Electrochemical reaction cell stack
The electrochemical reaction cell stack addresses the issue of separator deformation by using edge-side welded portions and controlled thicknesses to maintain efficient gas flow paths, improving power generation efficiency and reducing leakage.
Patent Information
- Application Number
- JP2023093863
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- Filing Date
- 2023-06-07
- Publication Date
- 2024-12-19
AI Technical Summary
In electrochemical reaction cell stacks, such as solid oxide fuel cells (SOFCs) and solid oxide electrolytic cells (SOECs), the deformation of separators near the welding edges can lead to a narrowing of gas flow paths, reducing power generation efficiency.
The cell stack design includes a configuration where the flow path constituent members and conductive members are arranged to overlap with joining members, with edge-side welded portions closer to the main welds, and the thickness of overlapping portions is controlled to minimize deformation and gas leakage.
This design effectively suppresses deformation of the joining members near the edges, preventing a decrease in power generation efficiency and gas leakage, thereby enhancing the overall performance of the cell stack.
Smart Images
Figure 2024175827000001_ABST
Abstract
Description
[Technical field]
[0001] The technology disclosed herein relates to electrochemical reaction cell stacks. [Background technology]
[0002] Solid oxide fuel cells (hereinafter referred to as "SOFCs") having an electrolyte layer containing a solid oxide are known as one type of fuel cell that generates electricity by utilizing an electrochemical reaction between hydrogen and oxygen. SOFCs are generally used in the form of a fuel cell stack in which a plurality of constituent units (electrochemical reaction units) are arranged in a predetermined direction. Each electrochemical reaction unit has a unit cell including an electrolyte layer containing a solid oxide, and an air electrode and a fuel electrode that face each other with the electrolyte layer in between. Two components that make up a fuel cell, for example an interconnector that electrically connects the unit cells of two adjacent electrochemical reaction units, and a separator that supports this interconnector, may be joined by welding (see Patent Document 1). [Prior art documents] [Patent documents]
[0003] [Patent Document 1] JP 2015-32559 A Summary of the Invention [Problem to be solved by the invention]
[0004] In the above configuration, for example, a portion of the separator closer to the edge than the welding position may be deformed and raised, protruding into the gas flow path that supplies gas to the air electrode or fuel electrode. If this occurs, the gas flow path may become narrow, and there is a concern that the power generation efficiency may decrease.
[0005] This issue is common even when the two components joined by welding are different components, the interconnector and the separator. In addition, this issue is also common to electrolysis cell stacks that include multiple electrolysis cell units, which are constituent units of solid oxide electrolysis cells (hereinafter referred to as "SOECs") that generate hydrogen using the electrolysis reaction of water, and is a common issue not limited to SOFCs and SOECs but also to other types of electrochemical reaction cell stacks. [Means for solving the problem]
[0006] (1) The electrochemical reaction cell stack disclosed in this specification comprises a unit cell in which an air electrode, an electrolyte layer, and an anode are stacked in this order, a flow path forming member that forms a gas flow path for at least one of supplying gas to the air electrode or the periphery of the anode and discharging gas from the periphery of the air electrode or the anode, and a conductive member that is electrically connected to the unit cell, wherein at least one of the flow path forming member and the conductive member includes a first joining member having an edge that is arranged in the gas flow path, and a second joining member that is arranged overlapping the first joining member and welded to the first joining member, and the welded portion between the first joining member and the second joining member comprises a main weld and an edge side weld that is arranged closer to the edge than the main weld.
[0007] According to the above configuration, it is possible to prevent the portion near the edge of the first joint member from being deformed so as to rise up from the second joint member, thereby preventing the gas flow path from narrowing and the power generation efficiency of the electrochemical reaction cell stack from decreasing.
[0008] (2) In the electrochemical reaction cell stack described in (1) above, the thickness of the first bonding member at a portion overlapping the second bonding member may be smaller than the thickness of the second bonding member at a portion overlapping the first bonding member.
[0009] According to this configuration, the first joint member, which is relatively thin and prone to deformation, is fixed at the edge by the edge-side weld, which more reliably prevents deformation of the edge of the first joint member and the resulting decrease in power generation efficiency.
[0010] (3) In the electrochemical reaction cell stack described in (1) or (2) above, the edge side weld may be disposed in a region within 10 mm from the edge.
[0011] With this configuration, deformation of the area near the edge of the first joining member and the resulting decrease in power generation efficiency can be reliably suppressed, compared to when the edge side weld is located in an area 10 mm or more from the edge.
[0012] (4) In the electrochemical reaction cell stack described in any one of (1) to (3) above, the main weld may be linear and extend along the edge.
[0013] With this configuration, it is possible to prevent gas from leaking out of the gas flow path through the gap between the two joining members.
[0014] (5) In the electrochemical reaction cell stack described in (4) above, the edge side weld may be a protruding portion that protrudes from the main weld toward the edge.
[0015] (6) The electrochemical reaction cell stack described in (5) above may include a plurality of the protrusions, and the distance between the first protrusion and the second protrusion, represented by the distance between a first perpendicular line drawn from a protruding end of a first protrusion among the plurality of protrusions to a center line of the main weld and a second perpendicular line drawn from a protruding end of a second protrusion among the plurality of protrusions adjacent to the first protrusion, to the center line of the main weld, may be shorter than the width of the main weld.
[0016] According to this configuration, since the two adjacent protrusions are spaced apart by a certain distance or less, deformation of the portion near the edge of the first joint member can be more reliably suppressed, and thus a decrease in power generation efficiency can be more reliably suppressed.
[0017] (7) In the electrochemical reaction cell stack described in any one of (1) to (4) above, the edge side weld may be disposed away from the main weld.
[0018] With this configuration, there is a greater degree of freedom in the shape and arrangement of the edge-side welds compared to when the edge-side welds are connected to the main welds.
[0019] (8) In the electrochemical reaction cell stack described in (7) above, the edge side welded portion may be linear and extend along the edge.
[0020] With this configuration, the portion of the first joint member near the edge can be more firmly fixed than when the edge-side weld is not linear and extends along the edge, so deformation of the portion of the first joint member near the edge and the resulting decrease in power generation efficiency can be more reliably prevented.
[0021] (9) In the electrochemical reaction cell stack described in (7) or (8) above, a plurality of the end edge side welds may be disposed at intervals.
[0022] With this configuration, the adverse effect that stress generated around the edge side weld has on the main weld can be reduced, compared to when the edge side weld is shaped to extend without any gaps.
[0023] (10) In the electrochemical reaction cell stack described in any one of (1) to (9) above, the edge may include a first edge located upstream of the gas flow path relative to a center of the unit cell, and a second edge located downstream of the gas flow path relative to the center of the unit cell, the main weld may include a first main weld arranged along the first edge and a second main weld arranged along the second edge, the edge side weld may include a first edge side weld arranged closer to the first edge than the first main weld and a second edge side weld arranged closer to the second edge than the second main weld, and the distance between the second edge and the second edge side weld may be smaller than the distance between the first edge and the first edge side weld.
[0024] In an electrochemical reaction cell stack, the electrochemical reaction between hydrogen and oxygen in the unit cell is an exothermic reaction, so that the downstream side of the unit cell is more likely to have a high temperature in the gas flow path than the upstream side. Therefore, deformation is more likely to occur in a portion of the edge of the first joining member that is closer to the downstream edge than to the edge that is relatively upstream based on the unit cell. Therefore, by arranging the edge side weld at a position relatively close to the edge in the vicinity of the second edge that is relatively downstream, deformation can be more effectively suppressed. This makes it possible to more reliably suppress a decrease in power generation efficiency. Effect of the Invention
[0025] According to the electrochemical reaction cell stack disclosed in this specification, it is possible to suppress a decrease in the power generation efficiency of the electrochemical reaction cell stack. [Brief description of the drawings]
[0026] [Figure 1] FIG. 1 is a perspective view showing the external configuration of a fuel cell stack according to a first embodiment; [Diagram 2] FIG. 2 is a cross-sectional view showing the fuel cell stack of the first embodiment taken along line II-II in FIG. [Diagram 3] FIG. 3 is a cross-sectional view showing the fuel cell stack of the first embodiment taken along line III-III in FIG. [Figure 4] FIG. 4 is a cross-sectional view showing the fuel cell stack of the first embodiment taken along line IV-IV in FIG. [Diagram 5] FIG. 2 is a cross-sectional view showing two adjacent electrochemical reaction units in the fuel cell stack of the first embodiment, taken along the same line as in FIG. 1 . [Figure 6] FIG. 2 is a cross-sectional view showing two adjacent electrochemical reaction units in the fuel cell stack of the first embodiment, taken along the same line as in FIG. 1 . [Figure 7] 1 is a plan view of an IC separator according to a first embodiment and an interconnector joined to the IC separator; [Figure 8] FIG. 8 is a partially enlarged cross-sectional view showing a portion where an IC separator and an interconnector are joined together in the first embodiment, taken along line VIII-VIII in FIG. [Figure 9] FIG. 1 is a partially enlarged cross-sectional view showing a step of forming a main weld by irradiating a laser onto a portion where an IC separator and an interconnector are overlapped in the first embodiment. [Figure 10] FIG. 1 is a partially enlarged cross-sectional view showing a step of forming an end-side welded portion by irradiating a laser onto a portion where an IC separator and an interconnector are overlapped in the first embodiment. [Figure 11] 1 is a plan view of an IC separator according to a second embodiment and an interconnector joined to the IC separator; [Figure 12] FIG. 12 is a partially enlarged plan view showing the inside of a frame F in FIG. 11 . [Figure 13] FIG. 13 is a partially enlarged cross-sectional view showing a portion where an IC separator and an interconnector are joined together in the second embodiment, taken along line XIII-XIII in FIG. [Figure 14] 12 is an enlarged plan view of the IC separator of embodiment 3 and the interconnector joined to the IC separator, showing the same region as the region indicated by the frame F in FIG. 11 . [Figure 15] 12 is an enlarged plan view of the IC separator of embodiment 4 and the interconnector joined to the IC separator, showing the same region as the region indicated by the frame F in FIG. 11 . [Figure 16]FIG. 13 is an enlarged plan view showing a part of an anode current collecting member and an interconnector joined to the anode current collecting member according to a fifth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0027] Specific examples of the technology disclosed in this specification will be described below with reference to the drawings. Note that the present invention is not limited to these examples, but is defined by the claims, and is intended to include all modifications within the meaning and scope of the claims.
[0028] <Embodiment 1> A first embodiment will be described with reference to Figures 1 to 10. A fuel cell stack 10 (an example of an electrochemical reaction cell stack) of this embodiment is used in a solid oxide fuel cell having an electrolyte layer 112 containing a solid oxide.
[0029] (Overall configuration of fuel cell stack 10) 1 to 4, the fuel cell stack 10 includes a power generation block 100, a first end plate 210, a second end plate 230, an end separator 220, and four gas passage members 280A, 280B. The power generation block 100 is composed of a plurality of (seven in this embodiment) electrochemical reaction units 100U (hereinafter, sometimes abbreviated as "reaction units 100U"). Each electrochemical reaction unit 100U includes a single cell 110, a single cell separator 120, an air electrode frame 130, an anode frame 140, an anode current collecting member 144, two interconnectors 190, and two IC separators 180.
[0030] The single cell separator 120, the air electrode frame 130, the fuel electrode frame 140, the interconnector 190, the IC separator 180, the end separator 220, and the second end plate 230 correspond to the flow path forming members. The flow path forming members are members for forming gas flow paths (manifolds 311, 312, 321, 322, air chamber 313, and fuel chamber 323) for supplying gas to the periphery of the single cell 110 and discharging gas from the periphery of the single cell 110. In addition, the fuel electrode current collecting member 144, the interconnector 190, the IC separator 180, the fuel electrode frame 140, the first end plate 210, the end separator 220, and the second end plate 230 correspond to the conductive members. The IC separator 180, the fuel electrode frame 140, the interconnector 190, the terminal separator 220, and the second end plate 210 serve as flow path forming members and conductive members. The conductive members are electrically connected to the unit cells 110 and are used to extract electrical energy generated by electrochemical reactions in the unit cells 110 from the fuel cell stack 10 to the outside.
[0031] The first end plate 210, the power generation block 100, the terminal separator 220, and the second end plate 230 have rectangular outer shapes of approximately the same size, and are arranged in this order, stacked in a predetermined arrangement direction (the vertical direction in FIG. 2).
[0032] As shown in FIG. 1 and FIG. 4, the fuel cell stack 10 has bolt holes BH near the four corners, which penetrate from the first end plate 210 to the terminal separator 220. A bolt B is inserted into each bolt hole BH. The second end plate 230 has four screw holes TH at positions corresponding to the four bolt holes BH. One end of each bolt B is screwed into each screw hole TH, and a nut N is screwed to the other end of each bolt B. The bolts B and nuts N fasten the members from the first end plate 210 to the second end plate 230 together. A first insulating sheet S1 is interposed between the nut N and the first end plate 210. As shown in FIG. 2 to FIG. 4, the four gas passage members 280A, 280B are connected to the second end plate 230.
[0033] The multiple reaction units 100U constituting the power generation block 100 are arranged side by side in a predetermined arrangement direction (the vertical direction in FIG. 2). As shown in FIG. 5 and FIG. 6, each reaction unit 100U is configured by stacking one IC separator 180, an air electrode frame 130, a single cell separator 120, an anode frame 140, and another IC separator 180 in this order. The single cell 110 is supported by the single cell separator 120, the two interconnectors 190 are supported by the two IC separators 180, respectively, and the anode current collecting member 144 is disposed between the single cell 110 and the interconnector 190.
[0034] 5 and 6, the IC separator 180 and the interconnector 190 are shared by two adjacent reaction units 100U. However, as shown in FIG. 2, the reaction unit 100U located at one end (the lower end in FIG. 2) of the multiple reaction units 100U does not have the IC separator 180 and the interconnector 190 adjacent to the fuel electrode frame 140, and the terminal separator 220 overlaps the fuel electrode frame 140.
[0035] (single cell 110) The unit cell 110 includes an electrolyte layer 112, an air electrode 114, and an anode 116. As shown in Figures 5 and 6, the air electrode 114, the electrolyte layer 112, and the anode 116 are arranged in this order, with a reaction prevention layer 118 interposed between the electrolyte layer 112 and the air electrode 114. The unit cell 110 of this embodiment is an anode-supported unit cell in which the other layers (electrolyte layer 112, air electrode 114, and reaction prevention layer 118) constituting the unit cell 110 are supported by the anode 116.
[0036] The electrolyte layer 112 is a rectangular flat member, and has one surface (upper surface in Figs. 5 and 6) on which the air electrode 114 is disposed, and the other surface (lower surface in Figs. 5 and 6) on which the fuel electrode 116 is disposed and parallel to the first surface. The electrolyte layer 112 is a layer including a solid oxide (e.g., YSZ (yttria-stabilized zirconia)). The air electrode 114 is a layer having a rectangular shape smaller than that of the electrolyte layer 112, and includes, for example, a perovskite-type oxide (e.g., LSCF (lanthanum strontium cobalt iron oxide)). The fuel electrode 116 is a layer having a rectangular shape of approximately the same size as the electrolyte layer 112, and includes, for example, Ni (nickel), a cermet made of Ni and ceramic particles, a Ni-based alloy, or the like. The reaction prevention layer 118 is a layer having a rectangular shape of approximately the same size as the air electrode 114, and includes, for example, GDC (gadolinium-doped ceria). The reaction prevention layer 118 has the function of suppressing the reaction of an element (e.g., Sr) diffused from the air electrode 114 with an element (e.g., Zr) contained in the electrolyte layer 112 to produce a highly resistive substance (e.g., SrZrO3).
[0037] (Separator for single cell 120) As shown in Figures 5 and 6, the single cell separator 120 is a rectangular frame-like member having a substantially rectangular through-hole 121 near the center, and is made of, for example, metal. The plate thickness of the single cell separator 120 is relatively thin, for example, about 0.05 mm or more and 0.2 mm or less. The peripheral portion of the through-hole 121 in the single cell separator 120 is joined to one surface of the electrolyte layer 112 (the surface on which the air electrode 114 is disposed: the upper surface in Figures 5 and 6) by a joint 124. The joint 124 is made of, for example, a brazing material (Ag brazing).
[0038] (Air electrode frame 130) As shown in FIGS. 5 and 6, the air electrode frame 130 is a rectangular frame-like member having a substantially rectangular through-hole 131 near the center, and is made of, for example, insulating ceramics (mica, etc.).
[0039] (fuel electrode frame 140) As shown in FIGS. 5 and 6, the fuel electrode frame 140 is a rectangular frame-like member having a substantially rectangular through-hole 141 near the center, and is made of, for example, metal.
[0040] (IC separator 180) As shown in Fig. 5 and Fig. 6, the IC separator 180 is a frame-like member having a substantially rectangular through-hole 181 near the center, and is formed of, for example, metal. The through-hole 181 is a hole defined by a substantially rectangular hole edge 181E (an example of an edge). As shown in Fig. 5, Fig. 6 and Fig. 8, the IC separator 180 has a first surface 180F1 that contacts the air electrode frame 130 and faces the single cell 110, and a second surface 180F2 that is the surface opposite to the first surface 180F1 and contacts the fuel electrode frame 140. As shown in Fig. 7, the IC separator 180 has four bolt holes BHA that constitute the four bolt holes BH.
[0041] (Interconnector 190 and anode current collecting member 144) As shown in Fig. 5 and Fig. 6, the interconnector 190 includes a rectangular flat plate portion 191, a plurality of plate-shaped air electrode current collectors 192 protruding from the flat plate portion 191 toward the air electrode 114, a coating layer 193, and an oxide coating 194. The flat plate portion 191 and the air electrode current collector 192 are conductive and made of a metal (e.g., ferritic stainless steel). The coating layer 193 is conductive and is disposed so as to cover the surface of the air electrode current collector 192 and the surface of the flat plate portion 191 on which the air electrode current collector 192 is disposed. The oxide coating 194 is disposed so as to cover the surface of the flat plate portion 191 opposite to the surface on which the air electrode current collector 192 is disposed.
[0042] As shown in Figs. 5, 6 and 7, the interconnector 190 has an outer shape slightly larger than the hole edge 181E, and is overlapped on the first surface 180F1 of the IC separator 180 so as to close the through hole 181. The flat plate portion 191 is overlapped on the peripheral portion of the through hole 181 in the IC separator 180 via an oxide film 194, and is joined by welding. As shown in Fig. 8, the thickness T2 of the portion of the interconnector 190 overlapping the IC separator 180 is larger than the thickness T1 of the portion of the IC separator 180 overlapping the interconnector 190. The "thickness T1 of the portion of the IC separator 180 overlapping the interconnector 190" is expressed as the distance from the first surface 180F1 that contacts the interconnector 190 to the second surface 180F2 on the opposite side in the portion of the IC separator 180. Furthermore, "thickness T2 of the portion of interconnector 190 welded to IC separator 180" is expressed as the distance from the surface in contact with first surface 180F1 of IC separator 180 (upper surface of oxide film 194 in FIG. 8) to the opposite surface (lower surface of coating layer 193 in FIG. 8) in that portion of interconnector 190. If the thickness of the portion of IC separator 180 overlapping interconnector 190 is not constant, the thickness value of the thickest portion may be taken as "thickness T1". If the thickness of the portion of interconnector 190 overlapping IC separator 180 is not constant, the thickness value of the thickest portion may be taken as "thickness T2".
[0043] The anode current collecting member 144 is a member that connects the interconnector 190 and the anode 116, and is formed of a conductive material such as nickel, a nickel alloy, or stainless steel. As shown in Figures 5 and 6, the anode current collecting member 144 includes an interconnector facing portion 146, an electrode facing portion 145 that is parallel to the interconnector facing portion 146, and a connecting portion (not shown) that connects the electrode facing portion 145 and the interconnector facing portion 146. The electrode facing portion 145 is in contact with the anode 116, and the interconnector facing portion 146 is in contact with a flat portion 191 of the interconnector 190.
[0044] As described above, the interconnector 190 is shared by two adjacent reaction units 100U. More specifically, as shown in Figs. 5 and 6, the air electrode current collector 192 is joined to the air electrode 114 of the unit cell 110 provided in one of the two adjacent reaction units 100U via a conductive bonding material 196 made of, for example, a spinel-type oxide, and is thus electrically connected to the air electrode 114. The flat plate portion 191 is electrically connected to the fuel electrode 116 of the unit cell 110 provided in the other of the two adjacent reaction units 100U via the fuel electrode current collector 144. This ensures electrical continuity between the two adjacent reaction units 100U.
[0045] However, as described above, the reaction unit 100U located at one end (the lower end in FIG. 2) of the multiple reaction units 100U does not have an interconnector 190 on the fuel electrode 116 side. The fuel electrode 116 included in this reaction unit 100U is connected to the terminal separator 220 via the fuel electrode current collecting member 144.
[0046] A spacer 149 made of, for example, mica is disposed between the electrode facing portion 145 and the interconnector facing portion 146. Therefore, the anode current collecting member 144 follows the deformation of the reaction unit 100U caused by temperature cycles and reactant gas pressure fluctuations, and the electrical connection between the anode 116 and the interconnector 190 (or the terminal separator 220) via the anode current collecting member 144 is well maintained.
[0047] (Air chamber 313 and fuel chamber 323) 5 and 6, the space partitioned by the single cell separator 120, the single cell 110, the air electrode frame 130, the IC separator 180, and the interconnector 190 faces the air electrode 114 and serves as an air chamber 313 through which the oxidant gas OG flows. The air electrode frame 130 partitions the air chamber 313 from the outside space all around, and seals the gap between the single cell separator 120 and the IC separator 180, preventing gas from leaking from the air chamber 313 to the outside space.
[0048] The space partitioned by the single cell separator 120, the single cell 110, the fuel electrode frame 140, the IC separator 180, and the interconnector 190 faces the fuel electrode 116 and serves as a fuel chamber 323 through which the fuel gas FG flows. The fuel electrode frame 140 partitions the entire periphery of the fuel chamber 323 from the external space, and seals the gap between the single cell separator 120 and the IC separator 180, thereby preventing gas from leaking from the fuel chamber 323 to the external space.
[0049] The single cell separator 120 separates the air chamber 313 and the fuel chamber 323, and suppresses gas leakage (cross leakage) from the air electrode 114 side to the fuel electrode 116 side or from the fuel electrode 116 side to the air electrode 114 side around the single cell 110. In addition, the IC separator 180 and the interconnector 190 suppress gas leakage between adjacent reaction units 100U.
[0050] A glass seal portion 125 containing glass is disposed near the edge of the through-hole 121 in the single cell separator 120. The glass seal portion 125 covers the edge of the through-hole 121 and is disposed so as to be in contact with the surface of the single cell 110 (the electrolyte layer 112 in this embodiment), thereby closing the gap between the edge of the through-hole 121 and the single cell 110. The glass seal portion 125 effectively suppresses cross-leakage of gas from the air electrode 114 side to the fuel electrode 116 side or from the fuel electrode 116 side to the air electrode 114 side.
[0051] (First end plate 210) The first end plate 210 is a rectangular frame-shaped member having a through hole 211 near the center, and is made of a conductive material such as stainless steel. The first end plate 210 is electrically connected to the reaction unit 100U arranged at the other end (the upper end in FIG. 2) of the multiple reaction units 100U that make up the power generation block 100. The first end plate 210 functions as a positive output terminal of the fuel cell stack 10.
[0052] (Terminal separator 220) The end separator 220 is a rectangular flat plate member, and is made of a conductive material such as a metal.
[0053] (Second end plate 230) The second end plate 230 is a rectangular frame-shaped member having a through hole 231 near the center, and is made of a conductive material such as stainless steel. The peripheral portion of the end separator 220 is sandwiched between the power generation block 100 and the second end plate 230 and joined to the second end plate 230 by welding, for example, and is electrically connected to the second end plate 230. The second end plate 230 is connected to the anode 116 provided in the reaction unit 100U arranged at one end (the lower end in FIG. 2) of the multiple reaction units 100U via the anode current collecting member 144 and the end separator 220, thereby electrically connecting the reaction unit 100U to the second end plate 230. The second end plate 230 functions as a negative output terminal of the fuel cell stack 10.
[0054] (Manifolds 311, 312, 321, 322) 1, 2, and 3, the fuel cell stack 10 has four holes that penetrate from the power generation block 100 to the second end plate 230. The four holes are an oxidant gas supply manifold 311, an oxidant gas discharge manifold 312, a fuel gas supply manifold 321, and a fuel gas discharge manifold 322, respectively.
[0055] 2, the oxidant gas supply manifold 311 is a gas flow path for supplying the oxidant gas OG introduced from outside the fuel cell stack 10 to the air chamber 313 of each reaction unit 100U. The oxidant gas discharge manifold 312 is a gas flow path for discharging the oxidant off-gas OOG discharged from the air chamber 313 of each reaction unit 100U to the outside of the fuel cell stack 10. For example, air is used as the oxidant gas OG. The oxidant gas supply manifold 311 and the oxidant gas discharge manifold 312 are arranged on opposite sides of each other with the air chamber 313 in between.
[0056] As shown in Fig. 3, the fuel gas supply manifold 321 is a gas flow path for supplying the fuel gas FG introduced from outside the fuel cell stack 10 to the fuel chamber 323 of each reaction unit 100U. The fuel gas discharge manifold 322 is a gas flow path for discharging the fuel off-gas FOG discharged from the fuel chamber 323 of each reaction unit 100U to the outside of the fuel cell stack 10. For example, hydrogen-rich gas obtained by reforming city gas is used as the fuel gas FG. The fuel gas supply manifold 321 and the fuel gas discharge manifold 322 are arranged on opposite sides of the fuel chamber 323.
[0057] As shown in FIG. 7, each IC separator 180 has manifold holes 311A and 312A which respectively constitute an oxidizer gas supply manifold 311 and an oxidizer gas discharge manifold 312, and manifold holes 321A and 322A which respectively constitute a fuel gas supply manifold 321 and a fuel gas discharge manifold 322.
[0058] (Gas passage members 280A, 280B) Two of the four gas passage members 280A, 280B are gas passage members 280A connected to the oxidizing gas supply manifold 311 and the oxidizing gas discharge manifold 312, respectively. As shown in FIG. 2, each gas passage member 280A has a substantially rectangular tubular main body portion 281A and a cylindrical branch portion 282A branched from a side surface of the main body portion 281A. The internal space of the branch portion 282A is connected to the internal space of the main body portion 281A. A gas pipe (not shown) is connected to the branch portion 282A. The two gas passage members 280A are each connected to the second end plate 230 via a second insulating sheet S2. The internal spaces of the two gas passage members 280A are each connected to the oxidizing gas supply manifold 311 and the oxidizing gas discharge manifold 312, respectively.
[0059] The other two of the four gas passage members 280A and 280B are gas passage members 280B connected to the fuel gas supply manifold 321 and the fuel gas exhaust manifold 322, respectively. As shown in FIG. 3, each gas passage member 280B has a cylindrical main body 281B and a cylindrical branch portion 282B branched from a side surface of the main body 281B. The internal space of the branch portion 282B is in communication with the internal space of the main body 281B. A gas pipe (not shown) is connected to the branch portion 282B. The two gas passage members 280B are each connected to the second end plate 230 via a second insulating sheet S2. The internal spaces of the two gas passage members 280B are in communication with the fuel gas supply manifold 321 and the fuel gas exhaust manifold 322, respectively.
[0060] (welded part 400) As described above, the interconnector 190 is overlapped on the first surface 180F1 of the IC separator 180 so as to close the through-hole 181. The flat plate portion 191 is overlapped on the peripheral portion of the hole edge 181E in the IC separator 180 via the oxide film 194, and joined by welding.
[0061] The welded portion 400 that joins the IC separator 180 and the interconnector 190 includes a main welded portion 410 and an edge side welded portion 420, as shown in FIGS.
[0062] As shown in Fig. 7, the main weld 410 is linear and extends along the edge 181E of the through hole 181. More specifically, the main weld 410 is disposed outside the edge 181E so as to surround the entire edge 181E. As shown in Fig. 8, the main weld 410 extends from the second surface 180F2 of the IC separator 180 to the vicinity of the lower end of the flat plate portion 191, and becomes thinner as it moves away from the second surface 180F2. A part of the main weld 410 may be disposed within a range of 20 mm from the edge 181E, and it is more preferable that the entire main weld 410 is disposed within a range of 15 mm from the edge 181E.
[0063] As shown in FIG. 7, the edge side weld 420 is arranged away from the main weld 410 and is linear extending along the hole edge 181E of the through hole 181. More specifically, the edge side weld 420 is arranged between the hole edge 181E and the main weld 410 so as to surround the hole edge 181E over the entire circumference. As shown in FIG. 8, the edge side weld 420 extends from the second surface 180F2 of the IC separator 180 to the vicinity of the lower end of the flat plate portion 191, and becomes thinner as it moves away from the second surface 180F2. The edge side weld 420 is preferably arranged within a range of 10 mm from the hole edge 181E. A part of the edge side weld 420 may be arranged within a range of 10 mm (more preferably within 5 mm) from the hole edge 181E, and it is more preferable that the entire part is arranged within a range of 10 mm from the hole edge 181E.
[0064] As described above, IC separator 180 has four bolt holes BHA and four manifold holes 311A, 312A, 321A, 322A. As shown in Fig. 7, welded portion 400 is arranged to avoid the positions of bolt holes BHA and manifold holes 311A, 312A, 321A, 322A. More specifically, welded portion 400 is arranged on the inside (closer to hole edge 181E) of bolt holes BHA and manifold holes 311A, 312A, 321A, 322A.
[0065] 7, the hole edge 181E includes a first hole edge 181EU (an example of a first edge) and a second hole edge 181ED (an example of a second edge). The first hole edge 181EU is an edge disposed adjacent to a manifold hole 321A constituting the fuel gas supply manifold 321, and is located upstream of the center of the unit cell 110 in the flow path of the fuel gas FG. The second hole edge 181ED is an edge disposed adjacent to a manifold hole 322A constituting the fuel gas discharge manifold 322, and is located downstream of the center of the unit cell 110 in the flow path of the fuel gas FG.
[0066] The main weld 410 includes a first main weld 410U disposed along the first hole edge 181EU and a second main weld 410D disposed along the second hole edge 181ED.
[0067] The edge side weld 420 includes a first edge side weld 420U and a second edge side weld 420D. The first edge side weld 420U is disposed along the first hole edge 181EU and is disposed closer to the first hole edge 181EU than the first main weld 410U. The second edge side weld 420D is disposed along the second hole edge 181ED and is disposed closer to the second hole edge 181ED than the second main weld 410D. A distance D2 between the second hole edge 181ED and the second edge side weld 420D is smaller than a distance D1 between the first hole edge 181EU and the first edge side weld 420U.
[0068] (Process of forming the welded portion 400) An example of a process for forming the above-mentioned welded portion 400 will now be described.
[0069] 9, the interconnector 190 is placed on a base BA, and the IC separator 180 is placed at a predetermined position on the interconnector 190. Next, the intermediate position between the portion of the IC separator 180 to be welded and the hole edge 181E is pressed with a jig J, and the interconnector 190 is brought into close contact with the IC separator 180.
[0070] In this state, a laser is applied to the first surface 180F1 side of the IC separator 180 using the laser head LH of the welding device, and the main weld 410 is formed.
[0071] As shown in Fig. 10, after the main weld 410 is formed, the jig J is removed. Then, using the laser head LH of the welding device, a laser is irradiated from the first surface 180F1 side of the IC separator 180 to a position closer to the hole edge 181E than the main weld 410, to form the edge side weld 420. At this time, since the interconnector 190 and the IC separator 180 are joined by the main weld 410, there is no need to use the jig J to bring the interconnector 190 into close contact with the IC separator 180. In other words, since the welding position is not restricted by the jig J, welding can be performed at a position closer to the hole edge 181E than in the process of welding the main weld 410.
[0072] As described above, thickness T1 of the portion of IC separator 180 overlapping interconnector 190 is smaller than thickness T2 of the portion of interconnector 190 overlapping IC separator 180. Therefore, by irradiating the laser from the relatively thin IC separator 180 side, main welds 410 and edge side welds 420 that penetrate IC separator 180 and reach interconnector 190 can be easily formed compared to the case of irradiating the laser from the relatively thick interconnector 190 side. This ensures that IC separator 180 and interconnector 190 are joined together.
[0073] (Operation of fuel cell stack 10) 2 and 5, the oxidizing gas OG is supplied to the air chamber 313 through the gas passage member 280A and the oxidizing gas supply manifold 311. Also, as shown in Figures 3 and 6, the fuel gas FG is supplied to the fuel chamber 323 through the gas passage member 280B and the fuel gas supply manifold 321.
[0074] When the oxidant gas OG is supplied to the air chamber 313 of each reaction unit 100U and the fuel gas FG is supplied to the fuel chamber 323, power is generated in the single cell 110 by an electrochemical reaction between the oxidant gas OG and the fuel gas FG. This power generation reaction is an exothermic reaction. As described above, the interconnector 190 is shared by two adjacent reaction units 100U, and the interconnector 190 ensures electrical continuity between the two adjacent reaction units 100U. That is, the multiple reaction units 100U included in the fuel cell stack 10 are electrically connected in series. In addition, the second end plate 230 is electrically connected to the reaction unit 100U located at one end (the lower end of FIG. 2) of the multiple reaction units 100U, and the first end plate 210 is electrically connected to the reaction unit 100U located at the other end (the upper end of FIG. 2). As a result, the electric energy generated in each reaction unit 100U is taken out from the second end plate 230 that functions as the output terminal of the fuel cell stack 10. Since SOFCs generate electricity at relatively high temperatures (e.g., 700°C to 1000°C), after startup, the fuel cell stack 10 may be heated by a heater (not shown) until the heat generated by power generation can maintain the high temperature.
[0075] As shown in Fig. 2, the oxidant off-gas OOG discharged from the air chamber 313 of each reaction unit 100U to the oxidant gas discharge manifold 312 passes through the inside of the gas passage member 280A and is discharged to the outside of the fuel cell stack 10. Also, as shown in Fig. 3, the fuel off-gas FOG discharged from the fuel chamber 323 of each reaction unit 100U to the fuel gas discharge manifold 322 passes through the inside of the gas passage member 280B and is discharged to the outside of the fuel cell stack 10.
[0076] Here, since the inside of the fuel cell stack 10 becomes hot during power generation, it is considered that the thermal history will cause the IC separator 180 to deform, causing the area near the hole edge 181E to lift off from the interconnector 190 and protrude into the inside of the fuel chamber 323. If such a situation occurs, the fuel chamber 323 will become narrower, obstructing the flow of the fuel gas FG, and there is a concern that the power generation efficiency of the fuel cell will decrease.
[0077] In this embodiment, the welded portion 400 between the interconnector 190 and the IC separator 180 has a main weld 410 and an edge side weld 420 arranged closer to the hole edge 181E than the main weld 410. This prevents the portion of the IC separator 180 close to the hole edge 181E from being deformed so as to float up, and prevents the flow of the fuel gas FG from being obstructed. This prevents a decrease in power generation efficiency.
[0078] Furthermore, thickness T1 of the portion of IC separator 180 that overlaps interconnector 190 is smaller than thickness T2 of the portion of interconnector 190 that overlaps IC separator 180.
[0079] Deformation is likely to occur in the IC separator 180 which is thinner than the interconnector 190. In the relatively thin IC separator 180, the portion near the hole edge 181E is fixed by the edge side weld 420, so that deformation such as lifting up of the portion of the IC separator 180 near the hole edge 181E is more reliably suppressed.
[0080] Moreover, the main weld 410 and the edge side weld 420 are linearly extending along the hole edge 181E and are arranged so as to surround the entire hole edge 181E. This makes it possible to prevent the fuel gas FG from leaking out of the fuel chamber 323 through the gap between the IC separator 180 and the interconnector 190. Also, deformation such that the portion of the IC separator 180 near the hole edge 181E is lifted is more reliably prevented.
[0081] In addition, with respect to the single cell 110 as a reference, the distance D2 between the second hole edge 181ED, which is located relatively downstream in the flow path of the fuel gas FG, and the second edge side weld 420D, is smaller than the distance D1 between the first hole edge 181EU, which is located relatively upstream, and the first edge side weld 420U.
[0082] Here, in the fuel cell stack 10, since the electrochemical reaction between hydrogen and oxygen in the unit cell 110 is an exothermic reaction, the downstream side of the unit cell 110 is more likely to become hotter than the upstream side. Therefore, in the IC separator 180, the portion located downstream of the unit cell 110 is more likely to deform due to heat than the portion located relatively upstream. In addition, the fuel off-gas FOG that has passed near the unit cell 110 contains water vapor generated by the electrochemical reaction in the unit cell 110, and therefore has a higher viscosity than the fuel gas FG before passing near the unit cell 110. Therefore, when deformation occurs at a downstream position relative to the unit cell 110 and the gas flow path becomes narrower, the pressure loss of the gas is more likely to increase. In this embodiment, the second edge side welded portion 420D is disposed at a position close to the second hole edge 181ED in the vicinity of the second hole edge 181ED located relatively downstream, so that deformation can be more reliably suppressed. This makes it possible to more reliably suppress a decrease in the power generation efficiency of the fuel cell stack 10.
[0083] (Action and effect) As described above, according to this embodiment, the fuel cell stack 10 includes a single cell 110 in which the air electrode 114, the electrolyte layer 112, and the fuel electrode 116 are stacked in this order, and flow path forming members (single cell separators) that form gas flow paths (air chamber 313, fuel chamber 323, and manifolds 311, 312, 321, 322) for supplying gas to the periphery of the air electrode 114 or the fuel electrode 116 and discharging gas from the periphery of the air electrode 114 or the fuel electrode 116. The fuel cell 323 includes a fuel electrode current collecting member 120, an air electrode frame 130, an anode frame 140, an interconnector 190, an IC separator 180, an end separator 220, and a second end plate 230) and conductive members electrically connected to the single cell 110 (anode current collecting member 144, an interconnector 190, an IC separator 180, an anode frame 140, a first end plate 210, an end separator 220, and a second end plate 230). Of the flow path forming members and conductive members, the IC separator 180 has a hole edge 181E disposed within the fuel chamber 323. The interconnector 190 is disposed so as to overlap the IC separator 180 and is welded to the IC separator 180. The welded portion 400 between the IC separator 180 and the interconnector 190 includes a main weld 410 and an edge side weld 420 that is disposed closer to the hole edge 181E than the main weld 410 is.
[0084] The above configuration can prevent the portion of the IC separator 180 near the hole edge 181E from being deformed so as to rise up from the interconnector 190. This can prevent the gas flow path from narrowing and the power generation efficiency of the fuel cell stack 10 from decreasing.
[0085] Furthermore, thickness T1 of the portion of IC separator 180 overlapping interconnector 190 is smaller than thickness T2 of the portion of interconnector 190 overlapping IC separator 180. With this configuration, the portion of IC separator 180 near hole edge 181E, which is the relatively thinner of the two joining members and more susceptible to deformation, is fixed by edge-side welded portion 420. This makes it possible to more reliably suppress deformation of the portion of IC separator 180 near hole edge 181E and the resulting decrease in power generation efficiency.
[0086] In addition, the edge-side welded portion 420 is disposed within 10 mm from the hole edge 181E. With this configuration, deformation of the portion of the IC separator 180 near the hole edge 181E and the resulting decrease in power generation efficiency can be reliably suppressed, compared to when the edge-side welded portion 420 is disposed in a region 10 mm or more from the hole edge 181E.
[0087] Moreover, the main weld 410 is linear and extends along the hole edge 181E. With this configuration, it is possible to prevent gas from leaking out of the gas flow path through the gap between the IC separator 180 and the interconnector 190.
[0088] In addition, the edge-side weld 420 is disposed away from the main weld 410. With this configuration, there is a greater degree of freedom in the shape and arrangement of the edge-side weld 420 compared to when the edge-side weld 420 is connected to the main weld 410.
[0089] In addition, the edge-side welded portion 420 is linear and extends along the hole edge 181E. With this configuration, the area near the hole edge 181E in the IC separator 180 can be more firmly fixed than when the edge-side welded portion 420 is not linear and extends along the hole edge 181E. This makes it possible to more reliably prevent deformation of the area near the hole edge 181E in the IC separator 180 and the resulting decrease in power generation efficiency.
[0090] In addition, the hole edge 181E includes a first hole edge 181EU located upstream of the gas flow passage from the center of the unit cell 110, and a second hole edge 181ED located downstream of the gas flow passage from the center of the unit cell 110, the main weld 410 includes a first main weld 410U arranged along the first hole edge 181EU and a second main weld 410D arranged along the second hole edge 181ED, and the edge side weld 420 However, it includes a first edge side weld 420U that is arranged closer to the first hole edge 181EU than the first main weld 410U, and a second edge side weld 420D that is arranged closer to the second hole edge 181ED than the second main weld 410D, and the distance D2 between the second hole edge 181ED and the second edge side weld 420D is smaller than the distance D1 between the first hole edge 181EU and the first edge side weld 420U.
[0091] In the fuel cell stack 10, the electrochemical reaction between hydrogen and oxygen in the unit cell 110 is an exothermic reaction, so that the downstream side of the unit cell 110 is more likely to have a high temperature in the gas flow path than the upstream side of the unit cell 110. Therefore, deformation is more likely to occur in the hole edge 181E of the IC separator 180, which is closer to the hole edge 181E located downstream than the hole edge 181E located relatively upstream based on the unit cell 110. Therefore, by arranging the edge side welded portion 420 in a position closer to the hole edge 181E in the vicinity of the second hole edge 181ED located relatively downstream, deformation can be more effectively suppressed. This makes it possible to more reliably suppress a decrease in power generation efficiency.
[0092] <Embodiment 2> The second embodiment differs from the first embodiment in the shape of a welded portion 510 that joins an IC separator 180 and an interconnector 190. The welded portion 510 includes a main weld 511 and a plurality of protrusions 512, 513, as shown in Figs.
[0093] As in the first embodiment, the main weld 511 has a linear shape extending along the hole edge 181E of the through hole 181. More specifically, the main weld 511 is disposed outside the hole edge 181E so as to surround the entire hole edge 181E. As shown in Fig. 13, the main weld 511 extends from the second surface 180F2 of the IC separator 180 to near the lower end of the flat plate portion 191, and becomes thinner with increasing distance from the second surface 180F2.
[0094] 12, some of the multiple protrusions 512, 513 are protrusions 512 (an example of an edge-side weld) that are arranged closer to the hole edge 181E than the main weld 511. The protrusions 512 protrude from one of the two side edges of the main weld 511 (the side closer to the hole edge 181E) toward the hole edge 181E. In this embodiment, the protrusions 512 become thinner as they move away from the main weld 511. The rest of the multiple protrusions 512, 513 are protrusions 513 that protrude from the other side edge of the main weld 511 (the side farther from the hole edge 181E).
[0095] The protrusions 512 are preferably arranged within 10 mm from the hole edge 181E. All of the protrusions 512 may be arranged within 10 mm from the hole edge 181E, some of the multiple protrusions 512 may be arranged within 10 mm from the hole edge 181E, or a portion of each of the protrusions 512 may be arranged within 10 mm from the hole edge 181E.
[0096] 12, a distance D3 between one protrusion (first protrusion 512A) of the multiple protrusions 512 and a second protrusion 512B adjacent to the first protrusion 512A is preferably shorter than a width W of the main weld 511, which is represented by the distance between two side edges of the main weld 511. The distance D3 between the first protrusion 512A and the second protrusion 512B is represented by the distance between a first perpendicular line PL1 drawn from the protruding end of the first protrusion 512A to the center line CL of the main weld 511, and a second perpendicular line PL2 drawn from the protruding end of the second protrusion 512B to the center line CL of the main weld 511.
[0097] The other configurations are the same as those of the first embodiment, so the same components as those of the first embodiment are given the same reference numerals and the description thereof is omitted.
[0098] According to this embodiment, the welded portion 510 between the interconnector 190 and the IC separator 180 has a main weld 511 and a protruding portion 512 disposed closer to the hole edge 181E than the main weld 511. As a result, as in the first embodiment, the portion of the IC separator 180 near the hole edge 181E is prevented from being deformed so as to rise up, and the flow of the fuel gas FG is prevented from being obstructed. This makes it possible to prevent a decrease in power generation efficiency.
[0099] Moreover, the welded portion 510 has a plurality of protrusions 512, and the distance between two adjacent protrusions 512A, 512B is shorter than the width W of the main welded portion 511.
[0100] According to this configuration, the two adjacent protrusions 512A, 512B are arranged at a constant interval or less, so that deformation of the area near the hole edge 181E of the IC separator 180 can be more reliably suppressed. This makes it possible to more reliably suppress a decrease in power generation efficiency.
[0101] <Embodiment 3> The third embodiment differs from the first embodiment in the shape of a welded portion 520 that joins an IC separator 180 and an interconnector 190. The welded portion 520 includes a main weld 521 and a plurality of edge welds 522, as shown in FIG.
[0102] Similar to the first embodiment, the main weld 521 has a linear shape extending along the edge 181E of the through hole 181. More specifically, the main weld 521 is disposed on the outer side of the edge 181E of the through hole 181 so as to surround the entire edge 181E.
[0103] The edge-side welds 522 are spaced apart from one another and arranged side by side to surround the hole edge 181E. The edge-side welds 522 are arranged closer to the hole edge 181E than the main welds 521. Each edge-side weld 522 is, for example, in the form of a spot, and the edge-side welds 522 are arranged at equal intervals.
[0104] The other configurations are the same as those of the first embodiment, so the same components as those of the first embodiment are given the same reference numerals and the description thereof is omitted.
[0105] According to this embodiment, as in the first embodiment, the portion of the IC separator 180 near the hole edge 181E is prevented from being deformed so as to rise up, and the flow of the fuel gas FG is prevented from being obstructed. This makes it possible to prevent a decrease in power generation efficiency.
[0106] In addition, the edge-side welds 522 are arranged at intervals. With this configuration, the adverse effect of stress generated around the edge-side welds 522 on the main welds 521 can be reduced, compared to a case in which the edge-side welds extend without any gaps.
[0107] <Embodiment 4> The fourth embodiment differs from the first embodiment in the shape of a welded portion 530 that joins an IC separator 180 and an interconnector 190. The welded portion 530 includes a plurality of main welds 531 and an edge side weld 532, as shown in FIG.
[0108] The main welds 531 are spaced apart from one another and arranged side by side to surround the hole edge 181E. Each of the main welds 531 is, for example, in the form of a spot. The main welds 531 are arranged at equal intervals.
[0109] The edge-side weld 532 is disposed closer to the hole edge 181E than the main weld 531. The edge-side weld 532 is linear and extends along the hole edge 181E of the through hole 181. More specifically, the edge-side weld 532 is disposed outside the hole edge 181E of the through hole 181 so as to surround the entire hole edge 181E.
[0110] The other configurations are the same as those of the first embodiment, so the same components as those of the first embodiment are given the same reference numerals and the description thereof is omitted.
[0111] According to this embodiment, as in the first embodiment, the portion of the IC separator 180 near the hole edge 181E is prevented from being deformed so as to rise up, and the flow of the fuel gas FG is prevented from being obstructed. This makes it possible to prevent a decrease in power generation efficiency.
[0112] Moreover, the edge side welded portion 532 is linearly extending along the hole edge 181E and is disposed so as to surround the entire hole edge 181E. This makes it possible to prevent the fuel gas FG from leaking out of the fuel chamber 323 through the gap between the IC separator 180 and the interconnector 190. Also, deformation such that the portion of the IC separator 180 near the hole edge 181E is lifted is more reliably prevented.
[0113] <Embodiment 5> In the fifth embodiment, an interconnector facing portion 146 provided on an anode current collecting member 144 (first joining member) is joined to an interconnector 190 (second joining member) by welding. The interconnector facing portion 146 has an edge 146E (see FIGS. 5 and 6). A welded portion 540 between the interconnector facing portion 146 and the interconnector 190 includes a plurality of main welds 541 and a plurality of edge side welds 542.
[0114] The main welds 541 are spaced apart from one another and lined up in a row along the edge 146E. Each main weld 541 is, for example, in the form of a spot, and the main welds 541 are arranged at equal intervals.
[0115] The edge-side welds 542 are spaced apart from one another and aligned in a row along the edge 146E. The edge-side welds 542 are disposed closer to the edge 146E than the main welds 541. Each edge-side weld 542 is, for example, in the form of a spot, and the edge-side welds 542 are disposed at equal intervals.
[0116] The other configurations are the same as those of the first embodiment, so the same components as those of the first embodiment are given the same reference numerals and the description thereof is omitted.
[0117] According to this embodiment, the welded portion 540 between the anode current collecting member 144 and the interconnector 190 includes a plurality of main welds 541 and an edge side weld 542 disposed closer to the edge 146E of the interconnector facing portion 146 than the main welds 541. With this configuration, deformation such that the portion near the edge 146E of the interconnector facing portion 146 is lifted is suppressed, and obstruction of the flow of the fuel gas FG is suppressed. This makes it possible to suppress a decrease in power generation efficiency.
[0118] Furthermore, since the entire anode current collecting member 144 is disposed inside the fuel chamber 323 and is not a member that separates the fuel chamber 323 from the external space, there is no need to seal the gap between the interconnector facing portion 146 and the interconnector 190. In such a case, the multiple main welds 541 may be disposed at intervals from one another, and the multiple edge side welds 542 may be disposed at intervals from one another.
[0119] <Other embodiments> (1) In the above embodiment, the welded portion 400 is formed by laser welding. However, the method for forming the welded portion is not limited to laser welding. For example, resistance welding may be used. (2) In embodiments 1-4, the first joining member is IC separator 180 and the second joining member is interconnector 190, and in embodiment 5, the first joining member is anode current collecting member 144 and the second joining member is interconnector 190. However, the first joining member and the second joining member may be, for example, an air electrode frame and a separator, or an anode frame and a separator, or may be members formed outside the cell stack and constituting a manifold. (3) In the above embodiment, the hole edge 181E of the IC separator 180 is disposed inside the fuel chamber 323. However, the position at which the edge of the first bonding member is disposed is not limited to the inside of the fuel chamber. For example, it may be inside the air chamber or inside the manifold. (4) In the first embodiment, the distance between the second hole edge 181ED and the second edge side weld 420D is smaller than the distance between the first hole edge 181EU and the first edge side weld 420U, but for example, the distance between the second edge and the second edge side weld may be equal to or larger than the distance between the first edge and the first edge side weld. Similarly, in other embodiments, the relationship between the distance between the second edge and the second edge side weld and the distance between the first edge and the first edge side weld is arbitrary. (5) In the second embodiment, the shape of the protrusion 512 is a substantially triangular shape, but the shape of the protrusion may be arbitrary, for example, a semicircular shape. (6) In embodiment 2, the protrusions 512, 513 are arranged on both of the two side edges of the main weld 511. However, the protrusions may be arranged only on the side edge closer to the end edge of the two side edges of the main weld. (7) In the third and fifth embodiments, the edge-side welds 522, 542 are evenly spaced apart, but the intervals between the edge-side welds may be any desired interval. Similarly, in the fourth and fifth embodiments, the main welds 531, 541 are evenly spaced apart, but the intervals between the main welds may be any desired interval. (8) In the third and fifth embodiments, the edge welds 522, 542 are spot-shaped, but the shape of each of the multiple edge welds may be any shape. Similarly, in the fourth and fifth embodiments, the main welds 531, 541 are spot-shaped, but the shape of each of the multiple main welds may be any shape. (9) In the above embodiment, the single cell separator 120, the air electrode frame 130, the fuel electrode frame 140, the interconnector 190, the IC separator 180, the terminal separator 220, and the second end plate 230 constitute both the oxidant gas supply manifold 311 and the fuel gas supply manifold 321, which are the gas flow paths on the supply side, and the oxidant gas discharge manifold 312 and the fuel gas discharge manifold 322, which are the gas flow paths on the discharge side, but the flow path constituent members may be members that constitute only one of the gas flow paths on the supply side and the gas flow paths on the discharge side. Alternatively, the flow path constituent members may be members that constitute only one of the gas flow paths for the oxidant gas and the gas flow paths for the fuel gas. (10) The first and second joining members may both be flow path forming members, or both may be conductive members, or one may be a flow path forming member and the other a conductive member. [Explanation of symbols]
[0120] 10: Fuel cell stack (electrochemical reaction cell stack) 110: Single cell 112: Electrolyte layer 114: Air electrode 116: Anode 140: Anode frame (Conductive member) 144: Anode current collector (Conductive member, first joint member) 146E: Edge 180: IC separator (flow path forming member, conductive member, first joint member) 181E: Hole edge (edge) 181ED: Second hole edge (second edge) 181EU: First hole edge (first edge) 190: Interconnector (flow path forming member, conductive member, second joint member) 210: First end plate (Conductive member) 220: Terminal separator (flow path forming member, conductive member) 230: Second end plate (flow path forming member, conductive member) 311: Oxidant gas supply manifold (gas flow path) 312: Oxidant gas exhaust manifold (gas flow path) 313: Air chamber (gas flow path) 321: Fuel gas supply manifold (gas flow path) 322: Fuel gas exhaust manifold (gas flow path) 323: Fuel chamber (gas flow path) 400, 510, 520, 530, 540: Welded parts 410, 511, 521, 531, 541: Main weld 410D: Second main weld 410U: First main weld 420, 522, 532, 542: Edge side weld 420D: Second edge side weld 420U: First edge side weld 512: Protrusion (edge side weld) 512A: First protrusion 512B: Second protrusion
Claims
1. a single cell including an air electrode, an electrolyte layer, and a fuel electrode stacked in this order; a flow path forming member that forms a gas flow path for at least one of supplying gas to the periphery of the air electrode or the anode and discharging gas from the periphery of the air electrode or the anode; A conductive member electrically connected to the unit cell; Equipped with At least one of the flow path forming member and the conductive member is a first joint member having an edge disposed within the gas flow path; a second joint member disposed to overlap the first joint member and welded to the first joint member; Including, The welded portion between the first joint member and the second joint member includes a main weld portion and an edge side weld portion disposed closer to the edge than the main weld portion. Electrochemical reaction cell stack.
2. a thickness of a portion of the first joint member overlapping the second joint member is smaller than a thickness of a portion of the second joint member overlapping the first joint member; The electrochemical reaction cell stack according to claim 1 .
3. The edge side weld is disposed in an area within 10 mm from the edge. The electrochemical reaction cell stack according to claim 1 or 2.
4. The main weld is linear and extends along the edge. The electrochemical reaction cell stack according to claim 1 or 2.
5. The edge side weld portion is a protrusion that protrudes from the main weld portion toward the edge. The electrochemical reaction cell stack according to claim 4 .
6. A plurality of the protrusions are provided, A distance between the first protrusion and the second protrusion, which is represented by a distance between a first perpendicular line drawn from a protrusion end of a first protrusion among the plurality of protrusions to a center line of the main weld, and a second perpendicular line drawn from a protrusion end of a second protrusion among the plurality of protrusions adjacent to the first protrusion to the center line of the main weld, is shorter than the width of the main weld. The electrochemical reaction cell stack according to claim 5 .
7. the edge weld is spaced apart from the main weld; The electrochemical reaction cell stack according to claim 1 or 2.
8. The edge side weld is a line extending along the edge. The electrochemical reaction cell stack according to claim 7 .
9. A plurality of the edge welds are spaced apart. The electrochemical reaction cell stack according to claim 7 .
10. The edge is a first edge located upstream of a center portion of the unit cell in the gas flow passage; a second edge located downstream of the gas flow passage from a center portion of the unit cell; Including, The main weld is a first main weld disposed along the first edge; and a second main weld disposed along the second edge; and Including, The edge weld portion is a first edge side weld disposed closer to the first edge than the first main weld; a second edge side weld disposed closer to the second edge than the second main weld; Including, a distance between the second edge and the second edge-side weld portion is smaller than a distance between the first edge and the first edge-side weld portion; The electrochemical reaction cell stack according to claim 1 or 2.
Citation Information
Patent Citations
Solid oxide fuel cell stack and interconnector with separator
JP2015032559A