Fuel cell structure

Abstract

To achieve a fuel battery cell structure capable of suppressing a decrease in sealability and joint strength.SOLUTION: There is provided a fuel battery cell structure (10) having a fuel electrode layer (24), an air electrode layer (28), and an electrolyte layer (26) provided between the fuel electrode layer and the air electrode layer. The fuel battery cell structure includes: a frame-like member (40) provided on the periphery of the electrolyte layer to separate fuel gas circulating in the fuel electrode layer from air circulating in the air electrode layer; a joining member (42) joining the frame-like member and the electrolyte layer to each other and including metal and ceramic; and a seal member (44) provided such that a seal target region (Rs) is air tightly adhered to the electrolyte layer, the seal target region being defined by the inner peripheral part (40a) of the frame-like member and the region (42a) of the joining member in contact with the inner peripheral part.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a fuel cell structure. [Background technology]

[0002] Patent Document 1 proposes a fuel cell structure in which a seal part is provided in the peripheral region of the electrolyte. This seal part hermetically bonds the electrolyte membrane to a metal frame-shaped separator (hereinafter referred to as a "metal frame") provided on the peripheral region of the electrolyte. Furthermore, the seal part is made of a glass composition containing both a metal element or a metalloid element contained in the electrolyte and a metal or a metalloid element contained in the metal frame. As a result, the seal part exerts a function of bonding the metal frame and the electrolyte, and a function of sealing the gap between the two to separate air (oxidizing atmosphere) and fuel gas (reducing atmosphere). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2019-185883 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, the seal portion of Patent Document 1 has an outer end exposed to a reducing atmosphere, while an inner end exposed to an oxidizing atmosphere. As described above, since the seal portion contains metal components, the inner side of the seal portion is continuously exposed to a more oxidizing atmosphere than the outer side, and this may cause the metal components (e.g., iron) contained in the inner part of the seal portion to oxidize and expand locally, causing a risk of cracks in the seal portion. As a result, there is a problem that the required sealing properties and bonding strength cannot be sufficiently guaranteed.

[0005] In view of the above circumstances, an object of the present invention is to provide a fuel cell structure capable of suppressing deterioration in sealing performance and bonding strength. [Means for solving the problem]

[0006] According to one aspect of the present invention, there is provided a fuel cell structure having an anode layer, an air cathode layer, and an electrolyte layer provided between the anode layer and the air cathode layer. This fuel cell structure includes a frame member provided on the periphery of the electrolyte layer to separate a fuel gas flowing through the anode layer from air flowing through the air cathode layer, a joining member that joins the frame member and the electrolyte layer together and contains a metal and a ceramic, and a seal member provided to hermetically seal a sealing target area defined by an inner periphery of the frame member and an area of ​​the joining member in contact with the inner periphery against the electrolyte layer. The joining member is made of a composition containing the ceramic contained in the electrolyte layer and the metal constituting the frame member. . Effect of the Invention

[0007] According to the present invention, it is possible to realize a fuel cell structure that can suppress deterioration in sealing performance and bonding strength. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a diagram illustrating the configuration of a fuel cell structure according to a first embodiment of the present invention. [Diagram 2] FIG. 2 is a diagram illustrating a support and seal structure in the fuel cell structure of the first embodiment. [Diagram 3] FIG. 3 is a diagram for explaining the function and effect of the welded portion. [Figure 4] FIG. 4 is a diagram illustrating a support and seal structure according to the second embodiment. [Diagram 5] FIG. 5 is a diagram illustrating a support and seal structure according to the third embodiment. [Figure 6] FIG. 6 is a diagram illustrating a support and seal structure according to the fourth embodiment. [Figure 7] FIG. 7 is a diagram illustrating a support and seal structure according to the fifth embodiment. [Figure 8] FIG. 8 is a diagram illustrating a support and seal structure according to the sixth embodiment. [Figure 9] FIG. 9 is a diagram illustrating the configuration of a support and seal structure according to a modified example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[0010] (First embodiment) 1 is a diagram illustrating the configuration of a fuel cell stack 10 as a fuel cell structure according to this embodiment. For ease of explanation, an XYZ orthogonal coordinate system is shown in each figure below. In addition, as necessary, the X-axis direction in the figure will be referred to as the "electrode width direction X", the Y-axis direction as the "gas flow direction Y", and the Z-axis direction as the "stacking direction Z".

[0011] As shown in the figure, the fuel cell stack 10 of this embodiment is a stacked type fuel cell in which a plurality of (two are shown in FIG. 1) unit cells 20 configured as solid oxide fuel cells (SOFC) and separators 30 are stacked in sequence.

[0012] In particular, the fuel cell stack 10 of this embodiment can be used as a stationary power source for various electrical devices, and as a mobile power source mounted on mobile vehicles such as electric automobiles and hybrid automobiles.

[0013] <Single cell 20> The unit cell 20 of the present embodiment mainly includes an anode electrode layer 24, a cathode electrode layer 28, an electrolyte layer 26, and a current collecting auxiliary layer 29. A separator 30 is provided on one surface of the cathode electrode layer 28 in the unit cell 20 (the surface opposite to the surface facing the electrolyte layer 26) with the current collecting auxiliary layer 29 interposed therebetween.

[0014] Furthermore, each unit cell 20 of this embodiment is provided with a support and seal structure S on its peripheral edge (end in the electrode width direction X). This support and seal structure S will be described in detail later.

[0015] <Anode electrode layer 24> The anode electrode layer 24 is a fuel electrode layer, and functions to generate oxides of the fuel gas by reacting oxide ions derived from the fuel gas and the oxidant gas, and to extract electrons. The anode electrode layer 24 is configured as a plate-shaped porous member provided so as to contact the lower surface of the electrolyte layer 26 in the figure. The anode electrode layer 24 is configured to have resistance to the reducing atmosphere Rr, and to have high gas permeability for transmitting the fuel gas, electronic conductivity, and ion conductivity. In this embodiment, the anode electrode layer 24 is configured to be thicker and have a larger area than the cathode electrode layer 28, and has a catalytic function for the oxidation reaction that reacts the fuel gas with the oxide ions. In particular, the unit cell 20 of this embodiment is configured as a so-called anode support cell in which the mechanical strength for supporting the cell structure is ensured by the anode electrode layer 24 configured to be thick in this way.

[0016] Examples of the material of the anode electrode layer 24 include metals such as nickel or iron, or thermite of the metal and solid oxide ceramics. Examples of the solid oxide ceramics include stabilized zirconia doped with rare earth oxides (e.g., one or more materials selected from the group consisting of Y2O3, Sc2O3, Gd2O3, Sm2O3, Yb2O3, and Nd2O3), ceria-based solid solutions, and perovskite-type oxides (e.g., SrCeO3, BaCeO3, CaZrO3, or SrZrO3).

[0017] The fuel that can be used in the fuel cell stack 10 of this embodiment is any hydrocarbon-based fuel that can generate hydrogen, particularly alkanes, alkenes, alkynes, or aromatic hydrocarbons, as well as alcohols, aldehydes, ketones, or ethers that contain functional groups containing elements other than hydrocarbons (e.g., oxygen), and in particular methane (CH4) fuel.

[0018] <Electrolyte layer 26> The electrolyte layer 26 has a function of separating the fuel gas and the oxidant gas. The electrolyte layer 26 is configured to pass oxide ions from the cathode electrode layer 28 to the anode electrode layer 24, but not to pass gas and electrons. In particular, the electrolyte layer 26 in this embodiment is configured to have approximately the same area as the anode electrode layer 24.

[0019] The electrolyte layer 26 is densely configured to block anode gas and cathode gas and exhibit high ion conductivity. More specifically, the density of the electrolyte layer 26 is not particularly limited as long as it has gas blocking properties, but is preferably 90% or more, more preferably 96% or more, and particularly preferably 98% or more. The electrolyte layer 26 is formed as a plate having a thickness of about several tens of microns.

[0020] Examples of the constituent material of the electrolyte layer 26 include solid oxide ceramics such as stabilized zirconia doped with rare earth oxides (e.g., one or more materials selected from the group consisting of Y2O3, Sc2O3, Gd2O3, Sm2O3, Yb2O3, and Nd2O3), ceria-based solid solutions, and perovskite-type oxides (e.g., SrCeO3, BaCeO3, CaZrO3, SrZrO3, etc.). More specifically, examples of the constituent material of the electrolyte layer 26 include YSZ (yttria-stabilized zirconia: Zr 1-x Y x O2), SSZ (Scandium-stabilized zirconia: Zr 1-x S cx O2), SDC (Samarium doped ceria: Ce 1-x Sm x O2), GDC (Gadolium doped ceria: Ce 1-x Gd x O2), or LSGM (Lanthanum Strontium Magnesium Gallate: La 1-x Sr x Ga 1-y Mg y O3) can be used.

[0021] <Cathode electrode layer 28> The cathode electrode layer 28 is an oxidizer electrode, and serves to convert oxygen molecules into oxide ions by reacting an oxidizer gas (particularly air) with electrons. The cathode electrode layer 28 is configured as a plate-shaped porous member provided so as to be in contact with the upper surface of the electrolyte layer 26 in the stacking direction Z. The cathode electrode layer 28 is also configured to be resistant to an oxidizing atmosphere Ro, and to have high gas permeability for transmitting an oxidizer gas, electronic conductivity, and ion conductivity. Furthermore, the cathode electrode layer 28 has a catalytic function for a reduction reaction that converts oxygen molecules into oxygen ions.

[0022] Examples of the constituent material of the cathode electrode layer 28 include an oxide of one metal selected from the group consisting of lanthanum, strontium, manganese (Mn), and cobalt, or an alloy of two or more metals. In particular, lanthanum strontium cobalt iron composite oxide (LSCF) can be used as the constituent material of the cathode electrode layer 28.

[0023] <Current collecting auxiliary layer 29> The current collecting auxiliary layer 29 is formed of, for example, an expanded metal on a wire mesh, and assists electrical contact between the separator 30 and the single cell 20. The separator 30 is formed as a member with an uneven cross section extending in the electrode width direction X by press molding a conductive metal material such as iron or chromium. Due to the cross-sectional shape, the space between the separator 30 and the surface of the anode electrode layer 24 is formed as a fuel gas flow path 32 for supplying fuel gas. The space between the separator 30 and the surface of the current collecting auxiliary layer 29 is formed as an oxidant gas flow path 34 for supplying oxidant gas (air).

[0024] <Support and seal structure S> The support and seal structure S of this embodiment is provided on the periphery of the unit cell 20 .

[0025] 2 is a diagram illustrating the configuration of the support and seal structure S in this embodiment. As shown in the figure, the support and seal structure S is mainly composed of a frame body 40 as a frame-shaped member provided for each unit cell 20, a joining frame body 42, a seal member 44, and a welded portion 46.

[0026] The frame body 40 is a frame-shaped member with a rectangular hole formed in the center, and is provided along the periphery of the electrolyte layer 26. In particular, the frame body 40 of this embodiment is disposed in a region of the electrolyte layer 26 that does not face the cathode electrode layer 28. Furthermore, the outer periphery of the frame body 40 protrudes outside the unit cell 20, and the outer end is joined to the end 30a of the separator 30 via a seal material 60. With this structure, the frame body 40 exerts a function of retaining the structure of the unit cell 20 (particularly, the layer structure of each layer included in the unit cell 20) from external forces such as vibration. In addition, an insulating member 62 is provided between the frame body 40 and the end 30a of the separator 30 to cut off electrical conduction therebetween (to prevent short circuit).

[0027] In the support and seal structure S of this embodiment, the frame body 40 separates the oxidizing atmosphere Ro around the cathode electrode layer 28 from the reducing atmosphere Rr around the anode electrode layer 24. Therefore, the frame body 40 is preferably made of a material, particularly a metal composition, suitable for blocking the flow of gas between the reducing atmosphere Rr and the oxidizing atmosphere Ro while realizing the function of holding the unit cell 20. In particular, the metal composition is preferably stainless steel, more preferably ferritic stainless steel containing aluminum, and particularly preferably one having a linear expansion coefficient close to that of the unit cell 20. The frame body 40 is bonded (fused) to the electrolyte layer 26 via a joining frame body 42.

[0028] The joining frame 42 is a member having a function of joining the frame body 40 and the electrolyte layer 26. The joining frame 42 is also formed in a frame shape like the frame body 40. The joining frame 42 is joined to the electrolyte layer 26 by a predetermined joining method, and then the frame body 40 is pressurized and joined to realize a layered structure consisting of the frame body 40, the joining frame 42, and the electrolyte layer 26 shown in FIG. 2. In particular, the support and seal structure S of this embodiment is configured such that the inner peripheral surface of the frame body 40 and the inner peripheral surface of the joining frame 42 are approximately flush with each other when the layered structure is realized.

[0029] Furthermore, the joining frame 42 is made of a composition containing the same kind of ceramic as that contained in the electrolyte layer 26 and the same kind of metal as that constituting the frame body 40. For example, when the electrolyte layer 26 is made of YSZ (yttria stabilized zirconia: Zr 1-x Y x O2), and in particular, when ferritic stainless steel containing Al in the base material is used as the metal composition constituting the frame body 40, the joining frame body 42 is preferably composed of a composition containing YSZ and ferritic stainless steel. In this way, the joining frame body 42 contains the same metal and ceramics as the frame body 40 and the electrolyte layer 26, respectively, so that the affinity at the joining between the joining frame body 42 and the frame body 40 and the electrolyte layer 26 is improved, and the joining strength can be increased. Furthermore, the joining frame body 42 preferably has a certain degree of density so as to have airtightness capable of blocking the flow of gas between the reducing atmosphere Rr and the oxidizing atmosphere Ro to a certain extent.

[0030] The sealing member 44 is provided so as to hermetically seal a region to be sealed Rs defined by the inner periphery of the frame body 40 (hereinafter referred to as "frame inner periphery 40a") and a region of the joining member in contact with the frame inner periphery 40a (hereinafter referred to as "joining member inner periphery 42a") against the electrolyte layer 26. Here, the region to be sealed Rs is a region near the joining interface between the frame inner periphery 40a and the joining member inner periphery 42a, and is defined as a region where a flow path for fuel gas from the reducing atmosphere Rr or air from the oxidizing atmosphere Ro is likely to occur.

[0031] This realizes a sealing function that blocks the flow of gas between the reducing atmosphere Rr and the oxidizing atmosphere Ro. In particular, by providing the sealing member 44 in this manner, the desired sealing function is realized without providing the joining frame 42 itself with airtightness. In addition, the sealing member 44 is made of a glass composition mainly composed of glass. This provides the sealing member 44 with insulating properties derived from glass, and therefore suppresses short circuits (short circuits that occur between the anode electrode layer 24 and the cathode electrode layer 28 through the frame 40 when the frame 40 and the anode electrode layer 24 are at the same potential). In particular, it is preferable to use a glass composition that bonds with the ceramic material contained in the joining frame 42, for example, a glass composition having BaO, Al2O3, and SiO2 as the main components (matrix) and leucite crystals (KASiO6 or 4SiO2·Al2O3·K2O) precipitated in the matrix. In this way, by making the sealing member 44 from a glass composition containing as its main component a glass that bonds with ceramics, the bonding strength between the sealing member 44 and the bonding frame 42 can be further increased.

[0032] The welded portion 46 is formed by welding between the frame body 40 and the joining frame body 42. In particular, the welded portion 46 in this embodiment is formed outside the sealing target region Rs in the frame body 40 and the joining frame body 42 (outside the positive Y-axis direction in the figure). More specifically, the welded portion 46 is formed by performing laser welding from the side surface of the frame body 40 to a partial region of the side surface of the joining frame body 42. In this way, the welded portion 46 is formed, so that the joining strength between the frame body 40 and the joining frame body 42 can be further improved. Furthermore, with the configuration of the support and seal structure S in this embodiment, the provision of the welded portion 46 also achieves the effects described below.

[0033] 3 is a diagram illustrating the effect of providing the welded portion 46. For example, when stacking pressure is applied to stack the unit cells 20 to form the fuel cell stack 10, or due to vibrations caused by the environment in which the fuel cell stack 10 is installed, it is expected that an external force will act on the peripheral portion of the unit cell 20 in the stacking direction Z (cell up-down direction). In contrast, with the fuel cell structure of this embodiment, the external force can be mitigated by the deformation of the frame body 40 shown in Figs. 3(A) and 3(B), and each layer can be protected from the external force.

[0034] However, depending on the magnitude of the external force, the frame body 40 may become deformed to a large extent, which may cause the seal member 44 to peel off from the joining frame body 42 and the seal member 44 (particularly the region to be sealed Rs). In contrast, in the fuel cell structure of this embodiment, the joining strength is higher (particularly the highest) at the position of the welded portion 46 on the outer circumferential side of the region to be sealed Rs in the frame body 40 and the joining frame body 42, so that the position of the welded portion 46 can be used as the starting point of deformation of the frame body 40. In other words, the transmission of the external force acting on the frame body 40 can be stopped at the position of the welded portion 46, so that the seal member 44 can be more reliably prevented from peeling off in the region to be sealed Rs. In particular, this effect is particularly beneficial when the fuel cell stack 10 is mounted on a moving body such as a vehicle, i.e., when the fuel cell stack 10 is used for applications where external forces due to vibrations or the like are likely to occur.

[0035] The configuration of the fuel cell stack 10 of this embodiment described above and the resulting effects will now be described.

[0036] The fuel cell stack 10 of this embodiment is configured as a fuel cell structure having a fuel electrode layer (anode electrode layer 24), an air electrode layer (cathode electrode layer 28), and an electrolyte layer 26 provided between the anode electrode layer 24 and the cathode electrode layer 28. In particular, the fuel cell stack 10 includes a frame body 40 provided on the periphery of the electrolyte layer 26 as a frame-shaped member for separating the fuel gas flowing through the anode electrode layer 24 from the air flowing through the cathode electrode layer 28, a joining frame body 42 as a joining member that joins the frame body 40 and the electrolyte layer 26 to each other and contains metal and ceramics, and a sealing target region Rs defined by the inner periphery (frame inner periphery 40a) of the frame body 40 and a region (joining member inner periphery 42a) of the joining frame body 42 in contact with the frame inner periphery 40a is provided so as to be airtightly attached to the electrolyte layer 26.

[0037] As a result, the metal components and ceramic components contained in the joining frame 42 ensure suitable joining properties to the frame body 40 and the electrolyte layer 26, while the seal member 44 configured separately from the joining frame 42 can block the flow of gas between the reducing atmosphere Rr around the anode electrode layer 24 and the oxidizing atmosphere Ro around the cathode electrode layer 28. Therefore, the joining frame 42 is isolated from the oxidizing atmosphere Ro by the seal member 44, while the seal member 44 is isolated from the reducing atmosphere Rr by the frame body 40 and the joining frame 42. This prevents deterioration of the joining frame 42 and the seal member 44, and suppresses a decrease in the sealing properties and joining strength required for the fuel cell structure (particularly the layers constituting the unit cell 20).

[0038] Furthermore, in the fuel cell stack 10 of this embodiment, the frame body 40 and the joining frame body 42 are provided with welds 46 on the outer circumferential side of the region to be sealed Rs.

[0039] This can further strengthen the joint between the frame body 40 and the joining frame body 42. In particular, by positioning the welded portion 46 on the outer periphery side of the region to be sealed Rs, bending deformation of the frame body 40 that occurs when an external force is input due to stacking or vibration, etc., can be stopped at the position of the welded portion 46. As a result, peeling of the seal member 44 from the region to be sealed Rs can be suppressed, and the sealing function of the seal member 44 can be more reliably maintained.

[0040] Furthermore, in the fuel cell stack 10 of this embodiment, the joining frame 42 contains the same type of ceramic material as the electrolyte layer 26 .

[0041] This can further improve the bonding affinity between the bonding frame 42 and the electrolyte layer 26, and more reliably prevent a decrease in the bonding strength of each layer in the fuel cell structure.

[0042] In particular, the sealing member 44 is made of a glass composition containing glass as a main component, which bonds with the ceramic material contained in the joining frame 42 .

[0043] This can increase the bonding strength between the sealing member 44 and the joining frame 42, and can further improve the reliability of the seal provided by the sealing member 44. In addition, the sealing member 44 can be provided with insulating properties derived from glass, which can also contribute to preventing short circuits.

[0044] Second embodiment The second embodiment will be described below, in which the same elements as those in the first embodiment are given the same reference numerals and the description thereof will be omitted.

[0045] 4 is a diagram illustrating the configuration of the support and seal structure S in this embodiment. As shown in the figure, the support and seal structure S in the fuel cell stack 10 of this embodiment differs from the first embodiment in that the volume ratio of ceramics to metal contained in the joining frame 42 is made different in the stacking direction Z.

[0046] In particular, the joining frame 42 is configured so that the ceramic content is greater than the metal content in a portion (hereinafter also referred to as the "frame side region 42A") relatively close to the frame body 40 in the stacking direction Z. On the other hand, the joining frame 42 is configured so that the metal content is greater than the ceramic content in a portion (hereinafter also referred to as the "electrolyte side region 42B") relatively close to the electrolyte layer 26 in the stacking direction Z.

[0047] That is, in the fuel cell stack 10 of this embodiment, the joining frame 42 is configured so that the volume ratio of ceramic to metal is smaller toward the frame body 40 and is larger toward the electrolyte layer 26 .

[0048] As a result, the metal contained in the frame side region 42A of the joining frame body 42 improves the joining strength with the frame body 40 (particularly, the metal frame body 40), while the ceramics contained in the electrolyte side region 42B improves the joining strength with the electrolyte layer 26 (particularly, the electrolyte layer 26 whose main component is a ceramic material).

[0049] Furthermore, when a configuration in which the frame body 40 and the joining frame body 42 are welded (a configuration in which the welded portion 46 is provided) is adopted as in this embodiment, the extension range of the weld bead can be limited to just before the electrolyte layer 26 (the portion of the frame side region 42A) by increasing the ratio of the ceramic content in the electrolyte side region 42B as described above. As a result, it is possible to suppress the occurrence of stress concentration in the electrolyte layer 26 due to the weld bead, and the electrolyte layer 26 can be more suitably protected.

[0050] Third embodiment The third embodiment will be described below, in which the same elements as those in the first or second embodiment are given the same reference numerals and the description thereof will be omitted.

[0051] 5 is a diagram illustrating the configuration of the support and seal structure S in this embodiment. As shown in the figure, the support and seal structure S in the fuel cell stack 10 of this embodiment differs from the first embodiment in that the joining frame 42 is densely formed so as to further provide gas impermeability.

[0052] This makes it possible to more reliably provide the joining frame 42 itself with the function of blocking the flow of gas between the reducing atmosphere Rr and the oxidizing atmosphere Ro, thereby further improving the sealing performance.

[0053] Furthermore, in the support and seal structure S of this embodiment, the welds 46 are formed over partial areas of the side surface of the frame body 40 and the side surface of the joining frame 42, so that the weld lines of the welds 46 function as a gas barrier between the reducing atmosphere Rr and the oxidizing atmosphere Ro. Therefore, the joining frame 42 itself and the weld lines of the welds 46 function as double sealing materials, so that the sealing function is made redundant and its reliability can be improved.

[0054] 5 shows an example in which the joining frame 42 is formed precisely on the premise of the support and seal structure S of the first embodiment. However, the present invention is not limited to this, and a configuration in which the joining frame 42 is formed precisely on the premise of the support and seal structure S of the second embodiment may be adopted.

[0055] (Fourth embodiment) The fourth embodiment will be described below, with the same elements as those in any of the first to third embodiments being given the same reference numerals, and the description thereof will be omitted.

[0056] Fig. 6 is a diagram for explaining the configuration of the support and seal structure S in this embodiment. In particular, Fig. 6(A) is a diagram showing the overall configuration of the main parts of the support and seal structure S, and Fig. 6(B) is an enlarged view of the main parts around the region to be sealed Rs.

[0057] As shown in the figure, the support and seal structure S in the fuel cell stack 10 of this embodiment differs from the first embodiment in that the inner periphery (joining member inner periphery 42a) of the joining frame 42 that comes into contact with the seal member 44 is formed to be porous. For ease of explanation, this portion that is formed to be porous will also be referred to as the "porous portion 42C" below.

[0058] In particular, the porous portion 42C is configured to have a relatively large porosity compared to other portions of the bonding frame 42, and is formed to a length that allows at least a part of the sealing member 44 to penetrate therein in the electrode width direction X. From the viewpoint of ensuring the sealing properties (density) of the bonding frame 42 as much as possible, it is preferable that the porous portion 42C is configured so that the length along the electrode width direction X is as short as possible (for example, so as to be equal to or shorter than the extension length of the sealing target region Rs in the electrode width direction X) while allowing the sealing member 44 to penetrate.

[0059] In the fuel cell stack 10 of this embodiment described above, the portion of the joining frame 42 that comes into contact with the sealing member 44 is formed to be porous.

[0060] This allows the sealing member 44 to penetrate into the porous portion 42C of the joining frame 42. As a result, an anchor effect can be exerted between the sealing member 44 and the joining frame 42, thereby further improving the bonding strength between the sealing member 44 and each layer constituting the unit cell 20 including the joining frame 42.

[0061] In addition, in Figure 6, an example is described in which a porous portion 42C is formed in the joining frame 42 based on the support and seal structure S of the first embodiment, but this is not limited to this, and the configuration may be adopted based on the support and seal structure S of the second or third embodiment.

[0062] Fifth embodiment The fifth embodiment will be described below, with the same reference numerals being used to designate the same elements as those in any of the first to fourth embodiments, and the description thereof will be omitted.

[0063] 7 is a diagram illustrating the configuration of the support and seal structure S in this embodiment. As shown in the figure, the support and seal structure S in the fuel cell stack 10 of this embodiment differs from the first embodiment in that an oxide coating (hereinafter also referred to as "oxide coating 50") is formed on the surface in contact with the seal member 44 in the inner periphery of the frame body 40 (inner frame periphery 40a).

[0064] This allows the frame body 40 and the seal member 44 to be bonded substantially by the bond between the oxide coating 50 and the seal member 44. In other words, the bond between the metal of the frame body 40 and the ceramics (particularly glass) of the seal member 44, which has low bond strength, can be eliminated, and the bond strength between the seal member 44 and each layer including the frame body 40 can be further improved.

[0065] In addition, in Figure 7, an example is described in which an oxide coating 50 is provided on the frame inner circumferential portion 40a based on the support and seal structure S of the first embodiment, but this is not limited to this, and the same configuration may be adopted based on the support and seal structure S of any of the second to fourth embodiments.

[0066] Sixth embodiment The sixth embodiment will be described below, with the same reference numerals being used to designate the same elements as those in any of the first to fifth embodiments, and the description thereof will be omitted.

[0067] 8 is a diagram illustrating the configuration of the support and seal structure S in this embodiment. As shown in the figure, the support and seal structure S in the fuel cell stack 10 of this embodiment differs from the first embodiment in that a seal member 44 is provided to cover the welded portion 46.

[0068] This prevents a decrease in the bonding strength of the welded portion 46 due to oxidation of the weld line, since the welded portion 46 is protected from the oxidizing atmosphere Ro by the seal member 44. As a result, a decrease in the bonding strength of each layer in the fuel cell structure can be more reliably prevented.

[0069] In addition, in Figure 8, an example has been described in which the seal member 44 is arranged to cover the welded portion 46, assuming the support and seal structure S of the first embodiment, but this is not limited to this, and the same configuration may be adopted, assuming the support and seal structure S of any of the second to fifth embodiments.

[0070] (Modification) 9 is a diagram illustrating the configuration of a fuel cell stack 10 according to a modified example. As shown in the figure, the fuel cell stack 10 of this modified example differs from the first embodiment in that the anode electrode layer 24 is configured to have substantially the same thickness as the cathode electrode layer 28, and a metal support 22 is provided between the separator 30 and the anode electrode layer 24. That is, the fuel cell stack 10 of this modified example is configured as a so-called metal support cell in which the metal support 22 ensures the mechanical strength for supporting the cell structure, and the support and seal structure S of the first embodiment is provided thereon.

[0071] In addition, in Figure 9, an example is described in which the support and seal structure S of the first embodiment is adopted for the metal support cell, but this is not limited to this, and the support and seal structure S of any of the second to sixth embodiments may be adopted for the metal support cell.

[0072] 1 to 8 or the metal support cell shown in Fig. 9, the support and seal structure S described in each of the above embodiments can be applied to any type of cell having a structure of the cell outer periphery of the unit cell 20 on which the support and seal structure S can be provided. For example, the support and seal structure S described in each of the above embodiments may be applied to a cathode support cell in which the cathode electrode layer 28 is made thicker than the anode electrode layer 24 and the cell structure is supported by the cathode electrode layer 28, or an electrolyte support cell in which the electrolyte layer 26 is made relatively thick and the cell structure is supported by the electrolyte layer 26.

[0073] Although each embodiment of the present invention has been described above, the above-mentioned embodiments merely illustrate some of the application examples of the present invention, and it is not intended to limit the technical scope of the present invention to the specific configurations of the above-mentioned embodiments.

[0074] For example, the welded joint at the welded portion 46 between the frame body 40 and the connecting frame body 42 is not essential, and may be omitted or an alternative joining means may be appropriately adopted. An example of the alternative joining means is a joining means that promotes a metallic bond between these members, such as brazing between the frame body 40 and the connecting frame body 42. [Explanation of symbols]

[0075] 10. Fuel Cell Stack 20 Single Cell 22 Metal support 24 Anode electrode layer 26 Electrolyte layer 28 Cathode electrode layer 40 Frame body 42 Joint frame 44 Sealing material 46 Welding 50 Oxide coating

Claims

1. A fuel cell structure having an anode layer, an air cathode layer, and an electrolyte layer provided between the anode layer and the air cathode layer, a frame-shaped member provided on a periphery of the electrolyte layer and separating a fuel gas flowing through the fuel electrode layer from air flowing through the air electrode layer; a joining member that joins the frame-shaped member and the electrolyte layer to each other and that contains a metal and a ceramic; a sealing member provided to hermetically seal a sealing target area defined by an inner periphery of the frame-shaped member and an area of ​​the joining member in contact with the inner periphery against the electrolyte layer; The bonding member is made of a composition containing the ceramic contained in the electrolyte layer and a metal constituting the frame-shaped member. Fuel cell structure.

2. 2. The fuel cell structure according to claim 1, The frame-shaped member and the joining member are provided with welded portions on an outer circumferential side of the region to be sealed. Fuel cell structure.

3. 2. The fuel cell structure according to claim 1, The sealing member is made of a glass composition containing glass as a main component that bonds with the ceramics contained in the joining member. Fuel cell structure.

4. The fuel cell structure according to any one of claims 1 to 3, The joining member is densely formed so as to have gas shielding properties. Fuel cell structure.

5. The fuel cell structure according to any one of claims 1 to 4, The joining member is formed to have a porous portion in contact with the sealing member. Fuel cell structure.

6. The fuel cell structure according to any one of claims 1 to 5, an oxide coating is formed on the surface of the inner periphery of the frame-shaped member that is in contact with the seal member; Fuel cell structure.

7. A fuel cell structure having an anode layer, an air cathode layer, and an electrolyte layer disposed between the anode layer and the air cathode layer, a frame-shaped member provided on a periphery of the electrolyte layer and separating a fuel gas flowing through the fuel electrode layer from air flowing through the air electrode layer; a joining member that joins the frame-shaped member and the electrolyte layer to each other and that contains a metal and a ceramic; a sealing member provided to hermetically seal a sealing target area defined by an inner periphery of the frame-shaped member and an area of ​​the joining member in contact with the inner periphery against the electrolyte layer; The frame-shaped member and the joining member are provided with welded portions on an outer circumferential side of the region to be sealed, The seal member is configured to cover the weld. Fuel cell structure.

8. A fuel cell structure having an anode layer, an air cathode layer, and an electrolyte layer provided between the anode layer and the air cathode layer, a frame-shaped member provided on a periphery of the electrolyte layer and separating a fuel gas flowing through the fuel electrode layer from air flowing through the air electrode layer; a joining member that joins the frame-shaped member and the electrolyte layer to each other and that contains a metal and a ceramic; a sealing member provided to hermetically seal a sealing target area defined by an inner periphery of the frame-shaped member and an area of ​​the joining member in contact with the inner periphery against the electrolyte layer; the joining member is configured such that a volume ratio of the ceramic to the metal is smaller toward the frame-shaped member and is larger toward the electrolyte layer. Fuel cell structure.

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