Fuel cell interconnect optimized for operation in hydrogen fuel

Abstract

To provide an interconnect that improves fuel cell performance such as fuel utilization and system efficiency.SOLUTION: A fuel cell interconnect 300A comprises: fuel ribs 312 disposed on a first side of the interconnect and defining fuel channels 310; and air ribs disposed on an opposing second side and defining air channels. The fuel channels 310 comprise central fuel channels 310C and peripheral fuel channels 310P disposed on opposing sides thereof. The air channels comprise central air channels and peripheral air channels disposed on opposing sides thereof. Further in the interconnect 300A, at least one of the central fuel channels or the central air channels has at least one of a different cross-sectional area or length from at least one of the peripheral fuel channels or the peripheral air channels so as to increase a hydrogen fuel flow through the central fuel channels or to increase an air flow through the peripheral air channels.SELECTED DRAWING: Figure 3A

Description

[Technical Field]

[0001] The present invention relates to fuel cell stack components, and more particularly to fuel cell stack interconnects and methods of making interconnects. [Background technology]

[0002] A typical solid oxide fuel cell stack contains multiple fuel cells separated by metallic interconnects (ICs), which provide both electrical connection between adjacent cells in the stack and channels for fuel and oxidant delivery and removal. The metallic interconnects are typically constructed from Cr-based alloys, such as the alloy known as CrFe, which has a composition of 95% Cr-5% Fe by weight, or Cr-Fe-Y, which has a composition of 94% Cr-5% Fe-1% Y by weight. CrFe and CrFeY alloys maintain their strength and are dimensionally stable at typical solid oxide fuel cell (SOFC) operating conditions, e.g., 700°C to 900°C, in both air and humid fuel atmospheres. Summary of the Invention

[0003] According to various embodiments, a fuel cell interconnect includes a fuel rib disposed on a first side of the interconnect and at least partially defining a fuel channel, and an air rib disposed on an opposing second side of the interconnect and at least partially defining an air channel. The fuel channels include a central fuel channel disposed within a central fuel zone and peripheral fuel channels disposed within peripheral fuel zones disposed on either side of the central fuel zone. The air channels include a central air channel disposed within the central air zone and peripheral air channels disposed within peripheral air zones disposed on either side of the central air zone. At least one of the central fuel channel or the central air channel has at least one of a cross-sectional area or a length that is different from at least one of the respective peripheral fuel channel or the respective peripheral air channel to increase hydrogen fuel flow through the central fuel channel or increase air flow through the peripheral air channel.

[0004] According to various embodiments, a method of operating a fuel cell stack including the above-described interconnect includes providing hydrogen fuel in the fuel channels, where more hydrogen fuel flows through the central fuel channel than through the peripheral fuel channels, and providing air in the air channels, where more air flows through the central air channel than through the peripheral air channels. [Brief explanation of the drawings]

[0005] [Figure 1A] FIG. 1A is a perspective view of a SOFC stack according to various embodiments of the present disclosure. [Figure 1B] FIG. 1B is a cross-sectional view of a portion of the stack of FIG. 1A. [Figure 2A] FIG. 2A is a top view of the air side of an interconnect according to various embodiments of the present disclosure. [Figure 2B] FIG. 2B is a top view of the fuel side of the interconnect of FIG. 2A. [Figure 3A] FIG. 3A is a top view of the fuel side of an interconnect according to various embodiments of the present disclosure. [Figure 3B] FIG. 3B is a top view of the fuel side of an interconnect according to various embodiments of the present disclosure. [Figure 3C] FIG. 3C is a top view of the fuel side of an interconnect according to various embodiments of the present disclosure. [Figure 3D] FIG. 3D is a top view of the fuel side of an interconnect according to various embodiments of the present disclosure. [Figure 4A] FIG. 4A is a top view of the air side of an interconnect according to various embodiments of the present disclosure. [Figure 4B] FIG. 4B is a top view of the air side of an interconnect according to various embodiments of the present disclosure. [Figure 4C] FIG. 4C is a top view of the air side of an interconnect according to various embodiments of the present disclosure. [Figure 4D] FIG. 4D is a top view of the air side of an interconnect according to various embodiments of the present disclosure. [Figure 5A] FIG. 5A is a top view of the fuel side of a cross-flow interconnect according to various embodiments of the present disclosure. [Figure 5B] FIG. 5B is a top view of the air side of the interconnect of FIG. 5A. DETAILED DESCRIPTION OF THE INVENTION

[0006] Figure 1A is a perspective view of a solid oxide fuel cell (SOFC) stack 100 according to various embodiments of the present disclosure, and Figure 1B is a cross-sectional view of a portion of the stack 100. With reference to Figures 1A and 1B, the stack 100 includes fuel cells 1 separated by interconnects 10. With reference to Figure 1B, each fuel cell 1 includes a cathode electrode 3, a solid oxide electrolyte 5, and an anode electrode 7.

[0007] Various materials can be used for the cathode electrode 3, electrolyte 5, and anode electrode 7. For example, the anode electrode 7 can include a cermet including a nickel-containing phase and a ceramic phase. The nickel-containing phase can consist entirely of nickel in a reduced state. This phase may form nickel oxide when in an oxidized state. Therefore, the anode electrode 7 is preferably annealed in a reducing atmosphere prior to operation to reduce the nickel oxide to nickel. The nickel-containing phase may include other metals in addition to nickel and / or nickel alloys. The ceramic phase can include stabilized zirconia, such as yttria and / or scandia-stabilized zirconia, and / or doped ceria, such as gadolinia, yttria, and / or samaria-doped ceria.

[0008] The electrolyte may include stabilized zirconia, such as scandia-stabilized zirconia (SSZ) or yttria-stabilized zirconia (YSZ). Alternatively, the electrolyte may include another ion-conducting material, such as doped ceria.

[0009] The cathode electrode 3 may comprise a conductive material such as a conductive perovskite material, e.g., lanthanum strontium manganite (LSM). Other conductive perovskites, such as LSCo, or metals, such as Pt, may also be used. The cathode electrode 3 may also comprise a ceramic phase similar to the anode electrode 7. The electrodes and electrolyte may each comprise one or more sublayers of one or more of the materials mentioned above.

[0010] Fuel cell stacks are often assembled from a multiplicity of SOFCs 1 in the form of planar elements, tubes, or other shapes. While the fuel cell stack in FIG. 1A is arranged vertically, the fuel cell stack can also be arranged horizontally or in any other orientation. Fuel and air can be provided to electrochemically active surfaces, which can be large in area. For example, fuel can be provided through fuel conduits 22 (e.g., fuel riser openings) formed in each interconnect 10.

[0011] Each interconnect 10 electrically connects adjacent fuel cells 1 in the stack 100. In particular, an interconnect 10 can electrically connect the anode electrode 7 of one fuel cell 1 to the cathode electrode 3 of an adjacent fuel cell 1. FIG. 1B shows the lower fuel cell 1 positioned between two interconnects 10. An optional Ni mesh can be used to electrically connect the interconnect 10 to the anode electrode 7 of the adjacent fuel cell 1.

[0012] Each interconnect 10 includes fuel ribs 12A that at least partially define fuel channels 8A and air ribs 12B that at least partially define oxidant (e.g., air) channels 8B. The interconnects 10 can operate as gas-fuel separators that separate a fuel, such as a hydrocarbon fuel, flowing to the fuel electrode (i.e., anode 7) of one cell in the stack from an 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 100, there can be air or fuel end plates (not shown) that provide air or fuel, respectively, to the end electrodes.

[0013] Each interconnect 10 can be formed from or contain a conductive material, such as a metal alloy (e.g., a chromium-iron alloy), having a thermal expansion coefficient similar to that of the solid oxide electrolyte in the cell (e.g., a difference of 0% to 10%). For example, the interconnect 10 can include a metal (e.g., a chromium-iron alloy, e.g., an alloy of 4 to 6 weight percent iron, optionally 1 weight percent or less yttrium, and the balance chromium) and can electrically connect the anode or fuel side of one fuel cell 1 to the cathode or air side of an adjacent fuel cell 1. A conductive contact layer, such as a nickel contact layer, can be provided between the anode electrode 7 and each interconnect 10. Another optional conductive contact layer, such as a lanthanum strontium manganite and / or manganese cobalt oxide spinel layer, can be provided between the cathode electrode 3 and each interconnect 10.

[0014] FIG. 2A is a top view of the air side of an interconnect 10 according to various embodiments of the present disclosure, and FIG. 2B is a top view of the fuel side of an interconnect 10 according to various embodiments of the present disclosure. Referring to FIGS. 1B and 2A, the air side includes air channels 8B. Air flows through the air channels 8B from the cathode electrode 3 of the adjacent fuel cell 1. A ring seal 20 can surround the fuel holes 22A of the interconnect 10 to prevent fuel from contacting the cathode electrode. A strip-shaped peripheral seal 24 is located on the peripheral portion of the air side of the interconnect 10. The seals 20, 24 can be formed of a glass or glass-ceramic material. The peripheral portion can be a raised plateau without ribs or channels. The surface of the peripheral region can be flush with the tops of the ribs 12B.

[0015] 1B and 2B, the fuel side of the interconnect 10 can include a fuel channel 8A and a fuel manifold 28. Fuel flows from one of the fuel holes 22A (e.g., an inlet hole forming part of a fuel inlet riser) into the adjacent manifold 28, through the fuel channel 8A, and to the anode 7 of the adjacent fuel cell 1. Excess fuel can flow into the other fuel manifold 28 and then into the outlet fuel hole 22B. A frame-like seal 26 is disposed in a peripheral region of the fuel side of the interconnect 10. The peripheral region can be a raised plateau that does not include ribs or channels. The surface of the peripheral region can be flush with the tops of the ribs 12.

[0016] 2A and 2B, one of the fuel holes 22A, 22B delivers fuel to each cell in the stack, and a corresponding manifold 28 distributes the fuel to each fuel channel 8A. The fuel flows straight down each fuel channel 8A, with unreacted fuel collecting in the other manifold 28 and exiting the stack through the other fuel hole 22A, 22B. This flow channel geometry is optimized for operation on natural gas with partial external pre-reforming.

[0017] The inventors have discovered that while the interconnect 10 shown in FIGS. 2A and 2B provides high fuel utilization when using hydrocarbon fuels (e.g., natural gas), the interconnect 10 cannot provide sufficiently high fuel utilization when using hydrogen as the fuel. While not wishing to be bound by any particular theory, it is believed that using hydrogen as the fuel increases thermal gradients. For example, in a natural gas fuel system, an endothermic steam reforming reaction occurs at the anode, partially cooling the fuel cell. However, when using pure hydrogen fuel, no reforming cooling occurs, and most of the heat generated by the fuel cell is removed by the reaction flow (e.g., primarily air flow). This results in higher thermal gradients within the cell 1 (e.g., in the region corresponding to the center of the interconnect 10 near the fuel inlet hole 22A), thereby worsening fuel distribution because fuel preferentially flows to cooler regions adjacent to the edges (i.e., periphery) of the interconnect 10, where the specific volume and viscosity of the gas is lower.

[0018] Embodiments of the present disclosure provide interconnect configurations that distribute hydrogen and / or air to increase fuel utilization and / or reduce thermal gradients.

[0019] 3A is a top view of the fuel side of an interconnect 300A according to various embodiments of the present disclosure. Interconnect 300A can be similar to interconnect 10. Therefore, only the differences from interconnect 10 will be discussed in detail.

[0020] 3A , the fuel side of the interconnect 300A may include a frame seal area 302, opposing fuel manifolds 304, fuel holes 306, fuel ribs 312, and fuel channels 310. The frame seal area 302 may be a flat surface extending along the periphery of the interconnect 300A. The frame seal area 302 may be flush with the tops of the fuel ribs 312. The fuel manifolds 304 may be located on either edge of the interconnect 300A, inward of the frame seal area 302. The fuel holes 306 may be formed in the center of each of the fuel manifolds 304, adjacent opposing first and second edges 301 and 303 of the interconnect 300A.

[0021] The fuel ribs 312 and fuel channels 310 may extend between the fuel manifolds 304 in a direction parallel to opposing third and fourth edges 305 and 307 of the interconnect 300A. The fuel channels 310 and fuel ribs 312 may be configured to guide fuel flow across the interconnect 300A between the fuel manifolds 304. The interconnect 300A may be divided into a central fuel zone 314 and peripheral fuel zones 316 disposed on either side of the central fuel zone 314 adjacent the third and fourth edges 305 and 307. The fuel channels 310 may include a central fuel channel 310C disposed in the central fuel zone 314 and a peripheral fuel channel 310P disposed in the peripheral fuel zone 316. In various embodiments, about 25% to about 50%, for example, about 30% to about 40%, of the fuel channels 310 can be central fuel channels 310C, and the remaining fuel channels 310 can be peripheral fuel channels 310P.

[0022] The interconnect 300A can be configured to provide a greater fuel (e.g., hydrogen) mass flow rate through the central fuel channel 310C than through the peripheral fuel channel 310P. In particular, the central fuel channel 310C can have a cross-sectional area, viewed perpendicular to the third edge 305 and the fourth edge 307, that is greater than the cross-sectional area of ​​the peripheral fuel channel 310P. For example, the central fuel channel 310C can be wider and / or deeper than the peripheral fuel channel 310P. In some embodiments, the cross-sectional area of ​​the central fuel channel 310C can be 5% to 40%, e.g., 8% to 30%, or 10% to 20% greater than the cross-sectional area of ​​the peripheral fuel channel 310P. Thus, a greater fuel mass flow rate can be provided to the central portion of an adjacent fuel cell via the central fuel channel 310C than that provided to the peripheral portion of the fuel cell via the peripheral fuel channel 310P. Thus, interconnect 300A can be configured to direct more hydrogen fuel to areas that have higher operating temperatures and corresponding higher fuel flow resistance due to the use of hydrogen as a fuel.

[0023] In various embodiments, the cross-sectional area of ​​the fuel channels 310 can be incrementally varied such that the fuel channels 310 closest to the third edge 305 and fourth edge 307 of the interconnect 300A have the smallest cross-sectional area and the fuel channels 310 extending through the center of the interconnect 300A (e.g., extending between the fuel holes 306) have the largest cross-sectional area.

[0024] In some embodiments, the depth of the fuel manifold 304 can vary longitudinally such that the fuel manifold 304 has a maximum depth adjacent the fuel holes 306 and a minimum depth adjacent the third edge 305 and fourth edge 307 of the interconnect 300A. The variation in depth can result in less fuel mass flow through the peripheral fuel channels 310P and more mass flow through the central fuel channel 310C. A variable depth fuel manifold 304 can be used with a relatively large central fuel channel 310C and relatively small peripheral fuel channels 310P, or with all the same sized fuel channels.

[0025] 3B is a top view of the fuel side of interconnect 300B according to various embodiments of the present disclosure. Interconnect 300B can be similar to interconnect 300A. Therefore, only the differences from interconnect 300A will be described in detail.

[0026] 3B , at least some of the peripheral fuel channels 310P can be longer than the central fuel channels 310C. In other words, the lengths of the fuel ribs 312 and fuel channels 310 can increase continuously or in steps as the distance between the fuel ribs 312 and fuel channels 310 and the third edge 305 and fourth edge 307 decreases. In some embodiments, at least some of the peripheral fuel channels 310P and corresponding fuel ribs 312 can extend into the fuel manifold 304.

[0027] Increasing the length of the peripheral fuel channels 310P may increase the fuel flow resistance through the peripheral fuel channels 310P. Thus, the relatively short central fuel channels 310C may have a higher fuel mass flow rate (e.g., lower flow resistance) than the relatively long peripheral fuel channels 310P.

[0028] In one embodiment of interconnect 300B, the shorter central fuel channel 310C can have a larger cross-sectional area (i.e., a larger width and / or depth) than the longer peripheral fuel channel 310P. In another embodiment of interconnect 300B, the shorter central fuel channel 310C can have the same cross-sectional area (i.e., the same width and depth) as the longer peripheral fuel channel 310P.

[0029] Variations in the length of the fuel channels 310 can advantageously increase the active area of ​​adjacent fuel cells, thereby resulting in improved electrochemical performance. In one embodiment, nickel mesh current collectors (not shown) can be used to improve contact between the fuel ribs 312 and the anodes of adjacent fuel cells. To realize the benefit of greater active area, the Ni mesh can be shaped to correspond to the shape of the longer fuel ribs 312. In other words, the Ni mesh can be configured to completely overlap the central fuel region 314 and the peripheral fuel region 316.

[0030] 3C is a top view of the fuel side of interconnect 300C according to various embodiments of the present disclosure. Interconnect 300C can be similar to interconnect 300A. Therefore, only the differences from interconnect 300A will be described in detail.

[0031] 3C , the interconnect 300C can include a fuel shutoff or fuel buffer 318 extending across one or more of the peripheral fuel channels 310P. The fuel shutoff 318 can extend longitudinally in a direction perpendicular to the fuel channels 310. The fuel shutoff 318 can be configured to reduce the fuel mass flow rate through the peripheral fuel channels 310P such that the fuel mass flow rate through the central fuel channel 310C is greater than the fuel mass flow rate through the peripheral fuel channels 310P. In some embodiments, the fuel shutoff 318 can be configured to create a fuel mass flow gradient such that the peripheral fuel channels 310P farther from the central fuel zone 314 have a lower mass flow rate than the peripheral fuel channels 310P closer to the central fuel zone 314, thereby increasing fuel utilization in the central portions of adjacent fuel cells.

[0032] In some embodiments, in addition to or instead of the fuel shutoff section 318, a manifold transition section 320 can be positioned within the fuel manifold 304 to redirect fuel through the fuel manifold 304 and into the fuel channels 310. For example, the transition section 320 can be configured to direct more fuel mass flow into the central fuel channel 310C than into the peripheral fuel channels 310P. The transition section 320 can be located within the fuel manifold 304 and can include ribs that extend perpendicular to the fuel channels 310 and the ribs 312. This configuration can provide the added benefit of increasing the active area of ​​adjacent fuel cells.

[0033] In various embodiments, a space S may be formed in the fuel flow direction between the fuel hole 306 and an adjacent fuel rib 312 in the central fuel zone 314. The space S may be configured to increase fuel mass flow rate through the central fuel channel 310C adjacent to the fuel hole 306.

[0034] In some embodiments of the interconnect 300C, the cross-sectional area of ​​the central fuel channel 310C can be larger than the cross-sectional area of ​​the peripheral fuel channels 310P to further increase the fuel mass flow rate through the central fuel channel 310C. However, in other embodiments, the fuel channels 310 can all have substantially the same cross-sectional area.

[0035] 3D is a top view of the fuel side of interconnect 300D according to various embodiments of the present disclosure. Interconnect 300D can be similar to interconnect 300C. Therefore, only the differences from interconnect 300C will be described in detail.

[0036] 3D, the interconnect 300D can have multiple fuel holes 306 in each fuel manifold 304. The multiple fuel holes 306 can improve fuel distribution and / or increase fuel mass flow through the central fuel channel 310C to the central portion of the adjacent fuel cell.

[0037] In various embodiments, a space S may be formed in the fuel flow direction between the fuel holes 306 and adjacent fuel ribs 312 in the central fuel zone 314. The space S may be configured to increase the fuel mass flow rate in the central fuel channel 310C between the fuel holes 306 on either side of the interconnect 300D.

[0038] In some embodiments of the interconnect 300D, the cross-sectional area of ​​the central fuel channel 310C can be larger than the cross-sectional area of ​​the peripheral fuel channels 310P to further increase the fuel mass flow rate through the central fuel channel 310C. However, in other embodiments, the fuel channels 310 can all have substantially the same cross-sectional area.

[0039] 4A is a top view of the air side of an interconnect 400A according to various embodiments of the present disclosure. Referring to FIG. 4A, the air side of the interconnect 400A can have a strip seal area 402, a ring seal area 404, an air (e.g., oxidant) channel 410, air ribs 412, and fuel holes 306. The ring seal area 404 can be a flat area surrounding the fuel holes 306. The strip seal area 402 can be a flat area located on both edges of the interconnect 400A. The ring seal area 404 and the strip seal area 402 can be flush with the tops of the air ribs 412.

[0040] The air ribs 412 can at least partially define air channels 410. The air channels 410 can be configured to guide air across the interconnect between the strip seal regions 402. The air side of the interconnect 400A can be divided into a central air region 414 and peripheral air regions 416 disposed on either side of the central air region 414 adjacent the third edge 305 and fourth edge 307 of the interconnect 400A. The air channels 410 can include a central air channel 410C disposed within the central air region 414 and a peripheral air channel 410P disposed within the peripheral air region 416.

[0041] In one embodiment, all of the air channels 410 can have a larger cross-sectional area than the air channels 8B of the comparative interconnect 10 shown in Figure 2A, which increases the air cooling on the air side of the interconnect 400A when hydrogen is used as a fuel on the fuel side of the interconnect 400A.

[0042] In another embodiment, the cross-sectional area of ​​the central air channel 410C can be greater than the cross-sectional area of ​​the peripheral air channels 410P of the interconnect 400A. For example, the central air channel 410C can be wider and / or deeper than the peripheral air channels 410P. In some embodiments, the cross-sectional area of ​​the central air channel 410C can be between 5% and about 40%, e.g., between 8% and 30%, or between 10% and 20%, greater than the cross-sectional area of ​​the peripheral air channels 410P. Thus, the air mass flow rate through the central air channel 410C can be correspondingly greater than the air mass flow rate through the peripheral air channels 410P. The greater air mass flow rate in the central air channel 410C increases cooling of the center of the adjacent fuel cell when hydrogen is used as a fuel, reducing thermal gradients within the fuel cell and the interconnect 400A.

[0043] In some embodiments, the cross-sectional area of ​​the air channels 410 can increase continuously or in steps as the distance to the adjacent third edge 305 and fourth edge 307 decreases. In some embodiments, the cross-sectional area of ​​the central air channels 410C can vary incrementally, such that the central air channels 410C closer to the center of the central air zone 414 can have a larger cross-sectional area than the central air channels 410C located closer to the peripheral air zone 416. However, in various embodiments, at least some of the central air channels 410C can have a larger cross-sectional area than the peripheral air channels 410P.

[0044] In some embodiments, the air ribs 412 located in the central air zone 414 adjacent the ring seal area 404 can be relatively short (i.e., shorter than the air ribs 412 located in the peripheral air zone 416) to provide an air space S that increases airflow around the ring seal area 404, thereby increasing the mass flow rate of airflow through the central air channels 410C extending between the ring seal areas 404 on either side of the interconnect 400A. In other words, at least some of the air ribs 412 in the central air zone 414 can be shorter than the remaining air ribs 412 to increase airflow through the central air channels 410C in the central air zone 414, thereby increasing cooling of the interconnect 400A and corresponding portions of the adjacent fuel cells. In some embodiments where the air ribs 412 have different lengths in the central and peripheral air zones, the cross-sectional area of ​​the central air channel 410C can be larger than the cross-sectional area of ​​the peripheral air channel 410P to further increase the air mass flow rate through the central air channel 410C in the central air zone 414. In other embodiments, the cross-sectional area of ​​the central air channel 410C can be the same as the cross-sectional area of ​​the peripheral air channel 410P.

[0045] 4B is a top view of the air side of interconnect 400B according to various embodiments of the present disclosure. Interconnect 400B can be similar to interconnect 400A. Therefore, only the differences from interconnect 400A will be discussed in detail.

[0046] 4B , the air side of interconnect 400B can have curved or bent peripheral air channels 410BP and corresponding curved or bent air ribs 412B. In particular, the end portions of the curved air ribs 412B can be shaped to form air spaces S adjacent to ring seal area 404. In other words, the edge portions of the curved peripheral air channels 410BP located near edges 301 and 303 of interconnect 400B are not parallel to edges 305 and 307 of the interconnect and are not parallel to central air channel 410C. For example, the edge portions of the curved peripheral air channels 410BP located near edges 301 and 303 of interconnect 400B extend at an angle of 30 degrees to 60 degrees relative to edges 305 and 307 of the interconnect and central air channel 410C. In contrast, the central portion of the curved peripheral air channel 410BP in the center of interconnect 400B is parallel to the edges 305 and 307 of the interconnect and to central air channel 410C.

[0047] The air space S can be configured to increase the mass air flow into the central channel 410C of the central air zone 414. In particular, the space S can operate to compensate for air blockage caused by the ring seal region 404. The curved air ribs 412B can also be configured to reduce the mass air flow through the peripheral air channels 410P adjacent the strip seal region 402. For example, the end portions of the curved air ribs 412B can partially block air flow into the outermost peripheral air channels 410P.

[0048] In some embodiments, the cross-sectional area of ​​the central air channel 410C can be larger than the cross-sectional area of ​​the peripheral air channel 410P to further increase the air mass flow rate through the central air channel 410C in the central air zone 414 of the interconnect 400B. In other embodiments, the cross-sectional area of ​​the central air channel 410C can be the same as the cross-sectional area of ​​the peripheral air channel 410P of the interconnect 400B.

[0049] 4C is a top view of the air side of interconnect 400C according to various embodiments of the present disclosure. Interconnect 400C can be similar to interconnect 400B. Therefore, only the differences from interconnect 400B will be discussed in detail.

[0050] 4C , the air side of the interconnect 400C may have a plurality of fuel holes 306 and a ring seal area 404 disposed on opposing top and bottom sides of the interconnect 400C. The ring seal area 404 may be disposed outside of the central air region 414 such that the central air channel 410C of the central air region 414 is not obstructed by the fuel seal. Thus, the air mass flow rate through the central air region 414 may be increased because it is not obstructed by the fuel seal.

[0051] In some embodiments, the cross-sectional area of ​​the central air channel 410C can be larger than the cross-sectional area of ​​the peripheral flow channels 410P to further increase air flow through the central air channel 410C. However, in other embodiments, all of the air channels 410 can have substantially the same cross-sectional area.

[0052] 4D is a top view of the air side of an interconnect 400D according to various embodiments of the present disclosure. Interconnect 400D can be similar to interconnect 400A. Therefore, only the differences from interconnect 400A will be discussed in detail.

[0053] 4D , at least some of the central air channels 410C can be shorter than the peripheral air channels 410P. Furthermore, the central air channels 410 in the center of the central air zone 414 can be shorter than the central air channels 410 in the peripheral portions of the central air zone 414. Furthermore, the central air channels 410 in the center of the central air zone 414 can have lengths that increase with distance from the center of the interconnect 400D (in the direction between the ring seal regions 404). For example, the edges of the central air channels 410 in the center of the central air zone 414 can form a semicircular shape around the ring seal region 404. In contrast, the central air channels 410 in the peripheral portions of the central air zone 414 can have the same length, with the edges of the central air channels 410 facing the edges 301 and 303 of the interconnect 400D forming straight lines.

[0054] In particular, due to the shortened air ribs 412 in the central air zone 414, an air space S can be formed around the ring seal area 404. The air space S is located between the air ribs 412 in the peripheral air zone 416 and the ring seal area 404. The air space S can be configured to increase the air mass flow rate through the central air channels 410C by providing additional space for air to flow around the ring seal area 404. The space S can also reduce the variation in air mass flow rate between the central air channels 410C. For example, the air mass flow rate through the variation between the central air channels 410C can be less than 25%, e.g., 20% to 25%. Furthermore, the air flow through the central air channels 410C can be at least 25% greater, e.g., 30% to 35% greater, than through the peripheral air channels 410P.

[0055] In some embodiments, the cross-sectional area of ​​the central air flow channel 410C can be larger than the cross-sectional area of ​​the peripheral air flow channels 410P to further increase air flow through the central air flow channel 410C, however, in other embodiments, all of the air flow channels 410 can have substantially the same cross-sectional area.

[0056] 3A-3D and 4A-4D, various embodiments can include interconnects having any combination of the described air-side and fuel-side features. For example, interconnects 300A-300D can have any of the air-side features shown in FIGS. 4A-4D, and interconnects 400A-400D can have any of the fuel-side features shown in FIGS. 3A-3D. Meanwhile, in some embodiments, an interconnect having multiple fuel holes 306 can have the fuel-side features of interconnect 300D and the air-side features of interconnect 400C.

[0057] According to various embodiments, the thickness of the interconnect may be increased compared to the comparative interconnect 10 shown in Figures 2A and 2B to increase lateral heat conduction. In other embodiments, the aspect ratio of the interconnect may be altered to increase the perimeter to active area ratio and decrease the heat conduction distance from the center to the edge of the interconnect.

[0058] In some embodiments, the thermal conductivity of the interconnect can be increased. For example, density can be increased by modifying the starting chromium powder (e.g., direct reduced chromium, different particle size, etc.). In some embodiments, the Fe content of the interconnect material powder can be increased, for example, from 5 wt% to about 7 wt% to about 10 wt% Fe. Thus, the interconnect comprises an alloy of 7 wt% Fe to 10 wt% Fe and the balance Cr (e.g., 7 wt% to 10 wt% iron and 90 wt% to 93 wt% chromium). Increasing the iron content can allow for the formation of denser interconnects via powder metallurgy, which can improve thermal conduction and increase temperature uniformity.

[0059] In various embodiments, the aspect ratio of the interconnect can be increased so that the interconnect is rectangular rather than square to increase the ratio of perimeter to active area and reduce the heat conduction distance from the center to the edge of the interconnect. This configuration can be advantageous for co-flow interconnects of Figures 3A-3D and 4A-4D, where fuel and air flow in parallel directions. Additionally, this configuration can be more advantageous for cross-flow interconnects, where the fuel and air flows are perpendicular to each other across the interconnect.

[0060] Figure 5A is a top view of the fuel side of a cross-flow interconnect 500 according to various embodiments of the present disclosure. Figure 5B is a top view of the air side of the interconnect 500 of Figure 5A. The interconnect 500 can be similar to the interconnects described above. Therefore, only the differences from the interconnects described above will be described in detail.

[0061] 5A and 5B, the interconnect 500 may have enlarged fuel holes 308 that act as fuel manifolds 304 (shown in FIG. 3A). The fuel holes 308 may optionally have supports (e.g., separators) 308S configured to increase the structural integrity of the interconnect 500 and / or the fuel holes 308. The interconnect 500 may include fuel ribs 312 that at least partially define fuel channels extending in a longitudinal direction L, which may be collinear with the fuel flow direction, and air ribs 412 that at least partially define air channels 410 extending in a width direction W, which may be collinear with the air flow direction and substantially perpendicular to the longitudinal direction L.

[0062] The interconnect 500 can have a length in the longitudinal direction L that is greater than 100 mm, e.g., 110 mm to 150 mm, and the fuel channel 310 can have a length of at least 100 mm, e.g., 100 mm to 115 mm. The interconnect 500 can have a width in the width direction W that is less than 100 mm, e.g., 70 mm to 90 mm. Thus, the interconnect 500 can have a length-to-width ratio greater than 1, e.g., 1.05 to 2.75, or 1.25 to 2.5.

[0063] Thus, in some embodiments, the interconnect has fuel channels with a larger cross-sectional area in the central fuel region than in the peripheral fuel regions by increasing the width, depth, or both the width and depth of the fuel channels in the central fuel region.

[0064] In various embodiments, the interconnect provides improved thermal uniformity when operating on hydrogen fuel, resulting in higher fuel utilization and system efficiency. In some embodiments, a larger active area reduces current density and improves fuel cell performance.

[0065] The fuel cell systems of the disclosed embodiments are designed to reduce greenhouse gas emissions and have a positive impact on the climate.

[0066] While the foregoing represents particularly preferred embodiments, it will be understood that the present invention is not limited thereto. Those skilled in the art will recognize that various modifications can be made to the disclosed embodiments and that such modifications are intended to be within the scope of the present invention. All publications, patent applications, and patents cited herein are hereby incorporated by reference in their entirety.

Claims

1. 1. A fuel cell interconnect, comprising: a fuel rib disposed on a first side of the interconnect and at least partially defining a fuel channel; an air rib disposed on an opposing second side of the interconnect and at least partially defining an air channel; a fuel hole extending through the interconnect; a sealing area disposed on the second side of the interconnect and surrounding the fuel hole; Equipped with the fuel channels include a central fuel channel disposed within a central fuel region and peripheral fuel channels disposed within peripheral fuel regions disposed on either side of the central fuel region; the central fuel channel is located between the fuel ribs and has a larger cross-sectional area than the peripheral fuel channels such that, when hydrogen is supplied to the fuel channel, a mass flow rate of hydrogen through the central fuel channel is higher than a mass flow rate of hydrogen through the peripheral fuel channels; the air channels include a central air channel disposed within the central air region and peripheral air channels disposed within peripheral air regions disposed on both sides of the central air region; some of the peripheral air channels extend from a first peripheral edge of the interconnect to an opposing second peripheral edge of the interconnect and have end portions located adjacent the first and second peripheral edges of the interconnect; the end portions are bent at an angle of 30 to 60 degrees relative to opposing third and fourth ends of the interconnect and the central air channel; Fuel cell interconnect.

2. the width of the central fuel channel is greater than the width of the peripheral fuel channels; The interconnect of claim 1 , wherein the cross-sectional area of ​​the central fuel channel is between 5% and 40% larger than the cross-sectional area of ​​the peripheral fuel channels.

3. The interconnect of claim 1 , wherein the central fuel channel has a length that is shorter than the peripheral fuel channels.

4. a fuel manifold formed on the first side of the interconnect and fluidly connected to the fuel channel; a fuel hole disposed in each of the fuel manifolds and extending through the interconnect; The interconnect of claim 1 further comprising:

5. 5. The interconnect of claim 4, wherein at least some of the peripheral fuel channels and corresponding fuel ribs extend into the fuel manifold such that peripheral fuel channels located closer to the central fuel zone are shorter than peripheral fuel channels located farther from the central fuel zone.

6. The interconnect of claim 4 , wherein each of the fuel manifolds has a maximum depth adjacent the fuel holes and a minimum depth adjacent opposite edges of the interconnect.

7. a fuel buffer disposed within the fuel manifold and configured to reduce fuel mass flow through the peripheral fuel channel; The interconnect of claim 4 , wherein the fuel buffer and the fuel channel extend elongately in directions perpendicular to each other.

8. a fuel shutoff disposed between the fuel ribs in the peripheral fuel zone and configured to reduce fuel mass flow through the peripheral fuel channel; The interconnect of claim 1 , wherein the fuel shutoff portion and the peripheral fuel channel extend longitudinally in directions perpendicular to each other.

9. 10. The interconnect of claim 1, wherein the interconnect comprises a chromium-iron alloy comprised of 7% to 10% iron and 90% to 93% chromium by weight.

10. The interconnect of claim 1 , wherein the central air channel has a larger cross-sectional area than the peripheral air channels.

11. The interconnect of claim 10, wherein the cross-sectional area of ​​the central air channel is between 5% and 40% larger than the cross-sectional area of ​​the peripheral air channels.

12. The interconnect of claim 1 , wherein the central air channel has a length that is shorter than the peripheral air channels.

13. An interconnect as described in claim 12, wherein end portions of the air ribs defining the curved peripheral air channels partially block air flow to the outermost peripheral air channel.

14. The interconnect of claim 13 , wherein the curved air channels are longer than at least some of the central air channels.

15. An interconnect as described in claim 1, wherein at least one of the central air channels has at least one of a larger cross-sectional area or a shorter length than at least one of each of the peripheral air channels so as to increase air flow through the central air channel.

16. A fuel cell stack comprising solid oxide fuel cells separated by the interconnect of claim 1.

17. A fuel cell system including a fuel cell stack as described in claim 16, wherein air is supplied into the air channels and the amount of air flowing through the central air channel is greater than the amount of air flowing through the peripheral air channels.

18. The fuel ribs comprising: a central fuel rib defining the central fuel channel; and peripheral fuel ribs defining the peripheral fuel channels; each of the central fuel channels is located entirely between two corresponding central fuel ribs; The interconnect of claim 1 , wherein each of the central fuel ribs extends longitudinally along the same longitudinal direction as the central fuel channel.

19. An interconnect as described in claim 1, wherein a fuel shut-off portion is positioned within the peripheral fuel region and not within the central fuel region.

20. The method of claim 20, wherein the first peripheral edge and the second peripheral edge of the interconnect are bent to form an air space disposed on at least one side of each of the sealing areas; The interconnect of claim 1 , wherein the air space is configured to increase mass flow of air around the seal area and through the central air channel.

21. The method of claim 20, wherein the first peripheral edge and the second peripheral edge of the interconnect are bent to form air spaces disposed on opposite sides of the respective sealing areas; The interconnect of claim 1 , wherein the air space is configured to increase mass flow of air around the seal area and through a central air channel.

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