interface assembly of the exemplary multi-cell COX electrolyzer stack of FIG. 6. [Figure 48] 48 illustrates the exemplary anode interface assembly of FIG. 47 in an assembled state. [Figure 49] FIG. 1 shows an example of a cathode flow basin having a single serpentine channel. [Figure 50] FIG. 1 illustrates an example of a multiple serpentine channel arrangement. [Figure 51] FIG. 10 illustrates another example of a multiple serpentine channel arrangement. [Figure 52] FIG. 1 shows an example of a cathode flow basin including a two-channel multiple serpentine channel arrangement. [Figure 53] 1A-1C illustrate examples of cathode flow basins that may be used in some implementations. [Figure 54] 1A-1C illustrate examples of cathode flow basins that may be used in some implementations. [Figure 55] 1A-1C illustrate examples of cathode flow basins that may be used in some implementations. [Figure 56] 1A-1C illustrate examples of cathode flow basins that may be used in some implementations. [Figure 57] 1A-1C illustrate examples of cathode flow basins that may be used in some implementations. [Figure 58] 1A-1C illustrate examples of cathode flow basins that may be used in some implementations. [Figure 59] FIG. 10 shows an example of a cathode flow basin having four cathode serpentine channels arranged in a multiple serpentine channel arrangement. [Figure 60] 1 shows a cross-sectional view of a cathode flow basin having serpentine channels of square or rectangular cross-section. [Figure 61] 1 shows a cross-sectional view of a cathode flow basin with multiple square or rectangular cross-section serpentine channels with rounded inner bottom edges. [Figure 62] 1 shows a cross-sectional view of a cathode flow basin with multiple U-shaped cross-section serpentine channels. [Figure 63] 1 shows an example of a cathode basin with a peninsular wall having variable wall thickness. [Figure 64]1 shows a plan view of a simplified representation of an exemplary cathode flow basin. [Figure 65] The cathode basin is shown with two zones and boundaries. [Figure 66] 1 shows a cathode flow field with symmetrically arranged serpentine channels. [Figure 67] The same cathode flow area as in FIG. 66 is shown enlarged and cut away so that the various features can be more easily seen and identified. [Figure 68] 1 shows a cathode flow field with serpentine channels arranged in a symmetrical manner. [Figure 69] The same cathode basin as in Figure 68 is shown enlarged and cut away so that the various features can be more easily labeled and identified. [Figure 70] 1 shows an example of a cathode flow basin with a parallel channel arrangement. [Figure 71] 1 shows a schematic diagram of an exemplary parallel channel basin. [Figure 72] An example of a branching-parallel channel basin is shown. [Figure 73] The same branch channel basin as in Figure 72 is shown in enlarged form, but with the center of the parallel channel omitted by cutting off the section. [Figure 74] 1 shows a schematic diagram of another example of a branching parallel channel basin. [Figure 75] 1 shows a schematic diagram of yet another example of a branching parallel channel basin. [Figure 76] 1 shows an example of a cathode flow basin featuring branching parallel channels. [Figure 77] 77 shows a detailed view of the left and right sides of the upper half of the cathode basin of FIG. 76, with the remaining basin omitted from the view. [Figure 78] 1 shows an example of a cathode flow field with an interdigitated channel configuration. [Figure 79] FIG. 2 shows a side view of a gas diffusion layer. [Figure 80] 1 shows a flow chart of an exemplary process for forming a pre-compressed stack of gas diffusion layers. [Figure 81]1 illustrates a partial cross-sectional view of an exemplary apparatus for forming a pre-compressed stack of gas diffusion layers. [Figure 82] FIG. 1 shows a partial cross-sectional view of an example roll-to-roll system for forming a pre-compressed stack of gas diffusion layers. [Figure 83] 7 illustrates a plan view of a portion of the exemplary anode basin of the exemplary multi-cell COX electrolyzer of FIG. 6. [Figure 84A] 84A-84A and 84B-84B show cross-sectional views of the exemplary anode basins of FIG. 83 taken along section lines 84A-84A and 84B-84B, respectively, according to some embodiments. [Figure 84B] 84A-84A and 84B-84B show cross-sectional views of the exemplary anode basins of FIG. 83 taken along section lines 84A-84A and 84B-84B, respectively, according to some embodiments. [Figure 85A] 7 illustrates a plan view of a portion of the exemplary anode basin of the exemplary multi-cell COX electrolyzer of FIG. 6. [Figure 85B] 85B-85B and 85C-85C show cross-sectional views of the exemplary anode flow areas of FIG. 85A taken along section lines 85B-85B and 85C-85C, respectively, according to some embodiments. [Figure 85C] 85B-85B and 85C-85C show cross-sectional views of the exemplary anode flow areas of FIG. 85A taken along section lines 85B-85B and 85C-85C, respectively, according to some embodiments. [Figure 86] 7 illustrates a plan view of an exemplary insulating plate of the exemplary multi-cell COX electrolysis device of FIG. 6. [Figure 87] 87 shows a cross-sectional view of the exemplary insulating plate of FIG. 86 taken along section line 87-87. [Figure 88] 7 illustrates a plan view of an exemplary end plate of the exemplary multi-cell COX electrolysis device of FIG. 6. [Figure 89] 89 shows a cross-sectional view of the example end plate of FIG. 88 taken along section line 89-89. [Figure 90] 10 shows an enlarged portion of the cross-sectional view of FIG. 9. [Figure 91] FIG. 1 shows a perspective view of an example multi-cell COX electrolyzer stack. [Figure 92] 92A-92C show side views of each of the exemplary multi-cell COX electrolyzer stacks of FIG. 91. [Figure 93] 92A-92C show side views of each of the exemplary multi-cell COX electrolyzer stacks of FIG. 91. [Figure 94] 92A-92C show respective cross-sectional views of the exemplary multi-cell COX electrolyzer stack of FIG. 91 taken along section lines 94-94 and 95-95, respectively. [Figure 95] 92A-92C show respective cross-sectional views of the exemplary multi-cell COX electrolyzer stack of FIG. 91 taken along section lines 94-94 and 95-95, respectively. [Figure 96] FIG. 92 illustrates a perspective view of an example of a port side assembly of the exemplary multi-cell COX electrolyzer stack of FIG. 91. [Figure 97] 97A-97C show top and bottom plan views of an example manifold block of the example port side assembly of FIG. 96. [Figure 98] 97A-97C show top and bottom plan views of an example manifold block of the example port side assembly of FIG. 96. [Figure 99] 97A-97C illustrate bottom and top plan views of an exemplary insulating plate of the exemplary port side assembly of FIG. 96. [Figure 100] 97A-97C illustrate bottom and top plan views of an exemplary insulating plate of the exemplary port side assembly of FIG. 96. [Figure 101] 92 shows a perspective view of an exemplary piston-side assembly of the exemplary multi-cell COX electrolyzer stack of FIG. 91 in an exploded state. [Figure 102] 102 shows a top plan view of the exemplary piston-side assembly of FIG. 101 in an assembled state. [Figure 103] 103 shows a cross-sectional view of the example piston-side assembly of FIG. 102 taken along section line 103-103. [Figure 104] 102 shows a perspective view of an exemplary end plate of the piston side assembly of the example of FIG. 101. [Figure 105] 105 shows top and bottom views of the exemplary end plate of FIG. 104. [Figure 106] 105 shows top and bottom views of the exemplary end plate of FIG. 104. [Figure 107] 102 shows a perspective view of an example of a piston of the piston-side assembly of FIG. 101. [Figure 108] 108 shows top and bottom views of the example piston of FIG. 107. [Figure 109] 108 shows top and bottom views of the example piston of FIG. 107. Detailed Description of the Invention

[0116] CO using membrane electrode assemblies X While electrolyzers, such as CO electrolyzers, may share some structural similarities with existing polymer electrolyte membrane (PEM) water electrolyzers, there are several ways in which CO electrolyzers may differ significantly from such PEM water electrolyzer systems.

[0117] Typical CO X In an electrolyzer, the membrane electrode assembly (MEA) may be one of multiple elements stacked together which may be referred to as a "cell", and in the following description the term "cell" will be used to refer to this assembly of multiple elements.

[0118] CO X An example of an MEA 100 for use in reduction is shown in FIG. 1. The MEA 100 has a cathode layer 120 and an anode layer 140 separated by an ion-conducting polymer layer 160, which provide a pathway for ions to travel between the cathode layer 120 and the anode layer 140. In certain embodiments, the cathode layer 120 includes an anion-conducting polymer and / or the anode layer 140 includes a cation-conducting polymer. In certain embodiments, the cathode layer 120 and / or the anode layer 140 of the MEA 100 are porous. The pores can facilitate gas and / or fluid transport and can increase the amount of catalyst surface area available for reaction.

[0119] The ion-conducting layer 160 may include, for example, two or three sublayers: a polymer electrolyte membrane (PEM) 165, an optional cathode buffer layer 125, and / or an optional anode buffer layer 145. One or more layers of the ion-conducting layer 160 can be porous. In certain embodiments, at least one layer is non-porous so that reactants and products of the cathode cannot pass to the anode via gas and / or liquid transport, and vice versa. In certain embodiments, the PEM layer 165 is non-porous. Example properties of anode and cathode buffer layers are described elsewhere herein. In some cases, the ion-conducting layer 160 includes only a single layer or two sublayers.

[0120] 2 shows a CO electrolyzer 203 configured to receive water (HO) and CO (e.g., humidified or dry gaseous CO) as reactants at the cathode 205 and output CO as a product. The electrolyzer 203 is also configured to receive water as a reactant at the anode 207 and output gaseous oxygen (O). The electrolyzer 203 includes a bipolar layer having an anion-conducting polymer 209 adjacent to the cathode 205 and a cation-conducting polymer 211 (shown as a proton exchange membrane) adjacent to the anode 207.

[0121] As shown in the close-up inset of the bipolar interface 213 of the electrolyzer 203, the cathode 205 includes an anion exchange polymer (in this example, the same anion conducting polymer 209 as in the bipolar layer), electronically conductive carbon support particles 217, and metal nanoparticles 219 supported on the support particles. CO and water are transported through pores (such as pore 221) to reach the metal nanoparticles 219, where they are converted into hydroxides (OH - ) ions to produce bicarbonate (HCO 3 ) ions and a reduction reaction product (not shown). CO 2 may also reach the metal nanoparticles 219 by transport within the anion exchange polymer 209.

[0122] Hydrogen ions are transported from the anode 207 and through the cation-conducting polymer 211 until they reach the bipolar interface 213, where they are prevented from further transport to the cathode 205 by the anion-exchange polymer 209. At the interface 213, the hydrogen ions may react with bicarbonate or carbonate ions to produce carbonic acid (HCO), which may decompose to produce CO and water. As described herein, the resulting CO may be carried in the gas phase and returned to the cathode 205 via a pathway within the MEA, where it may be reduced. The cation-conducting polymer 211 prevents the transport of anions, such as bicarbonate ions, to the anode 207. At the anode 207, the anions may react with protons to release CO, but this CO is no longer available to participate in reduction reactions at the cathode 205.

[0123] As shown, a cathode buffer layer having an anion-conducting polymer may work in concert with the cathode 205 and its anion-conducting polymer to block the transport of protons to the cathode 205. On the other hand, an MEA employing the appropriate type of electrically conductive, ion-conducting polymer in the cathode 205 and cathode buffer layer may prevent the transport of cations to the cathode 205, and an anode buffer layer, if present, may similarly prevent the transport of anions to the anode 207, where the cations and anions may again come into contact in interior regions of the MEA, such as the membrane layer.

[0124] As illustrated in Figure 2, bicarbonate and / or carbonate ions can combine with hydrogen ions between the cathode and anode layers to form carbonic acid, which decomposes to form gaseous CO. Delamination of the MEA can be observed, which is believed to be due to the evolution of gaseous CO, as it has no easy route to escape.

[0125] The delamination problem can be solved by employing a cathode buffer layer with an inert filler and associated pores. One possible explanation for its effectiveness is that the pores provide a pathway through which gaseous carbon dioxide can escape and return to the cathode 205 for reduction. In some embodiments, the cathode buffer layer is porous, but at least one layer between the cathode and anode layers is non-porous. This prevents the passage of gas and / or bulk liquid between the cathode and anode layers while simultaneously preventing delamination. For example, a non-porous layer can prevent the passage of water directly from the anode 207 to the cathode 205. The porosity of various layers within the MEA is further discussed elsewhere herein.

[0126] Example of a bipolar MEA As an example, the MEA includes a cathode layer including a reduction catalyst and a first anion-conducting polymer (e.g., Sustainion, FumaSepFAA-3, or Tokuyama anion exchange polymer); an anode layer including an oxidation catalyst and a first cation-conducting polymer (e.g., PFSA polymer); a membrane layer including a second cation-conducting polymer and disposed between the cathode layer and the anode layer to electrically conductively connect the cathode layer and the anode layer; and a cathode buffer layer including a second anion-conducting polymer (e.g., Sustainion, FumaSepFAA-3, or Tokuyama anion exchange polymer) and disposed between the cathode layer and the membrane layer to electrically conductively connect the cathode layer and the membrane layer. In this example, the cathode buffer layer can have a porosity of about 1 to 90 volume percent, but can additionally or alternatively have any suitable porosity (e.g., no porosity). In other examples, the cathode buffer layer can have any suitable porosity (eg, 0.01 to 95%, 0.1 to 95%, 0.01 to 75%, 1 to 95%, 1 to 90%, etc.).

[0127] If the porosity is too high, the ionic conductivity of the buffer layer may decrease. In some embodiments, the porosity is 20% or less, and in particular embodiments, it is 0.1-20%, 1-10%, or 5-10%. Porosity within these ranges may be sufficient to allow the movement of water and / or CO2 without loss of ionic conductivity. Porosity may be measured as described below.

[0128] In a related example, the membrane electrode assembly can include an anode buffer layer containing a third cation-conducting polymer, disposed between the membrane layer and the anode layer and electrically connecting them. The anode buffer layer preferably has a porosity of about 1 to 90 volume percent, but can additionally or alternatively have any suitable porosity (e.g., including no porosity). However, in other configurations and examples, the anode buffer layer can have any suitable porosity (e.g., 0.01 to 95%, 0.1 to 95%, 0.01 to 75%, 1 to 95%, 1 to 90%). As with the cathode buffer layer, in some embodiments, the porosity is 20% or less, e.g., 0.1 to 20%, 1 to 10%, or 5 to 10%.

[0129] In one example, the anode buffer layer can be used in an MEA having a cathode catalyst layer containing an anion exchange polymer, a cathode buffer layer containing an anion exchange polymer, a membrane containing a cation exchange polymer, and an anode buffer layer containing an anion exchange polymer. In such a structure, the anode buffer layer can be porous, which facilitates water transport to the membrane / anode buffer layer interface. At this interface, water splits, producing protons that migrate through the membrane and hydroxides that migrate to the anode catalyst layer. In some cases, at least one catalyst (such as a carbon catalyst or a metal catalyst) can be utilized to facilitate water splitting at this interface. For example, the at least one catalyst may include a cobalt-based catalyst, an iron-nickel-based catalyst, a palladium-based catalyst, a platinum-based catalyst, ruthenium(IV) dioxide (RuO), nickel-stabilized ruthenium dioxide (Ni-RuO), iridium(IV) dioxide (IrO), graphene, graphene oxide (GO), reduced graphene oxide (rGO), graphitic carbon nitride (gCN), graphene quantum dots (GQDs), graphene quantum sheets (GQS), or the like. One advantage of this structure is that it allows for the development of low-cost water oxidation catalysts that are stable only under basic conditions (e.g., NiFeO X ) may be possible.

[0130] In another specific example, the membrane electrode assembly includes a cathode layer including a reduction catalyst and a first anion-conducting polymer (e.g., Sustainion, FumaSepFAA-3, Tokuyama anion exchange polymer), an anode layer including an oxidation catalyst and a first cation-conducting polymer, a membrane layer including a second anion-conducting polymer (e.g., Sustainion, FumaSepFAA-3, Tokuyama anion exchange polymer) disposed between the cathode layer and the anode layer and electrically conductively connecting the cathode layer and the anode layer, and an anode buffer layer including the second cation-conducting polymer disposed between the anode layer and the membrane layer and electrically conductively connecting the anode layer and the membrane layer.

[0131] An MEA comprising an anion-exchange polymer membrane and an anode buffer layer containing a cation-exchange polymer can be used for CO reduction. In this case, water forms at the membrane / anode buffer layer interface. Pores in the anode buffer layer can facilitate water removal. One advantage of this structure is acid stability (e.g., IrO X ) hydroxylation catalyst.

[0132] In a related example, the membrane electrode assembly can include a cathode buffer layer comprising a third anion-conducting polymer and disposed between the cathode layer and the membrane layer, thereby conductively connecting the cathode layer and the membrane layer. The third anion-conducting polymer can be the same as or different from the first and / or second anion-conducting polymer. The cathode buffer layer preferably has a porosity of about 1 to 90 volume percent, but can additionally or alternatively have any suitable porosity (e.g., including no porosity). However, in other configurations and examples, the cathode buffer layer can have any suitable porosity (e.g., 0.01 to 95%, 0.1 to 95%, 0.01 to 75%, 1 to 95%, 1 to 90%). In some embodiments, the porosity is 20% or less, and in particular embodiments, it is 0.1 to 20%, 1 to 10%, or 5 to 10%.

[0133] As an example, a cathode catalyst layer containing 4 nm diameter Au nanoparticles supported on Vulcan XC72 or XC72R carbon and mixed with TM1 (mTPN-1) anion exchange polymer electrolyte may be used. The cathode catalyst layer may be approximately 15 μm thick, have a gold to gold plus carbon weight ratio (Au / (Au+C)) of 20%, a TM1 to catalyst mass ratio of 0.32, and a mass loading of 1.4-1.6 mg / cm. 2(total Au + C), with an estimated porosity of 0.56. In another example, an anion exchange polymer layer composed of TM1 and PTFE particles may be provided. The diameter of the PTFE particles may be approximately 200 nm, and the molecular weight of the TM1 may be approximately 30k-45k. Such an exemplary anion exchange polymer layer may be approximately 15 μm thick, and the PTFE particles may introduce approximately 8% porosity. A proton exchange membrane layer composed of a perfluorosulfonic acid polymer (e.g., Nafion 115 or Nafion 117) may also be provided with a thickness of approximately 100 μm to approximately 200 μm. The proton exchange membrane may form a continuous layer that prevents significant gas (CO2, CO, H2) migration through the layer. An anode catalyst layer composed of 10 μm thick Ir or IrOX nanoparticles (100-200 nm aggregates) may also be provided. CO X .

[0134] CO X Anion-exchange membrane-only MEA for reduction In some embodiments, the MEA does not include a cation-conducting polymer layer. In such embodiments, the electrolyte is not a cation-conducting polymer, and the anode, if it includes an ion-conducting polymer, does not include a cation-conducting polymer. Various examples are provided below.

[0135] In an AEM-only MEA, anions can conduct through the MEA. In embodiments where neither MEA layer has significant conductivity for cations, hydrogen ions have limited mobility within the MEA. In some implementations, the AEM-only membrane provides a neutral or alkaline pH environment (e.g., at least pH 7), which can promote CO2 and / or CO2 reduction by suppressing parasitic hydrogen evolution reactions at the cathode. As with other MEA designs, an AEM-only MEA allows ions, particularly anions such as hydroxide, bicarbonate, or carbonate ions, to migrate through the polymer electrolyte. In some embodiments, the pH may be lower, but a pH of 4 or higher may be sufficient to suppress hydrogen evolution. In an AEM-only MEA, electrons can also migrate to and through metals and carbon in the catalyst layer. In embodiments, an AEM-only MEA includes pores in the anode layer, pores in the cathode layer, and / or pores in the PEM, allowing liquid and gas migration through such pores.

[0136] In certain embodiments, an AEM-only MEA includes an anion-exchange polymer electrolyte membrane positioned between a cathode and an anode. The cathode and anode are each electrocatalyst layers. In some embodiments, one or both electrocatalyst layers also include an anion-exchange polymer electrolyte.

[0137] In certain embodiments, AEM-only MEAs are formed by depositing cathode and anode electrocatalyst layers onto porous conductive supports, such as gas diffusion layers, porous transport layers, etc., to form gas diffusion electrodes (GDEs). An anion exchange membrane is then sandwiched between the gas diffusion electrodes.

[0138] In certain embodiments, an AEM-only MEA is used to reduce CO. The use of an anion-exchange polymer electrolyte avoids the low pH environment that is unfavorable to CO reduction. Additionally, the use of an AEM transports water away from the cathode catalyst layer, thereby preventing water accumulation (flooding) within the cell's cathode that could impede reactant gas transport.

[0139] Water transport within the MEA occurs through various mechanisms, including diffusion and electroosmotic drag. In some embodiments, at the current densities of the CO electrolyzers described herein, electroosmotic drag is the dominant mechanism. As ions move through the polymer electrolyte, they drag water along with them. For cation exchange membranes such as Nafion membranes, the amount of water transport is well characterized and is understood to depend on membrane pretreatment / hydration. Protons move from a positive potential to a negative potential (anode to cathode), carrying two to four water molecules each, depending on pretreatment.

[0140] In certain embodiments, AEM-only MEAs can be used for CO reduction reactions. Unlike CO reduction reactions, the reduction of CO does not produce carbonate or bicarbonate anions that can migrate to the anode and release valuable reactants.

[0141] FIG. 3 shows an example structure of a CO2-reducing MEA 301 having a cathode catalyst layer 303, an anode catalyst layer 305, and an anion-conducting PEM 307. In certain embodiments, the cathode catalyst layer 303 may include metal catalyst particles (e.g., nanoparticles) that are unsupported or supported on a conductive substrate, such as carbon particles. In some implementations, the cathode catalyst layer 303 also includes an anion-conducting polymer. The metal catalyst particles can catalyze CO2 reduction, particularly in or within non-acidic environments. In certain embodiments, the anode catalyst layer 305 includes metal oxide catalyst particles (e.g., nanoparticles) that are unsupported or supported on a conductive substrate, such as a metal oxide or carbide. In some implementations, the anode catalyst layer 305 may further include an anion-conducting polymer. Examples of metal oxide catalyst particles for the anode catalyst layer 305 may include iridium oxide, nickel oxide, nickel iron oxide, iridium ruthenium oxide, platinum oxide, etc. Anion-conducting PEM307 may include any of a variety of anion-conducting polymers, such as HNN5 / HNN8 (Ionomr), FumaSep (Fumatech), TM1 (Orion), PAP-TP (W7energy), and Sustainion (Dioxide Materials). In addition to these anion-conducting polymers, other anion-conducting polymers may be used that have an ion exchange capacity (IEC) in the range of 1.1 to 2.6, a usable pH range of 0 to 14, limited solubility in some organic solvents, moderate thermal and mechanical stability, good ionic conductivity / ASR, and acceptable water absorption / swelling ratios. The polymer may be chemically exchanged with specific anions, such as bicarbonate or carbonate, instead of halogen anions, prior to use.

[0142] As illustrated in FIG. 3, CO, such as CO gas, may be supplied to the cathode catalyst layer 303. In certain embodiments, the CO may be provided via a gas diffusion electrode. In the cathode catalyst layer 303, the CO reacts to form, generally, C x O y H zThe anions produced in the cathode catalyst layer 303 may include hydroxides, carbonates, and / or bicarbonates, which may diffuse, migrate, or otherwise migrate to the anode catalyst layer 305. In the anode catalyst layer 305, an oxidation reaction, such as the oxidation of water or hydroxide ions, may occur to produce diatomic oxygen ions and hydrogen ions or water. In some applications, the hydrogen ions may react with the hydroxides, carbonates, and / or bicarbonates to produce water, carbonic acid, and / or CO2. In some cases, the fewer the number of interfaces, the lower the resistance at which the reaction(s) occur. In some embodiments, a relatively basic environment (e.g., at least above pH 7) is maintained to synthesize C2 and C3 hydrocarbons.

[0143] 4 shows an example structure of a CO reduction MEA 401 having a cathode catalyst layer 403, an anode catalyst layer 405, and an anion-conducting PEM 407. Overall, the structure of MEA 401 may be similar to that of MEA 301 of FIG. 3. However, the cathode catalyst may be selected to promote the CO reduction reaction, meaning that different reduction catalysts are used in the CO reduction and CO reduction embodiments.

[0144] In some embodiments, AEM-only MEAs may be advantageous for CO reduction. Selecting the water uptake of the AEM material can help regulate moisture at the catalyst interface, thereby improving CO availability to the catalyst. For this reason, AEM-only membranes may be preferred for CO reduction. Bipolar membranes may be more suitable for CO reduction due to their better resistance to CO dissolution and crossover in basic anolyte media.

[0145] In various embodiments, the cathode catalyst layer 403 may include metal catalyst particles (e.g., nanoparticles) that are unsupported or supported on a conductive substrate, such as carbon particles. In some implementations, the cathode catalyst layer 403 may further include an anion-conducting polymer. In certain embodiments, the anode catalyst layer 405 includes metal oxide catalyst particles (e.g., nanoparticles) that are unsupported or supported on a conductive substrate, such as a metal oxide, carbide, or the like. In some implementations, the anode catalyst layer 405 may further include an anion-conducting polymer. Examples of metal oxide catalyst particles in the anode catalyst layer 405 may include those identified for the anode catalyst layer 305 in FIG. 3. The anion-conducting PEM 407 may include any of a variety of anion-conducting polymers, such as those identified for the PEM 307 in FIG. 3.

[0146] As illustrated in FIG. 4, CO gas may be supplied to the cathode catalyst layer 403. In certain embodiments, CO may be provided via a gas diffusion electrode. In the cathode catalyst layer 403, CO reacts to form, generally, C x O y H z The reduction product can be produced as follows:

[0147] Anions produced in the cathode catalyst layer 403 may include hydroxide ions, which may diffuse, migrate, or otherwise migrate to the anode catalyst layer 405. In the anode catalyst layer 405, an oxidation reaction may occur, such as the oxidation of water or hydroxide ions, to produce diatomic oxygen ions and hydrogen ions or water. In some applications, hydrogen ions may react with hydroxide ions to produce water.

[0148] While the general configuration of MEA401 is similar to MEA301, there are some differences between the MEAs. For CO2 reduction, a significant amount of CO2 can be dissolved and transferred to the anode of an AEM-only MEA, such as that shown in Figure 3. For CO2 reduction, the potential for significant CO gas crossover is reduced. In this case, the reaction environment for CO2 reduction can be more basic than that for CO2 reduction. The MEA material, including the catalyst, can be selected to have excellent stability in high-pH environments.

[0149] AEM-only MEA example 1. Copper metal (40 nm thick Cu, approximately 0.05 mg / cm 2 ) was deposited on a porous carbon sheet (Sigracet 39BC gas diffusion layer) by electron beam evaporation. Ir metal nanoparticles were deposited at 3 mg / cm by drop casting or ultrasonic spray deposition. 2 The anion exchange membrane (Ionomr) (25-50 μm, OH- conductivity 80 mS / cm) was deposited on a porous titanium sheet at a loading of 1000 μm. 2 , HCO3- conductivity 2~3mS / cm 2 The membrane was sandwiched between a porous carbon sheet and a titanium sheet, with the electrocatalyst layer facing the membrane.

[0150] 2.80 nm spherical Cu nanoparticles (Sigma Aldrich) were mixed with FAA-3 anion-exchange solid polymer electrolyte (Fumatech), and the mass ratio of FAA-3 to catalyst was 0.10, as set out above.

[0151] Various features and embodiments of MEAs are described in U.S. Patent Application Publication No. 2017 / 0321334, published November 9, 2017, and U.S. Patent Application Publication No. 20190226103, published July 25, 2019, which are incorporated by reference in their entireties. All publications referenced herein are incorporated by reference as if fully set forth herein in their entirety. Multi-cell CO X Electrolyzer Stack

[0152] In the above explanation, CO X Having given a general overview of various aspects of MEA structure and properties, the following discussion focuses on multi-cell CO X It is aimed at addressing aspects of the electrolyzer stack.

[0153] Figure 5 shows the multi-cell CO X 6 shows an exploded view of an example electrolyzer stack. X 7 and 8 show perspective views of the exemplary multi-cell CO electrolysis device of FIG. X Figure 9 shows a side view of the electrolysis device. X FIG. 10 shows a cross-sectional view of an example electrolysis device taken along section line 9-9. X 11A shows a cross-sectional view of an exemplary electrolysis device taken along section line 10-10. X 17 shows an exploded view of an exemplary repeating unit of an electrolyzer stack. X 19 shows an exploded view of the cathode interface assembly of the exemplary multi-cell CO electrolyzer stack of FIG. X Exemplary CO electrolyzer stack X FIG. 1 shows an exploded view of the electrolyzer cell.

[0154] As can be seen in Figures 5-11A, 17, and 19, the multi-cell CO X The electrolyzer stack (or stack) 500 comprises a plurality of CO 2 electrolyzer cells, such as cells 501, formed by stacking a plurality of repeat units 503 (individually referred to as repeat units 503_1 through 503_n, where "n" is an integer greater than or equal to 1) between a cathode interface assembly 505 of a port-side assembly 507 and an anode interface assembly 509 of a bladder-side assembly 511. X In this way, multiple CO XAny given one of the electrolyzer cells may be formed by the combination of: 1) the cathode interface assembly 505 (including the MEA 1105) and the anode component 1101 of repeat unit 503_1; 2) the cathode component 1103 (including the MEA 1105) of a first repeat unit (e.g., repeat unit 503_1) and the anode component 1101 of a second repeat unit (e.g., repeat unit 503_2) adjacent to the first repeat unit; or 3) the repeat unit 503_n and the cathode component 1103 of the anode interface assembly 509. Thus, multiple CO X The MEA of any one of the electrolyzer cells may be configured to receive CO X It may be configured to facilitate the reduction process.

[0155] The port-side assembly 507 may include a cathode interface assembly 505, a bus (or terminal) plate 513, a manifold assembly 515, an insulating plate 517, and an end plate 519, which are stacked sequentially from a first side of the plurality of repeating units 503 in a first direction, e.g., an axial direction, which may extend parallel to the z-axis direction. Among other functions, the port-side assembly 507 may be configured to at least provide one or more reactants to the cell for feeding the COx reduction process and associated one or more by-products output from the cell. The bladder-side assembly 511 may include an anode interface assembly 509, a bus (or terminal) plate 521, an insulating plate 523, and an end plate 525, which are stacked sequentially from a second side of the plurality of repeating units 503 in a second direction opposite the first direction. Among other functions, the bladder side assembly 511 may be configured to constrain axial expansion of the cells at least during the COx reduction process, thereby preventing or reducing the possibility of excessive compression of the cells, while maintaining corresponding fluid seals and electrical conductivity between associated components of the stack 500.

[0156] The end plates 519 and 525 of the port side assembly 507 and the bladder side assembly 511, respectively, may be coupled to one another via a plurality of axially extending tension members 527 (e.g., anchors, bolts, studs, tie rods, etc.). As such, the end plates 519 and 525 may include a plurality of fastener holes 519h and 525h, respectively, through which the tension members 527 may pass. In some embodiments, the fastener holes 519H and 525H may be disposed about corresponding peripheral regions of the end plates 519 and 525, respectively. It should also be noted that the end plates 519 and 525 may be formed of any suitable material, such as aluminum, magnesium, titanium, etc. The tension members 527 may be at least partially threaded to engage, for example, threaded fasteners 529 (e.g., nuts, rivets, etc.), respectively. In this manner, an axially extending clamping force may be applied to the plurality of cells via the combination of the end plates 519, 525, the tension members 527, and the threaded fasteners 529. In this manner, end plates 519 and 525 may generally function to act as load distribution members that distribute clamp loads relatively evenly to other elements of stack 500. In some cases, first washers 531 may be disposed between the heads of tension members 527 and upper surfaces 519 a of end plates 519, respectively, and second washers 533 may be disposed between lower surfaces 525 b of end plates 525 and threaded fasteners 529, respectively. It is contemplated that one or more of first washers 531 may be formed as lock washers and / or may each be integral with the heads of tension members 527, as in the case of a flanged bolt. Similarly, one or more of second washers 533 may be formed as lock washers and / or may each be integral with threaded fasteners 529, such as in the case of a flanged nut.

[0157] The bus plates 513 and 521 may each have a terminal portion 513t, 521t projecting outward from the corresponding peripheral surface and may be connected to a power source. In some cases, the terminal portions 513t, 521t may include lugs, terminal blocks, and / or other electrical connection mechanisms to facilitate electrical connection between the bus plates 513 and 521 and a corresponding positive or negative voltage or current source, for example. For example, the terminal portion 513t on the cathode side of the stack 500 may be connected to the negative terminal of the power source, and the terminal portion 521t on the anode side of the stack 500 may be connected to the positive terminal of the power source. In this manner, the bus plates 513 and 521 may provide a common electrical connection for multiple cells of the stack 500, such as cell 501, such that an electrical potential or current may be generated in the multiple cells of the stack 500, thereby driving reduction and oxidation reactions within the multiple cells. When a voltage or current is applied to bus plates 513 and 521, thereby imposing a potential difference across the cells of stack 500, the resulting potential difference can cause oxidation reactions (e.g., oxidation of water to molecular oxygen) on the anode side of the cells and reduction reactions on the cathode side of the cells, e.g., resulting in the production of CO X is converted to carbon monoxide, hydrocarbons, and / or other catalyst-specific by-products. As will become more apparent below, the bus plate 513 may be sized so as not to interfere with the various fluid passageways through the stack 500.

[0158] According to various embodiments, the bus plates 513 and 521 may be formed of a first conductive material, such as aluminum, iron, nickel, lead, steel, zinc, etc., and may be coated (or plated) with a second, more conductive coating material, such as silver plating, gold plating, copper plating, or other material with relatively high electrical conductivity, thereby providing a higher level of electrical conductivity between the bus plates 513 and 521 and the corresponding flow areas (e.g., anode and cathode flow areas 1111 and 1127) of each cell of the stack 500.

[0159] The bus plate 513 may be electrically insulated from the end plate 519, for example, by an insulating plate 517 and / or at least one other layer of electrically insulating material. As shown, the insulating plate 517 is disposed between the conductive portion of the bus plate 513 and the end plate 519, and the insulating plate 517 may include a plurality of fastening holes 517h through which the tension members 527 may pass. In some cases, for example, when the manifold assembly 515 is formed of an electrically non-conductive material, electrical insulation between the bus plate 513 and the end plate 519 may additionally or alternatively be provided by the manifold assembly 515. Further, electrical insulation may additionally or alternatively be provided by forming (or adhering) an electrically insulating material on (or to) a surface of the bus plate 513 facing the end plate 519, a surface of the end plate 519 facing the bus plate 513, or at least one surface of the manifold assembly 515 facing the end plate 519 or the end plate 525. Regardless of how such electrical isolation is provided, bus plate 513 may be electrically insulated from end plate 519. However, if end plate 519 is made of an electrically non-conductive material, or if end plate 519 is otherwise electrically insulated from, for example, bus plate 521 and / or end plate 525, insulating plate 517 (or other electrically insulating material) may be omitted.

[0160] Like bus plate 513, bus plate 521 may be electrically insulated from end plate 525 by insulating plate 523 and / or at least one other layer of electrically insulating material, which may act similarly to bus plate 513 and end plate 519 as insulating plate 517 does to end plate 525 and bus plate 521. Like insulating plate 517, insulating plate 523 may include a plurality of fastening holes 523h through which tension members 527 may pass. In some embodiments, electrical insulation may additionally or alternatively be provided by forming (or adhering) electrically insulating material on (or to) the surface of bus plate 521 facing end plate 525 and / or the surface of end plate 525 facing bus plate 521. In some implementations, insulating plate 523 (or other electrically insulating material) may be omitted if end plate 525 is otherwise electrically isolated from bus plate 521. It is also contemplated that bus plate 521 may be able to make electrically conductive contact with end plate 525 if the various components of the cells of stack 500 are otherwise configured to maintain electrical isolation between bus plates 513 and 521 other than through the conductive paths through the various MEAs of the plurality of cells. However, as will become more apparent below, insulating plate 523 may be utilized in conjunction with bus plate 521 to constrain (e.g., actively constrain) axial expansion of the plurality of cells of stack 500. Note that example configurations of insulating plate 523 are described in more detail in connection with FIGS. 86 and 87.

[0161] According to some embodiments, insulating plate 523 may be coupled to end plate 525 via a plurality of first fasteners 535. Similarly, insulating plate 517 may be coupled to end plate 519 via a plurality of second fasteners 537. Additionally, bus plate 513 may be coupled to manifold assembly 515 via a plurality of third fasteners 539. First, second, and third fasteners 535, 537, and 539 may be any suitable fastening mechanism, such as flat head machine screws, rivets, etc., although embodiments are not limited thereto.

[0162] Manifold Assembly FIG. 12 illustrates the exemplary multi-cell CO X 12. A bottom view of an exemplary manifold block of an electrolysis device is shown. Figures 13-16 show side views of the exemplary manifold block of Figure 12. Note that hidden internal features of manifold block (or body) 541 that are not visible from the view of Figure 12 are shown in dashed line format.

[0163] Generally (with continued reference to FIGS. 5-10), the manifold assembly 515 may be configured to provide one or more reactants to multiple cells to power a COx reduction process. For example, in a COx electrolyzer, an anolyte (e.g., liquid water) may be supplied to the anode side of multiple cells of the stack 500 during operation, and a catholyte (e.g., gaseous CO2, such as CO and / or CO2) may be supplied to the anode side of the multiple cells of the stack 500 during operation. X) may be supplied to the cathode side of the cell. In some implementations, an aqueous solution may be provided instead of water, and references to water herein may be understood to include the use of an aqueous solution. Liquid water may undergo oxidation via an electrolysis reaction on the anode side of the cell to create oxygen (O) gas, H+ protons, and electrons. The H+ protons may be drawn through the MEAs (such as MEA 1105 in FIG. 11A ) of the multiple cells by an electrical potential applied to the cells via bus plates 513 and 521, by an electromagnetic field present within the cells, and react with bicarbonate and / or hydroxide and / or formate produced on the cathode side of the cells. Manifold assembly 515 may also be configured to allow one or more byproducts of the COx reduction process to be vented from the cells. Thus, as will become more apparent below, the manifold assembly 515 may include (or define), for example, at least a portion of one or more fluid inlet passages and at least a portion of one or more fluid outlet passages, which may be used to transport fluid between the anode and cathode sides of the multiple cells of the stack 500.

[0164] 5-10 and 12-16, the manifold assembly 515 may include a body 541, a first fluid inlet connector (or coupling) 543, a first fluid outlet connector 545, a second fluid inlet connector 547, and a second fluid outlet connector 549. The body 541 may be a generally rectangular plate-like body having a first surface 1201 and an axially opposing second surface 1203. While the body 541 is described as having a generally rectangular plate-like configuration, embodiments are not limited thereto and any suitable geometric configuration may be utilized, such as a generally circular, oval, triangular, pentagonal, hexagonal, or the like. When assembled as part of the stack 500, the first surface 1201 may face the end plate 525 and interface with the bus plate 513 and the cathode interface assembly 505, and the second surface 1203 may face the end plate 519 and interface with the insulating plate 517. First surface 1201 and second surface 1203 may be surrounded by third, fourth, fifth, and sixth surfaces 1205, 1207, 1209, and 1211. However, it should be noted that embodiments are not limited to the foregoing configurations, and body 541 may be formed having any other suitable geometric configuration with corresponding boundary surfaces.

[0165] In some embodiments, the main body 541 comprises first fluid inlet ports 1213 and 1215 configured to interface with a first fluid inlet connector (or inlet connector) 543 at the third surface 1205 and the fourth surface 1207, respectively; first fluid outlet ports (or outlet ports) 1217 and 1219 configured to interface with a first fluid outlet connector (or outlet connector) 545 at the third surface 1205 and the fourth surface 1207, respectively; a second fluid inlet port (or inlet port) 1221 configured to interface with a second fluid inlet connector (or inlet connector) 547 at the fifth surface 1209; and a second fluid outlet port (or outlet port) 1223 configured to interface with a second fluid outlet connector (or outlet connector) 549 at the sixth surface 1211. As such, the first and second inlet and outlet ports 1213-1223 may include corresponding threaded regions, such as threaded region 1215t of first fluid inlet port 1215 and threaded region 1221t of second fluid inlet port 1221, that mate with the respective threaded regions of the first and second fluid inlet and outlet connectors 543-549. Alternatively, the first and second fluid inlet and outlet connectors 543-549 may be welded (e.g., sweat welded) to the first and second inlet and outlet ports 1213-1223, respectively, or otherwise coupled to the first and second inlet and outlet ports 1213-1223.

[0166] First fluid inlet ports 1213 and 1215 may be fluidly connected to corresponding third fluid outlet ports in first surface 1201 via respective connecting passages. For example, first fluid inlet port 1215 may be fluidly connected to third fluid outlet port 1225 via connecting passage 1227. Similarly, first fluid outlet ports 1217 and 1219 may be fluidly connected to corresponding third fluid inlet ports in first surface 1201 via respective connecting passages. For example, first fluid outlet port 1217 may be fluidly connected to third fluid inlet port 1229 via connecting passage 1231. Third fluid outlet port 1225 and inlet port 1229 each include a plurality of holes fluidly connected to each other via corresponding connecting passages. For example, third fluid outlet port 1225 may include first and second outlet holes 1225a and 1225b fluidly connected to each other via connecting passage 1233, while third fluid inlet port 1229 may include first and second inlet holes 1229a and 1229b fluidly connected to each other via connecting passage 1235. Similarly, second fluid inlet port 1221 and second outlet port 1223 may be fluidly connected to corresponding fourth fluid outlet port 1237 and fluid inlet port 1239 in first surface 1201 via respective connecting passages 1241 and 1243. Thus, first fluid inlet ports 1213 and 1215, their respective connecting passages (e.g., connecting passage 1227), and corresponding third fluid outlet ports (e.g., third fluid outlet port 1225) may be coupled together to supply water to inlet passages 1001 and 1003 of stack 500. First fluid outlet ports 1217 and 1219, their respective connecting passages (e.g., connecting passage 1235), and corresponding third fluid inlet ports (e.g., third fluid inlet port 1229) may be coupled together to allow water to be discharged from outlet passages of stack 500. Note that the outlet passages of stack 500 may be similar to inlet passages 1001 and 1003, but may terminate at first fluid outlet connector 545 and begin at first fluid inlet connector 543.Further, the combination of the second fluid inlet port 1221, the connecting passage 1241, and the fourth fluid outlet port 1237 may be configured to supply gaseous COx to the inlet passage 901 of the stack 500, and the combination of the second fluid outlet port 1223, the connecting passage 1243, and the fourth fluid inlet port 1239 may be configured to discharge one or more by-products of the COx reduction process from the outlet passage 903 of the stack 500.

[0167] In some embodiments, first surface 1201 of body 541 may include a recessed region 1245 configured to receive at least a portion of bus plate 513 therein when manifold assembly 515 is assembled as part of stack 500. Recessed region 1245 may include one or more portions (e.g., portions 1245a and 1245b), any of which may receive terminal portion 513t of bus plate 513. Additionally, recessed region 1245 may include one or more threaded openings 1247 extending into body 541 configured to threadably engage third fasteners (e.g., flat head machine screws) 539, which may be utilized to couple bus plate 513 to manifold assembly 515. In some embodiments, threaded openings 1247 may be provided as blind openings, such as, for example, swage nuts pressed and / or tightened into body 541, such that third fasteners 539 engage the swage nuts. Furthermore, when manifold assembly 515 is incorporated as part of stack 500 and at least a portion of bus plate 513 is received in recessed area 1245, respective fluid seals may be formed between third fluid outlet and inlet ports 1225 and 1229 and corresponding ports (or openings) in cathode interface assembly 505 via gasket 553. Similarly, respective fluid seals may be formed between fourth fluid outlet and inlet port 1237 and 1239 and corresponding ports of cathode interface assembly 505 via gasket 555.

[0168] The body 541 may further include recesses 1249 and 1251 in the third surface 1205 and a recess 1253 in the fifth surface 1209, such that a reference rod 557 of the stack 500 can extend, for example, axially from the insulating plate 523 and at least partially into the corresponding recesses 1249-1253. During assembly of the stack 500, the reference rod 557 can be used to maintain alignment between the components of the stack 500. In some cases, an outer surface of the reference rod 557 may optionally abut outer surfaces of the recesses 1249-1253 of the multiple repeat units 503, the cathode interface assembly 505, the anode interface assembly 509, and / or the manifold assembly 515.

[0169] Repeating Unit FIG. 20 illustrates the exemplary multi-cell CO X Figure 21 shows a bottom view of a representative repeat unit of an electrolyzer stack. Figure 21 shows a cross-sectional view of the representative repeat unit of Figure 20 taken along section line 21-21. Figure 22 shows a cross-sectional view of the representative repeat unit of Figure 20 taken along section line 22-22. Figures 23 and 24 show enlarged portions of the cross-sectional view of Figure 22.

[0170] 11A and 20-24, an exemplary repeat unit (or repeat unit) 1100 may include a separator plate 1107 at least partially stacked between an anode component 1101 and a cathode component 1103. The anode component 1101 may include an anode PTL 1109, an anode flow field 1111, a first anode gasket set 1113, an anode frame 1115, and a second anode gasket set 1117. In some embodiments, the anode component 1101 may further include an anode annular insert 1118 (see FIGS. 11B and 11C). Note that various anode components, such as the first anode gasket set 1113 and the second anode gasket set 1117, are not shown in FIGS. 11B and 11C for ease of illustration. The cathode component 1103 may include an MEA unit 1119 having an MEA 1105 and a cathode GDL 1121 stacked between a first support frame 1123 and a second support frame 1125, and may include a cathode flow field 1127, a first cathode gasket 1129, a cathode frame 1131, and a second cathode gasket 1133. In some embodiments, the cathode component 1103 may further include a cathode annular insert 1134 (see FIGS. 11D and 11E). Note that various cathode components, such as the MEA 1105, the first support frame 1123 and the second support frame 1125, and the first cathode gasket set 1129 and the second cathode gasket set 1133, are not shown in FIGS. 11B and 11C for ease of illustration.

[0171] According to various embodiments, the anode frame 1115 may be coupled to the cathode frame 1131 via any suitable fastening mechanism(s), such as anchors, bolts, nuts, rivets, screws, etc. For example, the anode frame 1115 may be coupled to the cathode frame 1131 via a swage (or press) nut 1135 pressed and / or tightened onto the anode frame 1115 and a fastener 1137 (e.g., shoulder screw) that interfaces with the cathode frame 1131, extends through the separator plate 1107, and engages the swage nut 1135. In some embodiments, the swage nut 1135 may be pressed and / or tightened onto the cathode frame 1131 to the anode frame 1115 such that the fastener 1137 interfaces with the anode frame 1115, extends through the separator plate 1107, and engages the swage nut 1135 of the cathode frame 1131. It is also possible that a portion of the first swage nut 1135 is pressed and / or tightened into the anode frame 1115, and a portion of the second swage nut 1135 is pressed and / or tightened into the cathode frame 1131, thereby causing a portion of the corresponding first fastener 1137 to have an interface with the cathode frame 1131, extend through the separator plate 1107, and engage with a portion of the first swage nut 1135, and a portion of the corresponding second fastener 1137 to have an interface with the anode frame 1115, extend through the separator plate 1107, and engage with a portion of the second swage nut 1135 of the cathode frame 1131. In the following, it is assumed that the swage nut 1135 is incorporated as part of the anode frame 1115, and that the fastener 1137 has an interface with the cathode frame 1131, extends through the separator plate 1107, and engages with the swage nut 1135 of the anode frame 1115. In this manner, a second anode gasket set 1117 may be interposed between the anode frame 1115 and the separator plate 1107, and a second cathode gasket 1133 may be interposed between the separator plate 1107 and the cathode frame 1131.

[0172] As can be seen in Figures 20-24, the anode PTL 1109 and at least a portion of the anode field 1111 may be supported by one or more openings in the anode frame 1115, and the cathode field 1127 and at least a portion of the integrated MEA assembly 1119 may be supported by one or more openings in the cathode frame 1131. In this manner, the first cathode gasket 1129 may be interposed between the cathode frame 1131 and the integrated MEA assembly 1119 to surround, contain, confine, or enclose (hereinafter "surround") the cathode field 1127 and the bulge portion 1123c of the support frame 1123 (see Figures 25-27). The first anode gasket 1113a of the first anode gasket set 1113 may surround the anode flow area 1111 as well as be interposed between the anode frame 1115 and the anode PTL 1109. The second anode gasket 1113b and the third anode gasket 1113c of the first anode gasket set 1113 may have an interface with the anode frame 1115, thereby forming a fluid seal with an adjacent repeat unit or cathode interface assembly 505, as will become more apparent below.

[0173] According to various embodiments, when the repeat unit 1100 is assembled, the anode field 1111 may be supported in at least one opening in the anode frame 1115, such that a first surface of the anode field 1111 abuts a corresponding surface of the anode PTL 1109 and a second surface of the anode field 1111 abuts a corresponding surface of the separator plate 1107. If the repeat unit 1100 includes an anode annular insert 1118, the anode annular insert 1118 may be at least partially supported in at least one opening in the anode frame 1115 and may surround the anode field 1111. Thus, at least a portion of the first surface 1118a (e.g., upper surface) of the anode annular insert 1118 may abut one or more corresponding surfaces of an integrated MEA assembly stacked between two adjacent repeat units or an integrated MEA assembly of the cathode interfacial assembly 505. At least a portion of a second surface 1118b (e.g., a bottom surface) opposite the first surface 1118a of the anode annular insert 1118 may abut a corresponding surface of the anode frame 1115. Additional features and advantages of the anode annular insert 1118 are described below in connection with the anode frame 1115. Similarly, when the repeating unit 1100 is assembled, the cathode field 1127 may be supported in at least one opening in the cathode frame 1131 such that a first surface of the cathode field 1127 abuts a corresponding surface of the separator plate 1107 and a second surface of the cathode field 1127 abuts a corresponding surface of at least the cathode GDL 1121, which may be exposed by an opening 1123a in the support frame 1123 of the integrated MEA assembly 1119 (see FIGS. 25-27 ). When the repeat unit 1100 includes a cathode annular insert 1134 , the cathode annular insert 1134 may be at least partially supported in at least one opening in the cathode frame 1131 and may surround the cathode flow area 1127 .Thus, at least a portion of a first surface 1134a (e.g., a top surface) of the cathode annular insert 1134 may abut a corresponding surface of the cathode frame 1131, and at least a portion of a second surface 1134b (e.g., a bottom surface) of the cathode annular insert 1134 opposite the first surface 1134a may abut one or more corresponding surfaces of an associated repeat unit, for example, an integrated MEA assembly of the repeat unit 1100. Other features and advantages of the cathode annular insert 1134 are described below in relation to the cathode frame 1131.

[0174] Aspects of the various components of repeating unit 1100 are again described in more detail in conjunction with the description of cell 501 as well as the text associated with Figures 25-43, 49-79, Figures 83, 84A, 84B, and 85A-85C.

[0175] CO X Electrolyzer Cell Referring to FIG. 19 , an exploded view of cell 501 is shown. Cell 501 is formed between cathode component 1103_1 of repeat unit 503_1 and anode component 1103_2 of repeat unit 503_2. Separator plates 1107_1 and 1107_2 of repeat units 503_1 and 503_2 separate cell 501 from adjacent cells in stack 500. With this in mind, anode component 1101_1 of repeat unit 503_1 and cathode component 1103_2 of repeat unit 503_2 are shown partially assembled and form part of such cell adjacent to cell 501. In the following, components of cell 501 are followed by an underscore and an identifier to indicate the repeat unit of which they are part, without specifying the repeat unit itself.

[0176] The cell 501 may include an MEA 1105_1 interposed between an anode porous transport layer (PTL) 1109_2 and a cathode GDL 1121_1. In some cases, the MEA 1105_1 and cathode GDL 1121_1 may be part of an integrated MEA assembly, such as integrated MEA assembly 1119_1, which includes the MEA 1105_1 and cathode GDL 1121_1 sandwiched between support frames 1123_1 and 1125_1 (see also FIGS. 25-27). Support frames 1123_1 and 1125_1 may include respective openings 1123a_1 and 1125a_1 exposing corresponding surfaces of MEA 1105_1 and cathode GDL 1121_1 to adjacent components, and may include protruding tab portions 1123b_1 and 1125b_1, respectively, which may facilitate handling of integrated MEA assembly 1119_1 during manufacturing and testing. In some embodiments, protruding tab portions 1123b_1 and 1125b_1 may be silkscreened, stamped, embossed, or otherwise marked with identification information, such as identification information indicating the cell to which integrated MEA assembly 1119_1 belongs. The support frame 1123_1 may include a bulge portion 1123c_1 (see also bulge portion 1123c in FIG. 27) to accommodate the MEA 1105_1 and cathode GDL 1121_1 within a cavity (e.g., cavity 2701 in FIG. 27) formed between the support frames 1123_1 and 1125_1. The design of the integrated MEA assembly 1119_1 thus allows its components to be pre-assembled and tested prior to incorporation into, for example, cell 501, which can increase assembly efficiency and reduce both cell-level and stack-level defects.

[0177] 19 , the anode PTL 1109_2 may be interposed between the MEA 1105_1 and the anode field 1111_2, while the cathode GDL 1121_1 may be interposed between the MEA 1105_1 and the cathode field 1127_1. Thus, the opening 1125a_1 in the support frame 1125_1 may allow the MEA 1105_1 and the anode field 1111_2 to be fluidly connected via the anode PTL 1111_2, and the opening 1123a_1 in the support frame 1123_1 may allow the MEA 1105_1 and the cathode field 1127_1 to be fluidly connected via the cathode GDL 1127_1. As will become more apparent below, the anode PTL 1109_2 and anode field 1111_2 may, for example, be supported in one or more openings in the anode frame 1115_2 and surrounded by a first anode gasket 1113a_2 of the first anode gasket set 1113_2 on a first side of the anode frame 1115_2. Similarly, the cathode field 1127_1 and at least a portion of the integrated MEA assembly 1119_1 (and thereby at least the cathode GDL 1121_1) may be supported in one or more openings in the cathode frame 1131_1 and surrounded by a first cathode gasket 1129_1 on a first side of the cathode frame 1131_1. Next, the anode frame 1115_2 may be stacked between the integrated MEA assembly 1119_1 and the separator plate 1107_2, and the cathode frame 1131_1 may be stacked between the separator plate 1107_1 and the integrated MEA assembly 1119_1. A second anode gasket set 1117_2 may be disposed between the anode frame 1115_2 and the separator plate 1107_2, and a second cathode gasket 1133_1 may be disposed between the cathode frame 1131_1 and the separator plate 1107_1.In this manner, the first anode gasket 1117a_2 of the second anode gasket set 1117_2 may surround the anode flow area 1111_2 on the second side of the anode frame 1111_2, and the second cathode gasket 1133_1 may surround the cathode flow area 1127_1 on the second side of the cathode frame 1131_1.

[0178] Gaskets 1113a_2 and 1129_1 may not only provide a fluid seal between the integrated MEA assembly 1119_1 and the corresponding flow basins 1111_2 and 1127_1, but may also provide structural support to avoid over-compression of anode PTL 1109_2 and cathode GDL 1121_1. It should also be noted that gaskets 1113a_2 and 1129_1 may be formed thin enough to prevent under-compression of anode PTL 1109_2 and cathode GDL 1121_1 when assembled as part of stack 500. For example, gaskets 1113a_2 and 1129_1 may be sized such that anode PTL 1109_2 and cathode GDL 1121_1 are compressed and sealed against the corresponding surfaces of flow basins 1111_2 and 1127_1, thereby maintaining electrical contact while preventing or inhibiting fluid pooling during operation. Similarly, gaskets 1117a_2 and 1133_1 may provide a fluid seal between separator plates 1107_2 and 1107_1 and corresponding surfaces of flow basins 1111_2 and 1127_1.

[0179] Each element within cell 501 may provide a specific function to cell 501, and various components of stack 500 may provide a common function to each of the multiple cells that include cell 501. For example, end plates 519 and 525 may generally function to act as load distribution members that distribute clamping loads relatively evenly across the multiple cells of stack 500 that includes cell 501. Manifold assembly 515 may include, for example, a body 541 that forms at least a portion of one or more fluid inlet ports that may begin with inlet connector 543 and at least a portion of one or more fluid outlet ports that may terminate with outlet connector 545 and may be used to transport fluids to and from the anode side of the multiple cells of stack 500 that includes cell 501. As will become more apparent below, the fluid inlet port(s) and fluid outlet port(s) of manifold assembly 515 may be fluidly connected to corresponding inlet and outlet fluid passages not only in anode frame 1115_2 and cathode frame 1131_1 of cell 501, but also in the anode and cathode frames of other cells in stack 500. Similarly, body 541 of manifold assembly 515 forms at least a portion of one or more fluid inlet ports, which may begin at inlet connector 547, and at least a portion of one or more fluid outlet ports, which may terminate at outlet connector 549, and may be used to transport fluids to and from the cathode sides of multiple cells in stack 500, including cell 501. Thus, as will become more apparent below, the fluid inlet port(s) and fluid outlet port(s) of the manifold assembly 515 may be fluidly connected to the corresponding inlet and outlet fluid passages not only of the anode frame 1115_2 and cathode frame 1131_1 of cell 501, but also of the anode frames and cathode frames of other cells in the stack 500.

[0180] According to various embodiments, the bus plate 521 connects the anode interfacial separator 4703, anode flow field 1111, and anode PTL 1109 of the anode interfacial assembly 509 (see FIGS. 5-10 and 47), as well as the corresponding separator plate 1107, anode flow field 1111, anode PTL 1109, MEA 1105, cathode GDL 1121, and cathode flow field 1127 between the anode interfacial assembly 509 and the cell 501 (see also FIGS. 5-11). Similarly, the bus plate 513 may be electrically connected to the cathode field 1127_1 (and possibly the cathode frame 1131_1) via the cathode interfacial separator 1701, the cathode field 1127, the cathode GDL 1121, and the MEA 1105 of the cathode interfacial assembly 505 (see Figures 5-10 and Figure 17). The anode field 1111_2 and the cathode field 1127_1 may be made of any suitable material(s) that are electrically conductive and otherwise capable of withstanding relatively long-term exposure to the fluids flowing within the stack 500 during normal operating conditions. For example, basins 1111_2 and 1127_1 may be made from titanium or a titanium alloy, stainless steel (although stainless steel may have a higher susceptibility to corrosion than other materials), porous graphite, carbon fiber reinforced thermosetting polymer, etc.

[0181] Generally, the anode frame 1115_2 and the cathode frame 1131_1 may have inlets corresponding to fluid inlet passages beginning at inlet connectors 543 and 547, and outlets corresponding to fluid outlet passages terminating at outlet connectors 545 and 549. To this end, the anode flow field 1111_2 and the cathode flow field 1127_1 may each have one or more channels formed in the surface of the corresponding field in contact with the anode PTL 1109_2 and cathode GDL 1121_1, respectively, such that fluid conducted through the channels is routed to contact the adjacent PTL or GDL in a generally dispersed manner.

[0182] For example, the anode flow field 1111_2 may feature one or more inlet openings (or channels) and one or more outlet openings (or channels), each of which may be fluidly connected to a corresponding opening in the anode frame 1115_2. One or more anode channels, e.g., serpentine channels, may be provided on a surface of the anode flow field 1111_2 that is in contact with the anode TL 1109_2. The anode channels may also function to distribute fluid introduced to the anode side of the cell 501 to the anode PTL 1109_2, thereby allowing the anolyte to contact the anode PTL 1109_2 in a spatially distributed manner, thereby allowing the anolyte to flow through the anode PTL 1109_2 relatively uniformly across the entire area, or a substantial portion of the entire area, of the anode PTL 1109_2. An exemplary anode frame 1115 and several exemplary anode flow fields 1111 are described in more detail in connection with FIGS. 37-42 and 83-85.

[0183] Similarly, the cathode flow field 1127_1 may feature one or more inlet openings (or channels) and one or more outlet openings (or channels), each of which may be fluidly connected to a corresponding opening in the cathode frame 1131_1. One or more cathode channels may be provided on a surface of the cathode flow field 1127_1 that is in contact with the cathode GDL 1121_1. The cathode channels may also serve to distribute fluid introduced to the cathode side of the cell 501 across the cathode GDL 1121_1, allowing the cathode fluid to contact the cathode GDL 1121_1 in a spatially distributed manner, thereby allowing the cathode fluid to flow through the cathode GDL 1121_1 relatively uniformly across the entire area, or a large portion of the entire area, of the cathode GDL 1121_1. An exemplary cathode frame 1131 and some exemplary cathode flow areas 1127 are described in more detail in connection with FIGS.

[0184] Both the anode PTL 1109_2 and the cathode GDL 514 may function to aid in the diffusion of gases generated within or supplied through the anode field 1111_2 and the cathode field 1127_1, respectively, to the active area of ​​the MEA 1105_1. X A typical GDL suitable for use in an electrolyzer may include, for example, a fibrous substrate that provides structural support to the catalyst layer within the MEA 1105_1 and may allow gas to flow toward the MEA from adjacent flow areas (e.g., in a direction parallel to the plane of the MEA 1105_1, thereby allowing gas to flow laterally under portions of adjacent flow areas that may be in contact with the GDL). Such a GDL may allow water present within the MEA 1105_1, or trapped within the GDL, and / or between the GDL and the MEA 1105_1, to escape into the channel(s) of the flow area adjacent to the GDL, thereby allowing the water to be expelled from that area as a result of fluid flow through that area. The GDL may also function as an electrical conductor, functioning to conduct charge through the MEA 1105_1. Similarly, CO X A typical PTL suitable for use in an electrolyzer may include, for example, a porous metal matrix that provides structural support to a catalyst layer in the MEA 1105_1 and may allow water to flow from adjacent flow areas toward the MEA (allowing water to flow laterally over portions of adjacent flow areas that may be in contact with the PTL, such as in a direction parallel to the plane of the MEA 1105_1). Such a PTL may allow gas present in the MEA 1105_1 or trapped within the PTL and / or between the PTL and the MEA 1105_1 to escape into the channel(s) of the flow area adjacent to the PTL, thereby potentially allowing the water to be expelled from that area as a result of fluid flow through that area. The PTL also functions as an electrical conductor, conducting charge through the MEA 1105_1.

[0185] According to some embodiments, the MEA 1105_1 for a COx electrolyzer may feature a metal nanoparticle catalyst layer pressed into contact with the cathode GDL 1121_1. In some implementations, the metal nanoparticle catalyst layer may alternatively be formed on the cathode GDL 1121_1 and pressed into contact with the MEA 1105_1. In yet other cases, there may be metal nanoparticle catalyst layers formed on both the MEA 1105_1 and the cathode GDL 1121_1, which may then be pressed into contact with each other. One example of such a catalyst layer is a layer of carbon material supporting or incorporating a layer of gold nanoparticles. X Various types of MEAs and suitable catalysts for use in electrolyzers are discussed in U.S. Patent Application Publication Nos. 15 / 586,173 and 15 / 586,182, both filed May 3, 2017, and entitled "REACTOR WITH ADVANCED ARCHITECTURE FOR THE ELECTROCHEMICAL REACTION OF CO, CO, AND OTHER CHEMICAL COMPOUNDS," and U.S. Patent Application No. 62 / 939,960, filed November 25, 2019, and entitled "MEMBRANE ELECTRODE ASSEMBLY FOR COx REDUCTION," each of which is incorporated herein by reference in its entirety. However, it should be noted that these are merely examples and that other configurations are contemplated.

[0186] In the context of a multi-cell architecture, e.g., stack 500, multiple cells (such as cell 501) may be fed by common fluid inlet / outlet ports and / or a common electrical potential source. It should be noted that overall multi-cell stack performance may be defined in part by the uniformity of electrical efficiency and product selectivity across the multiple cells of stack 500, which may be driven by the uniformity of gas flow delivery to / among each of the multiple cells. At this point, the choice of flow field shape, relative to the pressure drop across the flow fields, can have a significant impact on overall stack flow uniformity. This is believed to be because flow uniformity is improved when the pressure drop across / through the multiple cells is approximately an order of magnitude greater than the pressure difference between discrete locations along the plenum where the collective flow is distributed to the individual cells in stack 500. When using a fixed plenum geometry, establishing appropriate dimensions can be critical to the overall performance of stack 500.

[0187] As mentioned above, CO X In operation, the electrolyzer may be supplied with liquid water on the anode side of the cell 501, while gaseous CO 2 is supplied to the cathode side of the cell 501. X may be supplied. In some implementations, an aqueous solution may be provided instead of water, and references to water herein may be understood to include the use of an aqueous solution. Liquid water undergoes oxidation via an electrolysis reaction on the anode side of cell 501, creating oxygen (O) gas, H+ protons, and electrons. The H+ protons may be drawn through MEA 1105_1 due to the electromagnetic field present within cell 501 due to the potential applied to cell 501, and may react with bicarbonate and / or hydroxide and / or formate produced on the cathode side.

[0188] Water can enter the cathode of MEA 1105_1 for a variety of other reasons. In some implementations, liquid water is transported to the cathode by one or more phenomena. Thus, water molecules from the anode side of cell 501 can be transported to the cathode side of cell 501 by, for example, electroosmotic attraction caused by the movement of H+ protons from the anode side of cell 501 to the cathode side of cell 501. The rate of water delivery to and / or production within the cathode side of cell 501 can be relatively high, e.g., due to CO X For every molecule of CO gas produced by gas reduction, there may be, for example, 5 to 9 molecules of water produced and / or attracted to the cathode side of cell 501. This imbalance presents a significant challenge—the CO gas reduced on the cathode side of cell 501 X For each molecule of gas, 5 to 9 water molecules may need to be removed from the cathode side of the cell 501. X In a gas electrolyzer, CO is reduced on the cathode side of the cell 501, such as may use a copper catalyst, which may be used to produce CH4. X For every molecule of gas, 5 to 36 water molecules may need to be removed from the cathode side of the cell 501, which presents an even greater water management challenge.

[0189] CO on the cathode side of cell 501 X This imbalance between the rate of gas reduction and the rate of water accumulation results in a relatively low gas flow rate of COx gas compared to typical gas flow rates on the cathode side of a fuel cell, as well as a relatively low CO X Further complications arise from the relatively low temperatures and high pressures used in electrolyzers. For example, fuel cells use nitrogen (N2) to dilute the O2 flow in the fuel cell cathode, thereby allowing a higher volumetric flow rate to be used in the fuel cell than can be used in a COx electrolyzer. This higher volumetric flow rate allows for the reduction of CO X It may be possible to increase the rate of water molecule emission in fuel cells compared to electrolyzers. XCO supplied to the electrolyzer X The gas is typically high purity CO X CO may be a gas X Combined with the high operating pressures that can be typical in electrolysers, this results in significantly lower CO emissions compared to a comparably sized fuel cell. X It is possible that much lower volumetric flow rates could be used to provide similar levels of desired reactant gas flow in an electrolyzer. In contrast to fuel cells, the generally slow flow rates present in a COx electrolyzer, combined with the high rates of water production at and / or transport to the cathode side of the cell 501, can cause significant problems if not handled properly in a COx electrolyzer, but this is not a significant concern in a fuel cell.

[0190] For example, approximately 90% of the water produced / supplied to the cathode side of the cell during fuel cell operation may be in the gas phase and therefore readily exits the cathode basin compared to the water produced / supplied to the cathode side of the cell 501 during COx electrolyzer operation. X In an electrolyzer, less than 2% of the gas phase produced at / delivered to the cathode side of the cell 501 may be water in the vapor phase, with the remainder being liquid. As a result of this significant liquid / vapor phase imbalance and the significantly higher rate of water condensation in a COx electrolyzer, COx electrolyzers face unique challenges in managing liquid water not encountered in fuel cells. Naturally, these issues do not exist in water electrolyzers either. This is because the reactant delivered to the cathode side of a water electrolyzer is liquid water, which migrates from the anode in the first place; therefore, the presence of liquid water at the cathode is not only expected, but desirable and by design.

[0191] CO X In an electrolysis system, when a high concentration of liquid water is present on the cathode side of the cell 501, CO XThere are certain challenges that must be overcome to operate an electrolyzer efficiently. In particular, CO X The presence of liquid water on the cathode side of the electrolyzer can buffer the flow of gaseous COx from the cathode GDL 1121_1 of cell 501 to the MEA 1105_1. For example, excess liquid water collecting within the cathode channels of the cathode basin 1127_1 and / or cathode GDL 1121_1 can block portions of the cathode channels of the cathode basin 1127_1 and / or cathode GDL 1121_1, creating a physical barrier that prevents gaseous COx from contacting some or all of the MEA 1105_1. This can limit the reduction efficiency of cell 501 and, in some cases, cause permanent damage to cell 501, reducing the CO reduction efficiency of cell 501 that would otherwise proceed even if the liquid water were later removed. X A further problem that can arise when there is excess liquid water in the electrolyzer is CO X Water may be reduced rather than gas, resulting in the production of hydrogen, which is not the desired reaction product.

[0192] CO X Electrolyzers offer significantly higher liquid water production rates than similarly sized fuel cell reactors, and in some respects are CO XElectrolyzers may tend to operate under conditions that tend to hinder their ability to compensate for increased liquid water production rates. For example, the input gas (e.g., air) supplied to the cathode side of a fuel cell tends to be supplied at a higher flow rate compared to the input gas supplied to the cathode side of a COx electrolyzer. Because air is abundantly available, supplying more air than is available for the fuel cell's reduction reactions is less of a concern for fuel cells. As a result, air may be supplied to the cathode flow region within the fuel cell at a much higher flow rate than may be needed to support the reduction reactions occurring within the fuel cell, thereby making more kinetic energy available in the fuel cell cathode input gas stream, which can be used to assist in forcing out water that has accumulated within the fuel cell cathode flow region. Furthermore, because oxidant gas in fuel cells is typically diluted with other gases, such as nitrogen in air, a higher flow rate can be used to ensure an adequate supply of oxidant gas to the cathode side of the fuel cell. The increased flow velocity within the fuel cell may serve to force any liquid droplets potentially present within the cathode flow basin channel(s) through the basin and out the cathode flow basin fluid outlet port, thereby rapidly draining any small amount of liquid water present within the flow basin channels from the basin.

[0193] In contrast, CO X The input gas to the electrolyzer is CO X CO is a gas X One of the main reasons for using electrolyzers is to reduce CO X CO, which may be harmful to the environment, can be reduced by converting the gas into other more desirable gases or liquids (e.g., gases or liquids that are commercially valuable or gases or liquids that are less harmful to the environment, such as water and / or oxygen). X Therefore, the goal is to reduce CO X For a given current density used in the electrolyzer, a high, preferably maximum, CO X While achieving the reduction of CO X Excess CO that flows through the electrolyzer but is not reducedX CO to a level where the amount of gas is also reduced or minimized. X It may be desirable to reduce the flow rate of the gas.

[0194] Due to these factors, CO X The electrolyzer receives high purity undiluted input gas stream(s), e.g., pure CO X gas or relatively pure CO X It may operate using gases that are flowed into the cathode side of the cell 501 at a relatively slow rate, at least compared to a comparably sized fuel cell of similar construction. For example, some CO X Electrolyzers may be able to operate at flow rates comparable to or lower than typical fuel cells. X The electrolyzer is configured to operate at an average COx gas flow velocity in the flow basin channel of about 0.02 m / s to about 30 m / s, about 0.02 m / s to about 15 m / s, about 15 m / s to about 30 m / s, about 0.02 m / s to about 7.5 m / s, about 7.5 m / s to about 15 m / s, about 15 m / s to about 23 m / s, about 23 m / s to about 30 m / s, about 0.02 m / s to about 3.8 m / s, about 3.8 m / s to about 7.5 m / s, about 7.5 m / s to about 11 m / s, about 11 m / s to about 15 m / s, about 15 m / s to about 19 m / s, about 19 m / s to about 23 m / s, about 23 m / s to about 26 m / s, or about 26 m / s to about 30 m / s. In some implementations, the CO X The electrolyzer is configured to operate at a COx gas flow velocity of between about 2 m / s and 10 m / s, or between about 5 m / s and 10 m / s, or between about 7.5 m / s and about 10 m / s.

[0195] As shown, in some implementations, a relatively low flow rate is often a low molar flow rate associated with a low volumetric or linear flow rate, resulting in a relatively high CO X CO XThis is advantageous for electrolyzers. Another advantage is that it maintains the MEA (e.g., MEA 1105_1 of cell 501) at an acceptable hydration level. High gas flow rates tend to dry out the MEA, which leads to degradation. Furthermore, for stationary applications, a flow basin design with short channels and therefore a high number of channels per cell allows for low gas velocities. In some embodiments, CO X The electrolysis device may generate CO in a flow channel at a velocity of about 0.02 m / s to about 5 m / s, about 0.02 m / s to about 2.5 m / s, about 2.5 m / s to about 5 m / s, about 0.02 m / s to about 1.3 m / s, about 1.3 m / s to about 2.5 m / s, about 2.5 m / s to about 3.8 m / s, about 3.8 m / s to about 5 m / s, about 0.02 m / s to about 0.64 m / s, about 0.64 m / s to about 1.3 m / s, about 1.3 m / s to about 1.9 m / s, about 1.9 m / s to about 2.5 m / s, about 2.5 m / s to about 3.1 m / s, about 3.1 m / s to about 3.8 m / s, about 3.8 m / s to about 4.4 m / s, or about 4.4 m / s to about 5 m / s. X It is configured to operate at a flow rate.

[0196] In contrast, CO X The typically low flow rates found in electrolyzers, coupled with the significantly higher rate of liquid water introduction into the cathode side of the cell 501, result in a CO X It becomes much more difficult to drain the water from the electrolyzer.

[0197] Therefore, CO X Accumulation of liquid water at the cathode of the electrolyzer, and CO XVarious features and techniques may be used to help reduce the adverse effects of liquid water supply in the anode of the electrolyzer. For example, the anode frame 1115_2, the cathode frame 1131_1, the anode basin 1111_2, and the cathode basin 1127_1 may be configured with one or more structural features that may enable more effective liquid water management in the cell 501. For example, the anode frame 1115_2, the cathode frame 1131_1, the anode basin 1111_2, and the cathode basin 1127_1 may have corresponding channels, risers, protrusions, distributors, collectors, etc., and may be designed to have particular properties that may contribute, for example, to: 1) more effective supply of water and gaseous COx to the anode and cathode sides of the cell 501; 2) more effective evacuation of water in the context of a COx electrolyzer; 3) more effective mitigation of potential performance degradation that may occur in such a COx electrolyzer if liquid water collects, for example, within the cathode side of the cell 501; and 4) more effective evacuation of by-products of the COx reduction process from the cell 501. Accordingly, the cathode frame 1131_1, anode frame 1115_2, cathode field 1127_1, and anode field 1111_2 will be discussed in more detail in connection with Figures 28-78, 83, 84A, 84B, and 85A-85C herein.

[0198] Cathode Frame 5-11A, the cathode flow field 1127 may be supported in an opening in the cathode frame 1131 between the separator plate 1107 and the integrated MEA assembly 1119, and may include a plurality of fluid passages to facilitate fluid flow (or communication) through the stack 500, and in particular through the cells of the stack 500, such as cell 501. Various details of the exemplary cathode frame 1131 are now discussed in more detail in connection with FIGS.

[0199] FIG. 28 shows a first perspective view of an exemplary cathode frame. FIG. 29 shows a bottom view of the exemplary cathode frame of FIG. 28. FIGS. 30 and 31 show enlarged portions of the exemplary cathode frame of FIG. 28. FIG. 32 shows a second perspective view of the exemplary cathode frame of FIG. 28. FIG. 33 shows a top view of the exemplary cathode frame of FIG. 32. FIG. 34 shows a cross-sectional view of the exemplary cathode frame of FIG. 33 taken along section line 34-34. FIG. 35 shows an enlarged portion of the exemplary cathode frame of FIG. 33. FIG. 36 shows a cross-sectional view of the exemplary cathode frame of FIG. 35 taken along section line 36-36.

[0200] The cathode frame (or frame) 1131 may be a generally rectangular plate-like body having a first surface 2801 (e.g., a top surface) and an opposing second surface 2803 (e.g., a bottom surface) in an axial direction 2901 (see FIG. 29 ). While the frame 1131 is described as having a generally rectangular plate-like configuration, embodiments are not limited thereto and any suitable geometric configuration may be utilized, such as a generally circular, oval, triangular, pentagonal, or hexagonal configuration. For convenience, the frame 1131 will be described with reference to a generally rectangular configuration. The first surface 2801 and the second surface 2803 may be bounded by one or more peripheral surfaces, such as peripheral surfaces (or surfaces) 2805, 2807, 2809, and 2811, which may be connected to one another via one or more other peripheral surfaces, such as peripheral surface (or surface) 2813. In some embodiments, the frame 1131 may have a symmetrical configuration about one or more reference planes that are perpendicular to the axial direction 2901 shown in Figure 29. For example, the configuration of the frame 1131 may be symmetrical about one or both of the reference planes 2903 and 2905 (see Figure 29), although embodiments are not limited thereto.

[0201] According to various embodiments, first fluid inlet passages 2815 and 2817 may be adjacent to periphery 2805, and first fluid outlet passages 2819 and 2821 may be adjacent to periphery 2809. First fluid inlet passages 2815 and 2817, in conjunction with inlet connector 543 of manifold assembly 515 (see FIGS. 5-10), may form part of inlet passages 1001 and 1003 (see FIG. 10) of stack 500 to supply input water to various anode frames (e.g., anode frame 1115 of FIG. 11A) of stack 500, and thereby to corresponding anode basins (e.g., anode basin 1111 of FIG. 11A) of multiple cells, such as cell 501. First fluid outlet passages 2819 and 2821 may form part of outlet passages (similar to inlet passages 1001 and 1003 (see FIG. 10), but associated with outlet connector 545 and inlet connector 543 (see FIG. 5) of manifold assembly 515) of stack 500 that output water from various anode frames of stack 500, such as anode frame 1115 of FIG. 11A, and thereby from corresponding anode basins of a plurality of cells (e.g., anode basin 1111 of FIG. 11). In some cases, first fluid inlet and outlet passages 2815-2821 may be defined by a plurality of respective holes that are separated from one another by corresponding partitions. For example, first fluid inlet passage 2815 may include first inlet hole 2815a and second inlet hole 2815b separated from one another by partition 2803s1, and first fluid outlet passage 2819 may include first outlet hole 2819a and second outlet hole 2819b separated from one another by partition 2803s2. Exemplary partitions are also shown in the cross-sectional views of FIGS. 23 and 34. For example, FIG. 34 shows partition 2803s3 separating first outlet hole 2821a and second outlet hole 2821b that form first fluid outlet passage 2821, and FIG. 23 shows partition 2803s4 separating first inlet hole 2817a and second inlet hole 2817b that form first fluid inlet passage 2817.The presence of these partitions, eg, partitions 2803s1-2803s4, may increase the structural rigidity of frame 1131 in the vicinity of first fluid inlet and outlet passages 2815-2821, thereby increasing reliability.

[0202] According to various implementations, the frame 1131 may include a through opening (or aperture) 2823 formed entirely through a first central portion of the frame 1131 and configured to receive at least a portion of the cathode flow area 1127 therein (see, e.g., FIGS. 11A, 23, and 24). As such, the opening 2823 may be shaped and sized to match the shape and size of the cathode flow area 1127. For example, the opening 2823 may have a generally rectangular shape with rounded corners, although embodiments are not limited thereto. The frame 1131 may include a blind opening (or aperture) 2825 formed in a second central portion of the frame 1131 that surrounds the first central portion of the frame 1131. In some cases, the opening 2825 may be omitted or, as will become more apparent below, may be at least partially filled by the cathode annular insert 1134. When included as part of the cathode frame 1131, the opening 2825 may terminate in a surface 2803r, which may be recessed from the second surface 2803 and configured to receive at least a portion of the integrated MEA assembly 1119 (see, e.g., FIGS. 11A, 23, and 24) and / or at least a portion of the cathode annular insert 1134 therein. As such, the opening 2825 may be shaped and sized to correspond to the shape and size of the integrated MEA assembly 1119 and / or the portion of the cathode annular insert 1134, although embodiments are not limited thereto. For example, the opening 2825 may have a generally rectangular shape with rounded corners, although embodiments are not limited thereto. In some implementations, sides of the opening 2825 extending adjacent to the surfaces 2805 and 2809 of the frame 1131, respectively, may bulge toward the surfaces 2805 and 2809, thereby bulging away from the opening 2823.29 and 31 , the side of opening 2825 extending adjacent surface 2809 of frame 1131 may not only have a central portion 2825a extending in a first direction parallel (or substantially parallel) to surface 2809, but may also have a second portion 2825b extending from central portion 2825a and angled inward from first portion 2825a toward opening 2823, for example, by angle 3101. Central portion 2825a may have a width 3103 in the first direction, while second portion 2825b may have a corresponding width 3105, which may be greater than width 3103. Curved (or arcuate) corners 2825c of opening 2825 may each extend from second portion 2825b to connect a side of opening 2825 extending adjacent surface 2809 to a corresponding side of opening 2825 extending in a second direction transverse to the first direction, e.g., extending parallel (or substantially parallel) to surfaces 2807 and 2811 of frame 1131. However, embodiments are not limited in this respect.

[0203] In those implementations that include a cathode annular insert 1134, the cathode annular insert 1134 may be at least partially supported within the opening 2825 such that a first surface 1134a of the cathode annular insert 1134 abuts the surface 2803r of the frame 1131 and an inner circumferential surface 1134c of the cathode annular insert 1134 surrounds the outer circumferential boundary of the cathode flow basin 1127, which in turn surrounds the inner circumferential boundary of the opening 2825 (see also FIGS. 11D and 11E). Thus, the outer circumferential surface 1134d of the cathode annular insert 1134 may be shaped and sized to correspond to the shape and size of the inner circumferential boundary of the opening 2825. In some cases, the thickness 1134t of the cathode annular insert 1134 may be equal to (or substantially equal to) the depth of the opening 2825, although implementations are not limited thereto. If the thickness 1134t of the cathode annular insert 1134 corresponds to the depth of the opening 2825, the cathode annular insert 1134 may fill the void in the cathode frame 1131 corresponding to the opening 2825. It is also contemplated that the cathode annular insert 1134 may include one or more cutout portions 1134n1 and 1134n2 so that the cathode annular insert 1134 does not completely fill the void corresponding to the opening 2825. In either case, the cathode annular insert 1134 may have a generally ring-like configuration and thus may not actually be annular. For example, the cathode annular insert 1134 may have a generally rectangular cross-section when viewed along the Z-axis, as shown in FIGS. 11D and 11E, resulting in a cathode annular insert with two-fold symmetry rather than axial symmetry. Thus, the cathode annular insert 1134 may have, for example, a circular, elliptical, polygonal, or any other suitable cross-sectional shape when viewed along the Z-axis direction shown in Figures 11D and 11E.

[0204] 29, openings 2823 and 2825 may be disposed between second fluid inlet and outlet passages 2827 and 2829, with respective portions of inlet passage 901 and outlet passage 903 of stack 500 formed in association with inlet connector 547 and outlet connector 549 of manifold assembly 515 (see FIGS. 5 and 9). Referring briefly to FIGS. 7, 9, 11A, 23, 24, and 29, inlet passage 901 may supply one or more reactants (e.g., gaseous COx) to frame 1131, which may thereby supply cathode field 1127, which is at least partially supported by opening 2823, when frame 1131 is incorporated as part of a cell, e.g., cell 501. However, outlet passage 903 may supply CO X One or more by-products of the reduction process may be allowed to be routed from frame 1131 and thereby from a corresponding cathode basin 1127 at least partially supported in one of openings 2823 and 2825. Returning to FIGS. 28-36, to enable such exchange of fluid between the cathode basin 1127 (see FIG. 11A ), second fluid inlet passage 2827 may be fluidly connected to opening 2823 via channel 3501, connecting riser 3001, and buffer passage 2831, and second fluid outlet passage 2829 may be fluidly connected to opening 2823 via channel 3301, connecting riser 3109, and buffer passage 2833.

[0205] The buffer passages 2831 and 2833 may be corresponding recesses formed in the surface 2803r and terminating at surfaces 2831a and 2833a, respectively. To facilitate the supply of reactants and the discharge of by-products to the corresponding cathode flow areas 1127 (see, e.g., FIGS. 23 and 24 ) at least partially supported by the openings 2823, the buffer passages 2831 and 2833 may have corresponding outer sidewalls 2831b and 2833b that expand from the connecting risers 3001 and 3109, respectively, toward the openings 2823. For example, but not limited to, the buffer passages 2831 and 2833 may have a generally triangular shape. In some cases, the width 3111 of each of the buffer passages 2831 and 2833 may be smaller than the width 3103 of the central portion 2825a of the opening 2825. The buffer passages 2831 and 2833 may include corresponding multiple protrusions 3003 spaced at one or more intervals to accelerate the flow of reactants / by-products between adjacent ones of the protrusions 3003 and between the protrusions 3003 and corresponding adjacent side walls 2831b and 2833b. In association with the buffer passage 2831, the protrusions 3003 may not only facilitate the drawing of reactants from the connecting riser 3001, but also facilitate the dispersed flow of reactants to the input portion of the cathode basin 1127 (see, e.g., FIGS. 23 and 24 ) at least partially supported within the opening 2823. In association with the buffer passage 2833, the protrusions 3003 may facilitate the drawing of by-products from the output portion of the cathode basin 1127 (see, e.g., FIGS. 23 and 24 ) at least partially supported within the opening 2823 to the connecting riser 3109. The protrusions 3003 are shown as generally cylindrical bosses, although embodiments are not limited thereto. For example, one or more of the protrusions 3003 may be a generally oval boss, a generally rectangular boss, a generally pentagonal boss, a generally hexagonal boss, etc. When incorporated as part of a cell such as cell 501, the cathode annular insert 1134 may be at least partially supported within the opening 2825 and at least partially filled in the void corresponding to the opening 2825.Filling the gap corresponding to the opening 2825 (formed between the opening 2823 and the recess 2835 in the frame 1131) reduces or eliminates the possibility that the input reactant(s) (e.g., gaseous COx) supplied to the cathode basin 1127 from the buffer passage 2831 will instead flow around the cathode basin 1127 via the opening 2825 (shown in FIG. 11D as reactant bypass flow 1136) and be exhausted via the buffer passage 2833. Note that the reactant bypass flow 1136 reduces the amount of input reactant flowing through the cathode basin 1134, potentially reducing the efficiency of the cell. In some cases, both the opening 2825 and the cathode annular insert 1134 may be omitted, thereby further reducing the possibility of reactant bypass flow 1136. An opening 2825 is formed in the frame 1131 and, if a cathode annular insert 1134 is not used, may function to reduce or prevent reactant bypass flow 1136 by compressing at least a portion of the integrated MEA assembly 1119 therein.

[0206] According to some embodiments, the inclusion of the cathode annular insert 1134 may help further compress the GDL 1121 in the area occupied by the cathode annular insert 1134 when the cell (e.g., cell 501) and / or stack 500 is assembled and compressed (either as part of the assembly process or during use of the stack 500). This further compression may reduce the in-plane permeability of the GDL 1121 in the area corresponding to the cathode annular insert 1134, further mitigating the possibility of reactant bypass flow 1136. However, when the cathode annular insert 1134 is present between the GDL 1121 and the frame 1131, there is a high possibility that the cathode annular insert 1134 will be compressed in the axial direction. Therefore, cutout portions 1134n1 and 1134n2 may be formed in the cathode annular insert 1134 in areas corresponding to the buffer passages 2831 and 2833, thereby preventing or reducing the possibility that the cathode annular insert 1134 will be compressed in the respective portions of the buffer passages 2831 and 2833 that interface with the opening 2823 of the frame 1131. Therefore, the cutout portions 1134n1 and 1134n2 may be formed such that tips corresponding to portions of the inner circumferential surface 1134c of the cathode annular insert 1134 overlap with corresponding protrusions 3003 formed on the buffer passages 2831 and 2833, respectively, thereby supporting the cathode annular insert 1134 in the areas corresponding to the buffer passages 2831 and 2833. For example, the tips of the cutout portions 1134n1 and 1134n2 may be supported by one or more of the protrusions 3003. In some examples, the tips of the cutout portions 1134n1 and 1134n2 may be supported by one or more protrusions 3003 located closest to the connecting riser 3001. However, the cutout portions 1134n1 and 1134n2 may be omitted. In some cases, additional protrusions 3003 may be provided in the buffer passages 2831 and 2833 to support the cathode annular insert 1134 thereon, which may also prevent or reduce the possibility of the cathode annular insert 1134 being compressed in the portions of the buffer passages 2831 and 2833 that interface with the opening 2823 of the frame 1131.

[0207] In some embodiments, the protrusions 3003 may be similar (or substantially similar) in size to one another, or at least one of the protrusions 3003 may be a different size than at least one other of the protrusions 3003. This may be with respect to the length, width, and / or height of the protrusions 3003. For example, the protrusions 3003 may include a first protrusion 3003 a, a second protrusion 3003 b, and a third protrusion 3003 c. With respect to a reference plane perpendicular to the axial direction, the cross-sectional area of ​​the first protrusion 3003 a may be larger than the cross-sectional area of ​​the second protrusion 3003 b, and the cross-sectional area of ​​the second protrusion 3003 b may be larger than the cross-sectional area of ​​the third protrusion 3003 c. In some cases, the second protrusions 3003b of the buffer passages 2831 and 2833 may be disposed closer to the connecting risers 3001 and 3109 than the first and third protrusions 3003a and 3003c, respectively. The third protrusion 3003c may be disposed within the first protrusion 3003a and may be positioned so that the third protrusion 3003c is disposed between the second protrusion 3003b and a majority of the first protrusion 3003a. However, embodiments are not limited to such configurations and / or arrangements of the protrusions 3003.

[0208] Frame 1131 may include recess 2835 in surface 2803 and recess 3303 in surface 2801, which are configured to receive corresponding portions of first cathode gasket 1129 and second cathode gasket 1133 therein, respectively, when frame 1131 is assembled (see FIG. 5 ) as a repeat unit (e.g., repeat unit 503_1 in FIG. 5 ) or as part of cathode interface assembly 505 (see FIG. 5 ) (e.g., FIGS. 11A , 23 , and 24 ). Recess 2835 may be formed to surround the periphery of opening 2825, and recess 3303 may be formed to surround the periphery of opening 2823. It should be noted that the coupling of the second fluid inlet passage 2827, the channel 3501, the connecting riser 3001, and the buffer passage 2831 allows a reactant supply to flow from an area outside the first cathode gasket 1129 (see, e.g., FIGS. 11A, 23, and 24) to an area inside the first cathode gasket 1129 without disturbing the integrity or seal provided by the first cathode gasket 1129. Similarly, the coupling of the buffer passage 2833, the connecting riser 3109, the channel 3301, and the second fluid outlet passage 2829 allows a by-product to flow from an area inside the first cathode gasket 1129 (see, e.g., FIGS. 11A, 23, and 24) to an area outside the first cathode gasket 1129 without disturbing the integrity or seal provided by the first cathode gasket 1129.

[0209] According to some embodiments, the frame 1131 may include a first protruding portion 3305 extending from the surface 2801 and surrounding the corresponding first fluid inlet and outlet passages 2815, 2817, 2819, and 2821. A second protruding portion 3307 may extend from the surface 2801 and surround the second fluid inlet passage 2827 and the fluid outlet passage 2829, respectively. In some implementations, the second protruding portion 3307 surrounding the second fluid inlet passage 2827 may also surround the channel 3501 and the connecting riser 3001, and the second protruding portion 3307 surrounding the second fluid outlet passage 2829 may also surround the channel 3301 and the connecting riser 3109. In some embodiments, first protruding portion 3305 and second protruding portion 3307 may protrude from surface 2801 by height 3401, although embodiments are not limited thereto. For example, one or more of first protruding portion 3305 and second protruding portion 3307 may have a different height than at least one other of first protruding portion 3305 and second protruding portion 3307. When assembled as part of a repeating unit (e.g., repeating unit 1100 in FIG. 11A ), the first protruding portion 3305 and the second protruding portion 3307 of the frame 1131 may be received within and through corresponding openings in a separator plate (separator plate 1107 in FIG. 11A ; also, FIGS. 23 and 24 ) or corresponding recesses 4607-4617 (see FIG. 46 ) of a cathode interface separator 1701 (see FIG. 17 ) of a cathode interface assembly 505 (e.g., see FIGS. 5-10 and 17 ).In this manner, one or more of the first protruding portion 3305 and the second protruding portion 3307 may be sized to form a respective clearance fit or interference fit with a corresponding opening in a separator plate (such as separator plate 1107 in FIG. 11A ) or corresponding recesses 4607-4617 (see FIG. 46 ) in the cathode interface separator 1701 (see FIG. 17 and FIG. 46 ) when the frame 1131 is assembled as part of a repeating unit (e.g., as repeating unit 503_1 in FIG. 5 , or as part of the cathode interface assembly 505, see e.g., FIGS. 5-10 , 17 , and 18 ).

[0210] In some embodiments, depending on the position of the stack 500 (e.g., separator plate 1107 in FIG. 11A ), or the frame 1131 within the stack 500, one or more of the first protruding portion 3305 and the second protruding portion 3307 may be sized to form a respective clearance fit with a corresponding feature in a separator plate or separator plates that interface with the frame 1131 when incorporated as part of the stack 500 (e.g., separator plate 1107 in FIG. 11A ), or part of the cathode interfacial separator 1701 (see FIG. 17 ). Furthermore, depending on the position of the frame 1131 within the stack 500, one or more of the first protruding portion 3305 and the second protruding portion 3307 may be sized to form a respective interference fit with a corresponding feature in a separator plate that interfaces with the frame 1131 when incorporated as part of the stack 500 (e.g., separator plate 1107 in FIG. 11A ), or part of the cathode interfacial separator 1701 (see FIG. 17 ). For example, the outer boundaries of each of the first and second protruding portions 3305 and 3307 may be about 0.01 to about 5% larger (in the case of an interference fit) or about 0.01 to about 10% smaller (in the case of a clearance fit) than the corresponding boundaries of the corresponding features in a separator plate (such as separator plate 1107 in FIG. 11A ) or cathode interfacial separator 1701 (see, e.g., FIG. 17 ), depending on the position of the frame 1131 within the stack 500. The clearance fit and / or interference fit may be utilized to constrain in-plane expansion (e.g., expansion in a plane parallel to the x-y plane (see FIG. 11A )) of the frame 1131 (and, in some embodiments, the anode frame 1115) during operation of the stack 500 without unduly stressing the frame 1131 and / or the anode frame 1115.In some embodiments, the first protruding portion 3305 and the second protruding portion 3307 can be sized to form a respective clearance fit with corresponding features in a separator plate (such as separator plate 1107 in FIG. 11A ) or cathode interfacial separator 1701 (see, e.g., FIG. 17 ) depending on the position of the frame 1131 within the stack 500 in a cooled, non-operational state of the stack 500 (see FIGS. 5 and 6 ), but can be expanded to form an interference fit corresponding to a steady-state operating condition of the stack 500. This can not only prevent (or at least reduce the likelihood of) misalignment, bunching, etc. of the cathode GDLs 1121 and anode PTLs 1109 of various cells of the stack 500, but can also prevent (or at least reduce the likelihood of) misalignment between adjacent frames of adjacent cells of the stack 500. Such a configuration also allows the frame 1131 and / or anode frame 1115 (see FIG. 11A ) to be formed from a more compliant material, which may in some cases be cheaper and / or easier to manufacture (and may in some cases be less conductive). However, it should be noted that the separator plate (e.g., separator plate 1107 of FIG. 11A ) or cathode interfacial separator 1701 (see, e.g., FIG. 17 ) may be formed from a stronger and / or stiffer material(s) to increase the strength and / or stiffness of various repeat units (e.g., repeat unit 1100 of FIG. 11A ; see also repeat unit 503 of FIGS. 5-10 ) and / or cathode interfacial assembly 505 (see, e.g., FIGS. 5-10 , 17 , and 18 ), depending on the position of the frame 1131 within the stack 500.

[0211] According to various embodiments, the first protruding portion 3305 can be sized and shaped to interface with the second anode gasket 1117b of the second anode gasket set 1117, and the second protruding portion 3307 can be sized and shaped to interface with the third anode gasket 1117c of the second anode gasket set 1117. In this manner, cross-flow between the first and second fluid inlet and outlet passages 2815, 2817, 2819, 2821, 2827, and 2829 can be prevented.

[0212] The frame 1131 may also include first fastener holes 2837 spaced at one or more intervals around the peripheral region of the frame 1131. In some embodiments, the pitch between adjacent first fastener holes 2837 may be constant (or substantially constant), although embodiments are not limited thereto. The second fastener holes 2839 and the third fastener holes 2841 may be inserted from the first fastener holes 2837 in a central portion of the frame 1131 near the second fluid inlet passage 2827 and the fluid outlet passage 2829, respectively. The pitch between adjacent second fastener holes 2839 and the pitch between adjacent third fastener holes 2841 may be smaller than the pitch(es) between adjacent first fastener holes 2837. In various embodiments, the first, second, and third fastener holes 2837, 2839, and 2841 can extend completely through the frame 1131 and may be countersunk relative to the surface 2803, for example. When assembled as part of a repeating unit (e.g., repeating unit 1100 of FIG. 11A), the first, second, and third fastening holes 2837, 2839, and 2841 can be configured to receive corresponding fasteners 1137 (see FIG. 11A), respectively, which, as will become more apparent below, may be engaged with, for example, swage nuts 1135 (see FIG. 11A) incorporated into (or as part of) the anode frame 1115 (see, e.g., FIGS. 11A and 21). When the frame 1131 is incorporated as part of the cathode interface assembly 505 (see, e.g., Figures 5-10, 17, and 18), the first, second, and third fastening holes 2837, 2839, and 2841 can be configured to receive corresponding fasteners 1137, respectively (see Figure 17), which may engage, for example, with first, second, and third threaded fastening holes 4539, 4541, and 4543 of the cathode interface separator 1701, as will become more apparent below (see, e.g., Figures 17, 18, and 45).

[0213] According to various embodiments, one or more of the countersunk portions of the first, second, and third fastening holes 2837, 2839, and 2841 can be sized to form a clearance fit or an interference fit, respectively, with a corresponding fastener 1137 (see FIG. 11A ) or a corresponding portion (e.g., head or shoulder) of the fastener 1137 (e.g., see FIG. 21 ) when the frame 1131 is assembled as part of a repeating unit (e.g., repeating unit 1100 of FIG. 11A ) or as part of the cathode interface assembly 505 (e.g., FIGS. 5-10 , 17 , and 18 ). In some embodiments, one or more of the countersunk portions of the first, second, and third fastening holes 2837, 2839, and 2841 may be sized to form a clearance fit with a corresponding fastener 1137 (see, e.g., Figures 11A, 17, and 21), respectively, and one or more of the countersunk portions of the first, second, and third fastening holes 2837, 2839, and 2841 may be sized to form an interference fit with a corresponding fastener 1137, respectively. For example, the width (e.g., diameter) of each of the counterbore portions of the first, second, and third fastener holes 2837, 2839, and 2841 may be about 0.01% to about 10% larger (for a clearance fit) or about 0.01% to about 5% smaller (for an interference fit) than the corresponding width (e.g., diameter) of each portion (e.g., head or shoulder) of the fastener 1137 (see, e.g., FIGS. 11A, 17, and 21). In some embodiments, when the frame 1131 is assembled as part of a repeat unit (e.g., repeat unit 1100 of FIG. 11A ) or as part of the cathode interface assembly 505 of, for example, FIGS. 5-10 , 17 , and 18 , one or more of the counterbore portions of the first, second, and third fastener holes 2837, 2839, and 2841 may be sized to form a respective clearance fit with a corresponding fastener 1137 (e.g., see FIGS. 11A , 17 , and 21 ) or a corresponding portion (e.g., head or shoulder portion) of the fastener 1137 (e.g., see FIG. 21 ), and the stack 500 (e.g., see FIG. 5 ) is cooled and in a non-operational state, but expanded to form an interference fit corresponding to the steady-state operating condition of the stack 500.These clearance and / or interference fits may be utilized to constrain in-plane expansion (e.g., in a plane parallel to the x-y plane (see FIG. 11A )) of the frame 1131 (and, in some embodiments, the anode frame 1115 of FIG. 11A ) during operation of the stack 500 without unduly stressing the frame 1131 and / or the anode frame 1115. This can prevent (or at least reduce the likelihood of) misalignment, bunching, etc. of the anode PTLs 1109 and cathode GDLs 1121 (e.g., see FIGS. 5-10 ) of various cells / repeat units of the stack 500, as well as misalignment between adjacent frames of adjacent cells / repeat units of the stack 500. Such a configuration also allows the frame 1131 and / or the anode frame 1115 to be formed of a more compatible material, which in some cases may be cheaper and / or easier to manufacture (in some cases, not electrically conductive).

[0214] According to some embodiments, the frame 1131 and / or the cathode annular insert 1134 may be formed from any suitable thermoplastic and / or thermoset material, such as polyethylene terephthalate (PET), polycarbonate (PC), polyimide (PI), polyamide (PA), poly(methyl methacrylate) (PMMA), polyethylene naphthalate (PEN), polyether ketone (PEK), polyether ether ketone (PEEK), polystyrene (PS), polyetherimide (PEI), polyphenylene sulfide (PPS), polyarylate (PAR), polyethersulfone (PES), cyclic olefin copolymer (COC), polyvinyl alcohol (PVA), ethylene chlorotrifluoroethylene (ECTFE), polytetrafluoroethylene (PTFE), polybutylene terephthalate (PBT), polychlorotrifluoroethylene (PCTFE), polyethylene terephthalate glycol (PETG), and the like. In some cases, the frame 1131 and / or the cathode annular insert 1134 may be formed of one or more metals or metal alloys, such as aluminum, aluminum alloys, copper, copper alloys, tin, tin alloys, titanium, titanium alloys, tungsten, tungsten alloys, zinc, zinc alloys, steel, stainless steel, etc. However, when formed of a metal or metal alloy, it is noted that in some embodiments, the frame 1131 includes a coating or other feature to, for example, electrically insulate the frame 1131 from the corresponding cathode GDL (e.g., cathode GDL 1121 in FIG. 11A ) and / or its associated cathode field (e.g., cathode field 1127 in FIG. 11A ). It is also contemplated that the base material of the frame 1131 may be coated, for example, with one or more other materials, e.g., one or more corrosion-resistant materials. In either case, the frame 1131 and / or cathode annular insert 1134 may be formed by any suitable method, such as additive manufacturing, stamping, injection molding, compression molding, casting, machining, or the like.

[0215] Anode Frame Similar to the cathode field 1127 (see, e.g., FIGS. 11A, 23, and 24), the anode field 1111 may be supported, at least in part, in an opening in the anode frame 1115 (see, e.g., FIGS. 11A, 23, and 24), which also supports the stack 500 (see, e.g., FIGS. 5-10), and in particular the CO X It also includes a plurality of fluid passages to facilitate fluid communication (or flow) through the electrolyzer cells, such as cell 501. Various details of the exemplary anode frame 1115 are discussed in further detail in connection with Figures 37-42.

[0216] Figure 37 shows a first perspective view of an exemplary anode frame. Figure 38 shows a top view of the exemplary anode frame of Figure 37. Figure 39 shows a second perspective view of the exemplary anode frame of Figure 37. Figure 40 shows a bottom view of the exemplary anode frame of Figure 39. Figure 41 shows an enlarged portion of the exemplary anode frame of Figure 38. Figure 42 shows an enlarged portion of the exemplary anode frame of Figure 40.

[0217] The anode frame (or frame) 1115 may be a generally rectangular plate-like body having a first surface 3701 (e.g., a top surface) and an opposing second surface 3703 (e.g., a bottom surface) in the axial direction 3801. While the frame 1115 is described as having a generally rectangular plate-like configuration, embodiments are not limited thereto and any suitable geometric configuration may be utilized, such as a generally circular, oval, triangular, pentagonal, or hexagonal configuration. For convenience, the frame 1115 will be described with reference to a generally rectangular configuration. The first surface 3701 and the second surface 3703 may be bounded by one or more perimeter surfaces, such as perimeter surfaces (or surfaces) 3705, 3707, 3709, and 3711, which may be connected to one another via one or more other perimeter surfaces, such as perimeter surface (or surface) 3713. In some embodiments, the frame 1115 may have a symmetrical configuration about one or more reference planes that are perpendicular to the axial direction 3801 (see FIGS. 38 and 40). For example, the configuration of the frame 1115 may be symmetrical about one or both of the reference planes 3803 and 3805 depicted in FIGS. 38 and 40, but embodiments are not limited thereto.

[0218] According to various embodiments, first fluid inlet passages 3715 and 3717 may be adjacent to periphery 3705, and first fluid outlet passages 3719 and 3721 may be adjacent to periphery 3709. First fluid inlet passages 3715 and 3717, in conjunction with inlet connector 543 (see FIGS. 5-10) of manifold assembly 515, may form part of inlet passages 1001 and 1003 (see FIG. 10) of stack 500, which supply input water to frame 1115 and thereby to corresponding anode basins 1111 associated with frame 1115 (see, e.g., FIGS. 11A, 23, and 24). The first fluid outlet passages 3719 and 3721 may form part of outlet passages (which are similar to the inlet passages 1001 and 1003 (see FIG. 10) but associated with the outlet connector 545 and the inlet connector 543 (see FIG. 5-10) of the manifold assembly 515) of the stack 500 that output water from the frame 1115 and thereby from the corresponding anode basin 1111 associated with the frame 1115 (see, e.g., FIGS. 11A, 23, and 24). In some implementations, the first fluid inlet passages and first fluid outlet passages 3715-3721 may be defined by respective multiple holes that are separated from one another via corresponding partitions. For example, first fluid inlet passage 3715 may include first inlet hole 3715a and second inlet hole 3715b separated from each other by partition 3701s1, and first fluid outlet passage 3719 may include first outlet hole 3719a and second outlet hole 3719b separated from each other by partition 3701s2. Exemplary partitions are also depicted in the enlarged view of FIG. 42 and the cross-sectional view of FIG. 23. That is, FIG. 42 shows partition 3701s3 separating first outlet hole 3721a and second outlet hole 3721b that form first fluid outlet passage 3721, and FIG. 23 shows partition 3701s4 separating first inlet hole 3717a and second inlet hole 3717b that form first fluid inlet passage 3717.Similar to the cathode frame 1131 (see, e.g., FIG. 11A), the presence of partitions, e.g., partitions 3701s1-3701s3, in the frame 1115 may increase structural rigidity, thereby enhancing the reliability of the frame 1115 in the vicinity of the first fluid inlet and outlet passages 3715-3721.

[0219] According to various embodiments, the frame 1115 may also include a through opening (or aperture) 3723 formed completely through a first central portion of the frame 1115 and configured to receive at least a portion of the anode flow area 1111 therein (see, e.g., FIGS. 11A, 23, and 24). As such, the opening 3723 may be sized and shaped to correspond to the size and shape of the anode flow area 1111. For example, the opening 3723 may have a generally rectangular shape with rounded corners, but embodiments are not limited thereto. The frame 1115 may include a blind opening (or aperture) 3725 formed in a second central portion of the frame 1115 that surrounds the first central portion of the frame 1115. In some cases, the opening 3725 may be omitted or, as will become more apparent below, may be at least partially filled by the anode annular insert 1118. If included as part of the frame 1115, the opening 3725 may terminate at the surface 3701r, may be recessed from the first surface 3701, and may be configured to receive at least a portion of the anode PTL 1109 (see, e.g., FIGS. 11A, 23, and 24) and / or at least a portion of the anode frame insert 1118 therein. As such, the opening 3725 may be sized and shaped to correspond to the size and shape of the anode PTL 1109 (see, e.g., FIGS. 11A, 23, and 24) and / or the anode frame insert 1118. For example, the opening 3725 may have a generally rectangular shape with rounded corners, although embodiments are not limited thereto. First fluid inlet passages 3715 and 3717 may be fluidly connected to opening 3723 via corresponding channels 4001, 4003, 4005, and 4007, respective connecting risers 3727 and 3729, distribution channel 3731, and supply (or inlet) channel 3733 to enable fluid flow between the anode basin 1111 (see, for example, Figures 11A, 23, and 24) that is at least partially supported in opening 3723.First fluid outlet passages 3719 and 3721 may be fluidly connected to opening 3723 via outlet channel 3735 , collection channel 3737 , respective connecting risers 3739 and 3741 , and corresponding channels 4009 , 4011 , 4013 , and 4015 .

[0220] In those implementations that include the anode annular insert 1118, the anode annular insert 1118 may be at least partially supported within the opening 3725 such that the second surface 1118b of the anode annular insert 1118 abuts the surface 3701r of the frame 1115 and the inner circumferential surface 1118c of the anode annular insert 1118 surrounds the outer circumferential boundary of the anode flow area 1111, which in turn surrounds the inner circumferential boundary of the opening 3723 (see also FIGS. 11B and 11C ). Thus, the outer circumferential surface 1118d of the anode annular insert 1118 may be shaped and sized to correspond to the shape and size of the inner circumferential boundary of the opening 3725. In some cases, the thickness 1118t of the anode annular insert 1118 may be equal to (or substantially equal to) the depth of the opening 3725, although implementations are not limited thereto. If the thickness 1118t of the anode annular insert 1118 corresponds to the depth of the opening 3725, the anode annular insert 1118 can fill the void in the frame 1115 corresponding to the opening 3725. It is also contemplated that the anode annular insert 1118 may not completely fill the void corresponding to the opening 3725, such as may be seen in FIGS. 11B and 11C. In such cases, the inner circumferential surface 1118c of the anode annular insert 1118 may be offset from the inner circumferential boundary of the opening 3723, and the PTL 1109 may fill the remaining space not filled by the anode annular insert 1118. In either case, the anode annular insert 1118 may have a generally ring-like configuration and therefore may not actually be annular. For example, the anode annular insert 1118 may have a generally rectangular cross-section when viewed along the z-axis direction shown in FIGS. 11B and 11C, thereby resulting in an anode annular insert with two-way symmetry rather than axial symmetry. As such, the anode annular insert 1118 may have, for example, a circular, elliptical, polygonal, or any other suitable cross-sectional shape when viewed, for example, along the z-axis direction shown in Figures 11B and 11C.

[0221] The inlet channel 3733 and the outlet channel 3735 may be blind recesses formed in the surface 3701r, such as those illustrated in Figures 37, 38, and 41, extending from the opening 3723 and terminating, in the case of the inlet channel 3733, in the distribution channel 3731 and connecting risers 3727 and 3729, and, in the case of the outlet channel 3735, in the distribution channel 3737 and connecting risers 3739 and 3741. In some cases, the inlet channel 3733 and the outlet channel 3735 may extend not only parallel (or substantially parallel) to one another but also parallel (substantially parallel) to the reference plane 3803. When incorporated as part of a cell such as the cell 501, the anode annular insert 1118 may be at least partially supported within the opening 3725 and at least partially fill the void corresponding to the opening 3725. As previously mentioned, the remaining area of ​​the void can be filled by the PTL 1109, and thus the anode annular insert 1118 can function to extend the outer boundary of the PTL 1109 further outward toward the recess 3747 in the frame 1115. Filling the void corresponding to the opening 3725 (formed between the opening 3723 and the recess 3747) reduces or eliminates the possibility that input water supplied to the anode basin 1111 from the inlet channel 3733 will instead flow around the anode basin 1111 via the opening 3725 (shown in FIG. 11B as bypass flow 1120) and be discharged via the outlet channel 3735. Note that the bypass flow 1120 reduces the amount of input water flowing through the anode basin 1111, potentially reducing the efficiency of the cell. In some cases, both the opening 3725 and the anode annular insert 1118 may be omitted, further reducing the feasibility of the bypass flow 1120. If an opening 3725 is formed in the frame 1115 and an anode annular insert 1118 is not used, the PTL 1109 may be formed to completely (or substantially completely) fill the opening 3725 to reduce or prevent the possibility of bypass flow 1120.

[0222] According to some embodiments, the presence of the anode annular insert 1118 may not only prevent or reduce the possibility of bypass flow 1120 occurring during operation of the stack 500, but may also prevent or reduce the possibility that the bypass flow 1120 or compressive forces within the system (such as the stack 500) will force the anode side of the MEA 1105 against the outer periphery of the PTL 1109, causing it to mechanically deteriorate by wearing, cutting, etc. The anode annular insert 1118 may, for example, prevent or reduce the possibility that the first anode gasket 1113a will intrude into one or more of the inlet channel 3733 and the outlet channel 3735.

[0223] To facilitate the distribution and collection of water to and from the anode basin 1111 (see, e.g., FIGS. 11A, 23, and 24), the inlet and outlet channels may each have an outer channel adjacent to a corresponding central channel. For example, as seen in FIG. 41, the outlet channel 3735 may be divided into a first outer outlet channel 3735a disposed in the first outer portion 4101, a second outer outlet channel 3735b disposed in the second outer portion 4103, and a central outlet channel 3735c disposed in the central portion 4105. The central outlet channel 3735c may be spaced apart from one another by a fixed distance 4107, and the first outer outlet channel 3735a and the second outer outlet channel 3735b may be spaced apart from one another by a variable distance that may increase in size with increasing distance from the central portion 4105. For example, adjacent first outer outlet channels 3735a near the central portion 4105 may be spaced apart by spacing 4109, and adjacent first outer outlet channels 4135a further away from the central portion 4105 may be spaced apart by spacing 4111, which may be greater than spacing 4109. The inlet channels 3733 may be positioned and configured similarly to the outlet channels 3735, but the inlet channels 3733 are to the inside of the openings 3723 and, relative to the outlet channels 3735, are on the outlet side of the openings 3723.

[0224] The central inlet and outlet channels (e.g., central outlet channel 3735c) of inlet channels 3733 and outlet channels 3735 may terminate at and be fluidly connected to distribution channels 3731 and 3737, respectively. Some of the first outer inlet and first outer outlet channels of inlet channels 3733 and outlet channels 3735 may terminate at and be fluidly connected to distribution channels 3731 and 3737, respectively, and others of the first outer inlet and first outer outlet channels of inlet channels 3733 and outlet channels 3735 (e.g., first outer outlet channel 3735a identified in FIG. 41) may terminate at and be fluidly connected to connecting risers 3727 and 3741, respectively. Similarly, some of the second outer inlet channels and second outer outlet channels of inlet channel 3733 and outlet channel 3735 may terminate at and be fluidly connected to distribution channels 3731 and 3737, respectively, and others of the second outer inlet channels and second outer outlet channels of inlet channel 3733 and outlet channel 3735 (e.g., second outer outlet channel 3735b identified in FIG. 41) may terminate at and be fluidly connected to connecting risers 3729 and 3739, respectively.

[0225] Distribution channels 3731 and 3737 may be formed as blind recesses in surface 3701r and may extend transversely to the extension direction of inlet and outlet channels 3735, such as those depicted in Figures 37, 38, and 41. In some embodiments, distribution channels 3731 and 3737 may extend parallel (substantially parallel) to reference surface 3805. Distribution channel 3731 may be flanked on either side by and fluidly connected to connecting risers 3727 and 3729, which may be formed as holes extending through frame 1115 from surface 3701r in the axial direction 3801 to surface 3703, such as can be seen in Figures 37-42. Similarly, distribution channel 3737 may be flanked on either side by and fluidly connected to connecting risers 3739 and 3741, which may be formed as holes extending through frame 1115 from surface 3701r in axial direction 3801 to surface 3703.

[0226] 39 and 40 , connecting risers 3727, 3729, 3739, and 3749 may be fluidly connected to first fluid inlet and outlet passages 3715-3721, respectively, via corresponding groups of channels 4001-4015. For example, connecting riser 3727 may be fluidly connected to first fluid inlet passage 3715 via channels 4001 and 4003, while connecting riser 3729 may be fluidly connected to first fluid inlet passage 3717 via channels 4005 and 4007. Furthermore, connecting riser 3739 may be fluidly connected to first fluid outlet passage 3719 via channels 4009 and 4011, while connecting riser 3741 may be fluidly connected to first fluid outlet passage 3721 via channels 4013 and 4015.

[0227] The channels 4001-4015 may be formed as blind recesses in the surface 3703 and may extend, for example, obliquely relative to the elongation direction of the reference plane 3803, such as can be seen in FIGS. 39, 40, and 42. For example, as seen in FIG. 42, the channels 4015 may not only extend parallel (or substantially parallel) to one another, but also extend from the first outlet hole 3721a of the first fluid outlet passage 3721 to the connecting riser 3741 at an oblique angle 4201. Similarly, the channels 4013 may not only extend parallel (or substantially parallel) to one another, but also extend from the second outlet hole 3721b of the first fluid outlet passage 3721 to the connecting riser 3741 at an oblique angle 4203, which may be smaller than the oblique angle 4201. In some embodiments, the channels 4013 and 4015 may be formed as respective groups of six channels, although embodiments are not limited thereto. For example, any number of channels less than or greater than six may be utilized. Furthermore, channels 4013 and 4015 may have the same or different numbers of individual channels. To this end, the individual channels of channels 4013 and 4015 may have equal (or substantially equal) cross-sectional areas in a plane perpendicular to their respective longitudinal directions. In some embodiments, some of the individual channels (such as channels 4013a and 4013b) may have equal (or substantially equal) cross-sectional areas, and at least one of the individual channels (e.g., channel 4013c) may have a different cross-sectional area. In the case of individual channel 4013c, the size of its cross-sectional area may vary, for example, increasing as the distance from second outlet hole 3721b of first fluid outlet passage 3721 increases. Channels 4001-4011 may be configured similarly to that described in connection with channels 4013 and 4015 with respect to the corresponding connecting risers and associated first fluid inlet and outlet passages.

[0228] According to various embodiments, openings 3723 and 3725 may be disposed between second fluid inlet passage 3743 and fluid outlet passage 3745, which, in conjunction with inlet connector 547 and outlet connector 549 of manifold assembly 515, form respective portions of inlet passage 901 and outlet passage 903 (see FIG. 9) of stack 500 (see, e.g., FIGS. 5-10). Inlet passage 901 (see FIG. 9) may supply one or more reactants (e.g., gaseous COx) to various cathode frames 1131 (see, e.g., FIG. 5) of stack 500, and thus to corresponding cathode flow fields 1127 (see, e.g., FIGS. 5-11A) supported in association therewith when frame 1115 is incorporated as part of a cell, such as cell 501. However, outlet passage 903 (see FIG. 9) allows CO X One or more by-products of the reduction process may be allowed to exit the various cathode frames 1131 (see, e.g., FIGS. 5-11A) of the stack 500 and, thereby, the corresponding cathode basins 1127 supported therewith.

[0229] The frame 1115 may also include recesses 3747-3759 in the surface 3701, which may be configured to receive corresponding portions of gaskets between the first anode gasket set 1113 (see, e.g., Figures 11A, 23, and 24), respectively, when the frame 1115 is assembled as part of a repeat unit (e.g., repeat unit 503_1 in Figure 5) or anode interface assembly 509 (e.g., repeat unit 503_1 in Figure 5) (e.g., Figures 5-10, 47, and 48). For example, with momentary reference to Figures 11A, 23, and 24 in addition to Figures 37-42, recess 3747 may be formed to surround opening 3725 and interface with first anode gasket 1113a of first anode gasket set 1113, and recesses 3749-3755 may be formed to surround first fluid inlet and fluid outlet passages 3715-3721, respectively, and to interface with second anode gasket 1113b of first anode gasket set 1113, respectively. It should be noted that by combining the first fluid inlet passages 3715 and 3717, channels 4001, 4003, 4005, and 4007, connecting risers 3727 and 3729, distribution channel 3731, and supply channel 3733, water can flow, for example, from the area outside the first anode gasket 1113a of the first anode gasket set 1113 (see, for example, Figures 11A, 23, and 24) to the area inside the first anode gasket 1113a of the first anode gasket set 1113, without disturbing the integrity of the first anode gasket 1113a of the first anode gasket set 1113 or the seal provided by the first anode gasket 1113a of the first anode gasket set 1113. The same is true for the integrity of or the seal provided by the second anode gasket 1113b of the first anode gasket set 1113, where the second anode gasket 1113b has an interface with recesses 3749 and 3751 (see, for example, Figures 11A, 23, and 24).Similarly, by coupling the first fluid outlet passages 3719 and 3721, the outlet channel 3735, the collection channel 3737, the connecting risers 3739 and 3741, and the channels 4009, 4011, 4013, and 4015, it is possible for water to flow, for example, from the area inside the first anode gasket 1113a of the first anode gasket set 1113 (e.g., Figures 11A, 23, and 24) to the area outside the first anode gasket set 1113a of the first anode gasket set 1113 without disturbing the integrity of or the seal provided by the first anode gasket 1113a of the first anode gasket set 1113. The same is true for the integrity of and the seal provided by second anode gasket 1113b of first anode gasket set 1113, which interfaces with recesses 3753 and 3755 (see, e.g., FIGS. 11A, 23, and 24). Additionally, recesses 3757 and 3759 may be formed to surround second fluid inlet passage 3743 and fluid outlet passage 3745, respectively, and to interface with third anode gasket 1113c of first anode gasket set 1113 (see, e.g., FIGS. 11A, 23, and 24).

[0230] Similar to recesses 3747-3759 formed in surface 3701, frame 1115 may also include recesses 4017-4029 in surface 3703, which may be configured to receive corresponding portions of gaskets, respectively, between second anode gasket set 1117 (see, e.g., FIGS. 11A, 23, and 24), for example, when frame 1115 is assembled as part of a repeat unit (e.g., repeat unit 503_1 in FIG. 5) or anode interfacial assembly 509 (e.g., FIGS. 5-10, 47, and 48). For example, recess 3717 may be formed to surround a periphery of opening 3723 and interface with first anode gasket 1117a of second anode gasket set 1117 (see, e.g., FIGS. 11A, 23, and 24). The recesses 4019-4025 may be formed to surround the combined peripheries of the associated first fluid inlet and outlet passages 3715-3721, corresponding channels 4001-4015, and respective connecting risers 3727, 3729, 3739, and 3741, respectively, and may each have an interface with the second anode gasket 1117b of the second anode gasket set 1117 (see, for example, Figures 11A, 23, and 24). For example, recess 4019 may be formed to surround the combined periphery of first fluid inlet passage 3717, channels 4005 and 4007, and connecting riser 3729 and have an interface with one of the second anode gaskets 1117b of second anode gasket set 1117 (see, for example, Figures 11A, 23, and 24), and recess 4021 may be formed to surround the combined periphery of first fluid inlet passage 3715, channels 4001 and 4003, and connecting riser 3727 and have an interface with another of the second anode gaskets 1117b of second anode gasket set 1117 (see, for example, Figures 11A, 23, and 24).Similarly, recess 4023 may be formed to surround the combined periphery of first fluid outlet passage 3721, channels 4013 and 4015, and connecting riser 3741 and to have an interface with yet another one of the second anode gaskets 1117b of second anode gasket set 1117 (see, for example, Figures 11A, 23, and 24), and recess 4025 may be formed to surround the combined periphery of first fluid outlet passage 3719, channels 4009 and 4011, and connecting riser 3739 and to have an interface with yet another one of the second anode gaskets 1117b of second anode gasket set 1117 (see, for example, Figures 11A, 23, and 24). It should be noted that by combining the first fluid inlet passages 3715 and 3717, channels 4001, 4003, 4005, and 4007, connecting risers 3727 and 3729, distribution channel 3731, and supply channel 3733, it is possible for water to flow, for example, from the area outside the first anode gasket 1113a of the first anode gasket set 1113 (see, for example, Figures 11A, 23, and 24) to the area inside the first anode gasket 1113a of the first anode gasket set 1113 without also interfering with the integrity of the seal provided by the second anode gasket 1117b of the second anode gasket set 1117 (see, for example, Figures 11A, 23, and 24). Further, the recesses 4027 and 4029 may be formed to at least surround the second fluid inlet passage 3743 and the fluid outlet passage 3745, respectively, and to have an interface with the third anode gasket 1117c of the second anode gasket set 1117 (see, for example, Figures 11A, 23, and 24).It should be noted that when the anode frame 1115 and cathode frame 1131 are stacked relative to other anode frames 1115 and cathode frames 1131 in the stack 500 (see, e.g., FIGS. 5-11A, 23, and 24), the size, shape, and location of the recesses 4019-4029 may correspond to the size, shape, and location of the protrusions 3305 and 3307 (see, e.g., FIGS. 32-36) on the cathode frame 1131 to enable the second anode gasket 1117b and the third anode gasket 1117c (see, e.g., FIGS. 11A, 23, and 24) to form corresponding seals between the anode frame 1115 and the cathode frame 1131. Thus, cross-flow between the first and second fluid inlet passages and the first and second fluid outlet passages 3715-3721, 3743, and 3745 may be prevented.

[0231] The frame 1115 may also include first fastener holes 3761 spaced at one or more intervals around the peripheral region of the frame 1115. In some embodiments, the pitch between adjacent first fastener holes 3761 may be constant (or substantially constant), although embodiments are not limited thereto. The second fastener holes 3763 and the third fastener holes 3765 may be inserted from the first fastener holes 3761 in a central portion of the frame 1115 near the second fluid inlet passage 3743 and the fluid outlet passage 3745. The pitch between adjacent second fastener holes 3763 and the pitch between adjacent third fastener holes 3765 may be smaller than the pitch(es) between adjacent first fastener holes 3761. In various embodiments, the first, second, and third fastener holes 3761, 3763, and 3765 can extend completely through the frame 1115 and may be countersunk relative to the surface 3701, for example. According to various embodiments, swage nuts 1135 (see, e.g., FIGS. 11A and 21) may be pressed into the counterbore of, for example, first fastening hole 3761, second fastening hole 3763, and third fastening hole 3765, thereby allowing frame 1115 to be assembled as part of a repeating unit (e.g., repeating unit 503_1 in FIG. 5) or as part of anode interface assembly 509 (see, e.g., FIGS. 5-10, 47, and 48). When assembled, the first fastening hole 3761, the second fastening hole 3763, and the third fastening hole 3765 may be configured to engage with corresponding fasteners 1137, respectively (see, e.g., Figures 11A and 21), which can be received in corresponding first fastening hole 2837, second fastening hole 2839, and third fastening hole 2841 of the cathode frame 1131 (see, e.g., Figures 11A, 21, 28, 29, 32, 33, and 35).

[0232] According to some embodiments, the frame 1115 and / or the anode annular insert 1118 may be formed of any suitable thermoplastic and / or thermoset material, such as, for example, PET, PC, PI, PA, PMMA, PEN, PEK, PEEK, PEI, PPS, PAR, PES, COC, PVA, PS, ECTFE, PTFE, PBT, PCTFE, PETG, etc. In some cases, the frame 1115 and / or the anode annular insert 1118 may be formed of one or more metals or metal alloys, such as, for example, aluminum, aluminum alloy, copper, copper alloy, tin, tin alloy, titanium, titanium alloy, tungsten, tungsten alloy, zinc, zinc alloy, steel, stainless steel, etc. However, it should be noted that, when formed of a metal or metal alloy, the frame 1115 and / or anode annular insert 1118, in some embodiments, include a coating or other feature to, for example, electrically insulate the frame 1115 or anode annular insert 1118 from the corresponding anode PTL (e.g., anode PTL 1109 in FIG. 11A ) and / or its associated anode field (e.g., anode field 1111 in FIG. 11A ). It is also contemplated that the base material of the frame 1115 and / or anode annular insert 1118 may be coated, for example, with one or more other materials, such as one or more corrosion-resistant materials. That said, in some cases, the anode annular insert 1118 may be formed of one or more materials having the same, substantially the same, or at least similar chemical inertness as the PTL 1109. Thus, the anode annular insert 1118 may have a porous or non-porous configuration. In any case, the frame 1115 and / or anode annular insert 1118 may be formed by any suitable method, such as additive manufacturing, injection molding, compression molding, stamping, casting, machining, or the like.

[0233] Separator Plate FIG. 43 shows a plan view of a separator plate of one example of the representative repeat unit of FIG. 11A.

[0234] The separator plate 1107 may be a generally rectangular plate-like body having a first surface 4301 (e.g., a top surface) opposing a second surface in the axial direction 4303. While the separator plate 1107 is described as having a generally rectangular plate-like configuration, embodiments are not limited thereto and any suitable geometric configuration may be utilized, such as a generally circular, oval, triangular, pentagonal, or hexagonal configuration. For convenience, the separator plate 11070 will be described with reference to a generally rectangular configuration. The first surface 4301 and the second surface may be bounded by one or more peripheral surfaces, such as peripheral surfaces (or surfaces) 4305, 4307, 4309, and 4311, which may be connected to each other via one or more other peripheral surfaces, such as peripheral surface (or surface) 4313. The separator plate 1107 may have terminals 4307t protruding from the peripheral surface 4307. It should be noted that if a corresponding separator plate (such as separator plate 1107) is interposed between adjacent cells in stack 500 (see FIGS. 5-10), the corresponding voltage drop between the adjacent separator plates (and thereby associated with each corresponding cell between the adjacent separator plates) may be probed via a respective terminal (e.g., terminal 4307t) of the corresponding separator plate, e.g., separator plate 1107 (see also FIG. 7). In some embodiments, separator plate 1107 may have a symmetrical configuration about one or more reference planes that are perpendicular to axial direction 4303. For example, the configuration of separator plate 1107 may be symmetrical about one or both of reference planes 4315 and 4317 (apart from the presence of terminal 4307t), although embodiments are not limited thereto.

[0235] According to various implementations, the separator plate 1107 includes first openings 4319 and 4321 adjacent the periphery 4305, second openings 4323 and 4325 adjacent the periphery 4309, a third opening 4327 adjacent the periphery 4305, and a fourth opening 4329 adjacent the periphery 4309. The openings 4319 and 4321 may be sized, shaped, and positioned to correspond to the size, shape, and location of the protrusion 3305 (see, e.g., FIGS. 32 and 33) adjacent the periphery 2805 of the cathode frame 1131 such that when the separator plate 1107 is incorporated as part of a repeating unit (e.g., repeating unit 1100 of FIG. 11A ), the protrusion 3305 adjacent the periphery 2805 of the cathode frame 1131 can be received in the openings 4319 and 4321 (see also FIG. 23 ). Similarly, the openings 4323 and 4325 may be sized, shaped, and positioned to correspond to the size, shape, and location of the protrusion 3305 adjacent the peripheral surface 2809 of the cathode frame 1131 (see, for example, Figures 32 and 33), such that when the separator plate 1107 is incorporated as part of a repeating unit (e.g., repeating unit 1100 in Figure 11A), the protrusion 3305 adjacent the peripheral surface 2809 of the cathode frame 1131 can be received in the openings 4323 and 4325. Additionally, the openings 4327 and 4329 may be sized, shaped, and positioned to correspond to the size, shape, and location of the protrusions 3307 adjacent the peripheral surfaces 2805 and 2809 of the cathode frame 1131 (see, e.g., FIGS. 24, 32, and 33) such that when the separator plate 1107 is incorporated as part of a repeating unit (e.g., repeating unit 1100 of FIG. 11A), the protrusions 3307 adjacent the peripheral surfaces 2805 and 2809 of the cathode frame 1131 may be received in the openings 4327 and 4329 (see also FIG. 24). The relative dimensions between the openings 4319-4329 and the first and second protrusions 3305 and 3307 have already been described in connection with the cathode frame 1131 and will not be repeated here to avoid obscuring the embodiments described herein.In this manner, when a repeating unit (e.g., repeating unit 1100 of FIG. 11A) is assembled, e.g., assembled in a compressed state (see also FIGS. 20-24), a first surface 4301 of separator plate 1107 may abut surface 3701 of anode frame 1115 (see, e.g., FIGS. 23, 24, 37, and 38), and a second surface of separator plate 1107 may abut surface 2801 of cathode frame 1131 (see, e.g., FIGS. 23, 24, 32, and 33).

[0236] The separator plate 1107 may also include first fastener holes 4331 spaced at one or more intervals about the peripheral region of the separator plate 1107. In some embodiments, the pitch between adjacent first fastener holes 4331 may be constant (or substantially constant), although embodiments are not limited thereto. The second fastener holes 4333 and the third fastener holes 4335 may be inserted from the first fastener holes 4331 near the third opening 4327 and the fourth opening 4329 in a central portion of the separator plate 1107. The pitch between adjacent second fastener holes 4333 and the pitch between adjacent third fastener holes 4335 may be smaller than the pitch(es) between adjacent first fastener holes 4331. In various embodiments, the first fastening hole 4331, the second fastening hole 4333, and the third fastening hole 4335 may extend completely through the separator plate 1107, such that when the separator plate 1107 is assembled as part of a repeating unit (e.g., repeating unit 1100 of FIG. 11A), the fasteners 1137 extending from the cathode frame 1131 may extend through the separator plate 1107 and may be threadably engaged with corresponding swage nuts 1135 pressed and / or clinched into the first fastening hole 3761, the second fastening hole 3763, and the third fastening hole 3765 of the anode frame 1115 (see also FIG. 11A and FIG. 21).

[0237] According to various embodiments, one or more of the first fastening hole 4331, the second fastening hole 4333, and the third fastening hole 4335 may be sized to form a respective clearance fit or interference fit with a corresponding fastener 1137 (see FIG. 11A) or a corresponding portion (e.g., shoulder portion) of the fastener 1137 (e.g., see FIG. 21) when the separator plate 1107 is assembled as part of a repeating unit (e.g., repeating unit 1100 of FIG. 11A). In some cases, one or more of the first fastening hole 4331, the second fastening hole 4333, and the third fastening hole 4335 may be sized to form a respective clearance fit with a corresponding fastener 1137 (see FIG. 11A) or a corresponding portion (e.g., a shoulder portion) of the fastener 1137 (see FIG. 21), and one or more of the first fastening hole 4331, the second fastening hole 4333, and the third fastening hole 4335 may be sized to form a respective interference fit with a corresponding fastener 1137 (see FIG. 11A) or a corresponding portion (e.g., a shoulder portion) of the fastener 1137 (see FIG. 21). For example, the size (e.g., diameter) of each of first fastening hole 4331, second fastening hole 4333, and third fastening hole 4335 may be about 0.01% to about 10% larger (for a clearance fit) or about 0.01% to about 5% smaller (for an interference fit) than the corresponding width (e.g., diameter) of each portion (e.g., shoulder) of fastener 1137 (see, e.g., FIGS. 11A, 17, and 21).In some embodiments, when the separator plate 1107 is assembled as part of a repeating unit (e.g., repeating unit 1100 in FIG. 11A) and the stack 500 (see, e.g., FIG. 5) is in a cooled, non-operational state, one or more of the first fastening hole 4331, the second fastening hole 4333, and the third fastening hole 4335 may be sized to form a respective clearance fit with a corresponding fastener 1137 (see, e.g., FIGS. 11A, 17, and 21) or a corresponding portion (e.g., shoulder portion) of the fastener 1137 (see, e.g., FIG. 21), but when the stack 500 is in a steady-state operating state, the fastener 1137 may expand to form a corresponding interference fit with one or more of the first fastening hole 4331, the second fastening hole 4333, and the third fastening hole 4335. These clearance and / or interference fits can be utilized to constrain in-plane expansion (e.g., expansion in a plane parallel to the xy plane (see FIG. 11A)) of the anode frame 1115 and the cathode frame 1131 during operation of the stack 500 (see, e.g., FIG. 5) without overstressing the anode frame 1115 and the cathode frame 1131.

[0238] It should be noted that when the separator plate 1107 is assembled as part of a repeating unit (e.g., repeating unit 1100 of FIG. 11A ) having a cathode frame 1131 coupled to an anode frame 1115 via fasteners 1137 and swage nuts 1135 (see also FIG. 11A and FIGS. 21-24 ), some of the various gaskets of the second anode gasket set 1117 not only interpose between the surface 4301 of the separator plate 1107 and some of the various recesses in the surface 3703 of the anode frame 1115 (see, e.g., FIGS. 39 and 40 ), but may also surround various protrusions extending from the surface 2801 of the cathode frame 1131 (see, e.g., FIGS. 32 and 33 ). For example, the second gasket 1117b of the second anode gasket set 1117 (see, e.g., FIGS. 11A and 23) not only interposes between the surface 4301 of the separator plate 1107 and the corresponding recesses 4019-4025 in the surface 3703 of the anode frame 1115 (see also FIGS. 39 and 40), but also surrounds the protrusion 3305 extending from the surface 2801 of the cathode frame 1131 (see also FIGS. 32 and 33), and may fluidly seal the corresponding first fluid inlet and outlet passages between the cathode frame 1131 and the anode frame 1115 (see, e.g., the second anode gasket 1117b fluidly sealing the first fluid inlet passage 2301 shown in dashed-dot-dotted format in FIG. 23). Similarly, the third gasket 1117c of the second anode gasket set 1117 (see, e.g., FIGS. 11A and 24) not only interposes between the surface 4301 of the separator plate 1107 and the corresponding recesses 4027-4029 in the surface 3703 of the anode frame 1115 (see also FIGS. 39 and 40), but also surrounds the protrusion 3307 extending from the surface 2801 of the cathode frame 1131 (see also FIGS. 32 and 33), and may fluidly seal the corresponding second fluid inlet and outlet passages between the cathode frame 1131 and the anode frame 1115 (see, e.g., the third anode gasket 1117c fluidly sealing the second fluid inlet passage 2401 shown in dashed-dotted-dotted format in FIG. 24).

[0239] According to various embodiments, separator plate 1107 may be formed of any suitable thermoplastic and / or thermoset material, such as PET, PC, PI, PA, PMMA, PEN, PEK, PEEK, PEI, PPS, PAR, PES, COC, PVA, PS, ECTFE, PTFE, PBT, PCTFE, PETG, etc. In some cases, separator plate 1107 may be formed of one or more metals or metal alloys, such as, for example, aluminum, aluminum alloy, copper, copper alloy, tin, tin alloy, titanium, titanium alloy, tungsten, tungsten alloy, zinc, zinc alloy, steel, stainless steel, etc. For example, in one embodiment, separator plate 1107 may be formed of titanium, which may increase the strength and rigidity of a repeating unit, such as repeating unit 1100 of FIG. 11A , as well as enable electrical conduction between adjacent cells of stack 500 (see, e.g., FIGS. 5 and 7 ). In some embodiments, the material(s) and / or configuration of the separator plate 1107 may be stronger and / or more rigid than the material(s) and / or configuration of the anode frame 1115 and the cathode frame 1131 (see also FIG. 11A ). In some cases, the electrical conductivity of the separator plate 1107 may be greater than the corresponding electrical conductivity of the anode frame 1115 and the cathode frame 1131 (see also FIG. 11A ). It is also contemplated that the base material of the separator plate 1107 may be coated with, for example, one or more other materials, e.g., one or more corrosion-resistant materials. In any case, the separator plate 1107 may be formed by any suitable method, such as additive manufacturing, injection molding, compression molding, stamping, casting, machining, etc.

[0240] Cathode Interface Assembly FIG. 17 illustrates the exemplary multi-cell CO XFigure 18 shows an exploded view of an exemplary cathode interface assembly of an electrolyzer stack. Figure 18 shows an example of the cathode interface assembly of Figure 17 in an unexploded state. Figures 45 and 46 show top and bottom views of an exemplary cathode interface separator of the exemplary cathode interface assembly of Figure 18.

[0241] As seen in FIGS. 5-10, 17, and 18, the cathode interface assembly 505 may include components equivalent to the cathode component 1103 of the repeat unit 1100 described in connection with FIG. 11A, except that the cathode interface assembly 505 may include a cathode interface separator 1701, a third cathode gasket 1703, and a fourth cathode gasket 1705. Accordingly, redundant descriptions of the equivalent components will be omitted so as not to obscure the embodiments disclosed herein. However, it should be noted that instead of the cathode frame 1131 being coupled to the anode frame 1115 as in the repeat unit 1100 (see FIG. 11A), the cathode frame 1131 may be coupled to the cathode interface separator 1701. This will be described in more detail in connection with FIGS. 45 and 46.

[0242] 45 and 46, the cathode interface separator 1701 may be a generally rectangular plate-like body having a first surface 4501 (e.g., a top surface) and an opposing second surface 4503 (e.g., a bottom surface) in the axial direction 4601. While the cathode interface separator 1701 is described as having a generally rectangular plate-like configuration, embodiments are not limited thereto and any suitable geometric configuration may be utilized, such as a generally circular, oval, triangular, pentagonal, or hexagonal configuration. For convenience, the cathode interface separator 1701 will be described in connection with a generally rectangular configuration. The first surface 4501 and the second surface 4503 may be bounded by one or more peripheral surfaces, such as peripheral surfaces (or surfaces) 4505, 4507, 4509, and 4511, which may be connected to one another via one or more other peripheral surfaces, such as peripheral surface (or surface) 4513. In some embodiments, cathode interfacial separator 1701 may have a configuration that is symmetrical about one or more reference planes that are perpendicular to axial direction 4601. For example, the configuration of cathode interfacial separator 1701 may be symmetrical about either or both of reference planes 4603 and 4605, although embodiments are not limited thereto.

[0243] According to various embodiments, cathode interfacial separator 1701 may include first fluid inlet passages 4515 and 4517 adjacent peripheral edge 4505 and first fluid outlet passages 4519 and 4521 adjacent peripheral edge 4509. With further reference to FIGS. 5-11A , first fluid inlet passages 4515 and 4517 may form part of inlet passages 1001 and 1003 of stack 500 in association with inlet connector 543 of manifold assembly 515, thereby providing input water to, for example, anode frame 1115 of stack 500 and thereby corresponding anode basins 1111 of a plurality of cells, such as cell 501. The first fluid outlet passages 4519 and 4521 may form part of the outlet passages of the stack 500 that output water from the anode frame 1115 and thereby from the corresponding anode basins 1111 of the plurality of cells, such as cell 501 (see, e.g., FIGS. 5-11A ) (which are similar to the inlet passages 1001 and 1003, but associated with the outlet connectors 545 and inlet connectors 543 of the manifold assembly 515). In some implementations, the first fluid inlet passages and first fluid outlet passages 4515-4521 may be defined by respective plurality of holes that are separated from one another via corresponding partitions. For example, first fluid inlet passage 4515 may include first and second inlet holes 4515a and 4515b separated from one another by partition wall 4501s1, and first fluid outlet passage 4519 may include first and second outlet holes 4519a and 4519b separated from one another by partition wall 4501s2. Similar to anode frame 1115 and cathode frame 1131 (see, e.g., FIG. 11A), the presence of these partition walls, e.g., partition walls 4501s1 and 4501s2, may increase the structural rigidity and thereby reliability of cathode interfacial separator 1701 in the vicinity of first fluid inlet and outlet passages 4515-4521.

[0244] The cathode interface separator 1701 may further include a second inlet passage 4523 and an outlet passage 4525 that, in conjunction with the inlet connector 547 and the outlet connector 549 of the manifold assembly 515, form part of the inlet passage 901 and the outlet passage 903 (e.g., FIG. 9), respectively, of the stack 500 (see, e.g., FIGS. 5 and 9). When the cathode interface separator 1701 is incorporated as part of a cell, e.g., a cell formed between the cathode interface assembly 505 and the repeat unit 503_1 (see, e.g., FIGS. 5-11A and 19), the inlet passage 901 (see FIG. 9) may supply one or more reactants (e.g., gaseous COx) to the various cathode frames 1131 (e.g., see, e.g., FIGS. 5 and 9) of the stack 500 and the corresponding cathode flow areas 1127 supported therein. However, the outlet passage 903 allows for the supply of CO X One or more by-products of the reduction process can be discharged from the various cathode frames 1131 of the stack 500 and, thereby, from the corresponding cathode basins 1127 supported in association therewith (see, e.g., Figures 5-11A and Figure 19).

[0245] Similar to the anode frame 1115 (see, e.g., Figures 11A, 37, and 38), the cathode interface separator 1701 may also include recesses 4527-4537 in the surface 4501, which may be configured to receive corresponding portions of gaskets 553 and 555, respectively, when the cathode interface assembly 505 is assembled as part of the stack 500, e.g., when the cathode interface assembly 505 is stacked against the manifold assembly 515 with the bus plate 513 interposed therebetween (see, e.g., Figures 5-10, 17, and 18). For example, recesses 4527-4533 may be formed to surround the periphery of first fluid inlet and outlet passages 4515-4521, respectively, and to interface with corresponding gaskets 553 (which may surround third fluid outlet port 1225 and fluid inlet port 1229, respectively, of manifold assembly 515 (see, e.g., FIG. 12 )), and recesses 4535 and 4537 may be formed to surround the periphery of second fluid inlet and outlet passages 4535 and 4537, respectively, and to interface with corresponding gaskets 553. The gaskets 555 may surround the fourth fluid outlet port 1239 and inlet port 1237 of the manifold assembly 515, respectively (see, e.g., FIG. 12). Thus, when the cathode interface assembly 505 is assembled as part of the stack 500 (see, e.g., FIGS. 5-10), corresponding fluid seals may be formed at the respective outlet and inlet ports of the manifold assembly 515 (see, e.g., FIGS. 5-10).

[0246] 46, the second surface 4503 may include first recesses 4607-4613 surrounding the first fluid inlet and outlet passages 4515-4521, respectively, and may also include second recesses 4615 and 4617 surrounding the second fluid inlet and outlet passages 4535 and 4537, respectively. In some embodiments, the first and second recesses 4607-4617 may be recessed into the surface 4503 by a depth equal to (or substantially equal to) the height 3401 of the first and second protrusions 3305 and 3307 of the cathode frame 1131 (see FIG. 34), although the embodiments are not limited thereto. For example, the depth to which the first and second recesses 4607-4617 extend into the surface 4503 may be greater or less than the height 3401 (see FIG. 34), provided that a sufficient fluid seal may be formed between the cathode interface separator 1701 and the cathode frame 1131 when a cell is formed between the cathode interface assembly 505 and the repeat unit 503_1 (see also FIGS. 5-10 and 17). In other words, the depth of the first and second recesses 4607-4617 may allow at least a portion of the first protrusion 3305 and the second protrusion 3307 of the cathode frame 1131 to be received therein when a cell is formed between the cathode interface assembly 505 and the repeat unit 503_1 (see also FIGS. 5-10). With this in mind, the first recesses and second recesses 4607-4613 can be sized and shaped to have interfaces with corresponding protrusions between the first protrusion 3305 and second protrusion 3307 of the cathode frame 1131 (see Figures 32-33).

[0247] The cathode interfacial separator 1701 may further include third recesses 4619-4625 in the surface 4503 surrounding the first fluid inlet and outlet passages 4515-4521 and associated recesses 4607-4613, respectively, and may also include fourth recesses 4627 and 4629 surrounding the second fluid inlet and outlet passages 4523 and associated recesses 4615-4617, respectively. It should also be noted that the third and fourth recesses 4619-4629 are sized, shaped, and positioned to further correspond to the size, shape, and position (see Figures 32-33) of the protrusions 3305 and 3307 of the cathode frame 1131, respectively, when a cell is formed between the cathode interface assembly 505 and the repeating unit 503_1 (see also Figures 5-10, 32, and 33), so that the third cathode gasket 1703 and the fourth cathode gasket 1705 can form corresponding seals between the cathode interface separator 1701 of the cathode frame 1131 and the first protrusion 3305 and the second protrusion 3307. Therefore, the combination of the first and second recesses 4607-4617 of the cathode interface separator 1701, the third and fourth recesses 4619-4629 of the cathode interface separator 1701, the first and second protrusions 3305 and 3307 of the cathode frame 1131 (see Figures 32-33), and the third and fourth cathode gaskets 1703 and 1705 can prevent cross-flow between the first fluid inlet passage and the second fluid outlet passage 4515-4525. It should also be noted that when a cell is formed between the cathode interface assembly 505 and the repeat unit 503_1 (see, for example, Figures 5-10), the second cathode gasket 1133 may be interposed between the surface 4503 in the cathode frame 1131 and the central portion of the recess 3303 (see Figures 17, 32, and 33) to form a fluid seal around the cathode flow area 1127 that is at least partially supported within the opening in the cathode frame 1131.In this way, the corresponding surface of the cathode flow field 1127 may abut against the surface 4503 of the cathode interface separator 1701 and the surface of the cathode flow field 1127 opposite the surface of the cathode GDL 1121, similar to how the corresponding surface of the cathode flow field 1127 may abut against the surface of the cathode GDL 1121 and the surface of the separator plate 1107 of the integrated MEA assembly 1119 (e.g., as described in connection with Figures 5-11A, Figure 23, and Figure 24).

[0248] The cathode interface separator 1701 may include first threaded fastening holes 4539 spaced at one or more intervals about the peripheral region of the cathode interface separator 1701. In some embodiments, the pitch between adjacent first fastening holes 4539 may be constant (or substantially constant), although embodiments are not limited thereto. The cathode interface separator 1701 may optionally include second threaded fastening holes 4541 and third threaded fastening holes 4543 inset from the first threaded fastening holes 4539 in a central portion of the cathode interface separator 1701 near the second fluid inlet passage 4523 and the fluid outlet passage 4525. The pitch between adjacent second threaded fastening holes 4541 and the pitch between adjacent third threaded fastening holes 4543 may be smaller than the pitch(es) between adjacent first threaded fastening holes 4539. In some embodiments, one or more of the first fastening hole, second fastening hole, and third threaded fastening hole 4539-4543 may be formed similarly to the first fastening hole, second fastening hole, and third fastening hole 3761-3765 of the anode frame 1115 (see, for example, Figures 11A and 37-42), thereby including a swage nut 1135 for the threaded fastening. In any event, when the cathode interface separator 1701 is assembled as part of the cathode interface assembly 505 (see also FIGS. 5-10 ), the first threaded fastening hole 4539, the second threaded fastening hole 4541, and the third threaded fastening hole 4543 may be configured to be received in and engage with corresponding fasteners 1137 extending from corresponding first fastening hole 2837, second fastening hole 2839, and third fastening hole 2841, respectively, in the cathode frame 1131 (see FIGS. 28 , 29 , 32 , 33 , and 35 ). Additionally, as can be seen from at least FIG. 17 , the cathode frame 1131 of the cathode interface assembly 505 may be coupled to the cathode interface separator 1701 via second, third, and fourth cathode gaskets 1133, 1703, and 1705.

[0249] According to various embodiments, the cathode interface separator 1701 may be formed of any suitable thermoplastic and / or thermoset material, such as PET, PC, PI, PA, PMMA, PEN, PEK, PEEK, PEI, PPS, PAR, PES, COC, PVA, PS, ECTFE, PTFE, PBT, PCTFE, PETG, etc. In some cases, the cathode interface separator 1701 may be formed of one or more metals or metal alloys, such as, for example, aluminum, aluminum alloys, copper, copper alloys, tin, tin alloys, titanium, titanium alloys, tungsten, tungsten alloys, zinc, zinc alloys, steel, stainless steel, etc. For example, in one embodiment, the cathode interface separator 1701 may be formed of titanium, which may increase the strength and rigidity of the cathode interface assembly 505 (see, e.g., FIGS. 5-10, 17, and 18). In some cases, the material(s) and / or configuration of the cathode interfacial separator 1701 may be stronger and / or more rigid than the material(s) and / or configuration of the anode frame 1115 and the cathode frame 1131 (see also FIG. 11A). Also, in some embodiments, the electrical conductivity of the cathode interfacial separator 1701 may be greater than the corresponding electrical conductivity of the anode frame 1115 and the cathode frame 1131 (see also FIG. 11A). It is also contemplated that the base material of the cathode interfacial separator 1701 may be coated with, for example, one or more other materials, e.g., one or more corrosion-resistant materials. In either case, the cathode interfacial separator 1701 may be formed by any suitable method, such as additive manufacturing, injection molding, compression molding, stamping, casting, machining, etc.

[0250] Anode Interface Assembly FIG. 47 illustrates the exemplary multi-cell CO X Figure 48 shows an exploded view of an exemplary anode interfacial assembly of an electrolyzer stack. Figure 48 shows the exemplary anode interfacial assembly of Figure 47 in an assembled state. Figure 44 shows the exemplary anode interfacial separator of Figure 47.

[0251] As seen in at least FIGS. 5, 6, 11A, 44, 47, and 48, the anode interface assembly 509 may include components equivalent to the anode component 1101 of the repeat unit 1100, and the anode interface assembly 509 may omit the third anode gasket 1117c of the second anode gasket set 1117 and include an anode frame 4701 in place of the anode frame 1115. Accordingly, redundant descriptions of equivalent components will be omitted so as not to obscure the embodiments disclosed herein. Additionally, the anode interface assembly 509 may include an anode interface separator 4703, which may be configured substantially identically to the separator plate 1107 of the repeat unit 1100, although the anode interface separator 4703 may not include the openings / holes 4319-4335 (see FIG. 43). It should also be noted that anode frame 4701 may be substantially equivalent to anode frame 1115 (see also Figures 37-42), but anode frame 4701 may omit second fluid inlet and outlet passages 3743 and 3745, recesses 4027 and 4029 in surface 3703, and first fastening hole 3761, second fastening hole 3763, and third fastening hole 3765, and swage nut 1135. Thus, instead of the anode frame 4701 being coupled to an adjacent cathode frame, such as the cathode frame 1115, as in at least the repeat unit 1100 described in connection with FIG. 11A, the anode frame 4701 may simply be interposed between the integrated MEA assembly 1119_n of the repeat unit 503_n and the anode interfacial separator 4703 when the anode interfacial assembly 509 is incorporated as part of the stack 500 (see also FIGS. 5-10).In this manner, the second anode gasket 1113b and the third anode gasket 1113c of the first anode gasket set 1113 may have interfaces with recesses in the surface 4701a of the anode frame 4701, similar to the recesses 3749-3759 in the surface 3701 of the anode frame 1115, and may abut against the surface 2803 of the cathode frame 1131 of the repeating unit 503_n around the first and second fluid inlet and outlet passages 2815-2821 (see also Figures 28-36). Furthermore, the first anode gasket 1113a of the first anode gasket set 1113 can have an interface with a recess in the surface 4701a of the anode frame 4701, similar to the recess 3747 in the surface 3701 of the anode frame 1115, and can abut a corresponding surface of the support frame 1125 of the integrated MEA assembly 1119 (see also Figures 25-27), and can surround an opening 1125a in the support frame 1125 (see also Figures 25-27). Similarly, the first and second anode gaskets 1117a and 1117b of the second anode gasket set 1117 may simply interface with recesses in surface 4701b of anode frame 4701, similar to recesses 4017-4025 in surface 3703 of anode frame 1115 (see also Figures 39, 40, and 42), and may abut against first surface 4703a of anode interfacial separator 4703.

[0252] Bladder As previously mentioned, the bladder side assembly 511 (see, e.g., FIG. 5) includes at least X During the reduction process(es), the stack 500 may be configured to constrain axial expansion of the plurality of cells, e.g., cell 501, in a manner that prevents or reduces the likelihood of the plurality of cells being overly compressed or undercompressed, but maintains corresponding fluid seals and electrical conductivity between associated components of the stack 500. These features may be provided by the combination of the bladder bus plate 521, the insulating plate 523, the end plate 525, the gaskets 559 and 561, and the fluid inlet connector 563 (see, e.g., FIGS. 5-10 ).

[0253] FIG. 86 illustrates the exemplary multi-cell CO X 87 shows a plan view of an exemplary insulating plate of an electrolysis device. FIG. 87 shows a cross-sectional view of the insulating plate of FIG. 86 taken along section line 87-87. FIG. 88 shows an exemplary multi-cell CO X 89 shows a plan view of an exemplary end plate of an electrolysis device. FIG. 89 shows a cross-sectional view of the exemplary end plate of FIG. 88 taken along section line 89-89. FIG. 90 shows an enlarged portion of the cross-sectional view of FIG. 9.

[0254] 86 and 87, insulating plate 523 may be a generally rectangular plate-like body having a first surface 8601 (e.g., a top surface) and an opposing second surface 8603 (e.g., a bottom surface) in axial direction 8605. While insulating plate 523 is described as having a generally rectangular plate-like configuration, embodiments are not limited thereto and any suitable geometric configuration may be utilized, such as a generally circular, oval, triangular, pentagonal, hexagonal, or the like. For convenience, insulating plate 523 will be described with reference to a generally rectangular configuration. First surface 8601 and second surface 8603 may be bounded by one or more perimeter surfaces, such as perimeter surfaces (or surfaces) 8607, 8609, 8611, and 8613, which may be connected to one another via one or more other perimeter surfaces, such as perimeter surface (or surface) 8615. In some embodiments, insulating plate 523 may have a symmetric configuration about one or more reference planes perpendicular to axial direction 8605. For example, insulating plate 523 may have a configuration symmetric about one or both of reference planes 8617 and 8619, although embodiments are not limited thereto.

[0255] According to various implementations, insulating plate 523 includes a first recess 8621 in a central portion of surface 8601. First recess 8621 may not only terminate at surface 8601 but also include extension portions 8625 and 8627 extending from the central region of first recess 8621 toward peripheral surfaces 8609 and 8613, respectively. The size, shape, and position of first recess 8621 may be configured so that at least a portion of bus plate 521 (see, e.g., FIGS. 5-10 ) is received therein when stack 500 is assembled. In this manner, a corresponding portion of terminal portion 521t of bus plate 521 (see, e.g., FIGS. 5-10 ) may be received in either extension portions 8625 and 8627. The central region of first recess 8621 may include a second recess 8629 in its peripheral region. The second recess 8629 may be configured to interface with the gasket 559 (see, e.g., FIGS. 5 and 90), such that when the bus plate 521 and the insulating plate 523 are assembled as part of the stack 500, the lower surface 521b (see FIG. 90) of the bus plate 521 may abut at least the gasket 559, and depending on the degree of compression of the various components of the stack 500, may abut the surface 8623 of the insulating plate 523 (as shown in FIG. 90) or may be axially spaced apart from the surface 8623, which may extend parallel (or substantially parallel) to the z-axis direction shown in FIGS. 5 and 90, and may be the same as the axial direction 8605. As will become more apparent below, the axial distance 8605 between the lower surface 521b of the bus plate 521 and the surface 8623 of the insulating plate 523 is X During the reduction process(es), axial expansion of a plurality of cells, such as cell 501 of stack 500 (see, e.g., FIGS. 5-10 ), may be controlled to be inhibited, thereby maintaining corresponding fluid seals and electrical conductivity between associated components of stack 500, while in this manner preventing or reducing the likelihood of the plurality of cells (and associated components of the cells) becoming overly compressed.

[0256] For example, one or more control fluids (e.g., gaseous CO ) may be disposed between the bus plate 521 and the insulating plate 523. X) may be introduced to adjust the distance between the underside 521b of the bus plate 521 and the surface 8623 of the insulating plate 523. In some embodiments, one or more control fluids may be provided via holes 8631 in the surface 8623 extending through the insulating plate 523 to the surface 8603. The size, shape, and location of the holes 8631 may correspond to the size, shape, and location of the blind holes 8801 in the surface 525a of the end plate 525 (see FIGS. 88-90). The blind holes 8801 in the end plate 525 may be fluidly connected to the fluid inlet connector 563 via fluid passages 8803, as seen in FIGS. 88-90. In this manner, one or more control fluids may be caused to flow between the bus plate 521 and the insulating plate 523 via the combination of the fluid inlet connector 563, the fluid passages 8803, the blind holes 8801, and the holes 8631, and one or more sources 9001 of control fluid (see FIG. 90). In some embodiments, the source of one or more control fluids 9001 may be, for example, gaseous CO X to second fluid inlet connector 547 (see FIG. 5 ). Regardless of the source, the distance between lower surface 521 b of bus plate 521 and surface 8623 of insulating plate 523 may be controlled based on the accumulated pressure of one or more control fluids in the region between lower surface 521 b of bus plate 521 and surface 8623 of insulating plate 523, which region is peripherally bounded by gasket 559 (see also FIGS. 5 and 90 ). In this manner, adjusting the distance between lower surface 521 b of bus plate 521 and surface 8623 of insulating plate 523 can be utilized to constrain axial expansion of multiple cells, such as cell 501, during operation. This can help maintain corresponding fluid seals and electrical conductivity between associated components of stack 500 (see, e.g., FIG. 5 ).

[0257] According to some embodiments, when the pressure built up in the region between the underside 521b of the bus plate 521 and the surface 8623 of the insulating plate 523 builds above a determined threshold, the distance between the underside 521b of the bus plate 521 and the surface 8623 of the insulating plate 523 may increase to a point where the fluid seal formed between the gasket 559 and the underside 521b of the bus plate 521 may be compromised. If the fluid seal formed between the gasket 559 and the underside 521b of the bus plate 521 is compromised, at least a portion of one or more control fluids may escape (or ooze) from the region between the underside 521b of the bus plate 521 and the surface 8623 of the insulating plate 523, which may cause the built up pressure to decrease along with the distance between the underside 521b of the bus plate 521 and the surface 8623 of the insulating plate 523. In some embodiments, the insulating plate 523 and / or the end plate 525 may be configured with one or more fluid passages interfacing with relief valves configured to vent excess pressure, constructed in the region between the underside 521b of the bus plate 521 and the surface 8623 of the insulating plate 523, thereby preventing over-compression of various components of the stack 500 (see, e.g., FIG. 5).

[0258] In some embodiments, surface 525a of end plate 525 (see FIG. 88) may include a recess 8805 surrounding blind hole 8801. Recess 8805 may be configured to interface with gasket 561 (see, e.g., FIGS. 5 and 90), such that when insulating plate 523, end plate 525, gasket 565, and gasket 561 are assembled as part of stack 500 (see, e.g., FIGS. 5 and 90), gasket 561 may not only be interposed between insulating plate 523 and end plate 525, but may also form a fluid seal between hole 8631 of insulating plate 523 and blind hole 8801 of end plate 525. The fluid seal between hole 8631 of insulating plate 523 and blind hole 8801 of end plate 525 may be strengthened via connection between insulating plate 523 and end plate 525. As such, insulating plate 523 may include a plurality of fastener holes 8633 (which may be countersunk relative to surface 8601) that allow first fasteners 535 (see FIG. 5) to extend through insulating plate 523 and engage corresponding fastener holes 8807 (see FIG. 88) in end plate 525. While only one set of mating holes configured to allow one or more control fluids to enter the region between underside 521 b of bus plate 521 and surface 8623 of insulating plate 523 is shown in FIGS. 86-90, insulating plate 523 and end plate 525 may be configured with a plurality of mating holes. In some cases, the plurality of mating holes may be provided and positioned around a central region of recess 8621 in insulating plate 523, e.g., at regular (or substantially regular) rotational angles about a reference axis coincident with axial direction 8605. Such a configuration may allow a more uniform axial force to be exerted on bus plate 521 as pressure builds in the area between lower surface 521b of bus plate 521 and surface 8623 of insulating plate 523.

[0259] According to various embodiments, source 9001 is gaseous CO Xat a first pressure to second fluid inlet connector 547 (see, e.g., FIGS. 5-9 ), and one or more control fluids (e.g., gaseous COx) at a second pressure to fluid inlet connector 563 (see, e.g., FIGS. 5-9 and 90 ). In some embodiments, the first pressure and the second pressure may be equal or substantially equal. In some cases, source 9001 may be configured to control (e.g., adjust) one or more of the first pressure and the second pressure based on a condition of stack 500, e.g., based on the degree of axial expansion of cells of stack 500, based on accumulated pressure in a region between lower surface 521 b of bus plate 521 and surface 8623 of insulating plate 523, based on the temperature of one or more components of stack 500, etc. (see also FIGS. 5-10 ). Thus, the first pressure and the second pressure may reach equilibrium depending on, for example, a steady state, such as a steady operating condition, of stack 500. Also, the source 9001 initially supplies gaseous CO X into a second fluid inlet connector 547 (see, e.g., FIGS. 5-9), and one or more control fluids (e.g., gaseous CO X ) to the fluid inlet connector 563 (e.g., see FIGS. 5-9 and 90) a second time. In some embodiments, the first and second times may occur simultaneously or substantially simultaneously. In some cases, the source 9001 may be configured to delay the supply of one or more control fluids to the fluid inlet connector 563 (e.g., see FIGS. 5-9 and 90) relative to the supply of gaseous COx to the second fluid inlet connector 547 (e.g., see FIGS. 5-9). For example, with reference to FIGS. 5-9 and 90, the source 9001 may be configured to delay the supply of one or more control fluids to the fluid inlet connector 563 until one or more conditions are met, e.g., until the degree of expansion of one or more of the cells of the stack 500 in the axial direction reaches one or more defined thresholds, until the temperature of one or more components of the stack 500 reaches one or more defined thresholds, until the flow of gaseous COx to the second fluid inlet connector 547 reaches steady-state condition(s), etc.

[0260] 86, 88, and 90, insulating plate 523 may include a plurality of datum openings 8635 configured to receive and support portions of datum rod 557 therein, and end plate 525 may further include a fluid inlet port 8809 configured to interface with fluid inlet connector 563. Fluid inlet port 8809 may include a threaded region 8809t, which may be configured to engage with a respective threaded region of fluid inlet connector 563. Alternatively, fluid inlet connector 563 may be welded, e.g., sweat welded, thereby omitting fluid inlet port 8809 and threaded portion 8809t.

[0261] Anode Basin FIG. 83 illustrates the exemplary multi-cell CO X 84A and 84B show plan views of a portion of an exemplary anode basin of an electrolysis device, respectively, taken along section lines 84A-84A and 84B-84B of the exemplary anode basin of FIG. 83, according to some embodiments.

[0262] 11A, 83, 84A, and 84B, the anode flow area 1111 may be a generally rectangular plate-shaped body including a plurality of protrusions 8301 axially protruding from a surface 8303 of a body portion 8305, which may extend parallel to the z-axis direction. In some embodiments, the protrusions 8301 may be rectangular prisms having a length 8307 transverse to the axial direction in a first direction (e.g., the x-axis direction), a width 8309 axially and transverse to the first direction in a second direction (e.g., the y-axis direction), and an axial height 8311, although embodiments are not limited thereto. For example, one or more of the protrusions 8301 may alternatively be formed as cylindrical prisms, triangular prisms, pentagonal prisms, and / or the like. The protrusions 8301 may be spaced apart from one another by a pitch 8313 in a first direction and a pitch 8315 in a second direction. While the protrusions 8301 are shown arranged in multiple parallel rows and columns, this is not a limiting embodiment. For example, adjacent rows and / or columns of protrusions 8301 may be offset from one another, as shown in FIG. 85A with respect to protrusion 8501. In some cases, the pitches 8313 and 8315 may be equal (or substantially equal) to one another, although this is not a limiting embodiment. In this manner, fluid passages 8317 may be formed between adjacent protrusions 8301, thereby forming flow paths through which water (or other anolyte) may be distributed and flow, generally from the supply channels 3733 of the anode frame 1115 to the collection channels 3735 of the anode frame 1115 (see FIGS. 37-42), thereby providing water to the anode PTL 1109 and, thereby, to the anode side of the MEA 1105 (see FIG. 11A).

[0263] Although the anode field 1111 has been described as having a generally rectangular plate-like body, any suitable geometric configuration may be utilized. For example, the anode field 1111 may have a generally circular, oval, triangular, pentagonal, hexagonal, or other configuration. Regardless of the configuration utilized, the anode field 1111 may be at least partially supported in an opening 3723 (see, e.g., Figures 23, 24, and 37-42) within the anode frame 1115. Furthermore, while the anode field 1111 has been described in connection with a pin-type implementation, embodiments are not limited thereto. Any other suitable anode field design may be utilized, such as, for example, parallel, serpentine, interdigitated, spiral, radial, etc. Examples of rotating pin-type embodiments are described in further detail with reference to Figures 85A-85C.

[0264] FIG. 85A illustrates the exemplary multi-cell CO X 85B and 85C show plan views of a portion of an exemplary anode basin of an electrolysis device, respectively, taken along section lines 85B-85B and 85C-85C, respectively, of the exemplary anode basin of FIG.

[0265] 11A and 85A-85C, the anode flow area 1111 may be formed in the same manner as described in connection with FIGS. 83, 84A, and 84B, except that the plurality of protrusions 8501 in FIGS. 85A-85C may be rotated by an angle 8503 relative to a first direction (e.g., the x-axis direction) such that the leading vertices 8501a of the protrusions 8501 divide and distribute the input anolyte flow 8505. Additionally, adjacent rows and columns of the protrusions 8501 may be offset from one another. For example, adjacent rows may be offset from one another in a first direction transverse to the axial direction (e.g., the z-axis direction) by an offset amount 8507, and adjacent columns may be offset from one another in a second direction transverse to the axial direction and the first direction (e.g., the y-axis direction) by an offset amount 8509. In some cases, offset amounts 8507 and 8509 may be equal (or substantially equal) to one another, although embodiments are not limited thereto.

[0266] Similar to the protrusions 8301 described in connection with FIGS. 83, 84A, and 84B, the protrusions 8501 may protrude axially from the surface 8511 of the body portion 8513 and may extend parallel (or substantially parallel) to the z-axis direction. As shown in FIGS. 85A-85C, the protrusions 8501 may be, but are not limited to, diamond-shaped prisms having respective lengths 8515 in a first direction, corresponding widths 8517 in a second direction, and respective heights 8519 in the axial direction. For example, one or more of the protrusions 8501 may alternatively be formed as elliptical prisms, oblong prisms, lenticular prisms, sinusoidal prisms, etc. The protrusions 8501 may be spaced apart from one another by a pitch 8521 in a first direction and a pitch 8523 in a second direction. In some cases, the pitches 8521 and 8523 may be equal (or substantially equal) to one another, but embodiments are not limited thereto. In this manner, fluid passages 8525 may be formed between adjacent protrusions 8501, thereby forming a flow path through which water (or other anolyte) may be distributed and flow, generally from the supply channels 3733 of the anode frame 1115 to the collection channels 3735 of the anode frame 1115 (see Figures 37-42), thereby providing water to the anode PTL 1109 and thereby to the anode side of the MEA 1105 (see Figure 11A).

[0267] Cathode basin The use of various functions and technologies X This may help mitigate the deleterious effects of liquid water accumulation at the cathode of the electrolyzer. For example, the cathode basin 1127 may be configured with one or more structural features that may enable more effective liquid water management within the cell 501.

[0268] For example, both the anode region 1111 and the cathode region 1127 may have corresponding anode channel(s) and cathode channel(s), respectively. The cathode channel(s) may be configured to carry, for example, CO XSuch CO may contribute to more effective water evacuation in the context of an electrolyzer and / or when liquid water is collected within the cathode side of the cell 501. X It may be designed with specific properties that can mitigate potential performance degradation that may occur in the electrolysis device.

[0269] Meandering channel basin CO X Although various shapes of flow channels may be used in the electrolyzer, multiple serpentine channels generally provide CO2 transport to the cathode GDL 1121 and therefore the MEA 1105. X It offers superior performance in terms of providing reliable and uniform distribution of gas, and also facilitates reliable removal of liquid water that may accumulate within the cathode flow basin 1127 and cathode GDL 1121 (see FIG. 11A). Serpentine channels typically consist of repeated long segments running in generally parallel directions, fluidly connected by alternating shorter segments interposed therebetween, often in a switchback fashion.

[0270] For purposes of this disclosure, the term "fluidically connected" is used in reference to volumes, plenums, holes, etc. that may be structurally connected to one another in some way to form a fluid connection, similar to how the term "electrically connected" is used in reference to components connected to one another to form an electrical connection. The term "fluidically intervening," when used, may also be used to refer to a component, volume, plenum, or hole that is fluidly connected to at least two other components, volumes, plenums, or holes, such that fluid flowing from one of the other components, volumes, plenums, or holes to another of the components, volumes, plenums, or holes first flows through the "fluidically intervening" component before reaching the other or another of these components, volumes, plenums, or holes. For example, if a pump is fluidly intervening between a reservoir and an outlet, fluid flowing from the reservoir to the outlet first flows through the pump before reaching the outlet.

[0271] In a single serpentine channel configuration, larger area cells (e.g., 100 cm) 2 (larger)CO X In the context of an electrolyzer, it may have limited drainage capabilities, although in some applications, that capability may be sufficient. For example, in a single serpentine channel arrangement as shown in FIG. 49, a single continuous serpentine channel 4956 switches back a region 4952 of the cathode basin 4916 bounded by a short segment 4962 and first and last long segments 4960. Thus, the serpentine channel 4956 drains CO2 entering the corresponding cathode GDL and MEA. X 4952 is the only conduit for gas and liquid water entering the cathode basin 4916 from the cathode GDL through that region. Thus, the rate at which liquid water is added to the serpentine channel 4956 is equal to the rate at which liquid water exits region 4952 and into the cathode basin 4916. The high rate at which liquid water is introduced into such serpentine channel 4956, combined with the long average distance such water must travel to be pushed through the serpentine channel 4956 before reaching a fluid exit port, such as fluid exit port 4930, generally makes it very difficult to adequately manage the level of liquid water in the cathode basin 4916. CO 2 filtration systems using such a single-channel serpentine cathode basin 4916 X The electrolyzer may be, for example, a CO electrolyzer using a multiple serpentine channel arrangement. X Performance is significantly compromised compared to electrolysis devices. In some implementations, the single serpentine channel has a total channel length (distance from inlet to outlet) of about 12 m or less, or about 6 m or less, or about 2 m or less.

[0272] Multiple serpentine channels can refer to multiple separate serpentine channels that generally follow a common serpentine path, resulting in an interleaved or nested arrangement of the separate serpentine channels, or multiple instances of the same (or nearly identical) serpentine channel that are arranged side-by-side or flowing in parallel. Figure 50 illustrates the former arrangement, which may also be referred to herein as a nested or interleaved multiple serpentine channel arrangement. Figure 50 shows four serpentine channels that generally follow the same serpentine path (two are shown with open interiors and two with solid interiors for ease of distinction; dashed rectangles are also shown representing the combined open channel and wall footprint areas of a basin with such an arrangement). Open channel area refers to the total area through which gas can exit a basin and migrate to the GDL; for basins with constant and equal-width paths, the open channel area is typically equal to the product of the total path length of the channel(s) and the channel width. The wall footprint area of ​​a watershed refers to the area of ​​the portion of the watershed that defines the wall between adjacent portions of the watershed's channel(s) and is forced into contact with the GDL. Therefore, both areas are evaluated in the plane of the watershed that is forced into contact with the GDL. Fluid can be introduced into or removed from the serpentine channel through inlet and outlet ports (short segments ending in small, solid black circles). In Figure 51, a similar arrangement is shown for a side-by-side arrangement of four multiple serpentine channels, which may also be referred to herein as side-by-side multiple serpentine channels. Similar conventions regarding inlets / outlets, pairing of open channel area with wall footprint area, and use of solid / unshaded fill to describe different channels are used in Figure 51 as in Figure 50.

[0273] In such an arrangement, the total length of each individual serpentine channel may be approximately equal to the total length of the other individual serpentine channels in the plurality of serpentine channels (although in nested or interleaved multiple serpentine channel arrangements, there may be some variation in length depending on how the channels are arranged (e.g., whether there is an odd or even number of long segments in each channel). This results in approximately equal flow resistances, pressure drops, and transit times between channels (assuming each such channel is fluidly connected to the same fluid environment at both ends).

[0274] 52 shows an example of a cathode basin 5216 including a two-channel, multiple serpentine channel arrangement. As can be seen, cathode basin 5216 has a fluid inlet port 5228 and a fluid outlet port 5230. Two serpentine channels 5256a and 5256b are shown following a common serpentine path (not shown, but generally represented by the path followed by a divider wall 5266, which separates the two serpentine channels 5256a and 5256b). Serpentine channels 5256a and 5256b switch back through region 5252, generally in tandem. As a result, fluids, such as CO2, flowing through either of serpentine channels 5256a and 5256b may flow in a tandem fashion. X Gas may generally be delivered uniformly to adjacent cathode GDLs in the region corresponding to region 5252. At the same time, any liquid water entering cathode basin 5216 from an adjacent cathode GDL may tend to be delivered uniformly to both serpentine channels 5256a and 5256b accordingly. Thus, each serpentine channel 5256 receives approximately half the water delivered to single serpentine channel 4956 in FIG. 49 , assuming cathode basin 5216 is a substitute for cathode basin 4916 in FIG. 49 . Generally speaking, the amount of water delivered to each serpentine channel in a cathode basin having a multiple serpentine channel arrangement is equivalent to the total amount of water received by the multiple serpentine channel arrangement divided by the number of individual channels in the multiple serpentine channel arrangement. This has the effect of reducing the amount of water that must be pumped out of each serpentine channel per unit time, reducing CO2 emissions if gas flow rates are maintained, or at least not reduced proportionately.X It may be more feasible to properly manage the state of liquid water within the electrolysis device. For example, a smaller amount of water per channel means less mass and less energy is required to push it through the channels to the fluid outlet port 5230 of the cathode basin 5216. As a result, a lower pressure differential may be used between the fluid inlet port 5228 and the fluid outlet port 5230 of the cathode basin 5216 while still providing efficient evacuation of liquid water from the cathode basin 5216.

[0275] Multiple serpentine channels may also enable a relatively uniform distribution of fluid flowing within those channels across the cathode GDL 1121, but reduce the total flow path length of each such serpentine channel compared to multiple or single serpentine channel implementations with fewer such channels having the same or similar channel depths, widths, and total open channel areas in contact with the cathode GDL 1121. For example, in a given serpentine channel arrangement, it may be desirable to maintain the distance between adjacent long portions of at least one serpentine channel within a minimum distance from each other. Using serpentine channels with progressively shorter overall lengths for each additional serpentine channel included in a multiple serpentine channel arrangement can help meet such inter-channel spacing constraints. For clarity, the total length of a serpentine channel refers to the sum of the average path lengths of all long segments of the serpentine channel, the sum of the average path lengths of the short segments fluidly connecting those long segments to each other, and the sum of the average path lengths of any other segments fluidly intervening between the inlet and outlet of the serpentine channel.

[0276] Furthermore, as the length of a serpentine channel decreases, the potential average distance that liquid water must travel to be discharged from such a serpentine channel also decreases, generally reducing the maximum amount of water that may need to be removed. As a result, if water is collected within such a serpentine channel, less energy is required to drain the water from such a serpentine channel. This is because the maximum amount of water that may need to be removed from such a serpentine channel is less than that of a longer channel (with the same general cross-sectional area), resulting in fewer masses to move. Furthermore, the distance that must be removed to push such a mass of water through such a channel to a fluid outlet port is generally shorter than the distance that must be removed to push a similar mass of water through a longer channel to a fluid outlet port. Naturally, the distance that a mass of water must be discharged to be forced through a channel to a fluid outlet port varies depending on where the mass of water is located within the channel. However, generally, on average, a mass of water that collects in a shorter channel will need to be discharged less than a mass of water that collects in a longer channel to move such a mass of water to a fluid outlet port of a watershed having such a channel. In basins with shorter passage lengths, slower gas flow rates and lower pressure drops may be used because less energy is required to move these water bodies (droplets). In some embodiments, the cathode basin has a serpentine channel that is about 12 meters or less, about 10 meters or less, or about 6 meters or less in length. For example, a serpentine channel having a total length of less than about 6 meters, e.g., less than about 6 meters, less than about 5.5 meters, less than about 5 meters, less than about 4.5 meters, less than about 4 meters, less than 3.5 meters, less than about 3 meters, less than about 2.5 meters, or less than about 2 meters, may provide a fluid flow path in the cathode basin 1127 in some implementations, thereby allowing for CO XThis allows the gas flow to be distributed over a wide area of ​​the cathode GDL 1121 while avoiding such serpentine channels becoming so long that it becomes very difficult to drain liquid water from within them. At the same time, if the serpentine channels are too short, it may be difficult to maintain a desired pressure drop across the cathode flow region 1127 (see below). Therefore, the serpentine channels in some cathode flow regions may be configured to have an overall length of 1.5 meters or more.

[0277] In some implementations, the length of the individual serpentine channels in the cathode basin is between about 1.5 m and about 12 m, between about 1.5 m and about 6 m, between about 1.5 m and about 3.8 m, between about 3.8 m and about 6 m, between about 1.5 m and about 2.6 m, between about 2.6 m and about 3.8 m, between about 3.8 m and about 4.9 m, between about 4.9 m and about 6 m, between about 1.5 m and about 2.1 m, between about 2.1 m and about 2.6 m, between about 2.6 m and about 3.2 m, between about 3.2 m and about 3.8 m, between about 3.8 m and about 4.3 m, between about 4.3 m and about 4.9 m, about 4.9 m to about 5.4 m, about 5.4 m to about 6 m, about 1.5 m to about 1.8 m, about 1.8 m to about 2.1 m, about 2.1 m to about 2.3 m, about 2.3 m to about 2.6 m, about 2.6 m to about 2.9 m, about 2.9 m to about 3.2 m, about 3.2 m to about 3.5 m, about 3.5 m to about 3.8 m, about 3.8 m to about 4 m, about 4 m to about 4.3 m, about 4.3 m to about 4.6 m, about 4.6 m to about 4.9 m, or about 4.9 m to about 5.2 m. Both above and below, references to a value being "between" two other values ​​will be understood to include the values ​​between the two other values ​​as well as the values ​​themselves, unless the context indicates otherwise.

[0278] The cathode flow region with serpentine channels may provide improved liquid water removal while simultaneously reducing CO2 transport to the cathode GDL. XIt may be beneficial to configure the serpentine channel to have certain structural features that enable efficient delivery of CO. For example, a serpentine channel within the above length ranges may be further constrained to have a particular width (the dimension of the serpentine channel that is parallel to the plane of the cathode GDL 1121 and transverse to the path the channel follows (or generally transverse to the nominal flow direction of fluid flow through the channel)) and depth (the dimension of the serpentine channel that is perpendicular to the plane of the cathode GDL 1121), thereby enabling efficient delivery of CO. X This further improves water removal performance in the context of an electrolyzer. For clarity, the cathode GDL 1121 is generally in the form of a thin sheet that, when laminated with the MEA 1105 (see, e.g., FIG. 11A) and the anode PTL 1109 (see, e.g., FIG. 11A), is compressed into a nominally planar shape between the cathode field 1127 and the anode field 1111; thus, references to the "plane of the cathode GDL" shall be understood to refer to a plane that is approximately parallel to and coincident with the cathode GDL 1121 in such state. For example, such a serpentine channel may have a "width" that is about 0.3 mm to about 2 mm, about 0.3 mm to about 1.2 mm, about 1.2 mm to about 2 mm, about 0.3 mm to about 0.72 mm, about 0.72 mm to about 1.2 mm, about 1.2 mm to about 1.6 mm, about 1.6 mm to about 2 mm, about 0.3 mm to about 0.51 mm, about 0.51 mm to about 0.72 mm, about 0.72 mm to about 0.94 mm, about 0.94 mm to about 1.2 mm, about 1.2 mm to about 1.4 mm, about 1.4 mm to about 1.6 mm, about 1.6 mm to about 1.8 mm, or about 1.8 mm to about 2 mm.

[0279] Such serpentine channels may have a depth that is about 0.3 mm to about 3 mm, about 0.3 mm to about 1.6 mm, about 1.6 mm to about 3 mm, about 0.3 mm to about 0.98 mm, about 0.98 mm to about 1.6 mm, about 1.6 mm to about 2.3 mm, about 2.3 mm to about 3 mm, about 0.3 mm to about 0.64 mm, about 0.64 mm to about 0.98 mm, about 0.98 mm to about 1.3 mm, about 1.3 mm to about 1.6 mm, about 1.6 mm to about 2 mm, about 2 mm to about 2.3 mm, about 2.3 mm to about 2.7 mm, or about 2.7 mm to about 3 mm.

[0280] In particular, in some cathode flow field implementations with serpentine channels, the channels have an open surface area per channel, i.e., the area enclosed by the edges of the channel that contact the cathode GDL, of about 750 mm 2 ~approx. 200,000mm 2 , about 750mm 2 ~approx. 100,000mm 2 , approximately 100,000mm 2 ~approx. 200,000mm 2 , about 750mm 2 ~approx. 51,000mm 2 , approximately 51,000 mm 2 ~approx. 100,000mm 2 , approximately 100,000mm 2 ~approx. 150,000mm 2 , approximately 150,000mm 2 ~approx. 200,000mm 2 , about 750mm 2 ~approx. 26,000mm 2 , approximately 26,000 mm 2 ~approx. 51,000mm 2 , approximately 51,000 mm 2 ~approx. 75,000mm 2 , approximately 75,000 mm 2 ~approx. 100,000mm 2 , approximately 100,000mm 2 ~approx. 130,000mm 2 , approximately 130,000mm 2 ~approx. 150,000mm 2 , approximately 150,000mm 2 ~approx. 180,000mm2 , or approximately 180,000 mm 2 ~approx. 200,000mm 2 The dimensions may be such that:

[0281] In some such implementations, such channels may further be dimensioned such that the cross-sectional area of ​​each such channel (or area, if the channel has a cross-sectional area that varies along its length), i.e., the area of ​​the channel in a plane that is perpendicular to the direction of fluid flow through the channel or the path that the channel follows across the cathode flow region under normal operating conditions, is less than or equal to about 0.15 mm 2 ~about 6mm 2 , about 0.15mm 2 ~Approx. 3.1mm 2 , about 3.1mm 2 ~about 6mm 2 , about 0.15mm 2 ~approx. 1.6mm 2 , about 1.6mm 2 ~Approx. 3.1mm 2 , about 3.1mm 2 ~about 4.5mm 2 , about 4.5mm 2 ~about 6mm 2 , about 0.15mm 2 ~about 0.88mm 2 , about 0.88mm 2 ~approx. 1.6mm 2 , about 1.6mm 2 ~about 2.3mm 2 , about 2.3mm 2 ~Approx. 3.1mm 2 , about 3.1mm 2 ~approx. 3.8mm 2 , approximately 3.8 mm 2 ~4.5mm 2 , about 4.5mm 2 ~5.3mm 2 , or approximately 5.3 mm 2 ~6mm 2 .

[0282] In yet another implementation, the total channel volume of each such channel is between about 200 μl and about 36,000 μl, between about 200 μl and about 18,000 μl, between about 18,000 μl and about 36,000 μl, between about 200 μl and about 9,200 μl, between about 9,200 μl and about 18,000 μl, between about 18,000 μl and about 27,000 μl, between about 27,000 μl and about 36,000 μl, It can be about 200 μl to about 4,700 μl, about 4,700 μl to about 9,200 μl, about 9,200 μl to about 14,000 μl, about 14,000 μl to about 18,000 μl, about 18,000 μl to about 23,000 μl, about 23,000 μl to about 27,000 μl, about 27,000 μl to about 32,000 μl, or about 32,000 μl to about 36,000 μl.

[0283] In some such implementations, the cathode flow region with serpentine channels may have structural features related to the thickness of the wall between one or more adjacent long segments of the serpentine channels. For example, the wall thickness between one or more adjacent long segments of the serpentine channels (and therefore the distance between the surfaces of the channels or between the channels closest to each other) may be between about 0.00005 and about 0.0013333, about 0.00005 and about 0.00069, or about 0.00069 and about 0.00133 of the average total length of the serpentine channel(s) (applies when a wall separates the long portions of two different serpentine channels from each other; for clarity, in this case, the "average" total length is half the sum of the overall lengths of both serpentine channels). 33, about 0.00005 to about 0.00037, about 0.00037 to about 0.00069, about 0.00069 to about 0.001, about 0.001 to about 0.0013333, about 0.00005 to about 0.00021, about 0.00021 to about 0.00037, about 0.00037 to about 0.00053, about 0.00053 to about 0.00069, about 0.00069 to about 0.00085, about 0.00085 to about 0.001, about 0.001 to about 0.0012, or about 0.0012 to about 0.0013333. In some such serpentine channel implementations having the above dimensional characteristics, the wall thickness can be, for example, about 0.3 mm to about 2 mm, about 0.3 mm to about 1.2 mm, about 1.2 mm to about 2 mm, about 0.3 mm to about 0.72 mm, about 0.72 mm to about 1.2 mm, about 1.2 mm to about 1.6 mm, about 1.6 mm to about 2 mm, about 0.3 mm to about 0.51 mm, about 0.51 mm to about 0.72 mm, about 0.72 mm to about 0.94 mm, about 0.94 mm to about 1.2 mm, about 1.2 mm to about 1.4 mm, about 1.4 mm to about 1.6 mm, about 1.6 mm to about 1.8 mm, or about 1.8 mm to about 2 mm.

[0284] Serpentine channel cathode basins having features such as those described above may have a reduced CO2 footprint compared to other serpentine channel cathode basins having such features, such as those that may be designed for use in fuel cells. X In the context of electrolysis, e.g., CO XIt can provide excellent liquid water drainage performance under operating conditions typically found in electrolysis devices (such as those previously described herein).

[0285] While it may generally be desirable to include more serpentine channels within the cathode basin, increasing the number of basin channels in the cathode basin 1127 indefinitely may be counterproductive. Each additional parallel basin channel present in the cathode basin 1127 may represent an alternative path for fluid flowing through the serpentine channels in a serpentine channel arrangement if fluid flowing through one or more other serpentine channels becomes blocked. When such a fluid rerouting occurs, the pressure differential along the channel, e.g., from the beginning to the end of the channel, may increase, causing the fluid pushing against the block to exert even greater pressure on the block, displacing the block (liquid water) and forcing it through the blocked serpentine channel and ultimately exiting the cathode basin 1127 via a basin outlet, e.g., basin outlet 5930. However, if there are a sufficient number of channels, blocking any one (or a small number) of them can result in a much smaller increase in pressure differential across any single channel than would occur if the same number of channels were blocked in a basin with a smaller number of channels. In other words, gas flow that is blocked and redirected to other unblocked channels may be split among more alternative channels, resulting in a smaller amount of extra gas needing to flow through each unblocked channel than would be the case with a similar blocked situation but with fewer channels. The smaller the amount of extra gas that needs to flow through each channel in a blocked situation, the smaller the change in pressure drop required to accommodate such a change. Consequently, as the number of channels present increases, the increase in pressure drop that may occur in an unlocked channel when a blocked channel(s) causes gas to flow a redirected path decreases.

[0286] At the same time, if the total length of the serpentine passage is long enough (e.g., 0.3 m to 6 m), the pressure drop across each such channel can be high enough to help displace any obstacles, such as water, that may be present within any individual serpentine channel, regardless of the number of channels present. X Serpentine channels for electrolysis devices may have dimensions and operating conditions, e.g., fluid inlet port pressure, selected to produce a pressure drop of 0.001 psi to 4 psi during normal operating flow through such serpentine channels, which may be high enough to displace potential water blocks that may exist within the serpentine channels. Higher pressure drops may be used, but with respect to water evacuation, this may be unnecessary and would simply waste the energy required to move fluid through the serpentine channels under such pressure drop conditions. In some implementations, CO X The serpentine channel for the electrolyzer is XDuring normal operating flow conditions of the electrolytic device, the electrolytic pressure may range from about 0.001 psi to about 4 psi, from about 0.001 psi to about 2 psi, from about 2 psi to about 4 psi, from about 0.001 psi to about 1 psi, from about 1 psi to about 2 psi, from about 2 psi to about 3 psi, from about 3 psi to about 4 psi, from about 0.001 psi to about 0.5 psi, from about 0.5 psi to about 1 psi, from about 1 psi to about 1.5 psi, from about 1.5 psi to about 2 psi, from about 2 psi to about 2.5 psi, from about 2.5 psi to about 3 psi, from about 3 psi to about 3.5 psi, from about 3.5 psi to about 4 psi, from about 0.001 psi to about 0.25 psi, about 0.25psi to about 0.5psi, about 0.5psi to about 0.75psi, about 0.75psi to about 1psi, about 1psi to about 1.3psi, about 1.3psi to about 1.5psi, about 1.5psi to about 1.8psi, about 1.8psi to about 2psi, about 2psi to about 2.3 psi, about 2.3psi to about 2.5psi, about 2.5psi to about 2.8psi, about 2.8psi to about 3psi, about 3psi to about 3.3psi, about 3.3psi to about 3.5psi, about 3.5psi to about 3.8psi, about 3.8psi to about 4psi, about 0.001psi to about 0. 13psi, about 0.13psi to about 0.25psi, about 0.25psi to about 0.38psi, about 0.38psi to about 0.5psi, about 0.5psi to about 0.63psi, about 0.63psi to about 0.75psi, about 0.75psi to about 0.88psi, about 0.88psi to about 1psi, about 1psi~about 1.1psi, about 1.1psi~about 1.3psi, about 1.3psi~about 1.4psi, about 1.4psi~about 1.5psi, about 1.5psi~about 1.6psi, about 1.6psi~about 1.8psi, about 1.8psi~about 1.9psi, about 1.9psi~ about 2 psi, about 2 psi to about 2.1 psi, about 2.1 psi to about 2.3 psi, about 2.3 psi to about 2.4 psi, about 2.4 psi to about 2.5 psi, about 2.5 psi to about 2.6 psi, about 2.6 psi to about 2.8 psi, about 2.8 psi to about 2.9 psi, about 2.9 psi to about 3 psi, about 3 psi to about 3.1 psi, about 3.1 psi to about 3.3 psi, about 3.3 psi to about 3.4 psi, about 3.4 psi to about 3.5 psi, about 3.5 psi to about 3.6 psi, about 3.6 psi to about 3.8 psi, about 3.8 psi to about 3.9 psi, or about 3.The dimensions and operating conditions, e.g., fluid inlet port pressure, may be selected to produce a pressure drop of between about 9 psi and about 4 psi. In some implementations, the CO. X The serpentine channel for the electrolyzer is X During normal operating flow conditions of the electrolytic device, the electrolytic device may be operated at temperatures ranging from about 4 psi to about 50 psi, from about 4 psi to about 27 psi, from about 27 psi to about 50 psi, from about 4 psi to about 16 psi, from about 16 psi to about 27 psi, from about 27 psi to about 38 psi, from about 38 psi to about 50 psi, from about 4 psi to about 9.8 psi, from about 9.8 psi to about 16 psi, from about 16 psi to about 21 psi, from about 21 psi to about 27 psi, from about 27 psi to about 33 psi, from about 33 psi to about 38 psi, from about 38 psi to about 44 psi, from about 44 psi to about 50 psi, from about 4 psi to about 6.9 psi, from about 6.9 psi to about 9.8 psi. The dimensions and operating conditions, e.g., fluid inlet port pressure, may be selected to produce a pressure drop of 8 psi, about 9.8 psi to about 13 psi, about 13 psi to about 16 psi, about 16 psi to about 18 psi, about 18 psi to about 21 psi, about 21 psi to about 24 psi, about 24 psi to about 27 psi, about 27 psi to about 30 psi, about 30 psi to about 33 psi, about 33 psi to about 36 psi, about 36 psi to about 38 psi, about 38 psi to about 41 psi, about 41 psi to about 44 psi, about 44 psi to about 47 psi, or about 47 psi to about 50 psi. X The serpentine channel for the electrolyzer is XThe dimensions and operating conditions (e.g., fluid inlet port pressure) may be selected to produce a pressure drop of about 0.001 psi to about 50 psi, about 0.001 psi to about 25 psi, about 25 psi to about 50 psi, about 0.001 psi to about 13 psi, about 13 psi to about 25 psi, about 25 psi to about 38 psi, about 38 psi to about 50 psi, about 0.001 psi to about 6.3 psi, about 6.3 psi to about 13 psi, about 13 psi to about 19 psi, about 19 psi to about 25 psi, about 25 psi to about 31 psi, about 31 psi to about 38 psi, about 38 psi to about 44 psi, or about 44 psi to about 50 psi during normal operating flow conditions of the electrolyzer. A pressure drop within the above ranges may be large enough to displace potential water blockages that may exist within such serpentine channels, especially in the context of the higher water production rates that COx electrolyzers tend to exhibit.

[0287] 53-55 show an example of a cathode flow area 5316 that may be used in some implementations. The illustrated flow area has 15 channels and 9 passes. In one implementation, the illustrated flow area has a volume of 700 cm 2 5358a, 5358b, and 5358c. The cathode basin 5316 has a planar surface area (facing the GDL) of 1,000 mm. Figure 53 shows an isometric view of the cathode basin 5316. Figure 55 shows a detailed view of the circled portion of Figure 53. Figure 54 shows the isometric view of Figure 53, but with most of the basin's channels omitted, making only three channels 5358a, 5358b, and 5358c visible. This view is intended to make it easier to see the typical serpentine paths followed by the various channels. The cathode basin 5316 actually contains 15 channels 5358. The channels of the exemplary cathode basin 5316 are each 0.66 mm deep by 0.81 mm wide, and each have a length of approximately 2,310 mm and a channel open area of ​​approximately 1,880 mm. 2 , volume approximately 1,240mm 3 In this example, the total open area of ​​the cathode basin 5316 is 28,200 mm 2Each of the 15 channels is separated from any adjacent channels by a 1.12 mm wide wall, and the cathode basin has dimensions of approximately 265 mm x 265 mm, so that approximately 40% of the surface area of ​​the cathode basin 5316 is occupied by channels 5358. The cathode basin 5316 shown is designed to receive (and deliver) fluid from an external manifold that may be attached to the outer edge of the cathode basin 5316, allowing fluid to flow in and out of the channels 5358 from the side.

[0288] 56-58 show an example of another cathode flow field 5616 that may be used in some implementations. The illustrated field has 34 channels and 7 passes. In one implementation, the illustrated field has a volume of 1,600 cm 2 53-55, FIG. 56 shows an isometric view of the cathode basin 5616, and FIG. 58 shows a detailed view of the circled portion of FIG. 56. FIG. 57 shows the isometric view of FIG. 56, but with most of the basin's channels omitted, making only three channels 5658a, 5658b, and 5658c visible. As with FIG. 55, this view is intended to more easily see the typical serpentine paths followed by the various channels. The cathode basin 5616 actually contains 34 channels 5658. The channels of the exemplary cathode basin 5616 are each 0.66 mm deep by 0.76 mm wide, and each have a length of approximately 2,440 mm and a channel open area of ​​approximately 1,880 mm. 2 , volume approximately 1,230mm 3 In this example, the total channel open area of ​​the cathode basin 5616 is 63,230 mm 2Because each of the 34 channels is separated from any adjacent channels by a 1.14 mm wide wall and the cathode basin 5616 has dimensions of approximately 360 mm x 450 mm, approximately 39% of the surface area of ​​the cathode basin 5616 is occupied by channels 5658. Like the cathode basin 5316, the illustrated cathode basin 5616 is designed to receive (and deliver) fluid from an external manifold that may be attached to the outer edge of the cathode basin, allowing fluid to flow into or out of the channels 5658 from the sides.

[0289] In certain embodiments, the channel depth in serpentine flow areas such as those of Figures 53-58 is about 0.5 mm to 1.5 mm. In certain embodiments, the nominal length of each flow channel in the flow areas of Figures 53-58 is about 300 mm to 3,000 mm. In certain embodiments, the nominal channel width in the flow areas of Figures 53-58 is about 0.5 mm to 1 mm. In certain embodiments, the nominal channel separation distance in the flow areas of Figures 53-58 is about 1 mm to 1.5 mm.

[0290] In some implementations, the serpentine channel cathode basin may feature serpentine channels with rounded or smooth transitions between long and short segments, rather than abrupt transitions between long and short segments. For example, FIG. 59 shows an example of a cathode basin 5916 having four cathode serpentine channels 5956 arranged in a multiple serpentine channel arrangement. Note that, unlike the single-channel and two-channel serpentine arrangements illustrated in FIGS. 49 and 52 , the transitions between the long segments are provided by arcuate short segments rather than straight short segments. In other implementations, the short segments may still include straight portions but be fluidly connected to adjacent long segments by smaller arcuate segments. In such cathode basins, the absence of sharp interior corners in the serpentine channels may further improve the drainage performance of the COx electrolyzer by eliminating potential dead zones or stagnant areas of fluid flow that could serve as a location where liquid water could collect and remain indefinitely during use of the cathode basin.

[0291] Other aspects of the basin channels may alternatively or additionally be modified to promote more effective liquid water drainage. Figure 60, for example, shows a cross-sectional view of a cathode basin 6016 pressed against a cathode GDL 6014. A plurality of square or rectangular cross-section serpentine channels 6056 are formed in the face of the cathode basin 6016 pressed against the cathode GDL 6014. These serpentine channels 6056 have sharp corners at their inner bottom ends 6057, which are characteristic of conventional CO2 pumps. X It may function to create small fluid flow stagnation areas that may prevent liquid water from easily draining during electrolyzer operating conditions.

[0292] In contrast, Figure 61 shows a cross-sectional view of a similar structure having a cathode basin 6116 pressed against a cathode GDL 6114. A plurality of square or rectangular cross-section serpentine channels 6156 are formed in the face of the cathode basin 6116 pressed against the cathode GDL 6114. Unlike the serpentine channels 6056, the serpentine channels 6156 have rounded corners on their inner bottom edges 6157, which serve to reduce flow stagnation in the bottom inner edge region of such channels, thereby improving the flow efficiency of conventional CO2. X The drainage of liquid water under the operating conditions of the electrolysis device can be facilitated.

[0293] Figure 62 shows the normal CO X 62. This is a further example of a cathode basin that can more easily drain liquid water during electrolysis device operating conditions. As can be seen, the cathode basin 6216 is pressed against the cathode GDL 6214. A plurality of U-shaped cross-section serpentine channels 6256 are formed in the face of the cathode basin 6216 that is pressed against the cathode GDL 6214. In this case, the bottom surface of such serpentine channels 6256 is semicircular, so that the internal bottom edge of the serpentine channels 6256 is effectively absent, which may act to further reduce flow stagnation in such channels, thereby improving the efficiency of normal CO2 electrolysis. XThe drainage of liquid water under electrolyzer operating conditions is further facilitated.

[0294] In some other or additional implementations, the cathode basin of a serpentine channel may have walls of variable width between some or all of the long segments of one or more serpentine channels. FIG. 63 shows an example of such a cathode basin. In FIG. 63, a cathode basin 6316 is shown having a four-channel serpentine arrangement, with each serpentine channel 6356 having a long segment 6360 and a short segment 6362. Note that the multiple serpentine channel arrangement has intervening "peninsula" walls 6364 between adjacent long segments 6360 of a common serpentine channel 6356a (or 6356b) that have opposite fluid flow directions as fluid flows through the serpentine channel 6356 (generally, all nested or interleaved multiple serpentine channel arrangements have peninsula-like walls; these are only specifically called out here due to the implementation details of this example).

[0295] As can be seen in FIG. 63 , the peninsular wall 6364 may have a variety of wall thicknesses. For example, the peninsular wall 6364 has a root width 6368 where the peninsular wall 6364 “connects” to the perimeter region of the cathode basin 6316 (which can be thought of as the “root” of the peninsular wall), and a tip width 6370 at its opposite end. The increased width at the root compared to the tip of the peninsular wall 6364 may reduce the likelihood of gas flow through the cathode GDL bypassing some or all of the long segment 6360 separated by the peninsular wall 6364 by passing under the wall, i.e., through the GDL sandwiched between the cathode basin 6316 and the MEA (not shown, but see FIG. 11A ), which effectively caps the cathode serpentine channel 6356.

[0296] For example, in a serpentine channel of a cathode flow region having portions adjacent to one another, e.g., the outermost or innermost serpentine channel in a multi-channel interleaved serpentine channel arrangement, gas flowing through such a channel, e.g., from point A to point B, when traveling from point A to point B via flow through point C may experience a pressure drop / flow resistance that, in some circumstances, may exceed the pressure drop / flow resistance that the gas would experience if it simply flowed more directly from point A to point B, e.g., by passing under the peninsula wall 6364 between points A and B, via the porous GDL that extends between points A and B and under the peninsula wall 6364. For example, if water accumulates in the channel between points A and C and / or between points C and B, the resulting blockage increases the pressure drop / flow resistance of the gas flowing along this path, which may exceed the pressure drop / flow resistance that the gas would experience if it traveled more directly from point A to point B, e.g., under the peninsula wall 6364. Because the flow path between points A and B under the peninsular wall 6364 may have less flow resistance than the flow path between A and B via point C, gas may preferentially flow to point B rather than from point A under the peninsular wall 6364 via point C, thus eliminating exposure of the GDL and MEA to gases that would normally flow through point C. This allows the cathode flow region 6316 to be used for CO XThe efficiency of the cell decreases. To prevent this from occurring, or at least reduce the likelihood of it occurring, in some implementations, the peninsular wall 6364 may simply have a constant thickness along its length, but may be thicker than the partition walls 6366 that may separate other adjacent long segments 6360 that have fluid flow in the same direction. This increases the flow resistance experienced by gas attempting to flow under the peninsular wall 6364. In other implementations, such as shown in FIG. 63 , the peninsular wall 6364 may taper toward its tip such that the tip width 6370 is smaller than the root width 6368, thereby reducing the flow resistance under the peninsular wall 6364 from that near the root of the peninsular wall 6364 as the flow approaches the tip of the peninsular wall 6364. This may help block the flow of gas under the peninsular walls 6364 near the root of those walls, but this effect may also decrease as the gas flow moves along the peninsular wall 6364 toward its tip. However, flow resistance along the desired flow path (e.g., via point C) may also be reduced. Thus, there may be less incentive for gas to flow under the peninsula wall near the tip of the peninsula wall 6364. By tapering the thickness of the peninsula wall, the area of ​​the cathode GDL that is compressed under the peninsula wall 6364 may be reduced compared to a non-tapered peninsula wall 6364, thereby increasing the area of ​​the cathode GDL directly exposed to gas flow through the channel and increasing the opportunity for reduction reactions to occur with such gases.

[0297] Miller meandering channel basin In the meandering channel basins described above, the described meandering channels generally do not exhibit mirror symmetry or bilateral symmetry. However, a further class of meandering channel basins may be characterized by meandering channels generally arranged bilaterally. In such basins, the basin is generally partitioned into two zones. The two zones may generally be of equal size and shape and may each contain a similar number of meandering channels. The meandering channel(s) within each zone may be arranged to be approximately mirror images of each other with respect to the boundary between the two zones; for example, the meandering channels may exhibit bilateral symmetry with respect to the boundary between the two zones.

[0298] FIG. 64 shows a plan view of a simplified representation of an example of a mirror-image cathode basin. In FIG. 64, the cathode basin 6416 is shown divided into two zones 6470 that are approximately the same shape and size. A boundary 6472 is defined between the two zones 6470, with the zones 6470 disposed approximately symmetrically on either side of the boundary 6472. While each zone 6470 in this example includes a single cathode serpentine channel 6456, each zone may include multiple cathode serpentine channels 6456 that follow a common path in a nested or interleaved manner, as in the previously discussed examples. Each cathode serpentine channel 6456 extends between a corresponding fluid inlet port 6428 and a corresponding fluid outlet port 6430 (it is understood that these fluid inlet ports 6428 may terminate at the same location, e.g., a common flow channel or manifold, and that the fluid outlet port 6430 may be similarly configured).

[0299] As discussed further below, a symmetric arrangement of the cathode serpentine channels 6456 may provide various advantages over an asymmetric arrangement of the cathode serpentine channels with respect to maintaining flow uniformity in the cathode flow area 6416. For example, two zones 6470 together may generally represent the active area of ​​the cathode flow area 6416. That active area may be traversed by the cathode serpentine channel(s) or channel(s) that shuttle between opposite sides of the active area, as shown, for example, in FIG.

[0300] FIG. 65 also shows a cathode basin 6516, two zones 6570, and a boundary 6572 similar to zone 6470 and boundary 6472. Cathode basin 6516 has a serpentine channel 6556, including a long segment A extending in a direction nominally perpendicular to a first set of opposing edges of the active area and a short segment B extending in a direction nominally parallel to a second set of opposing edges. The length of the long segment is typically on the same order of magnitude as the distance between the first set of opposing edges of the active area (although it may be slightly shorter to route additional cathode serpentine channels in a nested or interleaved manner). It can be seen that long segment A of cathode serpentine channel 6556 crosses boundary 6572 and extends into both zones 6570. In such an arrangement, a fluid flowing down a long segment A, through a short segment B, and into another long segment A adjacent to the original long segment A experiences a pressure drop approximately proportional to the sum of the lengths of the two long segments A and short segment B connecting them, for example, along the thick dashed line 6574 shown in association with the two long segments A at the left end of Figure 65.

[0301] However, gas flow through the cathode serpentine channels 6556 is not limited to remaining within the cathode serpentine channels 6556. For example, as previously discussed, the side of the cathode flow area 6516 on which the cathode serpentine channels 6556 are located may be compressed against a porous or fibrous GDL (not shown), providing an alternative flow path that allows gas to additionally or alternatively flow under the partition walls 6566 between each pair of adjacent long segments A, e.g., through a GDL sandwiched between the cathode flow area 6516 and an adjacent structure, e.g., an MEA. For example, gas flow may flow between the two long segments A on the left side of FIG. 65 via the flow path along dotted line 6576.

[0302] Generally speaking, the ratio of gas flowing along flow paths 6574 and flow paths 6576 may be biased toward gas flow along channel flow paths 6574 due to the fact that cathode serpentine channel 6556 has a relatively large, open cross-sectional area compared to GDL flow paths 6576. For example, cathode serpentine channel 6556 may be fully open and have a cross-section with relatively large dimensions (e.g., on the order of 1 millimeter in height and width), while the flow paths provided by the GDL may be on the order of hundreds of microns in height and may only be filled with the fibrous or porous material of the GDL. In other words, the flow resistance per unit length of the GDL may be much higher than the flow resistance per unit length of cathode serpentine channel 6556.

[0303] However, the overall flow resistance of flow path 6574 increases as the length of long segment A of cathode serpentine channel 6556 increases. Thus, the longer segment A of cathode serpentine channel 6556, the higher the flow resistance along flow path 6574, and the ratio of gas flowing through flow path 6574 to gas flowing through flow path 6576 decreases. In other words, if the length of long segment A is short, the gas flow along flow path 6576 will be less than if the length of long segment A were long.

[0304] Additionally, the flow resistance of flow path 6574 may also increase during operation due to potential blockage, for example, by liquid water or mineral deposits within cathode serpentine channel 6556. When such blockage occurs, this increases the flow resistance along the cathode serpentine channel, thereby causing a decrease in the ratio of gas flowing through flow path 6574 to gas flowing through flow path 6576.

[0305] Although only one flow path 6574 and one flow path 6576 are shown in FIG. 65, it is understood that such flow paths may generally be replicated for similar geometric features in the cathode flow area 6516, and that such additional flow paths may have similar characteristics and behavior.

[0306] Returning to FIG. 64 , it can be seen that by filling the same two zones 6470 with separate cathode serpentine channels 6456, the long segments A of those serpentine channels 6456 can be reduced compared to the long segments A of cathode serpentine channel 6556. In FIG. 64 , the long segments A of cathode serpentine channel 6456 are approximately half the length of the long segments A of cathode serpentine channel 6556. Assuming that cathode serpentine channels 6456 and 6556 are otherwise substantially similar, e.g., of similar cross-sectional area, the flow resistance along flow path 6474 is significantly less, e.g., on the order of about 50% of the flow resistance along flow path 6574. This, in turn, increases the proportion of gas that flows through cathode serpentine channel 6456, as opposed to leaking under peninsular wall 6466 (e.g., via flow path 6476). If the cathode serpentine channel 6456 passes through the zone 6470 in a manner that results in a more even distribution of gas through the zone 6470 than would occur in a cathode flow basin such as the cathode flow basin 6516.

[0307] 64 is that the cathode serpentine channels 6456 shown are arranged in a generally symmetrical manner so that at locations where the cathode serpentine channels in two zones are close to one another, e.g., in short segment B adjacent boundary 6472, the total flow resistance along the serpentine channels from their respective inlets to those segments is generally equal, thereby resulting in a generally equal pressure drop from the inlet to each set of locations. This avoids a scenario where two segments from different cathode serpentine channels are adjacent to one another but may have nominally different pressures, resulting in a pressure differential between them that could act to cause gas to cross from one such cathode serpentine channel to another.

[0308] For example, considering the flow resistance along the portion of the cathode serpentine channels 6456 between location C and the fluid inlet ports 6428 in FIG. 64 , it can be seen that gas flowing through each cathode serpentine channel 6456 from the corresponding fluid inlet port 6428 to...

Claims

1. CO Ｘ 1. An electrolysis apparatus ("apparatus") comprising: a first end assembly; a second end assembly coupled to the first end assembly via a plurality of tension members; a plurality of separator plates; Multiple COs Ｘ electrolyzer cells ("cells") interposed between the first end assembly and the second end assembly and arranged in an axial stack, each of the cells including an instance of a first component and an instance of a second component; wherein the first component is: a membrane electrode assembly ("MEA") having a cathode portion, an anode portion, and a separator between the cathode portion and the anode portion; a cathode frame adjacent to the cathode portion; a cathode flow area at least partially disposed within the first opening of the cathode frame; The second component comprises: an anode frame adjacent the anode portion of the MEA; an anode flow area at least partially disposed within the second opening of the anode frame; the cathode frames and the anode frames of adjacent ones of the cells are connected to one another via a corresponding plurality of frame fasteners, with any one of the separator plates interposed therebetween, and the frame fasteners are different from the tension members.

2. 10. The apparatus of claim 1, The first component further comprises a cathode gas diffusion layer (GDL) adjacent to the cathode frame and covering the cathode flow area, wherein the cathode GDL and the cathode flow area disperse gaseous CO through the first opening in a first direction transverse to the axial direction and in at least a second direction transverse to each of the axial and first directions. Ｘ configured to induce a flow of; the second component further comprises an anode porous transport layer (PTL) adjacent to the anode frame and covering the anode flow area, the anode PTL and the anode flow area configured to direct anolyte flow through the second openings in a third direction transverse to the axial direction and in a dispersive manner relative to at least the second direction.

3. The cathode frame is the first opening disposed in a central portion of the cathode frame; at least one first fluid inlet passage fluidly connected to the anode portion of the cell; at least one first fluid outlet passage fluidly connected to the anode portion of the cell; at least one second fluid inlet passage fluidly connected to the first opening; and at least one second fluid outlet passage fluidly connected to the first opening.

4. The anode frame is the second opening disposed in a central portion of the anode frame; at least one third fluid inlet passage fluidly connected to the second opening; at least one third fluid outlet passage fluidly connected to the second opening; at least one fourth fluid inlet passage fluidly connected to the cathode portion of the cell; and at least one second fluid outlet passage fluidly connected to the cathode portion of the cell.

5. Each of the separator plates comprises: a plurality of fastening holes through which the frame fasteners extend respectively; at least one first hole through which the inlet anolyte flow path extends; at least one second hole through which the outlet anolyte flow path extends; Inlet gaseous CO Ｘ at least one third hole through which the flow path extends; Exit CO Ｘ The device of claim 1 , further comprising at least one fourth hole through which the reduced byproduct flow path extends.

6. 4. The apparatus of claim 3, the cathode frame includes a first surface facing the MEA and a second surface facing opposite the first surface; the second surface of the cathode frame is at least one first protrusion through which the at least one first fluid inlet passage extends; at least one second protrusion through which the at least one first fluid outlet passage extends; at least one third protrusion through which the at least one second fluid inlet passage extends; the device including at least one fourth protrusion through which the at least one second fluid outlet passage extends.

7. 7. The apparatus of claim 6, the at least one first protrusion of the cathode frame is positioned and configured to extend through the at least one first hole in a first one of the separator plates and abut the anode frame of a first adjacent one of the cells, such that the at least one first fluid inlet passage of the cathode frame is substantially axially aligned with the at least one third fluid inlet passage of the anode frame of the first adjacent cell; the at least one second protrusion of the cathode frame is positioned and configured to extend through the at least one second hole of the first separator plate and abut the anode frame of the first adjacent cell, such that the at least one first fluid outlet passage of the cathode frame is substantially axially aligned with the at least one third fluid outlet passage of the anode frame of the first adjacent cell; the at least one third protrusion of the cathode frame is positioned and configured to extend through the at least one third hole of the first separator plate and abut the anode frame of the first adjacent cell, such that the at least one second fluid inlet passage of the cathode frame is substantially axially aligned with the at least one fourth fluid inlet passage of the anode frame of the first adjacent cell; the at least one fourth protrusion of the cathode frame is positioned and configured to extend through the at least one fourth hole in the first separator plate and abut the anode frame of the first adjacent cell such that the at least one second fluid outlet passage of the cathode frame is substantially axially aligned with the at least one fourth fluid outlet passage of the anode frame of the first adjacent cell.

8. 10. The apparatus of claim 1, the cathode frame further includes a plurality of first cathode fastening holes disposed about a peripheral region of the cathode frame, the peripheral region surrounding the first opening of the cathode frame; The anode frame is a plurality of first anode fastener holes disposed about a peripheral region of the anode frame, the peripheral region surrounding the second opening of the anode frame, the first anode fastener holes being substantially axially aligned with the first anode fastener holes; and the apparatus further comprising a plurality of first swage nuts, each of the first swage nuts disposed in one or the other of a corresponding one of the first anode fastening holes and a corresponding one of the first cathode fastening holes, the first swage nut configured to interface with a corresponding one of the frame fasteners.

9. 3. The apparatus of claim 2, The first component comprises: a first support frame interposed between the cathode GDL and the cathode frame, the first support frame including a first frame opening exposing a portion of the cathode GDL to the cathode flow area, the portion of the cathode GDL abutting the cathode flow area; a second support frame interposed between the MEA and the anode PTL, the second support frame including a second frame opening exposing the portion of the MEA to the anode PTL, the portion of the MEA abutting the anode PTL; the first support frame, the cathode GDL, the MEA, and the second support frame form an integrated MEA assembly.

10. 10. The apparatus of claim 9, The first component comprises: a first cathode gasket interposed between the first support frame and the cathode frame, the first cathode gasket surrounding the first opening in the cathode frame and forming a first fluid seal around the cathode flow area; and a second cathode gasket interposed between a first one of the separator plates and the cathode frame, the second cathode gasket surrounding the first opening in the cathode frame and forming a second fluid seal around the cathode flow field; The second component comprises: a first anode gasket set; and further comprising a second anode gasket set; The first anode gasket set comprises: a first anode gasket interposed between the second support frame and the anode frame, the first anode gasket surrounding the second opening in the anode frame and forming a first fluid seal around the anode flow field; at least one second anode gasket interposed between the cathode frame and the anode frame, the at least one second anode gasket surrounding the at least one first fluid inlet passage of the cathode frame and the at least one third fluid inlet passage of the anode to form at least one fluid seal; at least one third anode gasket interposed between the cathode frame and the anode frame, the third anode gasket surrounding the at least one first fluid outlet passage of the cathode frame and the at least one third fluid outlet passage of the anode frame to form at least one fluid seal; at least one fourth anode gasket interposed between the cathode frame and the anode frame, the at least one third anode gasket surrounding the at least one second fluid inlet passage of the cathode frame and the at least one fourth fluid inlet passage of the anode frame to form at least one fluid seal; and at least one fifth anode gasket interposed between the cathode frame and the anode frame, the at least one fifth anode gasket surrounding the at least one second fluid outlet passage and the at least one fourth fluid outlet passage of the anode frame and forming at least one fluid seal; the second anode gasket set: a sixth anode gasket interposed between the anode frame and a second one of the separator plates, the sixth anode gasket surrounding the second opening in the anode frame and forming a second fluid seal around the anode flow field; at least one seventh anode gasket interposed between the anode frame and the second separator plate, the at least one seventh anode gasket surrounding the at least one first hole in the second separator plate and the at least one third fluid inlet passage in the anode frame to form at least one fluid seal; at least one eighth anode gasket interposed between the anode frame and the second separator plate, the at least one eighth anode gasket surrounding the at least one second hole in the second separator plate and the at least one third fluid outlet passage in the anode frame to form at least one fluid seal; at least one ninth anode gasket interposed between the anode frame and the second separator plate, the at least one ninth anode gasket surrounding the at least one third hole in the second separator plate and the at least one fourth fluid inlet passage in the anode frame to form at least one fluid seal; at least one tenth anode gasket interposed between the anode frame and the second separator plate, the at least one ninth anode gasket surrounding the at least one fourth hole in the second separator plate and the at least one fourth fluid outlet passage in the anode frame to form at least one fluid seal.

11. 10. The apparatus of claim 1, the cells are formed of a plurality of repeating units, Each repeat unit among the repeat units is an instance of the first component; including an instance of the second component; the separator plate is interposed between the cathode frame of the first component instance and the anode frame of the second component instance, and the separator plate is interposed between the first component instance and the second component instance.

12. 12. The apparatus of claim 11, the first end assembly comprising a first end plate and a cathode interface assembly; the cathode interface assembly comprising: an instance of the first component, and a cathode interfacial separator plate interposed between the first end plate and a first one of the repeat units; a first end cell is formed between the cathode interface assembly and the instance of the second component of the first repeat unit, the first end cell being interposed between the first end plate and the plurality of cells.

13. 13. The apparatus of claim 12, Each of the separator plates comprises: a plurality of fastening holes through which the frame fasteners extend; at least one first hole through which the inlet anolyte flow path extends; at least one second hole through which the outlet anolyte flow path extends; Inlet gaseous CO Ｘ at least one third hole through which the flow path extends; Exit CO Ｘ the reduced byproduct flow path includes at least one fourth hole extending therethrough; the first end assembly further comprising a first insulating plate, a manifold, and a first bus plate between the first end plate and the cathode interface assembly; The manifold: at least one first inlet fluidly connected to the anode portion of the cell via the inlet anolyte flow path; at least one first outlet fluidly connected to the anode portion of the cell via the outlet anolyte flow path; The inlet gaseous CO Ｘ at least one second inlet fluidly connected to the cathode portion of the cell via a flow path; The outlet CO Ｘ at least one second outlet fluidly connected to the cathode portion of the cell via a reduced byproduct flow path; the first bus plate is configured to receive a first electrical potential; the first insulating plate is configured to electrically insulate the first end plate from the first bus plate.

14. the inlet anolyte flow path, the outlet anolyte flow path, the inlet gaseous CO Ｘ a flow path, and the outlet CO Ｘ The apparatus of claim 13 , wherein a reduced byproduct flow path does not extend into the bus plate and the first insulating plate.

15. the first end assembly further comprising a capping plate, an inlet runner, and an outlet runner; The apparatus of claim 14 , wherein the inlet runner and the outlet runner are coupled to the manifold so as to be axially stacked between the capping plate and the manifold.

16. 12. The apparatus of claim 11, the second end assembly comprising a second end plate and an anode interface assembly; the anode interfacial assembly an instance of the second component; and an anode interfacial separator plate interposed between a second one of the repeating units and the second end plate; a second end cell is formed between the instance of the first component of the second repeat unit and the anode interface assembly, the second end cell being interposed between the plurality of cells and the second end plate.

17. the second end assembly further includes a second bus plate and a second insulating plate stacked in axial order between the anode interface assembly and the second end plate; the second bus plate is configured to receive a second electrical potential; 17. The apparatus of claim 16, wherein the second insulating plate is configured to electrically insulate the second end plate from the second bus plate.

18. the second end assembly further comprising a bladder gasket; The second insulating plate a first recess formed in a central portion of the second insulating plate; a second recess surrounding a central region of the central portion, the second recess supporting the bladder gasket therein; and including a hole configured to receive one or more control fluids; the bus plate is slidably disposed within the first recess and configured to axially abut a surface of the first recess facing the bladder gasket and / or the bus plate; 17. The apparatus of claim 16, wherein an axial distance between the bus plate and the surface of the first recess axially facing the bus plate is configured to increase in response to accumulation of one or more control fluids in a region between the bus plate and the insulating plate that is fluid-tight sealed, at least via the bladder gasket.

19. 18. The apparatus of claim 17, The second end plate is a first body; a second end plate projection extending axially from the first body; and a second end plate opening extending in a direction opposite to the axial direction to a central portion of the second end plate projection and terminating in a concave surface facing the cell; the second end assembly further comprising a piston interposed between the second insulating plate and the second end plate, the piston comprising: a second body; a piston projection extending from the second body in a direction opposite to the axial direction and terminating in a projection surface facing the concave surface; At least a portion of the piston projection is slidably disposed within at least a portion of the second end plate opening; the second end plate further includes one or more holes fluidly connected to the second end plate opening, the one or more holes configured to receive one or more control fluids; the piston projection includes a plurality of piston gaskets surrounding the piston projection and axially offset from one another, the piston gaskets having an interface with one or more inner sidewalls of the second end plate opening, such that the second end plate opening, the piston projection, and the piston gaskets define a cavity within the second end assembly; The device is configured such that an axial distance between the protruding surface and the concave surface increases in response to an accumulation of the one or more control fluids within the cavity.

20. 20. The apparatus of claim 19, the second end assembly further comprising a plurality of biasing members; the piston projection includes a plurality of piston projection openings extending axially into the projection surface; the second end plate further includes a plurality of support protrusions extending axially from the concave surface and positioned corresponding to the piston protrusion openings; the biasing members are supported within the second end plate openings via corresponding ones of the support protrusions, such that in a first compressed state of the second end assembly, the biasing members are compressed between the protruding surface and the concave surface, and each portion of the support protrusion extends at least partially into a corresponding one of the piston protrusion openings; the second end plate further includes one or more holes fluidly connected to the second end plate opening, the one or more holes configured to receive one or more control fluids; the piston projection includes a plurality of piston gaskets surrounding the piston projection and axially offset from one another, the piston gaskets having an interface with one or more inner sidewalls of the second end plate opening, such that the second end plate opening, the piston projection, and the piston gaskets define a cavity within the second end assembly; The device is configured such that an axial distance between the protruding surface and the concave surface increases in response to an accumulation of the one or more control fluids within the cavity.

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