Patent Publication Number: US-2023146025-A1

Title: Fuel cell manifold having an embedded dielectric layer and methods of making thereof

Description:
FIELD 
     This disclosure is directed to fuel cell stacks in general, and to a fuel cell manifold in particular. 
     BACKGROUND 
     In a high temperature fuel cell system, such as a solid oxide fuel cell (SOFC) system, an oxidizing flow is passed through the cathode side of the fuel cell while a fuel flow is passed through the anode side of the fuel cell. The oxidizing flow is typically air, while the fuel flow can be a hydrocarbon fuel, such as methane, natural gas, pentane, ethanol, or methanol. The fuel cell, operating at a typical temperature between 750° C. and 950° C., enables the transport of negatively charged oxygen ions from the cathode flow stream to the anode flow stream, where the ion combines with either free hydrogen or hydrogen in a hydrocarbon molecule to form water vapor and/or with carbon monoxide to form carbon dioxide. The excess electrons from the negatively charged ion are routed back to the cathode side of the fuel cell through an electrical circuit completed between anode and cathode, resulting in an electrical current flow through the circuit. 
     Fuel cell stacks may be either internally or externally manifolded for fuel and air. In internally manifolded stacks, the fuel and air are distributed to each cell using risers contained within the stack. In other words, the gas flows through openings or holes in the supporting layer of each fuel cell, such as the electrolyte layer, and gas flow separator of each cell. In externally manifolded stacks, the stack is open on the fuel and air inlet and outlet sides, and the fuel and air are introduced and collected independently of the stack hardware. For example, the inlet and outlet fuel and air flow in separate channels between the stack and the manifold housing in which the stack is located. 
     Fuel cell stacks are frequently built from a multiplicity of cells in the form of planar elements, tubes, or other geometries. Fuel and air have to be provided to the electrochemically active surface, which can be large. One component of a fuel cell stack is the so called gas flow separator (referred to as a gas flow separator plate in a planar stack) that separates the individual cells in the stack. The gas flow separator plate separates fuel, such as hydrogen or a hydrocarbon fuel, flowing to the fuel electrode (i.e., anode) of one cell in the stack from oxidant, such as air, flowing to the air electrode (i.e., cathode) of an adjacent cell in the stack. Frequently, the gas flow separator plate is also used as an interconnect which electrically connects the fuel electrode of one cell to the air electrode of the adjacent cell. In this case, the gas flow separator plate which functions as an interconnect is made of or contains an electrically conductive material. 
     SUMMARY 
     According to an embodiment, a manifold plate for a fuel cell stack includes a lower manifold portion, an upper manifold portion, and a dielectric layer sandwiched between the lower manifold portion and the upper manifold portion. The manifold plate may further include a bottom inlet hole and a bottom outlet hole formed in a bottom surface of the lower manifold portion, wherein the bottom inlet hole and the bottom outlet hole extend through the dielectric layer; and top outlet holes and top inlet holes formed in opposing sides of a top surface of the upper manifold portion. The manifold plate may further include outlet channels fluidly connecting the top outlet holes to the bottom inlet hole and inlet channels fluidly connecting the top inlet holes to the bottom outlet hole. 
     According to another embodiment, a method of manufacturing a manifold plate for a fuel cell stack comprises providing a lower manifold portion and an upper manifold portion, providing a dielectric layer, and assembling the lower manifold portion, the upper manifold portion, and the dielectric layer into the manifold plate such that the dielectric layer is sandwiched between the lower manifold portion and the upper manifold portion. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings, which are incorporated herein and constitute part of this specification, illustrate example embodiments of the disclosure, and together with the general description given above and the detailed description given below, serve to explain the features of the disclosure. 
         FIG.  1 A  is a perspective view of a conventional fuel cell column. 
         FIG.  1 B  is a perspective view of one counter-flow solid oxide fuel cell stack included in the column of  FIG.  1 A . 
         FIG.  1 C  is a side cross-sectional view of a portion of the stack of  FIG.  1 B . 
         FIG.  2 A  is a top view of the air side of a conventional interconnect of the stack of  FIG.  1 B . 
         FIG.  2 B  is a top view of the fuel side of the conventional interconnect of the stack of  FIG.  1 B . 
         FIG.  3 A  is a perspective view of a fuel cell stack, according to various embodiments. 
         FIG.  3 B  is an exploded perspective view of a portion of the stack of  FIG.  3 A , according to various embodiments. 
         FIG.  3 C  is a top view of the fuel side of an interconnect included in the stack of  FIG.  3 A , according to various embodiments. 
         FIG.  3 D  is a schematic view of a fuel cell included in the stack of  FIG.  3 A , according to various embodiments. 
         FIG.  4 A  is a plan view showing an air side of the cross-flow interconnect of  FIG.  3 C , according to various embodiments. 
         FIG.  4 B  is a plan view showing an fuel side of the cross-flow interconnect of  FIG.  3 C , according to various embodiments. 
         FIG.  5 A  is an exploded top perspective view of a fuel flow structure, according to various embodiments. 
         FIG.  5 B  is an exploded bottom perspective view of the fuel flow structure of  FIG.  5 A , according to various embodiments. 
         FIG.  6 A  is a top view of a seal plate of the fuel flow structure of  FIGS.  5 A and  5 B , according to various embodiments. 
         FIG.  6 B  is a cross-sectional view of the seal plate of  FIG.  6 A  taken along the line L 3  of  FIG.  6 A , according to various embodiments. 
         FIG.  7 A  is a bottom view of a manifold plate of the fuel flow structure of  FIGS.  5 A and  5 B , according to various embodiments. 
         FIG.  7 B  is a cross-sectional view of the manifold plate of  FIG.  7 A  taken along the line L 4  of  FIG.  7 A , according to various embodiments. 
         FIG.  7 C  is a schematic top view of the manifold plate of  FIG.  7 A , according to various embodiments. 
         FIG.  8 A  is a vertical cross-sectional view of the fuel flow structure of  FIGS.  5 A and  5 B  taken along the line L 1  of  FIG.  5 A , showing an assembled fuel plenum and inlet conduit, according to various embodiments. 
         FIG.  8 B  is a vertical cross-sectional view of the fuel flow structure of  FIGS.  5 A and  5 B  taken along the line L 2  of  FIG.  5 A , showing the assembled fuel plenum and outlet conduit, according to various embodiments. 
         FIG.  9 A  is a three-dimensional top perspective view of a fuel cell manifold plate having an embedded dielectric layer, according to various embodiments. 
         FIG.  9 B  is a three-dimensional exploded view of the fuel cell manifold plate of  FIG.  9 A , according to various embodiments. 
         FIG.  10 A  illustrates an intermediate structure used in the formation of a dielectric layer for a fuel cell manifold plate, according to various embodiments. 
         FIG.  10 B  illustrates a further intermediate structure used in the formation of a dielectric layer for a fuel cell manifold plate, according to various embodiments. 
         FIG.  10 C  illustrates a further intermediate structure used in the formation of a dielectric layer for a fuel cell manifold plate, according to various embodiments. 
         FIG.  10 D  illustrates a dielectric layer for a fuel cell manifold plate, according to various embodiments. 
         FIG.  11    is a cross-sectional view of the manifold plate of  FIG.  9 A  taken along the line L 5  of  FIG.  9 A , according to various embodiments. 
         FIG.  12 A  is a vertical cross-sectional view of a fuel flow structure similar to that of  FIGS.  5 A and  5 B  including the manifold plate of  FIGS.  9 A and  9 B , according to various embodiments. 
         FIG.  12 B  is a vertical cross-sectional view of the fuel flow structure of  FIG.  12 A , according to various embodiments. 
     
    
    
     DETAILED DESCRIPTION 
     The various embodiments are described in detail with reference to the accompanying drawings. The drawings are not necessarily to scale, and are intended to illustrate various features of the disclosure. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts. References made to particular examples and implementations are for illustrative purposes, and are not intended to limit the scope of the disclosure or the claims. 
     Ranges can be expressed herein as from “about” one particular value, and/or to “about” another particular value. When such a range is expressed, examples include from the one particular value and/or to the other particular value. Similarly, when values are expressed as approximations, by use of the antecedent “about” or “substantially” it will be understood that the particular value forms another aspect. In some embodiments, a value of “about X” may include values of +/−1% X. It will be further understood that the endpoints of each of the ranges are significant both in relation to the other endpoint, and independently of the other endpoint. 
       FIG.  1 A  is a perspective view of a conventional fuel cell column  30 ,  FIG.  1 B  is a perspective view of one counter-flow SOFC stack  20  included in the column  30  of  FIG.  1 A , and  FIG.  1 C  is a side cross-sectional view of a portion of the stack  20  of  FIG.  1 B . 
     Referring to  FIGS.  1 A and  1 B , the column  30  may include one or more stacks  20 , a fuel inlet conduit  32 , an anode exhaust conduit  34 , and anode feed/return assemblies  36  (e.g., anode splitter plates (ASP&#39;s)  36 ). The column  30  may also include side baffles  38  and a compression assembly  40 . The side baffles  38  may be connected to the compression assembly  40  and an underlying stack component (not shown) by ceramic connectors  39 . The fuel inlet conduit  32  is fluidly connected to the ASP&#39;s  36  and is configured to provide the fuel feed to each ASP  36 , and anode exhaust conduit  34  is fluidly connected to the ASP&#39;s  36  and is configured to receive anode fuel exhaust from each ASP  36 . 
     The ASP&#39;s  36  are disposed between the stacks  20  and are configured to provide a hydrocarbon fuel containing fuel feed to the stacks  20  and to receive anode fuel exhaust from the stacks  20 . For example, the ASP&#39;s  36  may be fluidly connected to internal fuel riser channels  22  formed in the stacks  20 , as discussed below. 
     Referring to  FIG.  1 C , the stack  20  includes multiple fuel cells  1  that are separated by interconnects  10 , which may also be referred to as gas flow separator plates or bipolar plates. Each fuel cell  1  includes a cathode electrode  3 , a solid oxide electrolyte  5 , and an anode electrode  7 . 
     Each interconnect  10  electrically connects adjacent fuel cells  1  in the stack  20 . In particular, an interconnect  10  may electrically connect the anode electrode  7  of one fuel cell  1  to the cathode electrode  3  of an adjacent fuel cell  1 .  FIG.  1 C  shows that the lower fuel cell  1  is located between two interconnects  10 . 
     Each interconnect  10  includes ribs  12  that at least partially define fuel channels  8 A and air channels  8 B. The interconnect  10  may operate as a gas-fuel separator that separates a fuel, such as a hydrocarbon fuel, flowing to the fuel electrode (i.e. anode  7 ) of one cell in the stack from oxidant, such as air, flowing to the air electrode (i.e. cathode  3 ) of an adjacent cell in the stack. At either end of the stack  20 , there may be an air end plate or fuel end plate (not shown) for providing air or fuel, respectively, to the end electrode. 
       FIG.  2 A  is a top view of the air side of the conventional interconnect  10 , and  FIG.  2 B  is a top view of a fuel side of the interconnect  10 . Referring to  FIGS.  1 C and  2 A , the air side includes the air channels  8 B. Air flows through the air channels  8 B to a cathode electrode  3  of an adjacent fuel cell  1 . In particular, the air may flow across the interconnect  10  in a first direction A as indicated by the arrows. 
     Ring seals  23  may surround fuel holes  22 A of the interconnect  10 , to prevent fuel from contacting the cathode electrode. Peripheral strip-shaped seals  24  are located on peripheral portions of the air side of the interconnect  10 . The seals  23 ,  24  may be formed of a glass material. The peripheral portions may be in the form of an elevated plateau which does not include ribs or channels. The surface of the peripheral regions may be coplanar with tops of the ribs  12 . 
     Referring to  FIGS.  1 C and  2 B , the fuel side of the interconnect  10  may include the fuel channels  8 A and fuel manifolds  28  (e.g., fuel plenums). Fuel flows from one of the fuel holes  22 A, into the adjacent manifold  28 , through the fuel channels  8 A, and to an anode  7  of an adjacent fuel cell  1 . Excess fuel may flow into the other fuel manifold  28  and then into the adjacent fuel hole  22 A. In particular, the fuel may flow across the interconnect  10  in a second direction B, as indicated by the arrows. The second direction B may be perpendicular to the first direction A (see  FIG.  2 A ). 
     A frame-shaped seal  26  is disposed on a peripheral region of the fuel side of the interconnect  10 . The peripheral region may be an elevated plateau which does not include ribs or channels. The surface of the peripheral region may be coplanar with tops of the ribs  12 . 
     Accordingly, a conventional counter-flow fuel cell column, as shown in  FIGS.  1 A,  1 B,  1 C,  2 A, and  2 B , may include complex fuel distribution systems (fuel rails and anode splitter plates). In addition, the use of an internal fuel riser may require holes in fuel cells and corresponding seals, which may reduce an active area thereof and may cause cracks in the ceramic electrolytes of the fuel cells  1 . 
     The fuel manifolds  28  may occupy a relatively large region of the interconnect  10 , which may reduce the contact area between the interconnect  10  and an adjacent fuel cell by approximately 10%. The fuel manifolds  28  are also relatively deep, such that the fuel manifolds  28  represent relatively thin regions of the interconnect  10 . Since the interconnect  10  is generally formed by a powder metallurgy compaction process, the density of fuel manifold regions may approach the theoretical density limit of the interconnect material. As such, the length of stroke of a compaction press used in the compaction process may be limited due to the high-density fuel manifold regions being incapable of being compacted further. As a result, the density achieved elsewhere in the interconnect  10  may be limited to a lower level by the limitation to the compaction stroke. The resultant density variation may lead to topographical variations, which may reduce the amount of contact between the interconnect  10  a fuel cell  1  and may result in lower stack yield and/or performance. 
     Another important consideration in fuel cell system design is in the area of operational efficiency. Maximizing fuel utilization is a key factor to achieving operational efficiency. Fuel utilization is the ratio of how much fuel is consumed during operation, relative to how much is delivered to a fuel cell. An important factor in preserving fuel cell cycle life may be avoiding fuel starvation in fuel cell active areas, by appropriately distributing fuel to the active areas. If there is a maldistribution of fuel such that some flow field channels receive insufficient fuel to support the electrochemical reaction that would occur in the region of that channel, it may result in fuel starvation in fuel cell areas adjacent that channel. In order to distribute fuel more uniformly, conventional interconnect designs include channel depth variations across the flow field. This may create complications not only in the manufacturing process, but may also require complex metrology to measure these dimensions accurately. The varying channel geometry may be constrained by the way fuel is distributed through fuel holes and distribution manifolds. 
     One possible solution to eliminate this complicated geometry and the fuel manifold is to have a wider fuel opening to ensure much more uniform fuel distribution across the fuel flow field. Since fuel manifold formation is a factor in density variation, elimination of fuel manifolds should enable more uniform interconnect density and permeability. Accordingly, there is a need for improved interconnects that provide for uniform contact with fuel cells, while also uniformly distributing fuel to the fuel cells without the use of conventional fuel manifolds. 
     Owing to the overall restrictions in expanding the size of a hotbox of a fuel cell system, there is also a need for improved interconnects designed to maximize fuel utilization and fuel cell active area, without increasing the footprint of a hotbox. 
       FIG.  3 A  is a perspective view of a fuel cell stack  300 , according to various embodiments,  FIG.  3 B  is an exploded perspective view of a portion of the stack  300  of  FIG.  3 A ,  FIG.  3 C  is a top view of the fuel side of an interconnect  400  included in the stack  300 , and  FIG.  3 D  is a schematic view of a fuel cell included in the stack  300 . 
     Referring to  FIGS.  3 A- 3 D , the fuel cell stack  300 , which may also be referred to as a fuel cell column because it lacks ASP&#39;s, includes multiple fuel cells  310  that are separated by interconnects  400 , which may also be referred to as gas flow separator plates or bipolar plates. One or more stacks  300  may be thermally integrated with other components of a fuel cell power generating system (e.g., one or more anode tail gas oxidizers, fuel reformers, fluid conduits and manifolds, etc.) in a common enclosure or “hotbox.” 
     The interconnects  400  are made from an electrically conductive metal material. For example, the interconnects  400  may comprise a chromium alloy, such as a Cr—Fe alloy. The interconnects  400  may typically be fabricated using a powder metallurgy technique that includes pressing and sintering a Cr—Fe powder, which may be a mixture of Cr and Fe powders or an Cr—Fe alloy powder, to form a Cr—Fe interconnect in a desired size and shape (e.g., a “net shape” or “near net shape” process). A typical chromium-alloy interconnect  400  comprises more than about 90% chromium by weight, such as about 94-96% (e.g., 95%) chromium by weight. An interconnect  400  may also contain less than about 10% iron by weight, such as about 4-6% (e.g., 5%) iron by weight, may contain less than about 2% by weight, such as about zero to 1% by weight, of other materials, such as yttrium or yttria, as well as residual or unavoidable impurities. 
     Each fuel cell  310  may include a solid oxide electrolyte  312 , an anode  314 , and a cathode  316 . In some embodiments, the anode  314  and the cathode  316  may be printed on the electrolyte  312 . In other embodiments, a conductive layer  318 , such as a nickel mesh, may be disposed between the anode  314  and an adjacent interconnect  400 . The fuel cell  310  does not include through-holes, such as the fuel holes of conventional fuel cells. Therefore, the fuel cell  310  avoids cracks that may be generated due to the presence of such through-holes. 
     An upper most interconnect  400  and a lowermost interconnect  400  of the stack  300  may be different ones of an air end plate or fuel end plate including features for providing air or fuel, respectively, to an adjacent end fuel cell  310 . As used herein, an “interconnect” may refer to either an interconnect located between two fuel cells  310  or an end plate located at an end of the stack and directly adjacent to only one fuel cell  310 . Since the stack  300  does not include ASPs and the end plates associated therewith, the stack  300  may include only two end plates. As a result, stack dimensional variations associated with the use of intra-column ASPs may be avoided. 
     The stack  300  may include side baffles  302 , a fuel plenum  350 , and a compression assembly  306 . The side baffles  302  may be formed of a ceramic material and may be disposed on opposing sides of the fuel cell stack  300  containing stacked fuel cells  310  and interconnects  400 . The side baffles  302  may connect the fuel plenum  350  and the compression assembly  306 , such that the compression assembly  306  may apply pressure to the stack  300 . The side baffles  302  may be curved baffle plates, such each baffle plate covers at least portions of three sides of the fuel cell stack  300 . For example, one baffle plate may fully cover the fuel inlet riser side of the stack  300  and partially covers the adjacent front and back sides of the stack, while the other baffle plate fully covers the fuel outlet riser side of the stack and partially covers the adjacent portions of the front and back sides of the stack. The remaining uncovered portions for the front and back sides of the stack allow the air to flow through the stack  300 . The curved baffle plates provide an improved air flow control through the stack compared to the conventional baffle plates  38  which cover only one side of the stack. The fuel plenum  350  may be disposed below the stack  300  and may be configured to provide a hydrogen-containing fuel feed to the stack  300 , and may receive an anode fuel exhaust from the stack  300 . The fuel plenum  350  may be connected to fuel inlet and outlet conduits  320  which are located below the fuel plenum  350 . 
     Each interconnect  400  electrically connects adjacent fuel cells  310  in the stack  300 . In particular, an interconnect  400  may electrically connect the anode electrode of one fuel cell  310  to the cathode electrode of an adjacent fuel cell  310 . As shown in  FIG.  3 C , each interconnect  400  may be configured to channel air in a first direction A, such that the air may be provided to the cathode of an adjacent fuel cell  310 . Each interconnect  400  may also be configured to channel fuel in a second direction F, such that the fuel may be provided to the anode of an adjacent fuel cell  310 . Directions A and F may be perpendicular, or substantially perpendicular. As such, the interconnects  400  may be referred to as cross-flow interconnects. 
     The interconnect  400  may include fuel holes that extend through the interconnect  400  and that are configured for fuel distribution. For example, the fuel holes may include one or more fuel inlets  402  and one or more fuel (e.g., anode exhaust) outlets  404 , which may also be referred to as anode exhaust outlets  404 . The fuel inlets and outlets  402 ,  404  may be disposed outside of the perimeter of the fuel cells  310 . As such, the fuel cells  310  may be formed without corresponding through-holes for fuel flow. The combined length of the fuel inlets  402  and/or the combined length of the fuel outlets  404  may be at least 75% of a corresponding length of the interconnect  400  e.g., a length taken in direction A. 
     In one embodiment, each interconnect  400  contains two fuel inlets  402  separated by a neck portion  412  of the interconnect  400 , as shown in  FIG.  3 B . However, more than two fuel inlets  402  may be included, such as three to five inlets separated by two to four neck portions  412 . In one embodiment, each interconnect  400  contains two fuel outlets  404  separated by a neck portion  414  of the interconnect  400 , as shown in  FIG.  3 B . However, more than two fuel outlets  404  may be included, such as three to five outlets separated by two to four neck portions  414 . 
     The fuel inlets  402  of adjacent interconnects  400  may be aligned in the stack  300  to form one or more fuel inlet risers  403 . The fuel outlets  404  of adjacent interconnects  400  may be aligned in the stack  300  to form one or more fuel outlet risers  405 . The fuel inlet riser  403  may be configured to distribute fuel received from the fuel plenum  350  to the fuel cells  310 . The fuel outlet riser  405  may be configured to provide anode exhaust received from the fuel cells  310  to the fuel plenum  350 . 
     Unlike the flat related art side baffles  38  of  FIG.  1 A , the side baffles  302  may be curved around edges of the interconnects  400 . In particular, the side baffles  302  may be disposed around the fuel inlets  402  and outlets  404  of the interconnects  400 . Accordingly, the side baffles may more efficiently control air flow through air channels of the interconnects  400 , which are exposed between the side baffles  302  and are described in detail with regard to  FIGS.  4 A and  4 B . 
     In various embodiments, the stack  300  may include at least 30, at least 40, at least 50, or at least 60 fuel cells, which may be provided with fuel using only the fuel risers  403 ,  405 . In other words, as compared to a conventional fuel cell system, the cross-flow configuration allows for a large number of fuel cells to be provided with fuel, without the need for ASP&#39;s or external stack fuel manifolds, such as external conduits  32 ,  34  shown in  FIG.  1 A . 
     Each interconnect  400  may be made of or may contain electrically conductive material, such as a metal alloy (e.g., chromium-iron alloy) which has a similar coefficient of thermal expansion to that of the solid oxide electrolyte in the cells (e.g., a difference of 0-10%). For example, the interconnects  400  may comprise a metal (e.g., a chromium-iron alloy, such as 4-6 weight percent iron, optionally 1 or less weight percent yttrium and balance chromium alloy), and may electrically connect the anode or fuel-side of one fuel cell  310  to the cathode or air-side of an adjacent fuel cell  310 . An electrically conductive contact layer, such as a nickel contact layer (e.g., a nickel mesh), may be provided between anode and each interconnect  400 . Another optional electrically conductive contact layer may be provided between the cathode electrodes and each interconnect  400 . 
     A surface of an interconnect  400  that in operation is exposed to an oxidizing environment (e.g., air), such as the cathode-facing side of the interconnect  400 , may be coated with a protective coating layer in order to decrease the growth rate of a chromium oxide surface layer on the interconnect and to suppress evaporation of chromium vapor species which can poison the fuel cell cathode. Typically, the coating layer, which can comprise a perovskite such as LSM, may be formed using a spray coating or dip coating process. Alternatively, other metal oxide coatings, such as a spinel, such as an (Mn, Co) 3 O 4  spinel (MCO), can be used instead of or in addition to LSM. Any spinel having the composition Mn 2−x Co 1+x O 4  (0≤x≤1) or written as z(Mn 3 O 4 )+(1−z)(Co 3 O 4 ), where (⅓≤z≤⅔) or written as (Mn, Co) 3 O 4  may be used. In other embodiments, a mixed layer of LSM and MCO, or a stack of LSM and MCO layers may be used as the coating layer. 
       FIGS.  4 A and  4 B  are plan views showing, respectively, an air side and a fuel side of the cross-flow interconnect  400 , according to various embodiments. Referring to  FIG.  4 A , the air side of the interconnect  400  may include ribs  406  configured to at least partially define air channels  408  configured to provide air to the cathode of a fuel cell  310  disposed thereon. The air side of the interconnect  400  may be divided into an air flow field  420  including the air channels  408 , and riser seal surfaces  422  disposed on two opposing sides of the air flow field  420 . One of the riser seal surfaces  422  may surround the fuel inlets  402  and the other riser seal surface  422  may surround the fuel outlets  404 . The air channels  408  and ribs  406  may extend completely across the air side of the interconnect  400 , such that the air channels  408  and ribs  406  terminate at opposing peripheral edges of the interconnect  400 . In other words, when assembled into a stack  300 , opposing ends of the air channels  408  and ribs  406  are disposed on opposing (e.g., front and back) outer surfaces of the stack, to allow the blown air to flow through the stack. Therefore, the stack may be externally manifolded for air. 
     Riser seals  424  may be disposed on the riser seal surface  422 . For example, one riser seal  424  may surround the fuel inlets  402 , and one riser seal  424  may surround the fuel outlets  404 . The riser seals  424  may prevent fuel and/or anode exhaust from entering the air flow field  420  and contacting the cathode of the fuel cell  310 . The riser seals  424  may also operate to prevent fuel from leaking out of the fuel cell stack  100  (see  FIG.  3 A ). 
     Referring to  FIG.  4 B , the fuel side of the interconnect  400  may include ribs  416  that at least partially define fuel channels  418  configured to provide fuel to the anode of a fuel cell  310  disposed thereon. The fuel side of the interconnect  400  may be divided into a fuel flow field  430  including the fuel channels  418 , and an perimeter seal surface  432  surrounding the fuel flow field  430  and the fuel inlets and outlets  402 ,  404 . The ribs  416  and fuel channels  418  may extend in a direction that is perpendicular or substantially perpendicular to the direction in which the air-side channels  408  and ribs  406  extend. 
     A frame-shaped perimeter seal  434  may be disposed on the perimeter seal surface  432 . The perimeter seal  434  may be configured to prevent air entering the fuel flow field  430  and contacting the anode on an adjacent fuel cell  310 . The perimeter seal  434  may also operate to prevent fuel from exiting the fuel risers  403 ,  405  and leaking out of the fuel cell stack  300  (see  FIGS.  3 A and  3 B ). 
     The seals  424 ,  434  may comprise a glass or ceramic seal material. The seal material may have a low electrical conductivity. In some embodiments, the seals  424 ,  434  may be formed by printing one or more layers of seal material on the interconnect  400 , followed by sintering. 
     As shown in  FIG.  1 A , in a conventional fuel cell system, fuel and fuel exhaust are provided to and received from a fuel cell stack through metal anode splitter plates  36 . The anode splitter plates  36  which are fluidly connected to one another by the fuel inlet conduit  32  and the anode exhaust conduit  34 . The conduits  32 ,  34  include metal tubes that are welded to the anode splitter plates  36  and to ceramic components that serve as dielectric breaks. As such, fluidly connecting the anode splitter plates  36  relies upon expensive dielectric components and a significant amount of on-site welding. Therefore, there is a need for a more cost effective method for providing fuel to, and receiving fuel exhaust from, a fuel cell stack. 
       FIG.  5 A  is an exploded top perspective view of an fuel flow structure  500 , according to various embodiments of the present disclosure, and  FIG.  5 B  is an exploded bottom perspective view of the fuel flow structure  500  of  FIG.  5 A . Referring to  FIGS.  5 A and  5 B , the fuel flow structure  500  includes fuel conduits  320  and a fuel plenum  350 . The fuel plenum  350  may include a seal ring  354 , glass or glass ceramic seals  356 , a base plate  360 , a dielectric layer  364 , a cover plate  366 , a seal plate  370 , and a manifold plate  380 . 
     The fuel plenum  350  may be configured to form a fluid-tight connection with the fuel conduits  320 . The fuel conduits  320  may include an inlet conduit  320 A configured to provide fuel to the fuel plenum  350 , and an outlet conduit  320 B configured to receive fuel exhaust from the fuel plenum  350 . The fuel conduits  320  may include metal tubes  322 , metal bellows  324 , and dielectric rings  326 . The metal tubes  322  may be coupled to the bellows  324  and the dielectric rings  326  by brazing, welding, or press-fitting, for example. The bellows  324  may act to compensate for differences in coefficients of thermal expansion between fuel cell components by deforming to absorb stress. In alternate embodiments, the metal tubes  322  may themselves include, or be made entirely of bellows, rather than be coupled with the bellows  324  such that the metal tubes/bellows  322  may be directly coupled with the dielectric ring  326 . The dielectric rings  326  may operate as dielectric breaks, to prevent current from being conducted through the fuel conduits  320  and electrically shorting a fuel cell stack disposed on the fuel plenum  350 . 
     The base plate  360 , dielectric layer  364 , and cover plate  366  may respectively include inlet holes  361 A,  365 A,  367 A and outlet holes  361 B,  365 B,  367 B, which may be through-holes that extend through the respective plates and layer. The base plate  360  may include protrusions  362  configured to mate with ceramic connectors  39 , as shown in  FIG.  1 A . The base plate  360  and the cover plate  366  may be formed of a densified dielectric material. For example, the base plate  360  and the cover plate  366  may be formed of a substantially non-porous, electrically-insulating ceramic material, such as alumina, zirconia, yttria stabilized zirconia (YSZ) (e.g., 3% yttria stabilized zirconia), or the like. The base plate  360  and the cover plate  366  may be rigid plates configured to provide support to the dielectric layer  364 . 
     In some embodiments, the dielectric layer  364  may be formed of a ceramic material having a higher dielectric constant than the ceramic materials of the base plate  360  and/or the cover plate  366 . In other words, the dielectric layer  364  may be able to withstand a higher maximum electric field without electrical breakdown and becoming electrically conductive (i.e., have a higher breakdown voltage) than the base plate  360  and the cover plate  366 . For example, the dielectric layer  364  may be formed of one or more layers of a porous ceramic yarn or fabric that is highly electrically insulating at high temperatures, such as Nextel ceramic fabrics numbers 312, 440 or 610, available from 3M Co. 
     In other embodiments, the dielectric layer  364  may be formed of a ceramic matrix composite (CMC) material, or any comparable material that has high dielectric strength, due to having a high surface area to volume ratio. The CMC may include, for example, a matrix of aluminum oxide (e.g., alumina), zirconium oxide or silicon carbide. Other matrix materials may be selected as well. The fibers may be made from alumina, carbon, silicon carbide, or any other suitable material. In one embodiment, both matrix and fibers may comprise alumina. Accordingly, the dielectric layer  364  may be configured to operate as a dielectric break to prevent electrical conduction through the fuel plenum  350 . 
     The cover plate  366  and the base plate  360  may have a higher density than the dielectric layer  364 . For example, the cover plate  366  and/or the base plate  360  may be formed of a fully dense ceramic material, such as 97% to 99.5% dense alumina, or the like. The cover plate  366  is configured to separate the seal plate  370  from the dielectric layer  364 . As such, the cover plate  366  may be configured to prevent the diffusion of metallic species from the seal plate  370  into the dielectric layer  364 . For example, the cover plate  366  may reduce and/or prevent the diffusion of chromium species (e.g., chromium oxides) from the seal plate  370  into the dielectric layer  364 , in order to prevent the chromium species from reducing the dielectric strength of the dielectric layer  364  and/or otherwise degrading the structural integrity of the dielectric layer  364 . 
     The seal plate  370  and the manifold plate  380  may be formed of a metal or metal alloy, such as stainless steel, that may be easily welded to the fuel conduits  320 . For example, the seal plate  370  and/or the manifold plate  380  may be formed of 446 stainless steel or the like. 446 stainless steel includes 23 to 27 weight % Cr, 1.5 weight % or less Mn, 1 weight % or less of one or more of Si, Ni, C, P and/or S, and balance Fe. In some embodiments, the seal plate  370  and/or the manifold plate  380  may be formed by brazing multiple metal sub-plates together. In embodiments formed using metal sub-plates, each of the sub-plates may be cut to form various structures, such as holes and/or channels, prior to, or after, the brazing process. In some embodiments, laser cutting or the like may be used to cut such structures. 
     The seal plate  370  and the manifold plate  380  may respectively include coatings  372 ,  382  on one or both sides, such as at least on the sides of the plates  370 ,  380  that face each other. The coatings  372 ,  382  may have a thickness ranging from about 75 μm to about 200 μm, such as from about 100 μm to about 175 μm, from about 110 μm to about 140 μm, or about 120 μm. Typically, the coatings  372 ,  382  may comprise a metal oxide material, such as a perovskite material, for example, lanthanum strontium manganite (LSM). Alternatively, other metal oxide coatings, such as a spinel, such as an (Mn, Co)3O4 spinel (MCO), can be used instead of or in addition to LSM. Any spinel having the composition Mn2−xCo1+xO4 (0□x□1) or written as z(Mn3O4)+(1−z)(Co3O4), where (⅓□z□⅔) or written as (Mn, Co)3O4 may be used. In other embodiments, a mixed layer of LSM and MCO, or a stack of LSM and MCO layers may be used as the coatings  372 ,  382 . The coatings  372 ,  382  may be formed using a spray coating or dip coating process and may be applied to substantially all the outer surfaces of the seal plate  370  and the manifold plate  380 . 
     The seal plate  370  may include an inlet hole  374 A and an outlet hole  374 B, which may be through-holes that extend between top and bottom surfaces thereof. The manifold plate  380  may include a bottom inlet hole  384 A and a bottom outlet hole  384 B formed in the bottom surface thereof, and top inlet holes  390 A and top outlet holes  390 B, which may be formed in the top surface thereof, on opposing sides of the manifold plate  380 . While three top inlet holes  390 A and three top outlet holes  390 B are shown, the present disclosure is not limited to any particular number of top outlet and inlet holes  390 A,  390 B. For example, the manifold plate  380  may include two, four, five or more top inlet holes  390 A, and may include two, four, five or more top outlet holes  390 B, depending on a number of fuel inlets and outlets included in the interconnects  400  of a corresponding fuel cell stack. For example, if the interconnects has three inlets and three outlets, then the manifold plate  380  has three inlet holes  390 A and three outlet holes  390 B. 
     The base plate  360 , dielectric layer  364 , cover plate  366 , seal plate  370 , and manifold plate  380  may be stacked on one another, such that the inlet holes  361 A,  365 A,  367 A,  374 A,  384 A are aligned to form an inlet conduit passage  352 A, and the outlet holes  361 B,  365 B,  367 B,  374 B,  384 B are aligned to form an outlet conduit passage  352 B. The inlet and outlet conduits  320 A,  320 B may be inserted into the respective inlet and outlet conduit passages  352 A,  352 B such that ends  328  of the inlet and outlet conduits  320 A,  320 B may extend up to and/or past the upper surface of the seal plate  370 . 
       FIG.  6 A  is a top view of the seal plate  370 , and  FIG.  6 B  is a cross-sectional view taken along the line L 3  of  FIG.  6 A . An inlet seal region  378 A and an outlet seal region  378 B may be respectively formed around the inlet and outlet holes  374 A,  374 B in areas where the coating  372  is not applied to the top surface of the seal plate  370 . As such, the inlet and outlet seal regions  378 A,  378 B may have a depth D 2  equal to the thickness of the coating  372 , such as a depth D 2  of about 120 μm. 
       FIG.  7 A  is a bottom view of the manifold plate  380 ,  FIG.  7 B  is a cross-sectional view taken along the line L 4  of  FIG.  7 A , and  FIG.  7 C  is a schematic top view of the manifold plate  380 , according to various embodiments of the present disclosure. Referring to  FIGS.  7 A- 7 C , inlet and outlet recesses  386 A,  386 B may be formed in the bottom surface of the manifold plate  380 , respectively surrounding the bottom inlet and outlet holes  384 A,  384 B. The inlet and outlet recesses  386 A,  386 B may have a depth D 3  ranging from about 0.5 mm to about 6 mm, such as from about 1 cm to about 3 cm, such as from about 0.5 cm to about 2 cm, or about 1 cm. 
     Inlet and outlet seal regions  388 A,  388 B may be respectively formed around the inlet and outlet recesses  386 A,  386 B, in areas where the coating  382  is not applied to the bottom surface of the manifold plate  380 . As such, the inlet and outlet seal regions  388 A,  388 B may have a depth D 4  equal to the thickness of the coating  382 , such as a depth D 4  of about 120 μim. 
     The manifold plate  380  may also include internal inlet channels  392 A and outlet channels  392 B. The inlet channels  392 A may fluidly connect the bottom inlet hole  384 A to respective top inlet holes  390 A. The outlet channels  392 B may fluidly connect the bottom outlet hole  384 B to respective top outlet holes  390 B. The inlet channels  392 A may be configured such that substantially equal amounts of fuel (e.g., equal fuel flow rates) are provided to each top inlet hole  390 A from the common bottom inlet hole  384 A. The outlet channels  392 B may be configured such that substantially equal amounts of fuel exhaust are provided from each top outlet hole  390 B to the common bottom outlet hole  384 B. 
     In addition, the manifold plate  380  may include an electrical contact  381 . The manifold plate  380  may be electrically connected to the bottom of a fuel cell stack, and the electrical contact  381  may extend laterally from the manifold plate  380  and may be configured to provide a connection point for connecting the manifold plate  380  to a current collection circuit. 
       FIG.  8 A  is a vertical cross-sectional view taken along the line L 1  of  FIG.  5 A , showing the assembled fuel plenum  350  and inlet conduit  320 A, and  FIG.  8 B  is a vertical cross-sectional view or along the line L 2  of  FIG.  5 A , showing the assembled fuel plenum  350  and outlet conduit  320 B. 
     Referring to  FIGS.  5 A,  5 B,  8 A, and  8 B , the base plate  360 , dielectric layer  364 , cover plate  366 , seal plate  370 , and manifold plate  380  are stacked on one another, thereby forming the inlet conduit passage  352 A and the outlet conduit passage  352 B. The inlet conduit  320 A may be inserted in the inlet conduit passage  352 A, facing the bottom inlet hole  384 A. The outlet conduit  320 B may be inserted in the outlet conduit passage  352 B, facing the bottom outlet hole  384 B. 
     A first seal ring  354 A may be disposed in the inlet recess  386 A on the bottom surface of the manifold plate  380  and around the inlet conduit  320 A. A second seal ring  354 B may be disposed in the outlet recess  386 B on the bottom surface of the manifold plate  380  and around the outlet conduit  320 B. The inlet and outlet conduits  320 A,  320 B may be welded to the seal plate  370 . In particular, the welding process may include welding the first and second seal rings  354 A,  354 B to the inlet and outlet conduits  320 A,  320 B, and welding the first and second seal rings  354 A,  354 B to the surface of the seal plate  370  to ensure that a fluid-tight seal is formed between the inlet and outlet conduits  320 A,  320 B and the seal plate  370 . 
     A first glass or glass ceramic seal  356 A may be disposed in the inlet seal region  378 A of the seal plate  370 , and a second glass or glass ceramic seal  356 B may be disposed in the inlet seal region  388 A of the manifold plate  380 . A third glass or glass ceramic seal  356 C may be disposed in the outlet seal region  378 B of the seal plate  370 , and a fourth glass or glass ceramic seal  356 D may be disposed in the outlet seal region  388 B of the manifold plate  380 . However, in other embodiments, a single glass or glass ceramic seal may be used. The seals  356 A- 356 D may be heated to soften the seals  356 A- 356 D, such that the seals  356 A- 356 D form a fluid-tight connections that physically connect the seal plate  370  to the manifold plate  380 . 
     The inlet seal regions  378 A,  388 A may overlap to form an inlet seal area  358 A, and the outlet seal regions  378 B,  388 B may overlap to form an outlet seal area  358 B. The first and second seals  356 A,  356 B may be stacked on one another in the inlet seal area  358 A, and the third and fourth seals  356 C,  356 D may be stacked on one another in the outlet seal area  358 B. The coatings  372 ,  382  may be stacked on one another. As such, the height of the inlet and outlet seal areas  358 A,  358 B may be equal to the combined thickness of the coatings  372 ,  382 . 
     The inlet and outlet seal areas  358 A,  358 B may provide space for the glass or glass ceramic seals  356 A- 356 D to expand laterally when heated to fuel cell system operating temperatures, thereby reducing stress applied to the glass or glass ceramic seals  356 A- 356 D over time. In addition, since the seal plate  370  and the manifold plate  380  may be formed of the same materials, the seal plate  370  and the manifold plate  380  may have matched coefficients of thermal expansion (CTEs). Therefore, stress applied to the glass or glass ceramic seals  356 A- 356 D over time may be further reduced. 
     The glass or glass ceramic seals  356 A- 356 D may be formed of a high-temperature glass or glass ceramic material, such as a silicate or aluminosilicate glass or glass ceramic material. In some embodiments, the glass or glass ceramic seals  356 A- 356 D may be formed of a silicate glass or glass ceramic seal material comprising SiO 2 , BaO, CaO, Al 2 O 3 , K 2 O, and/or B 2 O 3 . For example, the seal material may include, by weight: SiO 2  in an amount ranging from about 40% to about 60%, such as from about 45% to about 55%; BaO in an amount ranging from about 10% to about 35%, such as from about 15% to about 30%; CaO in an amount ranging from about 5% to about 20%, such as from about 7% to about 16%; Al 2 O 3  in an amount ranging from about 10% to about 20%, such as from about 13% to about 15%; and B 2 O 3  in an amount ranging from about 0.25% to about 7%, such as from about 0.5% to about 5.5%. In some embodiments, the seal material may additionally include K 2 O in an amount ranging from about 0.5% to about 1.5%, such as from about 0.75% to about 1.25%. 
     In some embodiments, the glass or glass ceramic seals  356 A- 356 D may be formed of a silicate glass or glass ceramic seal material comprising SiO 2 , B 2 O 3 , Al 2 O 3 , CaO, MgO, La 2 O 3 , BaO, and/or SrO. For example, the seal material may include, by weight: SiO 2 in an amount ranging from about 30% to about 60%, such as from about 35% to about 55%; B 2 O 3  in an amount ranging from about 0.5% to about 15%, such as from about 1% to about 12%; Al 2 O 3  in an amount ranging from about 0.5% to about 5%, such as from about 1% to about 4%; CaO in an amount ranging from about 2% to about 30%, such as from about 5% to about 25%; MgO in an amount ranging from about 2% to about 25%, such as from about 5% to about 20%; and La 2 O 3  in an amount ranging from about 2% to about 12%, such as from about 5% to about 10%. In some embodiments, the seal material may additionally include BaO in an amount ranging from about 0% to about 35%, such as from about 0% to about 30%, or from about 0.5% to about 30%, including about 20% to about 30%, and/or SrO in an amount ranging from about 0% to about 20%, such as from about 0% to about 15%, of from about 0.5% to about 15%, including about 10% to about 15%. In some embodiments, the seal material may additionally include at least one of BaO and/or SrO in a non-zero amount such as at least 0.5 wt. %, such as both of BaO and SrO in a non-zero amount, such at least 0.5 wt. %. However, other suitable seal materials may be used. 
     When assembled in a fuel cell stack, such as the fuel cell stack  300  of  FIGS.  3 A- 3 C , the top inlet holes  390 A may be fluidly connected to the fuel inlets  402  of the interconnect  400  of the stack  300 , and the top outlet holes  390 B may be fluidly connected to the fuel outlets  404  of the interconnects  400 , as shown in  FIG.  4 A . For example, a glass or glass ceramic seal  424  may be disposed between the top inlet holes  390 A and the fuel inlets  402  of an adjacent interconnect  400 , and a glass or glass ceramic seal  424  may be disposed between the top outlet holes  390 B and the fuel outlets  404  of the adjacent interconnect  400 , in order to provide fluid-tight connections. 
       FIG.  9 A  is a three-dimensional top perspective view of a fuel cell manifold plate  380  having an embedded dielectric layer  396 , and  FIG.  9 B  is a three-dimensional exploded view of the fuel cell manifold plate  380  of  FIG.  9 A , according to various embodiments. The presence of the dielectric layer  396  may reduce leakage currents through the fuel cell manifold plate  380 , which may, in turn, act to reduce corrosion of the manifold plate  380  and other structures. The dielectric layer  396  may also prevent short circuit connections that may otherwise cause the system to malfunction and/or may cause damage to system components. 
     As shown in  FIG.  9 B , the fuel cell manifold plate  380  may include an upper manifold portion  380   a  and a lower manifold portion  308   b . The dielectric layer  396  may include a first dielectric layer portion  396   a  and a second dielectric layer portion  396   b . As shown, the dielectric layer  396  may be split along a split line  396   c . The presence of the split line  396  may reduce thermal stress/strain induced in the dielectric layer  396  due to differences in the CTE of the dielectric layer  396  relative to the CTE of the upper manifold portion  380   a  and the lower manifold portion  308   b . The fuel cell manifold plate  380  may further include seals  398  placed above and below the dielectric layer  396  as shown in  FIG.  9 B . The seals  398  may include an electrically insulating (e.g., glass or glass-ceramic) material and may have a ring-shape (i.e., “donut shape”) geometry. In other embodiments, the seals  398  may have other shapes and may include other materials. The seals  398  surround the bottom inlet hole  384 A and the bottom outlet hole  384 B which extend through the lower manifold portion  380   b  and the respective first and second dielectric layer portions  396   a  and  396   b . The seals  398  may prevent leakage of fuel and/or air between the upper manifold portion  380   a , the lower manifold portion  308   b , and the dielectric layer  396 . 
       FIGS.  10 A to  10 C  illustrate intermediate structures used in the formation of the dielectric layer  396  of  FIG.  9 B , and  FIG.  10 D  illustrates the dielectric layer  396 , according to various embodiments. The intermediate structures of  FIGS.  10 A to  10 C  illustrate the formation of one of the first dielectric layer portion  396   a  and the second dielectric layer portion  396   b . The intermediate structure of  FIG.  10 A  may be formed by placing an electrically insulating seal  1006  over a first dielectric shim  1002   a . For example, the seal  1006  may include an insulating (e.g., glass or glass-ceramic) material and may have a ring-shape (i.e., “donut shape”) geometry. In other embodiments, the seal  1006  may have other shapes and may include other materials. The first shim  1002   a  may include a first hole  1004   f  configured to form part of one of the inlet conduit passage  352 A and the outlet conduit passage  352 B, as described above. For example, the first hole  1004   f  may comprise upper portions of the bottom inlet hole  384 A or the bottom outlet hole  384 B described above. 
     In an example embodiment, the first dielectric shim  1002   a  may include a ceramic material, such as alumina. In other embodiments, the first dielectric shim  1002   a  may include other materials. The first dielectric shim  1002   a  may have a thickness of 0.5 mm to 5 mm, such as 2 mm to 3 mm. The intermediate structure of  FIG.  10 B  may be formed by placing a fabric  1008  over the first dielectric shim  1002   a . The fabric  1008  may include an insulating material that is stable at high temperatures. For example, the fabric  1008  may include fiberglass. The fabric may be 0.25 mm to 1 mm thick, such as approximately 0.5 mm thick. In other embodiments, the fabric  1008  may include other materials and may have other thicknesses. The fabric  1008  is cut in the shape of the first dielectric shim  1002   a  such that a second hole  1004   s  also extends through the fabric  1008 . The fabric  1008  is placed around the seal  1006  such that the second hole  1004   s  in the fabric  1008  is aligned with the seal  1006  and the first hold  1004   f.    
     The intermediate structure of  FIG.  10 C  may be formed by placing a second dielectric shim  1002   b  over the fabric  1008 . In an example embodiment, the second dielectric shim  1002   b  may include a ceramic material such as alumina. In other embodiments, the second dielectric shim  1002   b  may include other materials. The second shim  102   b  may have the same or different thickness as the first shim  102   a . For example, the first shim  1002   a  and the second shim  1002   b  may each be approximately 2 mm thick. In other embodiments, the first shim  1002   a  and the second shim  1002   b  may have other thicknesses. A third hole  1004   t  extends through the second shim  1002   b.    
     According to an embodiment, the intermediate structure of  FIG.  10 C  may then be sintered under mechanical load at 800° C. to 1200° C., such as 1000° C. at a rate of 1° C./min to 5° C./min, such as 2° C./min, soaked for a minimum of 3 hours, such as 3 to 10 hours, and cooled to room temperature at a rate of 1° C./min to 5° C./min, such as 2° C./min to thereby form a hermetic sandwich assembly. In other embodiments, the intermediate structure of  FIG.  10 C  may be processed in other ways. The resulting hermetic sandwich assembly may form one of the first dielectric layer portion  396 a and the second dielectric layer portion  396 b of the dielectric layer  396 . 
     As shown in  FIG.  10 D , the first dielectric layer portion  396   a  and the second dielectric layer portion  396   b  may be formed as mirror images of one another and may be placed next to one another to thereby be separated by the split line  396   c , which may be formed as a gap between the first dielectric layer portion  396   a  and the second dielectric layer portion  396   b . The first dielectric layer portion  396   a  and the second dielectric layer portion  396   b  may be nested between the upper manifold portion  380   a  and the lower manifold portion  308   b , as shown in  FIG.  9 B . As mentioned above, the presence of the split line  396  (i.e., the gap between first dielectric layer portion  396   a  and the second dielectric layer portion  396   b ) may mitigate thermal stresses/strains due to a mismatch between the CTE of the dielectric layer  396 , the upper manifold portion  380   a , and the lower manifold portion  308   b.    
     Each of the respective first dielectric layer portion  396   a  and the second dielectric layer portion  396   b  includes a respective hole  1004   a ,  1004   b  which may comprise upper portions of the bottom inlet hole  384 A and the bottom outlet hole  384 B described above. Thus, the electrically insulating fabric  1008  containing the second hole  1004   s  is placed between the first electrically insulating shim  1002   a  and the second electrically insulating shim  1002   b  to form an assembly (e.g., first or second portion of the insulating layer  396 ) in which the first, second and third holes ( 1004   f ,  1004   s ,  1004   t ) are aligned to each other to form a continuous hole (e.g.,  1004   a  or  1004   b ). 
       FIG.  11    is a cross-sectional view of the manifold plate  380  of  FIG.  9 A  taken along the line L 5  of  FIG.  9 A , according to various embodiments. As shown in  FIG.  11   , the manifold plate  380  may include the dielectric layer  396  having the first dielectric layer portion  396   a  sandwiched between the upper manifold portion  380   a  and a lower manifold portion  308   b . The remaining structural details of the manifold plate  380  are similar to those described above with reference to  FIG.  7 B . 
       FIG.  12 A  is a vertical cross-sectional view of a fuel flow structure similar to that of  FIG.  8 A  including the manifold plate  380  of  FIGS.  9 A and  9 B , according to various embodiments. In this example, the cross section is taken along the line L 5  of  FIG.  9 A . As shown, the fluid flow structure includes the first dielectric layer portion  396   a  sandwiched between the upper manifold portion  380   a  and a lower manifold portion  308   b . The remaining structural details of the fuel flow structure of  FIG.  12 A  are similar to those described above with reference to  FIG.  8 A . 
       FIG.  12 B  is a vertical cross-sectional view of the fuel flow structure of  FIG.  12 A  taken along the line L 6  of  FIG.  9 A , according to various embodiments. As shown, the fluid flow structure includes the second dielectric layer portion  396   b  sandwiched between the upper manifold portion  380   a  and a lower manifold portion  308   b . The remaining structural details of the fuel flow structure of  FIG.  12 B  are similar to those described above with reference to  FIG.  8 B . 
     While solid oxide fuel cell interconnects, end plates, electrolytes, and manifold plates are described above in various embodiments, embodiments may include any other fuel cell components, such as molten carbonate, phosphoric acid or PEM fuel cell electrolytes, interconnects or end plates, or any other shaped metal or metal alloy or compacted metal powder or ceramic objects not associated with fuel cell systems. 
     Fuel cell systems of the embodiments of the present disclosure are designed to reduce greenhouse gas emissions and have a positive impact on the climate. 
     The foregoing descriptions are provided merely as illustrative examples and are not intended to require or imply that the operations of the various embodiments must be performed in the order presented. As will be appreciated by one of skill in the art the order of operations in the foregoing embodiments may be performed in any order. Words such as “thereafter,” “then,” “next,” etc. are not necessarily intended to limit the order of the operations; these words may be used to guide the reader through the description of the methods. Further, any reference to claim elements in the singular, for example, using the articles “a,” “an” or “the” is not to be construed as limiting the element to the singular. Further, any operation or component of any embodiment described herein can be used in any other embodiment. 
     The preceding description of the disclosed aspects is provided to enable any person skilled in the art to make and/or use the disclosed embodiments. Various modifications to these aspects will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other aspects without departing from the scope of the disclosure. Thus, embodiments of the disclosure are not intended to be limited to the aspects shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.