Cell stack and cell stack assembly

Abstract

The electrochemical cell stack (12) comprises a plurality of stacked cell units (10) each defining an outer periphery, a housing (58) surrounding the stack (12) to define a volume around the periphery, and at least one electrically insulating beam (76) extending generally in a stacking direction of the stacked cell units (10), extending across the plurality of cell units (10) and positioned between the periphery and the housing (58), wherein an electrical connection member (54) of a current delivery system of the cell stack extends within the electrically insulating beam (76).

Description

[Technical field]

[0001] The present invention relates to an improved cell stack, a cell stack assembly including one or more such cell stacks, and a method for manufacturing the same. The present invention more particularly relates to a stack of fuel cells or electrolysis cells, commonly known as electrochemical cell units, which may be based on various battery chemistries such as solid oxide or PEM, in particular metal supported solid oxide fuel cells (MS-SOFC) or metal supported solid oxide electrolysis cells (MS-SOEC). The present invention also relates to an assembly including such fuel cells or electrolysis cells. [Background technology]

[0002] Electrochemical fuel cells use an electrochemical conversion process to oxidize fuel to produce electricity. They are typically in a planar configuration and are typically formed into multiple layers of fuel cell units with internal manifold fluid passages between upper and lower layers. Such fuel cell units are arranged in a stack, e.g., 10-200 fuel cell units, on top of each other in a stack configuration, and with fluid passages between the stacked cell units. Other fuel cells may instead use external manifold flow paths for the fuel and oxidant.

[0003] Each fuel cell unit operates to generate electricity when in operation.

[0004] The technology behind solid oxide fuel cells (SOFC) is based on a solid oxide electrolyte that conducts negative oxygen ions from the cathode to the anode across the electrolyte. Thus, a fuel or reformate contacts the anode (aka fuel electrode) of the fuel cell unit, and an oxidant such as air or an oxygen-rich fluid contacts the cathode (aka air electrode) of the fuel cell unit. Fluid passages within and between the cell units make this possible. Other forms of electrochemical cell units also exist.

[0005] Conventional ceramic-supported (e.g., anode-supported) SOFCs have low mechanical strength and are prone to breakage. Thus, metal-supported SOFCs have been developed, having active fuel cell component layers supported on a metal substrate. In these metal-supported solid oxide fuel cells, the ceramic layers can be made very thin, since they perform not only a structural reinforcement function but also an electrochemical function. Such stacks incorporating such metal-supported SOFC stacks are generally more robust than ceramic-supported SOFCs and can generally be fabricated at a lower cost. Both WO2020 / 126486 and WO2015 / 136295 disclose exemplary prior art configurations of such metal-supported SOFCs, examples from which are shown in Figures 1-7 of the present application to aid in explaining the operation of the stacks. However, the present invention is applicable to all forms of electrochemical cell units.

[0006] A solid oxide electrolysis cell (SOEC) is another form of electrochemical cell that may have the same structure as a SOFC, but operates essentially in reverse or regenerative mode to a SOFC, using a solid oxide electrolyte to accomplish the electrolysis of water and / or carbon dioxide to produce hydrogen gas and / or carbon monoxide and oxygen. Summary of the Invention [Problem to be solved by the invention]

[0007] The present invention is directed to a stack of repeating electrochemical cell units, which may have a structure suitable for use as an electrolysis cell or a fuel cell. For convenience, the electrochemical cell units of the stack are hereinafter referred to as "cell units". These may be for power generation or for use in a regenerative mode (i.e., including either or both SOEC or SOFC units, or other forms of electrochemical cell units).

[0008] The cell units of the stack and the stack itself face significant mechanical, electrical and thermal design challenges when designing the cell units and stacks, as they must maintain consistent electrical connections internally to avoid electrical spikes or arcs within the stack. This can be due to the presence of fuel and oxidant fluids in the stack. It is also important to achieve permanent fluid seals both within and between the cell units and through the stack, as well as to define and separate fluid passages for the fuel and oxidant in the cell units and stack, as it is important that the fuel and oxidant do not mix within the stack. Also, in some applications, such as when used in vehicle applications, the fuel and / or electrolysis cells experience significant thermal cycling when powered up and down or subject to large movements, requiring a consistent manufacturing process and design that allows for structural integrity over time and in use of the stack assembly. [Means for solving the problem]

[0009] According to a first aspect of the present invention, there is provided an electrochemical cell stack comprising: a plurality of stacked cell units, each defining a perimeter; a housing surrounding the stack to define a volume around an outer periphery; At least one electrically insulating beam extending generally in a stacking direction of the stacked cell units, extending across a plurality of cell units, and disposed between an outer periphery of the cell unit and the housing; wherein electrical connection members of a current delivery system of the cell stack extend into the electrically insulating beam; An electrochemical cell stack is provided.

[0010] Examples of electrochemical cell stacks include fuel cell stacks or electrolysis cell stacks.

[0011] This aspect of the invention helps to ensure that the current collector circuits are protected from electrical contact with the cell units, minimizing the risk of short circuits within the cell stack. In this regard, it should be noted that the electrical connection members, like the housing and the cell units (usually) are electrically conductive, and may cause an electrical short circuit if they are in direct contact with each other, especially when metal-supported. The presence of an electrically insulating beam (i.e., a non-conductive component) around the electrical connection members prevents such electrical short circuits.

[0012] Moreover, the beams can provide an additional beneficial function during assembly of the stack and subsequent use of the stack: because the beams are between the peripheries of the cell units and the housing, they can be positioned to engage the peripheries of at least some of the cell units during and after assembly, thus providing an alignment function for the cell units during and after assembly, and during use.

[0013] In some embodiments, one or more beams can be used to eliminate the need for alignment members during the assembly process, which would have to be removed at a later stage in the assembly process.

[0014] In some embodiments, there are at least two electrically insulating beams, with the (e.g., rigid, conductive, elongated) electrical connection members of the cell stack's current delivery system extending through at least one of the beams.

[0015] In some embodiments, each electrical connection member extending within one of the electrically insulating beams extends the entire length of that beam, ie in the stacking direction of the stacked cell units.

[0016] In some embodiments, the or each beam may be formed of two or more parts, for example an upper part and a lower part. In some embodiments, each part extends generally in the stacking direction of the stacked cell units, extends across a plurality of cell units, and is disposed between the outer periphery of the cell units and the housing. Electrical connection members of a current delivery system of the cell stack may extend into each part of the electrically insulating beam. In some embodiments, each part may be disposed to engage the outer periphery of at least some of the cell units. In some embodiments, each part provides an alignment function for the cell units both during and after assembly.

[0017] In some embodiments, the or each beam comprises two parts, an upper part and a lower part, the upper part being stacked on top of the lower part, with the electrical connection members extending through both parts.

[0018] In some embodiments, the length of the or each beam is adjustable, for example by providing one or more stepped surfaces between adjacent parts thereof, or by providing tapered surfaces, or by providing additional parts thereof.

[0019] In some embodiments, the beam, or parts of each beam, are provided with slots which allow an electrical connection member to be fitted through a part of the beam and then one or more other parts of the beam can be fitted around the electrical connection member to extend the beam.

[0020] In some embodiments, the or each beam has one or more cut out areas to increase fluid flow in that area, for example to allow more air flow resulting in greater cooling. The cut out areas may be in a one-piece beam or in a multi-part beam, in which case the cut out areas are in one or more parts of the multi-part beam.

[0021] In some embodiments, the cell unit comprises a solid oxide fuel cell (SOFC).

[0022] In some embodiments, the cell unit comprises a solid oxide electrolysis cell (SOEC).

[0023] In some embodiments, the cell unit includes one or more other suitable types of electrochemical cells.

[0024] In some embodiments, the cells and / or cell units are generally planar.

[0025] The cell units may, for example, be electrode or electrolyte supported, or metal supported, in which case the electrochemically active layers may be provided or coated on a perforated or porous metal structure.

[0026] The cell units may define a first fluid passageway within the cell unit, for example, between an upper plate and a lower plate of each cell unit.

[0027] The cell units may define a second fluid passageway between adjacent cell units.

[0028] The cell units may be flat or planar.

[0029] The housing may be a stack housing that defines a fluid volume that contains a stack of cell units. Alternatively, the housing may be a skirt of the stack housing. The skirt may be welded to the upper and lower end plates of the stack housing.

[0030] The housing or skirt may only be associated with a single stack (that it surrounds) and further, the beam may only be associated with a single stack (extending in the direction of that stack) rather than between separate stacks.

[0031] In some embodiments, the electrical connection members extending into the electrically insulating beam are dedicated electrical connection members for that stack for delivering electrical current from the current collecting plates provided for that stack.

[0032] In some embodiments, a stack may have more than one such dedicated electrical connection member.

[0033] In some embodiments, the stacked cell units are arranged electrically in series throughout, with a current collecting plate at each end of the stack.

[0034] In some embodiments, the stacked cell units are arranged in both series and parallel, with a current collecting plate provided at each pole of the stack.

[0035] In some embodiments, electrical connections in the form of bus bars extend from some or all of the current collecting plates to one or more end plates of the stack housing, preferably at one (or both) ends of the cell stack.

[0036] In some embodiments, the insulating beams, preferably mica or ceramic tubes, extend to at least one of the top or bottom of the stack of cell units, or to the inner surface of an end plate of the stack housing.

[0037] In some embodiments, the beam abuts the periphery of at least two of the plurality of cell units to exert a force resisting further movement of the plurality of cell units toward the beam.

[0038] In some embodiments, the force is generated by a housing (or skirt) that directly or indirectly engages the beam, pushing or urging the beam into the cell unit, or pushing or urging the beam between the housing and the cell unit, exerting a force that restrains or positions the cell unit to resist movement of the cell unit relative to the housing and / or beam.

[0039] Preferably, the outer periphery of every cell unit of the plurality of cell units abuts against the electrically insulating beam.

[0040] The electrical connection members that run inside the beams can be bus bars that connect to the connecting plates of the stack, or some other component of the current delivery system of the cell stack, for example this can include studs or cables that connect to the bus bars or current collecting plates.

[0041] In some embodiments, the electrical connections extend beyond the beams and through the top or bottom of the stack and out of the housing, for example through end plates of the stack enclosure.

[0042] In some embodiments, a further conductor is connected to the electrical connection member and exits the housing.

[0043] Some embodiments have further additional components to extend the current delivery system outside the housing.

[0044] According to a second aspect of the present invention, there is provided an electrochemical cell stack comprising: a plurality of stacked cell units, each defining a perimeter; a housing surrounding the stack to enclose a volume around an outer periphery; at least two electrically insulating beams each extending across the plurality of cell units and each engaging an outer periphery of at least two of the plurality of cell units; Equipped with the beams define a line extending between the two beams, the line defining a lateral line across each cell unit; a) the contact tangents between each beam and each of the plurality of cell units cooperate to resist movement of each of the plurality of cell units in both lateral directions along its defined transverse line and in at least one longitudinal direction generally perpendicular to its transverse line and generally in the plane of the periphery of its respective cell unit; or b) the contact tangents of each beam with each of the plurality of cell units cooperate with each beam to resist movement of each of the plurality of cell units in both at least one lateral direction along the defined lateral line of the cell unit and at least one longitudinal direction generally perpendicular to the lateral line and generally planar with respect to the perimeter; In one embodiment, an electrochemical cell stack is provided, wherein either or both of the

[0045] By resisting movement of each of the plurality of cell units in both lateral directions along its defined lateral line, the cell units cannot move left or right relative to the central longitudinal plane of the stack.

[0046] By resisting movement of each of the plurality of cell units in at least one vertical direction generally perpendicular to the horizontal line and generally in the plane of the periphery of each cell unit, the cell units cannot move forward (or backward, depending on the direction constrained) along a central vertical plane of the stack.

[0047] By resisting movement of each of the multiple cell units in at least one lateral direction along its defined lateral line, the cell units cannot move to the left or right (depending on the direction to which they are constrained) relative to the central vertical plane of the stack.

[0048] Such movement constraints are beneficial because they minimize relative movement of components within the stack, reducing the possibility that such movement could breach seals between adjacent components or cause elements to become displaced from their intended positions due to shock or vibration applied to the stack.

[0049] In some embodiments, the beam spans the full height of the fuel cell stack.

[0050] In some embodiments, the electrical connections of the current delivery system of the cell stack extend into one or both of the beams.

[0051] In some embodiments, the beam contacts at least 50% of the cell units in the stack of cell units. In other embodiments, the beam contacts all of the plurality of cell units. In further embodiments, the beam contacts more than 50% of the cell units in the plurality of cell units.

[0052] If the edges are not perfectly aligned throughout the stack of cell units, some cell units may not touch the beam.

[0053] The line between the beams is typically a line extending from the cross-sectional center of the beam or from the distal most end of the beam in the direction of air flow (or oxidant flow) through the fuel cell stack.

[0054] Typically, the shapes of the two beams are coincident. In some embodiments, they are mirror images of each other across the lateral width of the cell unit.

[0055] This second aspect of the invention may have features of the first aspect of the invention as well, and vice versa. In particular, the (e.g. rigid, conductive, elongated) electrical connection members of the current delivery system of the cell stack may extend inside the beam.

[0056] According to a third aspect of the present invention there is provided an electrochemical cell stack comprising: a plurality of stacked cell units, each defining a perimeter; a housing surrounding the stack to enclose a volume around an outer periphery; two opposing electrically insulating plates disposed between the housing and the plurality of stacked cell units, each of the two opposing sides of the plurality of stacked cell units being in contact with one of the two opposing sides of the plurality of stacked cell units; At least one electrically insulating beam extending across and engaging an outer periphery of a plurality of cell units in the stack; and the insulating beam also engages either or both of the housing and one of the electrical insulating plates. An electrochemical cell stack is also provided.

[0057] The engagement of both the cell units with the housing or electrical insulation plate automatically ensures that all of the components are properly aligned in the stack upon assembly. This allows any appropriate fluid passages within the cell units themselves to be properly configured for, for example, fuel or oxidant flow. It also prevents the edges of the cell units from approaching each other, reducing the chance of electrical shorts between the cell units in the stack.

[0058] In some embodiments, the electrical connections of the current delivery system of the cell stack extend into one or both of the beams.

[0059] In some embodiments, there are at least two electrically insulating beams, each extending across multiple cell units.

[0060] In some embodiments, the second beam engages the periphery of their respective plurality of cell units and engages either or both of the housing and one of the electrically insulating plates.

[0061] In some embodiments, each beam engages an outer periphery of a plurality of cell units and engages either or both of the housing and one of the electrically insulating plates.

[0062] In some embodiments, each of the beams is integrally formed with one of the electrically insulating plates, however, more typically they are separate components.

[0063] Each electrical insulating plate that engages with the edge of the cell unit has a cell engagement surface that provides the engagement. In some embodiments, the beam closest to the cell engagement surface of one of the electrical insulating plates has a cell engagement surface that extends distally to the cell engagement surface of that electrical insulating plate, i.e. away from it, towards the central longitudinal plane of the stack, for example into a recess in the edge of the cell unit, or partially across the respective edge of the cell unit. In a preferred embodiment, each of the two beams has a cell engagement surface that extends distally to the cell engagement surface of its closest electrical insulating plate. Due to the distal arrangement of the cell engagement surfaces of the two beams, the two beams provide a narrowing of the width of the cell unit between the two beams compared to the width between the two electrical insulating plates. Due to the narrowing, the beams provide a concentration of the air flow through the central stream of the second fluid passage near the narrowing between the beams, and less air flow to the sides of the second fluid passage near the distal extension of the beam, i.e. in the space to the sides of the central stream corresponding to the portions of the second fluid passage adjacent to the two sides of the cell unit where the electrical insulating plates are located.

[0064] In some embodiments, the two beams are located at or near the downstream end of the second fluid passage, or at or near the downstream end of the fluid passage carrying the oxidant, which is the same end in a parallel flow configuration. The downstream end carrying the oxidant is usually the hot end of the cell stack, and having a constriction at least at that end allows the oxidant flow (i.e., usually air flow) to be concentrated at that hot end, aiding in the need to increase the fluid flow to provide the required cooling. In other words, the flow density at that hot portion of the cell stack can be increased.

[0065] In the case of four beams, they can be located at either end of the fluid passage.

[0066] Each electrically insulating plate may also engage an inner wall of the housing, although in some embodiments the configuration may include two or more electrically insulating plates between each opposing side of a plurality of stacked cell units, i.e., stacked electrically insulating plates.

[0067] In some embodiments, the electrical insulating plates are positioned only on two of the sides of the stacked cell units, preferably on parallel opposing sides, more preferably on the long sides of the cell units, i.e., at the proximal and distal ends (relative to the direction of air flow / oxidant flow) of the stacked cell units, there are no such electrical insulating plates in contact with the outer periphery of the stacked cell units.

[0068] In some embodiments, more than one electrically insulating plate is disposed against opposite sides of each of the stacked cell units, side-by-side or stacked, in a common plane.

[0069] The third aspect of the invention further features one or more features of the first or second aspects of the invention, or vice versa. In particular, the (e.g. rigid, conductive, elongated) electrical connection members of the current delivery system of the cell stack may extend into the interior of the beam.

[0070] According to a fourth aspect of the present invention, there is provided a cell stack assembly comprising a cell stack as defined above, a fuel delivery port communicating with a first fluid passage in the cell stack, an oxidant delivery port communicating with a second fluid passage in the cell stack, a current collecting plate for collecting current from the cell stack or delivering current to the cell stack, and an electrical connection member for delivering current from the current collecting plate to an outside of the housing or to a current collecting plate within the housing.

[0071] The fourth aspect of the invention may further feature one or more features of any one or more of the first, second or third aspects of the invention, or vice versa.

[0072] According to a fifth aspect of the present invention, there is provided an electrochemical cell stack assembly comprising: a stack of cell units, each defining an outer periphery; a housing, initially divided into at least two separate parts, surrounding an outer periphery of the stacked cell units so as to define a volume around the periphery; at least two electrically insulating beams; one electrically insulating beam is assembled between one initially separate part of the housing and the stacked cell units, and a second electrically insulating beam is assembled between a second initially separate part of the housing and the stacked cell units, the at least two electrically insulating beams each extending across the plurality of cell units and abutting outer peripheries of at least two of the plurality of cell units to exert a force resisting further movement of the plurality of cell units toward the beam; the first and second initially separate parts of the housing clamp the at least two beams against an outer periphery of at least two of the plurality of cell units when the two parts of the housing are closed together. An electrochemical cell stack assembly is provided.

[0073] Typically, the two separate parts are not initially connected to each other.

[0074] Preferably, at least two parts of the housing are welded together in a clamped state to maintain the clamping force.

[0075] A fifth aspect of the invention further features one or more features of any one or more of the first, second, third or fourth aspects of the invention, or vice versa. In particular, the (e.g. rigid, conductive, elongated) electrical connection members of the current delivery system of the cell stack may extend into the interior of the beam.

[0076] According to a further aspect of the present invention there is provided an electrochemical cell stack comprising: a plurality of stacked cell units, each defining a perimeter; At least one electrically insulating beam extending generally in a stacking direction of the stacked cell units and extending across a plurality of the cell units; Equipped with the electrical connections of the cell stack's current delivery system extend into the electrically insulating beam; The or each beam is formed of two or more parts, An electrochemical cell stack is provided.

[0077] According to yet a further aspect of the present invention there is provided an electrochemical cell stack comprising: a plurality of stacked cell units, each defining a perimeter; At least one electrically insulating beam extending generally in a stacking direction of the stacked cell units and extending across a plurality of the cell units; Equipped with the electrical connections of the cell stack's current delivery system extend into the electrically insulating beam; the or each beam has one or more cut out areas to increase fluid flow in that area; An electrochemical cell stack is provided. The beam may be divided into one or more parts.

[0078] In these further aspects, which may also be according to any of the above aspects, there may be a first part, usually an upper part, and a second part, usually a lower part, for the or each beam. In some embodiments, there is a third part. There may also be further parts.

[0079] In some embodiments, each part extends generally in the stacking direction of the stacked cell units, extends across multiple cell units, and is disposed between the outer periphery of the cell units and the housing of the stack. Electrical connection members of a current delivery system of the cell stack may extend into each part of the electrically insulating beam. In some embodiments, each part may be disposed to engage the outer periphery of at least some of the cell units. In some embodiments, each part provides an alignment function for the cell units both during and after assembly.

[0080] In some embodiments, the or each beam comprises two parts, an upper part and a lower part, the upper part being stacked on top of the lower part, with the electrical connection members extending through both parts.

[0081] In some embodiments, the length of the or each beam is adjustable, for example by providing one or more stepped or castellated surfaces between adjacent parts thereof, or by providing tapered or chamfered surfaces.

[0082] In some embodiments, the or each beam has a slot in the side wall of one or more parts thereof, which allows fitting the electrical connection member through one or more parts of the beam, and then fitting one or more other parts of the beam around the electrical connection member, for example to extend the beam, after access to the free end of the electrical connection member is restricted.

[0083] In some embodiments, the or each beam has one or more cut out areas to increase fluid flow in that area, for example to allow more air flow resulting in greater cooling. The cut out areas may be in a one-piece beam or in a multi-part beam, in which case the cut out areas are in one or more parts of the multi-part beam.

[0084] The cell stacks and cell stack assemblies of the present invention may be used in domestic, industrial, commercial, or transportation / vehicle applications. In one such application, there is provided a fuel cell system comprising an electrochemical cell stack as defined above for use in a vehicle application.

[0085] According to a sixth aspect of the present invention there is provided a method of assembling an electrochemical cell stack comprising the steps of: providing stacked cell units, each defining a perimeter; providing at least one electrically insulating beam that extends across and engages an outer periphery of a plurality of the stacked cell units and is assembled to the stacked cell units; fitting a housing around the stacked cell units and the electrically insulating beam; Including, the housing defines a volume around an outer periphery, the housing being initially divided into at least two separate parts; the first and second initially separate parts of the housing are clamped against the outer periphery of at least two of the plurality of cell units when the two parts of the housing are closed together, exerting a force resisting further movement of the plurality of cell units towards the beam, and the initially separate parts are then connected or joined together in the clamped state to maintain a clamping force by the beam against the outer periphery of the at least two of the plurality of cell units. A method is provided.

[0086] In some embodiments, there are at least two electrically insulating beams; one electrically insulating beam is assembled between a first initially separate part of the housing and the stacked cell units, and a second electrically insulating beam is assembled between a second initially separate part of the housing and the stacked cell units, the at least two electrically insulating beams each extending across the plurality of cell units and abutting the outer peripheries of at least two of the plurality of cell units to exert a force resisting further movement of the plurality of cell units toward the beams; The first and second initially separate parts of the housing are clamped against the outer periphery of at least two of the plurality of cell units when the two parts of the housing are closed together, exerting a force resisting further movement of the plurality of cell units toward the beam, and the initially separate parts are then connected or joined to each other in a clamped state to maintain a clamping force by the beam against the outer periphery of the at least two of the plurality of cell units.

[0087] In some embodiments, the first and second initially separate parts of the housing are indirectly clamped to the outer periphery of at least two of the plurality of cell units via the or each electrically insulating beam as well as one or more electrically insulating plates.

[0088] In some embodiments, the one or more beams engage the periphery at a recess in the periphery.

[0089] The fuel or electrolysis cell stack of the method of the sixth aspect of the invention is the fuel or electrolysis cell stack of any one of the first to fifth aspects of the invention and may include any one or more of the preferred or optional features of the first to fifth aspects of the invention. In particular, the (e.g. rigid, conductive, elongated) electrical connection members of the current delivery system of the cell stack may extend within the beam.

[0090] In some embodiments, the beam is a circular beam.

[0091] In some embodiments, the beam is a tube.

[0092] In some embodiments, the busbar of the cell stack extends within at least one of the beams, for example to the center of the beam.

[0093] In some embodiments, there are two bus bars in the stack, each on one of the beams.

[0094] In some embodiments, the beam is made of mica.

[0095] In some embodiments, two opposing electrically insulating plates are positioned between the housing and the plurality of stacked cell units, each against one of two opposing sides of the plurality of stacked cell units, and an insulating beam is added to the electrically insulating plates.

[0096] In some embodiments, the beams also each contact one of the electrically insulating plates.

[0097] In some embodiments, the beam also contacts the housing.

[0098] In some embodiments, the beam extends the entire height of the stack.

[0099] In some embodiments, each beam contacts each cell unit.

[0100] In some embodiments, each beam defines a barrier to fluid flow into and out of the second fluid passage. This can be assisted by preventing or reducing fluid flow around the outside of the beam between the periphery and the housing, and by directing more of the fluid flow into the central stream of the second fluid passage.

[0101] In some embodiments, each beam defines a barrier to fluid flow into and out of the second fluid passage, concentrating airflow through a central stream of the second fluid passage and less airflow to the side of the second fluid passage adjacent to the straight side of the cell unit, which in some embodiments can be beneficial to provide more flow to hotter portions of the cell.

[0102] In some embodiments, the perimeter includes two straight sides and a shaped end.

[0103] In some embodiments, the beam is disposed at one of the shaped ends.

[0104] In some embodiments, the beam sits in a depression or recess formed in the straight side of the periphery, the depression or recess preferably having a configuration in a shape complementary to the shape of the beam, i.e., the portion of the beam that it fits or abuts.

[0105] In some embodiments, the cell units are generally rectangular.

[0106] In some embodiments, there is a beam on each long side of the rectangle.

[0107] In some embodiments, there are beams at or adjacent to two of the corners of the rectangle.

[0108] In some embodiments, the two corners are adjacent corners.

[0109] In some embodiments, the two corners are adjacent corners at the end of one of the shorter sides of the rectangle.

[0110] In some embodiments, the two corners are at the downstream end of the second fluid passage of the stacked cell units, or the air flow / oxidant flow fluid passage, which defines a vertical direction perpendicular to a horizontal line spanning the fluid passage and generally in plane with the periphery of at least one of the cell units.

[0111] In some embodiments, the fluid flow direction through the first fluid passage or the fuel flow fluid passage corresponds to the fluid flow direction through the second fluid passage, i.e., the stacked cell units use a parallel fluid flow configuration through the stacked cell units. Alternatively, there can be a counter-flow configuration, where the fluid flow direction through the second fluid passage is opposite to the fluid flow direction through the first fluid passage. In other configurations, the flows can be at other angles to each other, for example 90 degrees to each other.

[0112] In some embodiments, there are three or four beams.

[0113] In some embodiments, each cell unit has two straight sides that accommodate two beams each.

[0114] In some embodiments, the cell unit has two or four corners, with each corner having one of the beams.

[0115] In some embodiments, different portions of the perimeter define respective depressions or recesses into which each beam is seated.

[0116] In some embodiments, each corner has a recess or indentation to accommodate one of the beams.

[0117] In some embodiments, the depression or recess is in the center of the side of each cell unit.

[0118] In some embodiments, the depression or recess wraps around the beam over at least a 90 degree segment.

[0119] In some embodiments, the depression or recess wraps around the beam over at least a 180 degree segment.

[0120] In some embodiments, the depression or recess has curved walls.

[0121] In some embodiments, the depression or recess is a recess with two or more straight wall portions against which the beam presses, the straight wall portions being angled relative to each other in each depression or recess.

[0122] In some embodiments, the beams extend vertically across the cell units, i.e. parallel to the length or stack height of the stack.

[0123] In some embodiments, the peripheries of all the cell units are aligned with one another around the entire periphery.

[0124] In some embodiments, the housing has a bottom and a top, and a skirt that surrounds the periphery of the cell unit.

[0125] In some embodiments, the skirt is formed of at least two parts that are joined together at their seams, for example by welding.

[0126] In some embodiments, the housing is provided with separate top and bottom components and the skirt is joined to the top and bottom components, for example by welding.

[0127] In some embodiments, each of the stacked cell units comprises a separator plate and a metal support plate, the separator plate and the metal support plate overlapping each other; one or more first fluid passages extend through the cell units between a respective separator plate and a metal support plate of each cell unit; The stacked cell units include a second fluid passage extending between adjacent cell units; The first and second fluid passages are for distributing the fuel and oxidant through the stack.

[0128] In some embodiments, the stack has active and inactive cell units.

[0129] In some embodiments, each active cell unit has one or more cell chemistry layers disposed on a porous or perforated region of a metal plate of the cell unit.

[0130] In some embodiments, the cell chemistry layer includes multiple layers, including an anode layer, an electrolyte layer, and a cathode layer.

[0131] In some embodiments, at least one fluid port is provided in each cell unit, and each fluid port of adjacent cell units is aligned with and communicates with the first fluid passage of each cell unit.

[0132] In some embodiments, the cell units include separator plates with molded outward protrusions to partially separate adjacent cell units to define a second fluid passage between adjacent cell units.

[0133] In some embodiments, the outward projections of a first cell unit engage, at their ends, the outer surface of the cell chemistry layer of an adjacent cell unit.

[0134] In some embodiments, the cell unit includes a metal support plate with a molded port feature formed around its port, the molded port feature extending toward a separator plate of the cell unit, and elements of the molded port feature spaced apart from one another to define a fluid path from the port to the elements to enable passage of fluid from the port to a first fluid passage in the cell unit between the metal support plate and the separator plate.

[0135] In some embodiments, each cell unit is flat.

[0136] In some embodiments, each cell unit has at least one recess on at least one edge, and these recesses are aligned across the width or length of the cell unit.

[0137] In some embodiments, the recesses are configured, at least in part, to conform to and abut opposing portions of adjacent electrically insulating beams or tubes.

[0138] In some embodiments, the electrically insulating beam is disposed between and in contact with the periphery of the housing and the cell unit so as to prevent or close a fluid flow path between the electrically insulating beam and the housing or its skirt.

[0139] In some embodiments, two of the electrically insulating beams are positioned adjacent to the internal manifold fluid ports or fluid outlet ports and act to define and limit or restrict the fluid flow path to the internal manifold fluid ports or fluid outlet ports where the beams contact the outer periphery of the cell unit.

[0140] In some embodiments, each cell unit has at least one recess on at least one edge into which one of the electrically insulating beams is assembled, and the at least one recess has an inverse shape to the portion of the electrically insulating beam that is assembled within the recess (respective recesses of adjacent recesses are aligned to define a recessed channel extending in the stacking direction).

[0141] According to a further aspect of the present invention, there is provided a method of assembling an electrochemical cell stack, comprising the steps of: providing cell units, each defining a perimeter; providing at least one electrically insulating beam assembled to the cell units such that the electrically insulating beam extends across and engages an outer periphery of each of the plurality of stacked cell units with electrical connection members of a current delivery system of the cell stack extending into the electrically insulating beam; Including, Fitting a first part of an electrical insulating beam onto the electrical connection member, stacking the cell unit in contact with the first part of the electrical insulating beam, and then fitting a second part of the electrical insulating beam onto the electrical connection member and the first part of the electrical insulating beam; A method is provided that includes:

[0142] This method may be combined with any one or more of the other aspects of the invention.

[0143] In some embodiments, the or each beam is formed from only two separate parts, hi some embodiments, the beam is formed from three or more separate parts.

[0144] In some embodiments, the or each beam has one or more cut out areas to increase fluid flow in that region within the stack.

[0145] In some embodiments, the length of the or each beam is adjustable, for example by providing one or more stepped or castellated surfaces between adjacent parts thereof, or by providing tapered surfaces.

[0146] In this aspect of the invention, the method includes initially installing the first and second parts of the beam in a shortened length configuration on the respective electrical connection members, then making a connection between the tops of the respective electrical connection members to the upper electrical connector, after which the beam can be extended to a further extended length. Alternatively, when initially installed at a further extended length, access to the tops of the electrical connection members may be blocked by the upper current collecting plate at the top of the stack of cell units, by the tops of the beam, or both.

[0147] In some embodiments, the length of the beam is adjusted to fit under the upper current collecting plate.

[0148] In some embodiments, the or each beam has a slot in the side wall of one or more parts thereof, which allows fitting the electrical connection member through one or more parts of the beam, and then fitting one or more other parts of the beam around the electrical connection member, for example to extend the beam, after access to the free end of the electrical connection member is restricted.

[0149] In some embodiments, the or each beam has one or more cut out areas to increase fluid flow in that region within the stack.

[0150] It will be understood by those skilled in the art that each feature of each embodiment may be used with each of the other embodiments as well, either alone or in combination with other features of each embodiment.

[0151] These and other features of the invention will now be described in more detail, by way of example only, with reference to the accompanying drawings, in which: [Brief description of the drawings]

[0152] [Figure 1] FIG. 2 is an exploded view of a prior art cell unit in which two cell units are arranged in a vertical stack. [Diagram 2] FIG. 2 is an exploded view of a prior art cell unit in which two cell units are arranged in a vertical stack. [Diagram 3] FIG. 3 shows the stack of FIG. 2 in assembled form. [Figure 4] FIG. 2 is a diagram similar to FIG. 1, but showing a further variation of the cell unit with separate metal cell components and a metal support plate. [Diagram 5] FIG. 2 is an exploded view of an alternative prior art cell unit. [Figure 6] FIG. 1 illustrates a prior art cell stack assembly in exploded form with a portion of the cell unit removed for clarity. [Figure 7]FIG. 1 illustrates a prior art cell stack assembly in assembled form. [Figure 8] FIG. 2 is a plan view of a first embodiment of the present invention with four bus bars and two electrically insulating beams extending upwardly from a current collecting plate 52. [Figure 9] FIG. 2 shows a second embodiment of the invention similar to the first embodiment but with only two bus bars extending upwardly from the current collecting plate. [Figure 10] FIG. 9 shows a modification of the cell stack of FIG. 8 in which the corners of the cell units are shaped differently to provide four electrically insulating beams, one at each corner. [Figure 11] FIG. 10 illustrates a further variation of the cell stack of FIG. 8 with four electrically insulating beams, one at each corner, showing a co-current fuel and oxidant (air) flow configuration. [Figure 12] FIG. 12 is a perspective view of the cell stack of FIG. 11 without the four bus bars. [Figure 13] FIG. 13 shows the cell stack of FIG. 12 with four bus bars present. [Figure 14] FIG. 13 shows the cell stack of FIG. 12 with a portion of its housing removed. [Figure 15] 13 is a partial cutaway view of an assembly step for assembling a housing around a stack of cell units in the cell stack of FIG. 12. [Figure 16] 13 is a partial cutaway view of an assembly step for assembling a housing around a stack of cell units in the cell stack of FIG. 12. [Figure 17] 13 is a partial cutaway view of an assembly step for assembling a housing around a stack of cell units in the cell stack of FIG. 12. [Figure 18] FIG. 13 shows a further variation of the invention with a portion of the housing removed. [Figure 19] FIG. 13 shows a further variation of the invention with a portion of the housing removed. [Figure 20]FIG. 13 shows yet another further variation of the present invention with a one-piece housing. [Figure 21] FIG. 13 shows a further variation of the invention with four two-piece beams. [Figure 22] FIG. 13 shows a further variation of the invention with four two-piece beams, each having a stepped surface to vary the length of the beam. [Figure 23] FIG. 23 shows the two-piece beam from FIG. 22 in more detail. [Figure 24] FIG. 13 shows a further variation of the invention with four two-piece beams, each with a tapered surface to vary the length of the beam. [Diagram 25] FIG. 25 shows the two-piece beam from FIG. 24 in more detail. [Figure 26] FIG. 2 shows a further variation of the invention, comprising four three-piece beams, a central first part and two outer parts, each having a slot to allow the outer part to be inserted after the central first part has been fitted around the electrical connection members of the stack. [Figure 27] FIG. 13 shows a further variation of the invention comprising four beams, the ends of which have cut out areas to increase fluid flow in those areas, for example to allow more air flow resulting in greater cooling. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0153] Referring initially to FIG. 1, a prior art configuration of fuel cell unit 10 is shown, two of which are shown in exploded form to illustrate a possible internal structure of the fuel cell units 12, arranged as a stack 12, with fluid passages formed in the center inside of the fuel cell unit 10 accessible via ports 16 at each end. Details of this form of fuel cell unit 10 are described in depth in WO2020 / 126486, the entire contents of which are incorporated herein by reference. However, in brief, each of these fuel cell units 10 in this example comprises two plates or layers, in the form of an upper metal support plate 18 and a lower separator plate 20. The metal support plate 18 has an active fuel cell component layer 22 thereon, and the separator plate 20 has a number of stamped central projections and recesses 24 and further projections and recesses 36, along with a raised rim 26 for joining the separator plate to the underside of the metal support plate 18.

[0154] Figure 2 shows a variation of the fuel cell unit of Figure 1 in which an additional further protrusion and recess 36 is provided around the port 16 of the metal support plate 18 to face the further protrusion and recess around the port 16 of the separator plate 20. Similarly, a raised rim is provided on the metal support plate to overlap a similar rim on the separator plate.

[0155] As can be seen by comparing Figures 1 and 2, the underside of the plate is visible in Figure 2 while Figure 1 shows the upper side, so that a protrusion in Figure 1 is a recess in Figure 2 and vice versa. Thus, these terms are interchangeable.

[0156] 2 also shows that the lower region of the metal support plate underlying the fuel cell component layer 22 includes an array of perforations 30. These perforations allow access to both sides of the fuel cell component layer even though the fuel cell component layer is formed on the metal support plate, and are present in the example of FIG.

[0157] These exploded views, along with Figures 3 and 4, are useful in helping to explain possible internal configurations of the cell units of the present invention, as the present invention may employ similar cell unit structures, but with different peripheral profiles in exemplary embodiments of the invention, as described below. Additional or fewer ports 16 may be provided depending on the fluid flow requirements of the stack.

[0158] In each active fuel cell unit of the stack, the fuel cell component layers may be electrochemically active layers, typically metal (usually stainless steel) foils deposited on and supported on a metal support plate 18. The electrochemically active layers include each of an anode layer, an electrolyte layer, and a cathode layer, as known in the art. Additional layers, such as cover layers or control layers, may also be included, as known in the art.

[0159] Referring to Figure 3, the fuel cell units 10 of Figure 2 are shown in assembled form, with the metal support plate 18 and separator plate 20 of each fuel cell unit 10 bonded together around their edges. As can be seen in this cross-sectional view, a central projection and recess 24 in the separator plate 20 maintains the space between the two plates of each unit to define the first fluid passage 14, and also maintains a second space between adjacent fuel cell units 10 to define the second fluid passage 32. Gaskets 34 maintain the spacing at the edges of the fuel cell units 10 and overlap further projections or recesses 36 around the ports 16 of both the separator plate and the metal support plate. The gaskets 34 are annular, so that their central openings overlap the ports 16. Thus, a "chimney" or passage 38 is formed through the stack, which is sealed by the gaskets 34 from the second fluid passage 32 between adjacent fuel cell units 10, but which leads to the first fluid passage 14 inside the fuel cell unit. Thus, fluid can enter and exit the first fluid passageway through port 16. Fluid through the second fluid passageway instead circulates around the outside of the fuel cell unit, as described in more detail below.

[0160] In Figure 4 the further protrusions and recesses 36 are only provided in the separator plate as in Figure 1 and in some embodiments they cannot be added and therefore longer / deeper protrusions / recesses may need to be punched out. However, in this embodiment the fuel cell component layer is instead deposited on a further support plate 40 and bonded to the metal support plate 18 in a further step as further described in WO2020 / 126486, so that the thickness of the support plate 18 present as the fuel cell component layer can be further increased. As can be seen in Figure 4, an array of perforations is instead provided on the underside of that further support plate.

[0161] Figures 1 to 4 are from WO2020 / 126486, whereas figures 5 to 7 are from WO2015 / 136295. They show further possible prior art fuel cell configurations. A stack of metal supported SOFCs is again provided, the operation being largely the same. However, instead of the further projections and recesses of the separator plates, instead of the metal support plate in the case of figures 2 and 3, in this example a spacer plate 42 is used between the metal support plate 18 and the separator plate 20. Furthermore, the separator plate 20 uses beams and grooves 24 instead of projections and recesses 24.

[0162] In this example, the spacer plate 42 has a central opening 44 which (when assembled) defines the first fluid passage 14 within the cell unit, and which connects via vent passages 46 to the separator plate 20 and ports 16 in the metal support plate 18. In addition, the three plates 18, 20, 42 also have further ports 48 for venting to (or from) the second fluid passage 32 between adjacent fuel cell units 10, as described in WO2015 / 136295, the entire contents of which are incorporated herein by reference.

[0163] Figure 6 shows a plurality of fuel cell units 10 of Figure 5 arranged into a fuel cell stack 12. Also shown is a dummy cell 48, which may not have all the layers or perforations necessary to activate the fuel cell component layers, but otherwise appears complete in a coherent design configuration as known in the art. Also shown is a current collector plate 52 for collecting charge generated by the stack of fuel cell units 10.

[0164] To maximize their charge capture, the fuel cell units are typically arranged electrically in series through the stack, with current collecting plates at either end of the series stack, although the fuel cell units in a stack may also (or instead) include units arranged in parallel, as is known in the art, with current collecting plates appropriately positioned at opposite poles of the parallel stack.

[0165] The current collecting plates 52 may be connected to or integrally formed with one or more bus bars 54 and / or terminals 56 (as shown by the left collecting plate in FIG. 8) for carrying the current therefrom to the outside of the stack assembly. Such current collecting plates 52, bus bars, and terminals can be seen in FIG. 6 and FIG. 8, and the terminals 56 can be seen in FIG. 7 to extend to the outside of the stack assembly when it is fully assembled.

[0166] In assembling the stack 12, multiple fuel cell units 10 are used, and the fuel cell units 10 are stacked one after the other between two end plates 62, with current collecting plates 52 at both ends of the stack of fuel cell units, and insulating plates 50 between the current collecting plates 52 and the end plates 62.

[0167] In FIG. 6, the solid oxide fuel cell units are held in compression in the assembled stack using a number of tie bars 64 (four shown) that extend between the two end plates 62 through guide holes 66 (see FIG. 5) in the three plates 18, 20, 42 of the fuel cell unit 10. As can be seen in FIG. 7, nuts on the ends of the tie bars 64 provide the compression. In another example, the compression can be preloaded and held by welding the skirts around the cells to the end plates. This latter approach is used in the example of the invention from FIG. 9 onwards, although compression bolts could be used instead, but careful design consideration is required as the tie bars are close to the edges of the guide holes (i.e. the edges of the metal components that define the guide holes of at least one fuel cell stack) and there is a risk of short circuits between the tie bars and the stacks when the components expand at high temperatures in a mixed atmosphere that may contain steam, reacted and unreacted hydrocarbons and air, so restraint by the skirt is preferred.

[0168] All of the above examples of prior art fuel cells are described as examples of one possible type of cell unit that can use the features and advantages of the present invention in a cell stack or cell stack assembly. Those skilled in the art will appreciate that additional shapes of cell units, busbar / electrical take-off designs, and housing shapes can also be used. The following description of exemplary embodiments of the present invention describes such additional designs.

[0169] Referring now to FIG. 8, one embodiment of the present invention is shown. In this cell stack assembly 12, the cell stack comprises a plurality of cell units 10 arranged as a stack inside a housing 58, which in this embodiment is a skirt formed of two halves 68, 70 joined together at the long sides of the cell units 10. The joining can be a weld at a weld line 72 in the middle of the long side of the stack, as shown in FIG. 8. It does not have to be in the middle, but it is convenient to be in the middle for symmetry or ease of manufacture and assembly, so that the two halves can be easily replaced during assembly. In an alternative version of FIG. 10, the weld line 72 can be at the short end of the cell unit 10, and in FIG. 10, the weld line 72 is shown in the middle of the side of the cell unit 10, which is also optional, but is preferred for symmetry or ease of manufacture and assembly.

[0170] The cell unit 10 is generally rectangular, albeit with shaped corners 74, which can accommodate electrical insulating beams such that the beams are located between the corners 74 and the housing or skirt 58. In these examples, the electrical insulating beams 76 take the form of circular or tubular shaped beams with a central void, such as a pipe or tube as shown. In the preferred example, they are made of mica, but other electrical insulating materials, including many ceramics, can also be used, preferably non-fragile electrical insulating materials. In FIG. 8, only two of the corners are provided with beams 76. They are both at the short end of the stack, which in this embodiment is the fluid outlet end of the stack as shown in FIG. 11. In some embodiments, only one beam 76 can be provided. In other embodiments, three or four or more beams can be provided. FIG. 10 shows four.

[0171] In the example of Figure 8, four bus bars or electrical connection posts 54 are shown, each in electrical contact with a current collecting plate 52 at the bottom of the stacked cell units 10. In this example, they are all of a common pole and therefore all collect current from that pole. Additional current collecting plates may be provided at the opposite pole, and additional bus bars or direct connectors may be used.

[0172] These bus bars, and any connectors connected to the bus bars, allow current generated by the stacked cell units 10 to be collected and distributed externally to the stack, distally from the current collecting plates, similar to the stack of Figure 6. Although four bus bars 54 are shown in this example, it is possible to provide only one bus bar, or two (as in Figure 9), or any desired number, or to replace the bus bars with other forms of electrical connections or terminals.

[0173] In Figure 8 the two busbars 54 are threaded through central holes in two beams 76 and are therefore surrounded by the beams insulating the busbars from the cell units and the housing. As the busbars are electrically conductive, typically stainless steel, and the housing / skirt and cell units (which are metal supported in this embodiment) are also primarily made of steel, insulating the busbars from them provides an advantage as it allows the components to be packed more compactly into the housing.

[0174] 9, there are only two bus bars. Similarly, as in FIG. 8, there are two beams 76. In this embodiment, both bus bars 54 are disposed within the beams 76.

[0175] In the example of Figure 9, electrically insulating beams 76 are provided at two corners 74 of the stack. The other two corners 74 are devoid of such beams. As shown, each beam is unique to its stack and engages the stack along substantially all (if not all) of its length.

[0176] In these embodiments, the housings facing these beams 76 are chamfered. Thus, the long sides of the housings are joined to the short sides of the housings by angled chamfers 90 such that the housings 68, 70 abut the beams 76 with a net force diagonally across the cell units 10. This helps to maintain the cell units 10 in their proper position and prevents the cell units 10 from shifting when the stack 12 is subjected to vibration or other shocks during use or transport, etc.

[0177] Electrical insulating plates 78 are also provided along the long sides of the cell unit 10. In FIG. 9, as in FIGS. 8 and 10-17, these electrical insulating plates 78 extend along the long sides of the cell unit 10 and meet at their ends at the beginning of the chamfers 90. In other examples, they extend only partway along the long sides of the housings 68, 70. For example, there may be multiple electrical insulating plates 78 along each long side. For example, as shown in FIG. 20, there may be multiple electrical insulating plates 78 separated by one or more beams 76. As in FIG. 20, this may be a single beam 76 in the center of the side.

[0178] It should be noted that in the alternative embodiment of FIG. 20, the beam 76 has a rectangular cross-section rather than a circular one, although other shapes are possible, as would be readily understood by one skilled in the art.

[0179] Returning to FIG. 9, the shaped corner 74 of the cell unit 10 is shown to have a curved shape with a convex radius on either side of a concave radius, which is shaped to follow the adjacent contour of the beam 76 that sits thereon. In this embodiment, the curved shape matches and aligns vertically with all the cell units of the stack. By following or matching the shape of the beam in this way, multiple contact points (or a long single continuous line of contact) can be achieved between the beam 76 and the corner 74 of the cell unit 10 (indeed, in the preferred configuration of all the cell units 10). In particular, it is preferred that the beam abuts and engages the cell unit closely. This helps to reduce point loads on the cell unit 10 and to grip or otherwise control the cell unit (e.g., through the diagonal loads mentioned above) to resist movement of the cell unit during operation of the stack assembly. In FIG. 9, the convex radius follows the circumference of the circular beam over a segment of approximately 90 degrees. Meanwhile, in FIG. 19, it follows approximately 180 degrees, i.e., a semicircle of the beam. This latter configuration does not create a net diagonal retention force, but instead, by wrapping sufficiently around the beam, retains the beam against longitudinal movement in both directions (forward or rearward) in addition to retaining it laterally (towards the beam).

[0180] An alternative configuration is shown in FIG. 10 where the corner 74 instead has two perpendicular sides, i.e., a square or rectangular cutout. Thus, a square or rectangular beam may be used to match that shape, but in this embodiment, the beam 76 still maintains its circular (tubular) cross section. In this alternative configuration, the beam 76 still has multiple (two) contact points with the corner / recess 74. Thus, there are two tangent lines between the corner 74 and the beam 76, still exerting a net oblique force on the cell unit 10. These still grip the cell unit by the beam to resist movement of the cell unit during use, i.e., both lateral and longitudinal movement.

[0181] 20, now a rectangular recess is provided in the middle of the two sides and a rectangular beam is used. Thus, the cell unit 10 is also gripped by the beam 76 to resist movement of the cell unit 10 during use, i.e., both lateral and longitudinal movement. However, here the rectangular recess wraps around the beam sufficiently to hold the beam against longitudinal movement in both directions (forward or backward) in addition to lateral retention (towards the beam), as in FIG. 19.

[0182] Furthermore, those skilled in the art will understand that when the beam 76 fits into a recess in a corner or side of the cell unit 10 between the cell unit and the housing 58, many different shapes of the recess in the corner 74 or other locations where the recess is provided, as well as shapes of the beam 76, are suitable.

[0183] Additionally, the beam 76 does not have to be at a corner or in the center of the side, but can be anywhere along the length of the side of the cell unit 10. Figures 18 and 19 show the beam 76 located near a corner, while Figure 20 shows the beam in the center portion of the side. Thus, the beam 76 can be located anywhere along the side of the cell unit 10.

[0184] Note that although there are only two beams in Figure 9, they are preferably at the downstream end of the cell unit relative to the direction of fluid flow through the stacked cell units (see Figure 10 for the flow direction).

[0185] Similarly, it can be seen from Figures 10-19 that instead of just two beams 76, in many preferred embodiments there are four, two on each side of the cell unit 10 and at or near each end.

[0186] Fluid ports 60 are also shown in Figures 8 to 20. In the example of Figures 8 to 17, there are two fluid ports at the end regions of the cell unit 10, giving the cell unit 10 a total of four fluid ports, while end plates 62 at each end of the cell unit 10 on which the cell units 10 are stacked (separated from the cell units 10 by current collecting plates 52 and insulating plates 50, not shown (see Figure 6 for an example)) are provided with a single fluid port 60. These allow for the circulation of fuel and air / oxidant through the stack 12.

[0187] 11, for the fuel cell, the fluid ports 60 in the end plates 62 are ports for oxidant flow, while the two pairs of fluid ports 60 toward the ends of the cell units 10 are fuel ports. However, depending on the configuration of the active electrochemical component layers of the fuel cell, these may be reversed to ensure that the fuel and oxidant contact the appropriate cathode or anode of the cell units.

[0188] Referring now to Figure 11, a further embodiment is shown, which is similar to the embodiment of Figure 10 with four beams 76, but instead of the square recesses at the corners 74, the rounded corners from Figure 9 are used.

[0189] In FIG. 11, the fuel flow and air flow (oxidant flow) in the fuel cell operating mode are shown diagrammatically. As can be seen, two fluid ports 60 (hereinafter air flow input port 80 and air flow output port 82) in the end plate 62 allow air or oxidant to enter the volume defined by the housings 68, 70 at one end of the cell unit 10, circulate up through the cell unit 10 between adjacent cell units 10, and down through the air flow output port 82. This flow direction defines a central vertical flow line 88 from the first end of the cell unit 10 to the far end of the cell unit 10. Side flow paths 89 for air are also shown, which run closer to the beam and near the sides of the cell unit 10. In reality, there are multiple flow paths through the stacked cell units 10, which may be linear or convoluted depending on the design of the cell units, particularly any protrusions or recesses, bars or troughs in the separator plates of the cell units, see Figures 1-5 for a variety of potentially different shaped protrusions / bars / grooves / recesses that define the flow paths. Other designs known in the art will be apparent to one of ordinary skill in the art.

[0190] Due to the direction of the air or oxidant flow, in FIG. 9 it can be seen that there are only two electrically insulating beams 76, which are preferentially located at the outflow end (at least with respect to the air / oxidant flow) of the cell unit 10. This is the preferred end for the beam 76, since the air flow tends to push the cell unit 10 towards its outflow end, which is usually the hot end of the stack when parallel flow is used for fuel and oxidant. Thus, by providing the beam 76 at its far end, the contact point between the corner 74 and the beam 76 has a net angular return force at least partially towards the inflow end, and the beam resists such pushing of the cell unit. Thus, the cell unit 10 can resist movement with the air flow by the beam 76. On the other hand, the electrically insulating plates only rest on the sides, and therefore have no angle of retention force against such pushing of the cell unit, and over time the cell units 10 may slide against the electrically insulating plates 78, and therefore may eventually lose contact with their lateral electrically insulating plates 78.

[0191] 11, while the fuel flow in this embodiment is shown flowing in the same direction as the air / oxidant flow, it is instead between the layers of individual cell units and therefore internal to the cell unit 10. Thus, in this example, this is a parallel flow configuration. To this end, the pair of fluid ports 60 at each end of the cell unit 10 comprise a pair of fuel input ports 84 and a pair of fuel output ports 86, respectively, located towards opposite ends of the cell unit 10, and are so numbered in FIG.

[0192] As described with respect to Figures 1-7, air and fuel flow through or between the cell units in a manner such that they do not mix, but can both flow over appropriately opposing layers of the electrochemically active layers of the cell units to provide the desired function of the cell stack assembly, and in the case of metal support, the metal support plate can be perforated or porous to later allow interaction of the fuel with the electrochemically active layers, as shown in Figures 2, 3, and 4.

[0193] It can also be observed from FIG. 11 that the airflow flows between the opposing beams 76 at the far end of the cell unit 10 where the airflow is constricted between the two beams 76 compared to the area in front of those beams, as shown by the curved airflow lines 89 in FIG. 11. That constriction ensures that the airflow is more concentrated between those beams 76 compared to the wider space in front of those beams 76. This is an advantageous feature since in a parallel flow configuration the hottest end of the cell unit is at the fuel and air outlet end. That constriction, and therefore the increased density of the airflow, increases the cooling effect and therefore helps control the temperature of that outlet end of the cell unit. This is particularly advantageous in a parallel flow configuration, but can also be beneficial in a counter flow configuration since the air heats up as it crosses the cell unit 10 and therefore the density of the airflow needs to be increased to provide the same degree of cooling.

[0194] 12, a nearly fully assembled cell stack is shown. In FIG. 12, a plurality of stacked cell units 10 are shown in a configuration with an electrically insulating beam at each corner 74 as in FIG. 11. There is an electrically insulating plate 78 extending down each of its two long sides. In addition, the two halves 68, 70 of the housing 58 are fitted around the stacked cell units. In this embodiment, it can be seen that the two halves 68, 70 of the housing 58 are arranged to press the edge of the electrically insulating plate 78 against and directly against the beam 76. This provides a net clamping force on the beam 76, forcing the beam 76 into the recessed corner 74 of the cell unit 10 with both lateral and longitudinal force components relative to the central flow line 88 (see FIG. 11). This bidirectional clamp provides a holding force to hold the stack of cell units 10 together, so that each individual cell unit 10 in the stack remains laterally fixed and also resists forward vertical movement. Additionally, because of the presence of beams at the input ends of the cell units, the cell units also cannot move backwards. Thus, the cell units are clamped or held side-by-side and locked against relative movement, thus reducing the likelihood that an external force applied to the stack assembly will destroy or move the cell units, and thus maintaining the effectiveness of the seal between the layers (seals are known in the art and are usually provided by electrically insulating gaskets, typically mica gaskets).

[0195] As described with respect to Figures 1-7, gaskets are typically placed between the cell units 10 to manifold the ports together so that a passage is formed for fluid (only fuel in the examples of Figures 1-4 and 8-20, but potentially oxidant as in Figures 5-7) through the stack.

[0196] Thus, in the present invention, relative disturbance between the cell units 10 is avoided and therefore the integrity of these fluid passages is maintained, as loss of integrity would be highly undesirable given the possibility of ignition and potentially explosion due to mixing of fuel and oxidizer at the normal operating temperatures of these cell units.

[0197] Referring now to Figure 13, the arrangement of Figure 12 is again shown, but now with four bus bars 54 extending from a current collecting plate 52 (not shown, see Figure 14) through the four beams. These allow the collected current to be sent to a terminal on the top plate (not shown, see Figure 7 for a similar arrangement with two terminals).

[0198] 14, the arrangement of FIG. 12 is again shown, this time with one of the housing portions 70 and one of the electrical insulating plates 78 removed, revealing the current collecting plate 52 beneath the stacked cell units 10. Between that current collecting plate and the lower end plate 62, a further electrical insulating plate 50 can be provided which insulates the end plate 62 from the current collecting plate, similar to that shown in FIG.

[0199] With the second part 70 of the housing removed, the oxidant outlet port 82 in the lower end plate 62 is also visible. As shown, the current collecting plate 52 does not extend over the oxidant ports 80, 82. The electrical insulation plate is not similar, although in some examples the electrical insulation plate 50 may be similar and, if so, may be provided with a corresponding port such that the port remains open to the interior volume of the housing at the end of the cell unit 10.

[0200] 15, 16 and 17, there are shown various steps in the assembly process of a cell stack assembly. These are preferred steps according to the sixth aspect of the present invention. Figures 14-16 are partial cutaway views of the stack assembly of Figure 13, where the beam 76 has been cut shorter and fewer cell units 10 have been stacked, in order to allow the electrical insulation plate 78 behind it to be seen.

[0201] 15, a stack of cell units 10 is stacked on the lower end plate 62 together with the first insulating plate 50, the current collecting plate 52, and the four electrically insulating beams 76. The four beams 76 are positioned at the four corners of the stacked cell units. To hold two beams (as shown) behind the stacked cell units 10, a first electrically insulating plate 78 is fitted behind these two beams 76 along the far long sides of the cell units 10, and the first housing half 68 holds them in place.

[0202] FIG. 16 then shows a second electrically insulating plate 78 positioned against the two nearer beams 76 (as shown) and the nearer long edge (as shown) of the cell unit 10 .

[0203] FIG. 17 then shows the rear half of the housing 70 fitted against a second electrically insulating plate 78 and the two near beams 76 (as shown) to clamp the assembled components together.

[0204] Finally, the two halves 68, 70 of the housing 58, which in this embodiment is a skirt, can be welded or otherwise joined together in a clamped state along a pair of weld lines 72 at each end, in this example provided at the short ends of the cell stack.

[0205] Providing the housing or skirt in two halves simplifies the process of assembling the cell units 10 with the beams and electrical insulation plates and welding the skirts together while clamping the assembled components together thus maintaining a compressive force across the beams and cell units which holds the cell units in their desired relative positions and thus maintains the integrity of the fluid columns formed therein by the fluid ports on each cell unit and the gaskets between the ports, as seen, for example, in Figures 3, 4 and 6.

[0206] 18 and 19, an alternative configuration is shown in which the beams 76 are instead moved away from the corners. The housing 58 is also shown divided into two halves 68, 70, although here only the front half 68 is shown. To complete the assembly of this stack assembly 12, a second electrically insulating plate 78 must be fitted in a mirror image of the first electrically insulating plate 68 already shown, and then the back half 70 of the housing 58 is placed in compression or clamping fashion between the beams 76 across the cell units.

[0207] In this embodiment, the housing does not compress both directly and indirectly against the beam, but only directly against the beam, and the housing 58 does not compress the beam 76 through the electrically insulating plate 78. The electrically insulating plate 78 instead compresses only against the sides of the cell unit 10. However, the beam 76 still compresses against the cell unit in multiple directions due to the shape of the recess in the cell unit 10, which in this example matches the shape of the opposing walls of the beam. However, other shapes of recess and beam are within the scope of the claimed invention, as shown in Figures 10 and 20, where square or rectangular recesses are provided and different beam shapes are provided.

[0208] 20, it can be seen that the housing is a one-piece sleeve that fits over the component at once. It can be flexed to fit over the component and still be biased against the beams. It also surrounds the beams 76 and electrical insulating plates 78 on the two long sides of the cell unit 10.

[0209] 21, a further embodiment of the present invention is shown. In this embodiment, which is generally similar to the embodiment of FIGS. 11-17, the beams 76 also have bus bars 54 extending through each of them, abutting the corners 74 of the fuel cell units 10, where there is one beam 76 for each corner 74 of the stack of cell units 10. Furthermore, each bus bar 54 connects to a current collector plate 52 on the underside of the stack of cell units 10 and extends upwards therefrom. However, the beams are not one-piece, but are each made of two parts, a first or lower part 92 and a second or upper part 94, with the second part 94 stacked on top of the first part 92.

[0210] In this embodiment, the two parts are in the form of the same tube or cylinder with a busbar 54 extending through a central hole therein.

[0211] During assembly, the four bus bars 54 may be welded or otherwise electrically connected to the current collecting plates 52 that are stacked on the end plates 62 of the cell stack assembly 12 .

[0212] The cell units 10 can then begin to be stacked on the current collecting plate 52, with the four first parts 92 positioned on the busbar 54 to align the stack of cell units 10. As the stack approaches the top of the first parts 92, a second part can be placed on the busbar, after which the stack of cell units 10 is completed within the space between the four second parts 94 of the beam 76. Finally, an upper current collecting plate (not shown), an upper end plate (not shown), an electrical insulating plate 78 (one shown), and a housing 58 (one shown) can be fitted to surround the stack of cell units 10.

[0213] In some embodiments, especially for higher stacks, more than two parts may be provided.

[0214] Referring now to Figure 22, a further modification is shown. In this embodiment, the two parts 92, 94 of the beam 76 are provided to be adjustable in length. This allows the same two parts to be used for a variety of different stack heights. Figure 23 shows these two parts in more detail. Figure 24 shows an alternative form of the parts 92, 94 of the beam 76 to allow the length of the beam 76 to be adjustable, which parts 92, 94 are shown in more detail in Figure 25.

[0215] 22 and 23, the length of the beam is adjustable by providing the two parts 92, 94 with stepped or castellated ends 100, which face each other in the middle of the beam 76. These stepped or castellated ends 100 have risers and flats that can interact with opposing risers and flats of the opposing part, allowing one part to be rotated relative to the other about an axis defined by a central hole (e.g., rotated about the busbar 54), such that the different risers and flats can engage with each other, resulting in a change in the length of the stacked parts 92, 94.

[0216] During assembly, the stacked parts 92, 94 may first be placed at a shortened length on top of their respective bus bars 54. This allows access to the tops of the bus bars 54 for welding or otherwise electrically connecting them to an upper electrical connector (not shown). If instead placed at full length, access to the tops of the bus bars may be blocked by the upper current collecting plate or the tops of the beams 76, or both. Then, once the tops of the bus bars 54 are electrically connected to the upper electrical connector (not shown), the length of the beams 76 can be adjusted to fit under the upper current collecting plate.

[0217] 24 and 25, an alternative form of beam 76 is shown, also adjustable in length, but now more infinitely variable in length between a maximum and a minimum length, rather than the predefined stepwise changes provided by risers and flats. To this end, the opposing ends 100 of the two parts 92, 94 each have a chamfered or angled / inclined surface 100 and a stop member 102. By rotating the two parts 92, 94 relative to each other about their central axis (i.e. about the busbar 54), the length of the beam 76 can also be changed, with the same advantages as above. As the stop members 102 at each end 100 interact at the end points of the length change, the stop members provide a predetermined limit to the length change.

[0218] In each of these two variations where the beam length is adjustable, the length can be locked after installation, for example, by the use of thermal paste or adhesive, or by providing keying features.

[0219] 26, an alternative approach is provided to provide access to the underside of the upper current collecting plate, for example to make it easier to connect the ends of the busbar 54 to the upper electrical connector. In this embodiment, the upper part 94 is a slotted component, generally tubular as already mentioned, but with a slot 104 extending from its central hole to its side wall, the slot 104 being wide enough to allow it to be placed on the busbar 54 without accessing the free end of the busbar 54. With this configuration, the first part (and here the separate middle part 96) can be placed first on the busbar 54, with the cell units 10 stacked between them, and further stacking can be continued up to the top of the stack, then the upper current collecting plate (and upper electrical connector) can be placed, and then the upper part 94 of the beam 76 can be fitted, by fitting them on the busbar 54 using the slot 104. The upper part 94 can then be rotated so that the slot 104 faces away from the corner 74 of the cell unit 10, to prevent them from coming loose.

[0220] In this embodiment, the first part 92 is also shown to be a slotted part because it may be desirable to remove it (or later install it on the intermediate part 96), for example to access for connecting the bus bar 54 to the lower collecting plate 52 (or for maintenance).

[0221] In some embodiments, this slotted part configuration may also feature the stepped or chamfered surfaces of the previous embodiment.

[0222] 27, a further alternative configuration of the beams 76 is shown. In this embodiment, the beams are shown as one-piece beams, although they may be made of more than one piece as previously described. However, in this embodiment, the tops of the beams have a cutout portion 98, forming a semicircle at the top as shown. This semicircle abuts the corners 74 of the cell units 10 at the top of the stack, but its flat surface faces outward, providing a flow path around the outside of the beams 76 at the top of the stack. Such flow provides an additional route for air to flow into the top of the stack (to flow between the cell units) as well as the gaps between the beams at each end of the stack. This increased air flow can improve thermal management at the top of the stack, which is typically a hotter location in the stack versus the bottom or middle of the stack.

[0223] In this embodiment, for the sake of symmetry of the structure (and therefore to reduce the manufacturing costs of the component), the first part 92 of the beam is also provided with a cutout 98. However, its lower part 92 does not need to have a cutout 98, if such additional flow is not required there.

[0224] The middle section 96 in this embodiment is shown as being fully tubular with no notches, but may be notched if desired to provide additional cooling in the middle region of the stack.

[0225] Instead of a semicircular contoured cutout, other shapes of cutouts would provide similar additional flow paths. For example, the part of the beam having the cutout 98 could be a coaxial tube structure with a portion of the outer tube cut away. Such a structure would allow the busbar 54 to remain insulated around its periphery even in the cutout area, which helps prevent airborne contaminants (or dust) from easily accessing the busbar.

[0226] In these alternative embodiments, the beam is still provided with a straight final surface to face toward the corner 74 of the cell unit 10 so that the beam still functions as an alignment guide for the stack of cell units 10. This straight final surface, which may be radiused as a portion (segment) of the tube, rotates to engage the corner 74 of the cell unit 10.

[0227] The beam parts 92, 94, 96 are preferably formed from mica tubing, however, because the stepped ends 100, chamfered ends 100 and stops 102, and slots 104 form smaller details on the beam that reduce the structural integrity of the shape, it may be preferable to instead make one or more of the beam parts 92, 94, 96 from a ceramic material that has more suitable structural strength.

[0228] As will be apparent to those skilled in the art, various structural shapes of the cell units have been described herein, ranging from the generally oval shapes of Figures 1-4 to the generally rectangular shapes of Figures 5-20. However, the present invention can be used with many other shapes of cell units and is applicable to many electrochemical cell chemistry types. Indeed, those skilled in the art will appreciate that the shape of the cell units can be widely varied while still using the electrically insulating beams 76 of the present invention. Thus, the present invention has been described above by way of example only, and modifications of detail can be made thereto within the scope of the claims appended hereto.

Claims

1. 1. An electrochemical cell stack, comprising: a plurality of stacked cell units, each defining a perimeter; a housing surrounding the stack to define or enclose a volume around the periphery; two opposing electrical insulating plates disposed between the housing and the plurality of stacked cell units, each of the electrical insulating plates contacting one of two opposing sides of the plurality of stacked cell units; at least one electrically insulating beam extending across and engaging an outer periphery of a plurality of cell units of the stack; Equipped with the electrically insulating beam also engages either or both of the housing and one of the electrically insulating plates; The electrically insulating beam extends generally in a stacking direction of the stacked cell units, A cell stack, wherein the electrically insulating beam is disposed between the outer periphery of the cell unit and a housing.

2. The cell stack includes at least two electrically insulating beams each extending across the plurality of cell units and each engaging an outer periphery of at least two of the plurality of cell units; the beams define a line extending between two beams, the line defining a lateral line across each cell unit; So, a) the contact tangents between each beam and each of the plurality of cell units cooperate to resist movement of each of the plurality of cell units in both lateral directions along its defined lateral line of the cell unit and in at least one longitudinal direction generally perpendicular to its lateral line and generally in the plane of the periphery of its respective cell unit; or b) the contact tangents of each beam with each of the plurality of cell units cooperate with each beam to resist movement of each of the plurality of cell units in both at least one lateral direction along the defined lateral line of the cell unit and at least one longitudinal direction generally perpendicular to the lateral line and generally planar with respect to the periphery; The cell stack according to claim 1 , wherein the first and second electrodes are either or both of the first and second electrodes.

3. 2. The cell stack of claim 1, wherein the or each electrically insulating plate that engages with an edge of a cell unit has a cell engagement surface that provides the engagement, and a beam closest to the cell engagement surface of one of the electrically insulating plates has a cell engagement surface that extends distally to the cell engagement surface of the electrically insulating plate.

4. 4. The cell stack of claim 3, wherein there are two beams, each having a cell engaging surface that extends distally of the cell engaging surface of its nearest electrical insulating plate, said two beams providing a narrowing of the width of the cell unit between said two beams compared to the width between two electrical insulating plates.

5. The cell stack of any one of claims 1 to 4, wherein each electrically insulating plate also engages an inner wall of the housing.

6. The cell stack of claim 1 , wherein two or more electrical insulating plates are provided between each opposing side of the plurality of stacked cell units and the housing.

7. The cell stack of claim 1 , wherein the electrical insulation plates are disposed on only two of the sides of the stacked cell units.

8. The cell stack of claim 1 , wherein more than one electrical insulating plate is disposed, side-by-side or stacked, in a common plane against two respective opposing sides of the stacked cell units.

9. The cell stack of claim 1 , wherein the or each beam is formed of two or more parts.

10. The cell stack of claim 1 , wherein the or each beam has an adjustable length.

11. The cell stack of claim 1 , wherein the or each beam has one or more cut out areas to increase fluid flow in that area.

12. 1. An electrochemical cell stack assembly, comprising: a stack of cell units, each defining an outer periphery; a housing surrounding a periphery of the stacked cell units to define a volume around the periphery, the housing initially comprising at least two separate parts; at least one electrically insulating beam assembled between one initially separate part of the housing and the stacked cell units, the electrically insulating beam extending across the plurality of cell units and abutting an outer periphery of at least two of the plurality of cell units to exert a force resisting further movement of the plurality of cell units toward the beam; Equipped with A cell stack assembly, wherein the first and second initially separate parts of the housing clamp or engage at least one beam against the outer periphery of at least two of the plurality of cell units when the two parts of the housing are closed together.

13. The cell stack assembly of claim 12 , wherein at least two parts of the housing are welded together in a clamped state to hold a clamping force.

14. The cell stack of claim 1 or 12, wherein the at least one beam defines a barrier to fluid flow in and out of the stacked cell units, preventing or reducing fluid flow around the outside of the beam between the outer periphery of the cell unit and the housing, and directing the fluid flow through or toward a central stream through the stacked cell units.

15. The cell stack of claim 1 or 12, wherein the at least one beam defines a barrier to fluid flow in and out of the stacked cell units, thereby concentrating air flow through a central stream through the stacked cell units and reducing air flow to a side of the central stream adjacent to the side of the cell unit.

16. The cell stack of claim 1 or 12, wherein the at least one beam is seated in a recess or depression formed in an outer periphery of the cell unit.

17. The cell stack of claim 16 , wherein the depression or recess wraps around the beam for at least a 90 degree segment.

18. 13. The cell stack of claim 1 or 12, wherein the housing comprises a skirt around the cell unit, the skirt being formed of at least two parts joined together at their seams.

19. 1. A method of assembling an electrochemical cell stack, the method comprising: cell units, each cell unit defining a perimeter; at least one electrically insulating beam assembled to the stacked cell units such that the electrically insulating beam extends across and engages an outer periphery of each of the plurality of cell units, with electrical connection members of a current delivery system of the cell stack extending into the electrically insulating beam; providing The method comprises: fitting a first part of the electrical insulating beam onto the electrical connection member, stacking the cell unit in contact with the first part of the electrical insulating beam, and then fitting a second part of the electrical insulating beam onto the electrical connection member and the first part of the electrical insulating beam. A method comprising:

20. 1. A method of assembling an electrochemical cell stack, the method comprising: a stack of cell units, each cell unit defining a perimeter; At least two electrically insulating beams each extending across a plurality of stacked cell units and assembled to the stacked cell units so as to engage the periphery of the plurality of stacked cell units; providing The method comprises: fitting a housing around the stacked cell units and the electrically insulating beam, the housing defining a volume around the periphery, the housing being initially divided into at least two separate parts. Including, The method, wherein the first and second initially separate parts of the housing are clamped against the outer periphery of at least two of the plurality of cell units when the two parts of the housing are closed together, exerting a force resisting further movement of the plurality of cell units toward the beam, and the initially separate parts are then connected or joined to each other in a clamped state to maintain the clamping force by the beam against the outer periphery of the at least two of the plurality of cell units.

21. There are at least two electrically insulating beams; one electrically insulating beam is assembled between a first initially separate part of the housing and the stacked cell units, and a second electrically insulating beam is assembled between a second initially separate part of the housing and the stacked cell units, the at least two electrically insulating beams each extending across the plurality of cell units and abutting the outer peripheries of at least two of the plurality of cell units to exert a force resisting further movement of the plurality of cell units toward the beam; 21. The method of claim 20, wherein the first and second initially separate parts of the housing are clamped against the outer periphery of at least two of the plurality of cell units when the two parts of the housing are closed together, exerting a force resisting further movement of the plurality of cell units toward the beam, and the initially separate parts are then connected or joined to each other in a clamped state to maintain a clamping force by the beam against the outer periphery of the at least two of the plurality of cell units.

22. 22. The method of claim 20 or claim 21, wherein the first and second initially separate parts of the housing are indirectly clamped to the outer periphery of at least two of the plurality of cell units via one or more electrically insulating plates in addition to the or each electrically insulating beam.

Images