JP2014123498A - Fuel cell stack and method for manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel cell stack capable of improving sealability of a manifold part and electric conductivity of a collector part in a simple configuration and steps.SOLUTION: A solid oxide fuel cell 12 constituting a fuel cell stack 10 comprises a separator 22 and an electrolyte-electrode assembly 20. A first sealing member 24a is arranged between a frame member 23 and a surface 22a of the separator 22. A second sealing member 24b is arranged between the frame member 23 and a surface 22b of the separator 22. A third sealing member 24c is arranged between the frame member 23 and an electrolyte exposed part 14a. A softening point of the first sealing member 24a is set lower than each softening point of the second sealing member 24b and the third sealing member 24c.

Description

  The present invention includes a solid oxide fuel cell in which an electrolyte / electrode assembly constituted by sandwiching an electrolyte between an anode electrode and a cathode electrode is laminated between separators, and a plurality of the solid oxide fuel cells are provided. The present invention relates to a fuel cell stack having a stacked body and a manufacturing method thereof.

  Usually, a solid oxide fuel cell (SOFC) uses an oxide ion conductor, for example, stabilized zirconia, as an electrolyte, and an electrolyte / electrode assembly in which an anode electrode and a cathode electrode are disposed on both sides of the electrolyte. (MEA) is sandwiched between separators (bipolar plates). This fuel cell is normally used as a fuel cell stack in which a predetermined number of electrolyte / electrode assemblies and separators are laminated.

  In this type of fuel cell stack, it is necessary to stack the fuel cells in a desired pressurized state in order to obtain an output voltage efficiently. Furthermore, in order to prevent leakage of reaction gases such as fuel gas and air as much as possible, it is necessary to pressurize in the stacking direction to securely seal the reaction gas manifold.

  For this reason, for example, a solid oxide fuel cell plate disclosed in Patent Document 1 is known. As shown in FIG. 11, the solid oxide fuel cell plate supports the solid oxide fuel cell 1a, the solid oxide fuel cell 1a, and separates fuel gas and air. A cell support 2a, and a joint portion 3a for bonding the solid oxide fuel cell 1a and the cell support 2a are provided.

  The cell support 2a includes a metal ring 4a and a protective coating layer 5a in which the surface of the metal ring 4a is covered with glass. The joint portion 3a includes a first glass layer 7a bonded to the electrolyte layer 6a, a protective coating layer 5a, and a second glass layer 8a that is disposed between the first glass layer 7a and bonds them together. I have.

  And the softening point of the 2nd glass layer 8a is set lower than the softening point of the protective film layer 5a and the 1st glass layer 7a.

  In addition, the solid oxide fuel cell stack disclosed in Patent Document 2 is formed by stacking a plurality of solid oxide fuel cell cells each having a solid electrolyte body having a fuel electrode in contact with fuel gas and an air electrode in contact with air. It is configured.

  Outer edge holding members are provided on both sides in the stacking direction of the solid oxide fuel cell stack, and the outer edge holding members are tightened by bolts and nuts to press the solid oxide fuel cell stack from both sides. The outer edge holding member is constituted by a frame body that presses only the outer peripheral edge portion of the end surface in the stacking direction of the solid oxide fuel cell stack.

  Furthermore, as shown in FIG. 12, the solid oxide fuel cell disclosed in Patent Document 3 is configured by sandwiching a power generation cell 1b between current collector plates 2b and 3b. The power generation cell 1b has a negative electrode 5b and a positive electrode 6b on both surfaces of the ceramic thin film 4b. A vitreous first seal member 9b1 is sandwiched between the concave portion 7b at the outer end portion of the current collector plate 2b and the convex portion 8b at the outer end portion of the current collector plate 3b. A glassy second seal member 9b2 is disposed inside the convex portion 8b of the current collector plate 3b so as to be positioned between the outer end portion of the ceramic thin film 4b.

JP 2007-115481 A JP 2007-317490 A JP-A-8-7902

  In the above-mentioned Patent Document 1, the gas sealing property between the solid oxide fuel cell 1a and the metal cell support 2a is maintained, and the height adjustment function between the fuel gas and the air manifold is individually provided. Must be performed by an adjusting device (not shown). For this reason, there is a problem that the configuration becomes complicated and the stacking height of the manifold portion and the current collector portion must be individually adjusted, resulting in a decrease in workability.

  Moreover, in said patent document 2, while a manifold part is clamp | tightened and sealed with a packing and a volt | bolt, the outer periphery of a solid electrolyte body is provided with the metal foil for absorbing the displacement of the said manifold part. Therefore, the height adjustment is performed by the metal foil, while the insulation is performed by another configuration. Accordingly, there is a problem that the configuration is complicated and not economical.

  Moreover, in said patent document 3, the pressure P is absorbed by the 1st sealing member 9b1, and the failure | damage of the cell 1b for electric power generation is prevented. For this reason, there is a problem that the second seal member 9b2 becomes unstable by absorbing the pressure by the first seal member 9b1. In addition, there is a problem that the load on the current collector is reduced, resulting in performance degradation and variations.

  The present invention solves this type of problem, and provides a fuel cell stack capable of improving the sealing performance of the manifold section and the electrical conductivity of the current collecting section with a simple configuration and process, and a method for manufacturing the same. The purpose is to provide.

  The present invention includes a solid oxide fuel cell in which an electrolyte / electrode assembly constituted by sandwiching an electrolyte between an anode electrode and a cathode electrode is laminated between separators, and a plurality of the solid oxide fuel cells are provided. The present invention relates to a fuel cell stack having a stacked body to be stacked.

  In this fuel cell stack, in the electrolyte / electrode assembly, the planar dimension of the cathode electrode is set smaller than the planar dimension of the electrolyte, so that the outer peripheral edge of the electrolyte is exposed outside the outer peripheral part of the cathode electrode. It has an electrolyte exposure part.

  The separator sandwiches the electrolyte / electrode assembly, and includes a fuel gas passage for supplying fuel gas along the electrode surface of the anode electrode, and an oxidant gas passage for supplying oxidant gas along the electrode surface of the cathode electrode. Further, sandwiching portions provided individually on the front and back sides, at least a fuel gas supply communication hole for supplying the fuel gas to the fuel gas passage, or an oxidant gas for supplying the oxidant gas to the oxidant gas passage The supply communication hole includes a manifold portion formed in the stacking direction.

  On the other hand, between the separators, a frame member that is located outside the electrolyte-electrode assembly across the electrolyte exposed portion and that has at least a fuel gas supply communication hole or an oxidant gas supply communication hole is interposed. Yes.

  A first seal member is disposed between the frame member and the surface of the separator on the oxidant gas passage side, and a second seal is disposed between the frame member and the surface of the separator on the fuel gas passage side. A member is disposed, and a third seal member is disposed between the frame member and the electrolyte exposing portion. Here, the softening point of the first seal member is set lower than the softening point of the second seal member, and the softening point of the first seal member is set lower than the softening point of the third seal member.

  In this fuel cell stack, the first seal member, the second seal member, and the third seal member are glass-based seal members, and the glass component content ratio of the first seal member is the glass content of the second seal member. It is preferable that the glass component content ratio of the first seal member is set higher than the glass component content ratio of the third seal member.

  For this reason, the softening point of the first seal member is set lower than the softening point of the second seal member, and the softening point of the first seal member is set lower than the softening point of the third seal member. Become. Therefore, the second sealing member and the third sealing member having a high softening point, that is, high strength, can improve the sealing performance on the anode side, while the first sealing member having a low softening point, that is, a softness. Can improve the contact property on the cathode side. Thereby, it becomes possible to improve the sealing performance of the manifold portion and the electrical conductivity of the electrolyte / electrode assembly.

  Furthermore, in this fuel cell stack, the first seal member, the second seal member, and the third seal member are glass-based seal members, and the non-glass component content ratio of the first seal member is the same as that of the second seal member. It is preferable that the non-glass component content ratio is lower than the non-glass component content ratio, and the non-glass component content ratio of the first seal member is set lower than the non-glass component content ratio of the third seal member.

  For this reason, the softening point of the first seal member is set lower than the softening point of the second seal member, and the softening point of the first seal member is set lower than the softening point of the third seal member. Become. Therefore, the second sealing member and the third sealing member having a high softening point, that is, high strength, can improve the sealing performance on the anode side, while the first sealing member having a low softening point, that is, a softness. Can improve the contact property on the cathode side. Thereby, it becomes possible to improve the sealing performance of the manifold portion and the electrical conductivity of the electrolyte / electrode assembly.

  Furthermore, in this fuel cell stack, it is preferable that the second seal member and the third seal member are made of the same material. For this reason, the manufacturing cost of the second seal member and the third seal member is favorably reduced, and handling workability is effectively improved.

  In this fuel cell stack, the softening point of the first seal member is lower than the operating temperature of the solid oxide fuel cell, and the softening points of the second seal member and the third seal member are the operating temperatures. It is preferable that the temperature is higher than that. Therefore, during the operation of the fuel cell stack, the first sealing member can be surely softened to have the desired flexibility, and the cathode side contact can be improved, so that good power generation performance is achieved. It becomes possible.

  Furthermore, in this fuel cell stack, the second seal member surrounds at least the fuel gas supply communication hole or the oxidant gas supply communication hole of the frame member, and more than a portion corresponding to the third seal member of the frame member. It is preferable to arrange at the outer edge. Thereby, it can suppress reliably that fuel gas leaks from the anode side of an electrolyte electrode assembly.

  Furthermore, in this fuel cell stack, it is preferable that the frame member is set such that the thickness of the portion where the second seal member is disposed is larger than the thickness of the portion where the third seal member is disposed. For this reason, the thickness at the time of lamination | stacking is suppressed and size reduction of the lamination direction of a fuel cell stack is easily performed.

  The present invention also includes a solid oxide fuel cell in which an electrolyte / electrode assembly formed by sandwiching an electrolyte between an anode electrode and a cathode electrode is laminated between separators, and a plurality of the solid oxide fuel cells The electrolyte / electrode assembly has a laminate in which a battery is laminated, and the cathode electrode has a planar dimension set to be smaller than a planar dimension of the electrolyte, so that the outer peripheral edge of the electrolyte is the cathode electrode. A fuel gas passage for supplying fuel gas along the electrode surface of the anode electrode, and the separator sandwiches the electrolyte-electrode assembly; and An oxidant gas passage for supplying an oxidant gas along the electrode surface of the cathode electrode is provided with a sandwiching portion provided separately on the front and back, and at least the fuel gas in the fuel gas passage A fuel gas supply communication hole for supplying or a oxidant gas supply communication hole for supplying the oxidant gas to the oxidant gas passage is formed in a stacking direction. It relates to a manufacturing method.

  In this manufacturing method, a first step of firing a precursor of an electrolyte / electrode assembly to obtain a fired body, a surface of the separator on the fuel gas passage side, the fired body corresponding to the fuel gas passage, and the firing A second seal member corresponding to at least the fuel gas supply passage or the oxidant gas supply passage, a third seal member corresponding to the electrolyte exposure portion, and straddling the electrolyte exposure portion Frame members that are located outside the electrolyte-electrode assembly and at least the fuel gas supply communication hole or the oxidant gas supply communication hole are respectively disposed, and these are integrally fired to form a coupling member. And obtaining the second step, laminating the coupling members, arranging a current collector corresponding to the cathode electrode, and adjoining the frame member constituting one of the coupling members and one of the coupling members Other to do Wherein between said oxidant gas passage-side surface of the separator of the coupling member, the first seal member is interposed, and a third step of firing these.

  The softening point of the first seal member is set lower than the softening point of the second seal member, and the softening point of the first seal member is set lower than the softening point of the third seal member.

  According to the present invention, the softening point of the first seal member is set lower than the softening point of the second seal member, and the softening point of the first seal member is set lower than the softening point of the third seal member. ing. For this reason, an optimal load can be applied to each part of the fuel cell stack by using the flexible first seal member and the high-strength second seal member and third seal member. Therefore, it is possible to improve the sealing performance of the manifold portion and the electrical conductivity of the electrolyte / electrode assembly. Thereby, the contact property between the cathode electrode having a particularly high electrical resistance and the current collector or the separator is improved, and the electrical conductivity is favorably improved.

  Further, according to the present invention, in the second step, the anode side sealability can be improved by the second seal member and the third seal member having a high softening point. Furthermore, in the third step, the contact property on the cathode side can be improved by the first sealing member having a low softening point. For this reason, the sealing performance of the manifold part and the electrical conductivity of the electrolyte / electrode assembly can be improved satisfactorily.

1 is a schematic perspective view of a fuel cell stack according to an embodiment of the present invention. It is a partially exploded perspective view of the fuel cell stack. FIG. 2 is an exploded perspective view of a solid oxide fuel cell constituting the fuel cell stack. FIG. 4 is a cross-sectional view of the solid oxide fuel cell taken along line IV-IV in FIG. 3. FIG. 5 is a cross-sectional view of the solid oxide fuel cell taken along line VV in FIG. 3. It is explanatory drawing of the kind of sealing member. It is explanatory drawing of the softening point temperature of the said sealing member, and a main component. It is a perspective view explaining the manufacturing method which concerns on this invention. It is a perspective explanatory view of the connecting member baked by the manufacturing method. It is a perspective view explaining the said manufacturing method. 2 is an explanatory diagram of a solid oxide fuel cell plate of Patent Document 1. FIG. FIG. 6 is a cross-sectional explanatory view of a solid oxide fuel cell of Patent Document 3.

  As shown in FIGS. 1 and 2, the fuel cell stack 10 according to the embodiment of the present invention is configured by stacking a plurality of solid oxide fuel cells 12 in the arrow C direction (vertical direction). The fuel cell stack 10 is used for various purposes such as in-vehicle use as well as stationary use. The solid oxide fuel cell 12 generates electricity by an electrochemical reaction between a fuel gas (a hydrogen-containing gas, for example, a gas in which hydrogen gas is mixed with methane and carbon monoxide) and an oxidant gas (air).

  As shown in FIGS. 3 to 5, the solid oxide fuel cell 12 includes, for example, a cathode electrode 16 and an anode on both surfaces of an electrolyte (electrolyte plate) 14 made of an oxide ion conductor such as stabilized zirconia. An electrolyte-electrode assembly (MEA) 20 provided with an electrode 18 is provided. The cathode electrode 16 is set to have a smaller plane size than the anode electrode 18 and the electrolyte 14, and an electrolyte exposed portion 14 a that is exposed outside the outer peripheral portion of the cathode electrode 16 is formed on the outer peripheral edge portion of the electrolyte 14. The

  A current collector 19 is laminated on the cathode electrode 16. The current collector 19 is set to have substantially the same dimensions as the cathode electrode 16 and is formed with a relatively large thickness. For example, the current collector 19 is made of a foam metal or a metal mesh made of a metal such as nickel.

  The electrolyte / electrode assembly 20 is formed in a rectangular shape (rectangular shape or square shape), and a barrier layer (not shown) is provided at least on the outer peripheral end surface portion to prevent entry and discharge of the oxidant gas and the fuel gas. Z).

  The solid oxide fuel cell 12 includes a metal frame member 23, a first seal member 24a, a second seal member 24b, and a third seal between a pair of separators (interconnectors) 22 having a rectangular shape (or a square shape). A single electrolyte / electrode assembly 20 is sandwiched between the member 24c and the member 24c.

  As shown in FIG. 3, the solid oxide fuel cell 12 has a rectangular shape (or a square shape), and a plurality of, for example, three oxidizers are provided on one end side in the long side direction (arrow A direction). The gas supply communication holes 26a are formed so as to be arranged in the short side direction (arrow B direction). For example, three oxidant gas discharge communication holes 26b are formed on the other end side in the long side direction of the solid oxide fuel cell 12 in the direction of arrow B.

  On one end side of the solid oxide fuel cell 12 in the short side direction (arrow B direction), for example, one fuel gas supply communication hole 28a is formed. For example, one fuel gas discharge communication hole 28 b is formed on the other end side in the short side direction of the solid oxide fuel cell 12.

  The separator 22 is made of a sheet metal such as a stainless alloy. In the separator 22, an oxidant gas passage 30 for supplying an oxidant gas along the electrode surface of the cathode electrode 16 is formed on a surface 22 a of the electrolyte / electrode assembly 20 facing the cathode electrode 16. The oxidant gas passage 30 is composed of a plurality of flow channel grooves extending in the direction of arrow A, and both ends terminate in the vicinity of the oxidant gas supply communication hole 26a and the oxidant gas discharge communication hole 26b.

  In the separator 22, a fuel gas passage 32 for supplying fuel gas along the electrode surface of the anode electrode 18 is formed on a surface 22 b facing the anode electrode 18 constituting the electrolyte / electrode assembly 20. The fuel gas passage 32 is constituted by a plurality of flow channel grooves extending in the direction of arrow B, and both ends terminate in the vicinity of the fuel gas supply communication hole 28a and the fuel gas discharge communication hole 28b.

  The separator 22 is provided on both surfaces 22a and 22b of which the oxidant gas passage 30 and the fuel gas passage 32 are individually front and back, a sandwiching portion 34 for sandwiching the electrolyte / electrode assembly 20, and an oxidant gas supply communication hole. 26a and an oxidant gas discharge communication hole 26b formed in the stacking direction, an oxidant gas manifold portion 36 formed in the stacking direction, a fuel gas supply communication hole 28a and a fuel gas discharge communication hole 28b formed in the stacking direction Is provided.

  As shown in FIGS. 3 to 5, the frame member 23 is set to the same dimension as the outer dimension of the separator 22, and an opening 23 a is formed inside. The opening 23a is set to be larger than the outer dimension of the cathode electrode 16 and smaller than the outer dimension of the electrolyte 14 (see FIG. 4). The frame member 23 is provided with a thin portion 23b cut out in the thickness direction corresponding to the outer dimension of the electrolyte 14 on the peripheral wall portion of the opening 23a. As shown in FIG. 4, the thickness t1 of the thin portion 23b is set to be smaller than the thickness t2 of other portions of the frame member 23.

  As shown in FIG. 3 and FIG. 5, a groove 40 a that connects the oxidant gas supply communication hole 26 a and the opening 23 a is formed on the surface side of the frame member 23 that faces the oxidant gas passage 30. A groove 40b is formed to communicate the oxidant gas discharge communication hole 26b and the opening 23a.

  The first seal member 24a has a substantially frame shape, and includes an inlet connection passage 42a for communicating each of the oxidant gas supply communication holes 26a and the oxidant gas passage 30, and each of the oxidant gas discharge communication holes 26b. And an outlet connecting passage 42 b communicating with the oxidant gas passage 30.

  The first seal member 24 a is set to have the same external dimensions and the same opening dimensions as the frame member 23. The second seal member 24 b has a frame shape and is set to the same outer dimensions as the frame member 23, that is, the separator 22.

  The second seal member 24b has an inlet connection passage 44a for communicating the fuel gas supply passage 28a and the fuel gas passage 32, and an outlet connection passage for connecting the fuel gas discharge passage 28b and the fuel gas passage 32. 44b is formed. The opening dimension of the second seal member 24 b is set to the same dimension as the outer dimension of the electrolyte 14.

  The third seal member 24 c has a frame shape, has the same outer dimension as the outer dimension of the electrolyte 14, and the opening dimension is set larger than the outer dimension of the cathode electrode 16.

  As shown in FIGS. 4 and 5, the first seal member 24a is disposed between the frame member 23 and the surface 22a of the separator 22 (surface on the oxidant gas passage 30 side), and the second seal member 24b is It is arranged between the frame member 23 and the surface 22b of the separator 22 (surface on the fuel gas passage 32 side). The third seal member 24c is disposed between the frame member 23 and the electrolyte exposed portion 14a of the electrolyte 14, that is, between the thin portion 23b and the electrolyte exposed portion 14a.

  The softening point of the first seal member 24a is set lower than the softening point of the second seal member 24b, and the softening point of the first seal member 24a is set lower than the softening point of the third seal member 24c. In the present embodiment, the first seal member 24a, the second seal member 24b, and the third seal member 24c are made of glass-based seal members.

As shown in FIG. 6, the first seal member 24a uses the seal type β (Example 1) or the seal type γ (Example 2), while the second seal member 24b and the third seal member 24c Are the same seal type α. The softening point temperatures and main components of the seal types α, β and γ are shown in FIG. The glass component includes, for example, SiO ₂ (silicon dioxide) as a main component and a ceramic component such as Al ₂ O ₃ (alumina) as a non-glass component.

  The glass component content ratio (mol% or weight%) of the first seal member 24a is higher than the glass component content ratio of the second seal member 24b, and the glass component content ratio of the first seal member 24a is the third seal. It is set higher than the glass component content ratio of the member 24c. Further, the non-glass component content ratio (mol% or wt%) of the first seal member 24a is lower than the non-glass component content ratio of the second seal member 24b, and the non-glass component content ratio of the first seal member 24a. Is set lower than the non-glass component content ratio of the third seal member 24c.

  The operating temperature of the solid oxide fuel cell 12 is around 700 ° C. to 750 ° C., the softening point of the first seal member 24a is set to be lower than the operating temperature, and the second seal member 24b and the third seal member 24a. The softening point of the seal member 24c is set to be higher than the operating temperature.

  As shown in FIGS. 1 and 2, the plurality of solid oxide fuel cells 12 are stacked in the direction of arrow C to form a stacked body 46. The laminated body 46 is placed on the lower end plate (base part) 50 with the electrode sheet 49a and the insulating plate 48a interposed therebetween.

  The lower end plate 50 has dimensions in the directions of the arrows A and B set to be larger than the dimensions of the laminated body 46, and the oxidant gas supply communication hole 26a, the oxidant gas discharge communication hole 26b, the fuel A gas supply communication hole 28a and a fuel gas discharge communication hole 28b are formed (see FIG. 2).

  A plurality of screw holes 52 are formed in the lower end plate 50 along the periphery. The screw holes 52 are formed, for example, in the vicinity of the four corners of the lower end plate 50 and in the approximate center of each side. Although not shown, the lower end plate 50 is provided with a manifold for supplying and discharging oxidant gas and fuel gas.

  An upper end plate 54 is disposed at the upper end (the other end) in the stacking direction of the stacked body 46 with an electrode sheet 49b and an insulating plate 48b interposed therebetween. The dimensions of the upper end plate 54 in the direction of arrow A and arrow B are set to the same dimensions as the dimensions of the laminated body 46, and the upper end plate 54 is formed of a rectangular (or square) flat plate. The

  On the upper end plate 54, a load plate (mounting part) 56 is laminated. A hole 58 is formed at the peripheral edge of the load plate 56, and a bolt 60 is inserted into the hole 58, and the bolt 60 is screwed into the screw hole 52 of the lower end plate 50.

  Next, a method for manufacturing the fuel cell stack 10 will be described below.

  First, a precursor of an electrolyte / electrode assembly 20 in which the cathode electrode 16 and the anode electrode 18 are provided on both surfaces of the electrolyte 14 is prepared. A fired body is obtained by firing this precursor (first step).

  Therefore, as shown in FIG. 8, on the surface 22b of the separator 22, an electrolyte / electrode assembly 20 that is a fired body, the second seal member 24b surrounding the electrolyte / electrode assembly 20, and the electrolyte / electrode A frame member 23 is disposed on the outer side of the electrolyte / electrode assembly 20 across the third seal member 24c and the electrolyte exposed portion 14a corresponding to the electrolyte exposed portion 14a of the joined body 20. Is done. These are fired integrally to obtain a coupling member 70 as shown in FIG. 9 (second step).

  In the firing process in the second step, the firing temperature is set to, for example, 770 ° C. to 900 ° C., the temperature is raised at a rate of temperature rise of 1 ° C./min to 5 ° C./min, and is maintained for 120 min to 250 min. Further, 100N to 500N is given as the firing load.

  Further, as shown in FIG. 10, the coupling members 70 are laminated with each other, the current collector 19 is disposed corresponding to the cathode electrode 16, and the frame member 23 constituting one of the coupling members 70 is adjacent to The first seal member 24a is interposed between the surface 22a of the separator 22 constituting the other coupling member 70. These are integrated by a baking process (third step).

  In this baking treatment, the baking temperature is set to 650 ° C. to 850 ° C., and the temperature is increased at a temperature increase rate of 1 ° C./min to 10 ° C./min, and then maintained for 30 min to 250 min. Moreover, 100N-1000N is provided to a baking load after 100N-500N. At that time, there is a region where the firing temperature exceeds the softening point (770 ° C.) of the second seal member 24b and the third seal member 24c, but the glass component immediately passes through the softening point. It does not change from solid to liquid.

  Further, the binder of the second seal member 24b and the third seal member 24c is volatilized at the firing stage for obtaining the coupling member 70. Therefore, the second seal member 24b and the third seal member 24c are hardly crushed in the second firing process, and are mainly caused by the volatilization of the binder and the low softening point of the first seal member 24a. Absent. Thereby, the fuel cell stack 10 is integrated.

  The operation of the fuel cell stack 10 manufactured in this way will be described below.

  As shown in FIG. 2, the lower end plate 50 constituting the fuel cell stack 10 is supplied with fuel gas (for example, hydrogen gas) and oxidant gas, for example, air through a manifold (not shown). . The air moves vertically upward along the oxidant gas supply communication hole 26a.

  In each solid oxide fuel cell 12, as shown in FIGS. 3 and 5, the oxidant gas of the separator 22 passes through the inlet connection passage 42a that communicates with the oxidant gas supply communication hole 26a of the first seal member 24a. It is supplied to the passage 30. The air is supplied to the cathode electrode 16 of the electrolyte / electrode assembly 20 while moving in the direction of arrow A through the oxidant gas passage 30 and then the oxidant gas discharge communication hole from the outlet connection path 42b of the first seal member 24a. It is discharged to 26b.

  On the other hand, as shown in FIGS. 3 and 4, the fuel gas moves vertically upward along the fuel gas supply communication hole 28a, passes through the inlet connection path 44a of the second seal member 24b, and passes through each solid oxide. Supplied to the fuel gas passage 32 of the separator 22 constituting the fuel cell 12. The fuel gas is supplied to the anode electrode 18 of the electrolyte / electrode assembly 20 while moving in the arrow B direction along the fuel gas passage 32, and then the fuel gas discharge communication from the outlet connection path 44b of the second seal member 24b. It is discharged into the hole 28b.

  Therefore, in the electrolyte / electrode assembly 20, fuel gas is supplied to the anode electrode 18 and air is supplied to the cathode electrode 16. As a result, oxide ions move to the anode electrode 18 through the electrolyte 14, and power generation is performed by a chemical reaction.

  In this case, in this embodiment, as shown in FIGS. 4 and 5, a first seal member 24 a is disposed between the frame member 23 and the surface 22 a of the separator 22, and the frame member 23 and the separator 22 are disposed. A second seal member 24b is disposed between the surface 22b and a third seal member 24c is disposed between the frame member 23 and the electrolyte exposing portion 14a.

  The softening point of the first seal member 24a is set lower than the softening point of the second seal member 24b, and the softening point of the first seal member 24a is set lower than the softening point of the third seal member 24c. ing. For this reason, the optimal load can be applied to each part of the fuel cell stack 10 by using the first seal member 24a having flexibility and the second seal member 24b and the third seal member 24c having high strength. .

  Therefore, the sealing performance of the oxidant gas manifold portion 36 and the fuel gas manifold portion 38 and the electrical conductivity of the electrolyte / electrode assembly 20 can be improved. Thereby, the contact property between the cathode electrode 16 having a particularly high electrical resistance and the current collector 19 (or the separator 22) is improved, and the effect of improving the electrical conductivity is obtained.

  Further, according to the present embodiment, in the second step, the second seal member 24b and the third seal member 24c having a high softening point can improve the sealing performance on the anode side. Furthermore, in the third step, the contact property on the cathode side can be improved by the first seal member 24a having a low softening point. For this reason, it becomes possible to improve the sealing performance of the oxidant gas manifold portion 36 and the fuel gas manifold portion 38 and the electrical conductivity of the electrolyte / electrode assembly 20.

Furthermore, the first seal member 24a, the second seal member 24b, and the third seal member 24c are glass-based seal members. The glass component (SiO ₂₎ content of the first seal member 24a is higher than the glass component content ratio of the second seal member 24b, and a glass component content of the first seal member 24a, the third seal It is set higher than the glass component content ratio of the member 24c.

  Accordingly, the softening point of the first seal member 24a is set lower than the softening point of the second seal member 24b, and the softening point of the first seal member 24a is set lower than the softening point of the third seal member 24c. Will be.

  Thereby, the second seal member 24b and the third seal member 24c having a high softening point, that is, high strength, can improve the sealing performance on the anode side, while the softening point is low, that is, the second seal member 24c has flexibility. The one seal member 24a can improve the contact property on the cathode side. For this reason, it becomes possible to improve the sealing performance of the oxidant gas manifold portion 36 and the fuel gas manifold portion 38 and the electrical conductivity of the electrolyte / electrode assembly 20.

The first seal member 24a, the second seal member 24b, and the third seal member 24c are glass-based seal members. The non-glass components (Al ₂ O ₃₎ content ratio of the first seal member 24a is lower than the non-glass components content of the second seal member 24b, and a non-glass component content of the first seal member 24a Is set lower than the non-glass component content ratio of the third seal member 24c.

  Accordingly, the softening point of the first seal member 24a is set lower than the softening point of the second seal member 24b, and the softening point of the first seal member 24a is set lower than the softening point of the third seal member 24c. Will be.

  Thereby, the second seal member 24b and the third seal member 24c having a high softening point, that is, high strength, can improve the sealing performance on the anode side, while the softening point is low, that is, the second seal member 24c has flexibility. The one seal member 24a can improve the contact property on the cathode side. For this reason, it becomes possible to improve the sealing performance of the oxidant gas manifold portion 36 and the fuel gas manifold portion 38 and the electrical conductivity of the electrolyte / electrode assembly 20.

  Further, the second seal member 24b and the third seal member 24c are made of the same material. Therefore, the manufacturing cost of the second seal member 24b and the third seal member 24c is reduced well, and the handling workability is effectively improved.

  Furthermore, the softening point of the first seal member 24a is lower than the operating temperature of the solid oxide fuel cell 12, and the softening points of the second seal member 24b and the third seal member 24c are higher than the operating temperature. Is also hot. Thereby, during the operation of the fuel cell stack 10, the first seal member 24a can be surely softened to have a desired flexibility, and the contact property on the cathode side can be improved. Performance becomes feasible.

  Further, the second seal member 24b surrounds at least the fuel gas supply communication hole 28a or the oxidant gas supply communication hole 26a of the frame member 23, and more than a portion corresponding to the third seal member 24c of the frame member 23. Located on the outer edge. For this reason, it is possible to reliably suppress the fuel gas from leaking from the anode side of the electrolyte / electrode assembly 20.

  Further, in the frame member 23, the thickness of the portion where the second seal member 24b is disposed (thin wall portion 23b) is set larger than the thickness of the portion where the third seal member 24c is disposed. Therefore, the thickness at the time of stacking is suppressed, and miniaturization in the stacking direction of the fuel cell stack 10 is easily performed.

DESCRIPTION OF SYMBOLS 10 ... Fuel cell stack 12 ... Solid oxide fuel cell 14 ... Electrolyte 16 ... Cathode electrode 18 ... Anode electrode 19 ... Current collector 20 ... Electrolyte / electrode assembly 22 ... Separator 24a-24c ... Seal member 26a ... Oxidant gas Supply communication hole 26b ... Oxidant gas discharge communication hole 28a ... Fuel gas supply communication hole 28b ... Fuel gas discharge communication hole 30 ... Oxidant gas passage 32 ... Fuel gas passage 34 ... Nipping part 36 ... Oxidant gas manifold part 38 ... Fuel Gas manifold section 46 ... Laminated body 70 ... Coupling member

Claims (8)

A laminate in which an electrolyte / electrode assembly configured by sandwiching an electrolyte between an anode electrode and a cathode electrode includes a solid oxide fuel cell laminated between separators, and a plurality of the solid oxide fuel cells are laminated. A fuel cell stack having a body,
The electrolyte-electrode assembly is configured such that the outer peripheral edge of the electrolyte is exposed outside the outer periphery of the cathode electrode by setting the planar dimension of the cathode electrode to be smaller than the planar dimension of the electrolyte. Part
The separator sandwiches the electrolyte / electrode assembly and supplies a fuel gas along the electrode surface of the anode electrode, and an oxidant gas supplies an oxidant gas along the electrode surface of the cathode electrode. A sandwiching portion in which the agent gas passage is individually provided on the front and back sides;
A fuel gas supply communication hole for supplying at least the fuel gas to the fuel gas passage or an oxidant gas supply communication hole for supplying the oxidant gas to the oxidant gas passage is formed in the stacking direction. Manifold section,
While comprising
Between the separators, there is interposed a frame member that is located outside the electrolyte-electrode assembly across the electrolyte exposed portion and at least the fuel gas supply communication hole or the oxidant gas supply communication hole is formed. Dressed,
A first seal member is disposed between the frame member and the surface of the separator on the oxidant gas passage side, and a first seal member is disposed between the frame member and the surface of the separator on the fuel gas passage side. 2 seal members are disposed, and a third seal member is disposed between the frame member and the electrolyte exposing portion,
The softening point of the first seal member is lower than the softening point of the second seal member, and the softening point of the first seal member is set lower than the softening point of the third seal member. A fuel cell stack. The fuel cell stack according to claim 1, wherein the first seal member, the second seal member, and the third seal member are glass-based seal members,
The glass component content ratio of the first seal member is higher than the glass component content ratio of the second seal member, and the glass component content ratio of the first seal member is a glass component content ratio of the third seal member. A fuel cell stack characterized by being set higher than the above. The fuel cell stack according to claim 1, wherein the first seal member, the second seal member, and the third seal member are glass-based seal members,
The non-glass component content ratio of the first seal member is lower than the non-glass component content ratio of the second seal member, and the non-glass component content ratio of the first seal member is the non-glass component content ratio of the third seal member. A fuel cell stack, wherein the fuel cell stack is set lower than the glass component content ratio.   4. The fuel cell stack according to claim 1, wherein the second seal member and the third seal member are made of the same material. 5.   5. The fuel cell stack according to claim 1, wherein a softening point of the first seal member is lower than an operating temperature of the solid oxide fuel cell, and the second seal member and The fuel cell stack, wherein the softening point of the third seal member is higher than the operating temperature.   The fuel cell stack according to any one of claims 1 to 5, wherein the second seal member surrounds at least the fuel gas supply communication hole or the oxidant gas supply communication hole of the frame member, and The fuel cell stack, wherein the fuel cell stack is disposed on an outer edge of a portion of the frame member corresponding to the third seal member.   The fuel cell stack according to any one of claims 1 to 6, wherein the frame member has a thickness of a portion where the second seal member is disposed, and a thickness of a portion where the third seal member is disposed. A fuel cell stack characterized in that the fuel cell stack is set larger than the above. A laminate in which an electrolyte / electrode assembly configured by sandwiching an electrolyte between an anode electrode and a cathode electrode includes a solid oxide fuel cell laminated between separators, and a plurality of the solid oxide fuel cells are laminated. Having a body,
The electrolyte-electrode assembly is configured such that the outer peripheral edge of the electrolyte is exposed outside the outer periphery of the cathode electrode by setting the planar dimension of the cathode electrode to be smaller than the planar dimension of the electrolyte. Part
The separator sandwiches the electrolyte / electrode assembly and supplies a fuel gas along the electrode surface of the anode electrode, and an oxidant gas supplies an oxidant gas along the electrode surface of the cathode electrode. A sandwiching portion in which the agent gas passage is individually provided on the front and back sides;
A fuel gas supply communication hole for supplying at least the fuel gas to the fuel gas passage or an oxidant gas supply communication hole for supplying the oxidant gas to the oxidant gas passage is formed in the stacking direction. Manifold section,
A method of manufacturing a fuel cell stack comprising:
A first step of firing a precursor of the electrolyte / electrode assembly to obtain a fired body;
A surface of the separator on the fuel gas passage side corresponding to the fuel gas passage surrounds the fired body, the fired body, and corresponds to at least the fuel gas supply communication hole or the oxidant gas supply communication hole. A second seal member, a third seal member corresponding to the electrolyte exposed portion, and an outer side of the electrolyte / electrode assembly across the electrolyte exposed portion and at least the fuel gas supply communication hole or A second step in which the frame members in which the oxidant gas supply communication holes are formed are disposed, and these are integrally fired to obtain a coupling member;
The coupling members are stacked, a current collector is disposed corresponding to the cathode electrode, and the frame member constituting one of the coupling members and the other coupling adjacent to the one coupling member A third step of interposing a first seal member between the surface of the separator constituting the member on the side of the oxidant gas passage side and firing them;
Have
The softening point of the first seal member is lower than the softening point of the second seal member, and the softening point of the first seal member is set lower than the softening point of the third seal member. A method for manufacturing a fuel cell stack.

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