JP2007123004A - Fuel battery cell, cell stack as well as fuel battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel battery cell capable of suppressing deformation, a cell stack, and a fuel battery. <P>SOLUTION: The fuel battery cell is equipped with a power generating element 45 in which a solid electrolyte 33 is interposed between a fuel electrode layer 32 and an oxygen electrode layer 34, and a support substrate on which the power generating element 45 is installed. A recessed groove 47 is provided at the outside of the support substrate 31 in the position where the power generating element 45 is installed and the space between the recessed groove 47 and the fuel electrode layer 32 is made a gas passage 31a. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a fuel cell, a cell stack, and a fuel cell, and more particularly, to a fuel cell, a cell stack, and a fuel cell in which a power generation element having a solid electrolyte sandwiched between an inner electrode and an outer electrode is provided on a support. is there.

  In recent years, various fuel cells in which a stack of fuel cells is accommodated in a storage container have been proposed as next-generation energy.

  FIG. 6 shows a cell stack of a conventional hollow plate type solid oxide fuel cell. This cell stack gathers a plurality of fuel cells 13 (13a, 13b), A current collecting member 15 made of metal felt or the like is interposed between the other fuel cell 13b, and an inner electrode (oxygen side electrode) 17 of one fuel cell 13a and an outer electrode (fuel) of the other fuel cell 13b. Side electrode) 18 is electrically connected.

  The fuel cell 13 (13 a, 13 b) is configured by sequentially providing a solid electrolyte 19 and an outer electrode 18 on the outer peripheral surface of the flat inner electrode 17, and the inner electrode exposed from the solid electrolyte 19 and the outer electrode 18. 17 is provided with an interconnector 20 so as not to be connected to the outer electrode 18. A plurality of gas passages 22 constituting gas passages are formed in the inner electrode 17.

The electrical connection between one fuel battery cell 13a and the other fuel battery cell 13b is performed by connecting the inner electrode 17 of one fuel battery cell 13a via the interconnector 20 and the current collecting member 15 provided on the inner electrode 17. Then, it is performed by connecting to the outer electrode 18 of the other fuel battery cell 13b (see, for example, Patent Documents 1 and 2).
JP-A-1-169878 Japanese Patent Laid-Open No. 2004-234969

  However, in the fuel cell described above, the inner electrode 17 is porous because it is necessary to supply gas from the gas passage 22 to the solid electrolyte 9, and the strength is inevitably low. When layers made of different materials are formed on both main surfaces, there is a problem of warping after firing or during power generation. In particular, in recent years, the support (inner electrode 17) is being thinned in order to obtain a small and high-power fuel cell, and the thinner the support, the lower the strength of the support, There was a problem that warpage was likely to occur.

  Further, a solid electrolyte 19 is continuously formed on the one side main surface of the inner electrode 17 in the gas passage formation direction, and the other side main surface is continuous in the gas passage formation direction so as to face the solid electrolyte 19. The interconnector 20 is formed, and layers made of different materials (different thermal expansion coefficients and the like) are formed on the opposing main surfaces of the inner electrode 17, so that the fuel cell is shown during power generation. As shown in FIG. 7, there is a problem that the interconnector 20 side warps so as to be back.

That is, the fuel cell is usually produced by sintering in the atmosphere and exposed to a reducing gas during power generation. However, the interconnector material made of LaCrO ₃ system usually causes a dimensional change in a reducing atmosphere. It is known that there is a problem that the fuel cell is deformed due to the dimensional change in the reducing atmosphere.

That is, the solid electrolyte 19 made of ZrO ₂ , CeO ₂ , lanthanum gallate, or the like formed on one main surface of the inner electrode 17 has a small dimensional change in a reducing atmosphere, but is provided on the other main surface. The resulting interconnector 20 has a large dimensional change in a reducing atmosphere, and therefore, as shown in FIG. 7, there is a problem that the fuel cell warps with the interconnector side facing away (so that the interconnector side is convex). .

  The warpage of the fuel battery cell occurs not only in the case of bowing in the length direction as shown in FIG. 7 (a-2) but also in the width direction as shown in FIG. 7 (a-3). In particular, in order to increase the amount of power generated per cell, the problem is that if the length of the fuel cell is increased, it tends to warp in the length direction, and if the width of the fuel cell is increased, it tends to warp in the width direction. was there.

  In addition, the cell stack is manufactured by connecting a plurality of fuel cells with current collecting members. However, as described above, when the fuel cells are warped, electrical connection by the current collecting members of the plurality of fuel cells is performed. There was a problem that it was canceled and it was impossible to collect power from a plurality of fuel cells.

  On the other hand, even during firing, there is a problem of deformation due to a difference in thermal expansion coefficient between the solid electrolyte material and the interconnector material.

  An object of the present invention is to provide a fuel cell, a cell stack, and a fuel cell that can suppress deformation.

  The fuel cell of the present invention includes a power generation element in which a solid electrolyte is sandwiched between an inner electrode and an outer electrode, and a support on which the inner electrode side of the power generation element is provided, and at a position where the power generation element is provided. A concave groove is provided on the outer surface of the support, and a space between the concave groove and the inner electrode serves as a gas passage.

  In such a fuel cell, since the gas flows through the gas passage formed by the space between the concave groove and the inner electrode, and the inner electrode faces the gas passage, the gas flowing through the gas passage is porous inside. It can diffuse to the solid electrolyte through the electrode. Therefore, since it is not necessary to make the support porous so that gas can permeate unlike the conventional case, the support can be made denser and the support strength can be improved.

Thereby, even when layers having different firing shrinkage rates and thermal expansion coefficients are formed on the outer peripheral surface of the support, it is possible to prevent the fuel cell from warping.

  Further, since the Young's modulus of the support can be increased and it is not necessary to separately form a gas passage at the center of the support as in the prior art, the thickness of the support is reduced when it is in the form of a substrate. In addition, the amount of the support material used can be reduced, the cost can be reduced, and the resistance can be reduced when the support is conductive.

  In the fuel cell according to the present invention, the support is plate-shaped, and the power generation element is provided on a main surface of the support. In such a fuel cell, since it is not necessary to give the support a gas diffusion function, the strength can be improved without worrying about the porosity, the thickness of the support can be reduced, and the size can be reduced. In addition, when the support is conductive, the electrical resistance between the power generation element formed at the opposing position and the interconnector can be reduced, and the power generation performance can be improved.

  Furthermore, the fuel battery cell of the present invention is characterized in that an interconnector is formed at a position of the support body facing the power generation element. In such a case, since different material layers are formed at opposite positions of the support, warping is likely to occur. However, according to the present invention, the support is not required to be porous. Even if the Young's modulus can be improved and the interconnector is formed at a position facing the power generation element of the support, the warpage of the fuel cell can be suppressed.

  Moreover, the fuel cell of the present invention is characterized in that the support is conductive. In such a fuel cell, the support can be made dense to improve the support strength, and the support thickness can be reduced. For example, when an interconnector is formed at a position facing the power generation element of the support. Can reduce the electrical resistance between the inner electrode of the power generation element and the interconnector, improve the current collection characteristics, and improve the power generation performance.

  Furthermore, in the fuel cell of the present invention, an interconnector is formed at a position facing the power generating element of the support, the support is insulative, and a via-hole conductor provided on the support Thus, the inner electrode of the power generation element and the interconnector are electrically connected.

  In such a fuel battery cell, since the support body can be made of an insulator material, the fuel battery cell can be manufactured at low cost, and the inside of the power generation element provided at a position facing through the support body. The electrode and the interconnector can be electrically connected by a via hole conductor.

  In the fuel cell of the present invention, the support is dense. In such a fuel cell, since the support is dense, the gas passing through the gas passage permeates the support and can prevent gas leakage from the support surface.

  Furthermore, the fuel battery cell of the present invention is characterized in that the support is porous and a portion other than the power generation element of the support is covered with a dense layer. In such a fuel battery cell, since the porosity of the support is not concerned, it can be made suitable, and even in such a support, the outer surface of the support other than the power generation element is dense. Since it is covered with the material layer, the gas passing through the gas passage can be prevented from diffusing and leaking from the support.

  In the cell stack of the present invention, the fuel battery cells are erected on a plurality of gas manifolds, the gas in the gas manifold passes through the gas passages of the fuel battery cells, and the plurality of fuel battery cells are electrically connected. Are connected in series. In such a cell stack, since the warpage of the standing fuel cell is suppressed, for example, even when a current collecting member is arranged between the cells and the cells are electrically connected to each other, Electrical connection reliability can be improved. Furthermore, since the strength of the cell can be improved, breakage at the portion fixed to the manifold of the cell can be prevented.

  The fuel cell of the present invention is characterized in that the cell stack is accommodated in a storage container. In such a fuel cell, warpage can be suppressed and the connection reliability between cells can be improved, so that long-term reliability can be improved.

  In the fuel cell of the present invention, gas flows through the gas passage formed by the space between the concave groove and the inner electrode, and the inner electrode faces the gas passage, so that the gas flowing through the gas passage is porous inside. It can diffuse to the solid electrolyte through the electrode. As a result, it is not necessary to make the support porous so that gas can permeate as in the conventional case, so that the support can be made denser, the strength and Young's modulus of the support can be improved, and the warpage of the fuel cell is improved. Can be suppressed.

  In addition, the strength of the support can be increased, and since it is not necessary to separately form a gas passage in the center of the support as in the prior art, when the support is in the form of a substrate, its thickness can be reduced. The amount of the support material used can be reduced, the cost can be reduced, and the resistance can be reduced when the support is conductive.

  In FIG. 1 showing a cross section of the fuel battery cell of the present invention, and in FIG. 2 showing a perspective view, the fuel battery cell shown as 30 as a whole is in the shape of a hollow flat plate, the cross section is flat, and the overall shape is an elongated substrate. Support substrate (support) 31 is provided. On the outer surface of the support substrate 31, a plurality of fuel gas passages 31 a (forming gas passages) are formed penetrating in the length direction (axial length direction) at appropriate intervals. The support substrate 31 has a structure in which various members are provided on the main surface. A plurality of such fuel cells 30 are connected to each other in series by a current collecting member 40 as shown in FIG. 3, thereby forming a cell stack constituting the fuel cell.

  As can be understood from the shape shown in FIGS. 1 and 2, the support substrate 31 includes a flat portion A and arcuate portions B at both ends of the flat portion A, and the flat portion A constitutes a main surface. . Both main surfaces of the flat portion A are formed substantially parallel to each other, and a fuel electrode layer (inner electrode) 32 is provided so as to cover one main surface of the flat portion A and the arc-shaped portions B on both sides, A dense solid electrolyte layer 33 is laminated so as to cover the fuel electrode layer 32, and one of the flat portions A is disposed on the solid electrolyte layer 33 so as to face the fuel electrode layer 32. An oxygen electrode layer (outer electrode) 34 is laminated on the main surface. The fuel electrode layer 32 and the solid electrolyte layer 33 are continuously formed on one main surface of the flat portion A in the gas flow path forming direction.

  In the fuel cell of the present invention, the portion sandwiched between the fuel electrode layer 32 and the oxygen electrode layer 34 is a portion that substantially generates power, that is, a power generation element 45, and the position where the power generation element 45 is provided. Seven concave grooves 47 are provided on the outer surface (one main surface, in other words, one flat portion A) of the support substrate 31, and the space between the concave grooves 47 and the fuel electrode layer 32 is defined as the fuel gas passage 31a. Has been. An interconnector 35 is formed at a position of the support substrate 31 facing the power generation element 45 (the other main surface, in other words, the other flat portion A).

  That is, seven linear concave grooves 47 extending in the length direction at predetermined intervals in the width direction are formed on the one side main surface of the support substrate 31. The power generation element 45 is provided on one main surface of the support substrate 31 so as to close the groove 47, and a fuel gas passage 31a is formed between the fuel electrode layer 32 of the power generation element 45 and the concave groove 47.

  Thus, seven fuel gas passages 31a are formed, which are formed in the length direction (axial length direction) of the fuel cell, and the fuel gas passing through the fuel gas passage 31a passes through the fuel electrode layer 32. The solid electrolyte layer 33 can be diffused. Note that the thickness of the fuel electrode layer 32 is desirably 0.5 to 2 mm, which is thicker than before, from the viewpoint of sufficiently diffusing the fuel gas through the fuel electrode layer 32 to the solid electrolyte layer 33.

  In the above example, the linear groove 47 is formed to form the linear fuel gas passage 31a. However, the shape of the groove 47 may be, for example, a meandering shape. It can correspond to any shape. Further, although the seven concave grooves 47 are formed, for example, one concave groove 47 can be formed in a meandering manner in the fuel cell, and one fuel gas passage 31a can be formed.

  Furthermore, a groove can be formed so as to intersect the seven linear grooves 47, that is, a passage connecting the seven fuel gas passages 31a can be formed. In this case, the fuel gas can be sufficiently supplied to the power generation element 45.

  In the present invention, seven concave grooves 47 are provided on one main surface of the support substrate 31 and the space between the concave grooves 47 and the fuel electrode layer 32 is used as the fuel gas passage 31a. In addition, the function of supplying and diffusing the fuel gas is not provided, and thus the porosity of the support substrate 31 is not considered, and more specifically, the support substrate 31 can be dense, and the support substrate 31 can be made dense. Even if a layer made of a different material is formed on both opposing main surfaces of the support substrate 31, the warpage amount of the fuel battery cell 30, particularly the length direction of the fuel battery cell, can be improved. The amount of warpage in can be reduced.

  In the fuel cell of the present invention, the length of the support substrate 31 is 120 mm or more, the thickness of the support substrate 31 (the distance between the flat portions A and A) is 8 mm or less, and the width (the distance between the arc-shaped portions BB) is 20 mm. It can be used suitably when it is above. That is, in a hollow flat plate type fuel cell, when the length is long, as shown in FIG. 7 (a-2), when the cell is viewed in the length direction, it is easy to warp like a bow with the interconnector side as the back. Therefore, the present invention can be used effectively, and when the width is widened, as shown in FIG. 7 (a-3), when the fuel cell is viewed in the width direction, that is, in the width direction. In addition, the present invention can be used effectively because it tends to warp in a crescent shape with the interconnector side as the back.

  Further, when the thickness of the support substrate of the fuel cell is 8 mm or less, the distance between the main surfaces facing each other is small, so that the fuel cell tends to warp in the length direction and the width direction, so that the present invention can be used effectively. .

  In the fuel cell having the above structure, the portion of the fuel electrode layer 32 facing the oxygen electrode layer 34 operates as a fuel electrode to generate electric power. That is, an oxygen-containing gas such as air is allowed to flow outside the oxygen electrode layer 34, and a fuel gas (hydrogen) is supplied to the gas passage 31a of the support substrate 31 and heated to a predetermined operating temperature. Electricity is generated by generating an electrode reaction of the following formula (1) and generating an electrode reaction of the following formula (2), for example, at the portion of the fuel electrode layer 32 that becomes the fuel electrode.

Oxygen electrode: 1 / 2O ₂ + 2e ⁻ → O ²⁻ (solid electrolyte) (1)
Fuel electrode: O ²⁻ (solid electrolyte) + H ₂ → H ₂ O + 2e ⁻ (2)
The current generated by the power generation is collected through the interconnector 35 attached to the support substrate 31.

  In such a fuel battery cell, the support substrate 31 has conductivity, and the solid electrolyte layer 33 is formed on one main surface of the conductive support substrate 31 with the fuel electrode layer 32 interposed therebetween. Since the support substrate 31 required for the gas and the fuel electrode layer 32 required for the reactivity with the gas are separately formed, the material, the structure and the like corresponding to each function can be used. This can be easily performed, and an optimal fuel cell can be produced.

  An interconnector 35 is formed on the other main surface of the flat portion A where the fuel electrode layer 32 and the solid electrode layer 33 are not stacked. As is clear from FIG. 1, the fuel electrode layer 32 and the solid electrolyte layer 33 extend to both sides of the interconnector 35 and are configured so that the surface of the support substrate 31 is not exposed to the outside.

(Support substrate 31)
In the fuel cell 30 having the above-described structure, the support substrate 31 is made conductive to collect current via the interconnector 35, and cracks such as solid electrolyte due to thermal expansion difference during simultaneous firing Although it is required that there is no exfoliation, the catalytically active metal and its oxidation are satisfied for the purpose of satisfying such a requirement and at the same time suppressing cracks such as solid electrolyte caused by volume expansion of the support substrate 31 in the reduction / oxidation cycle. And an inorganic aggregate that does not generate a reaction product of the catalytic metal and its oxide, for example, a solid electrolyte that is a metal oxide or a rare earth element oxide containing at least one rare earth element To do.

  As the catalyst metal, there are iron group components such as Fe, Co, and Ni, which may be a single metal, or an oxide, an alloy, or an alloy oxide. In the present invention, any of them can be used, but it is preferable that Ni and / or NiO are contained because they are inexpensive and stable in fuel gas.

Further, as the inorganic aggregate, the solid electrolyte layer 33 is formed in order to increase the so-called three-phase interface (electrolyte / catalyst metal / gas phase interface) in order to promote the electrode reaction of (2). A material equivalent to zirconia bromide, a lanthanum gallate-based perovskite type composition, or the like may be used, or a rare earth oxide may be used to lower the thermal expansion coefficient and approximate the solid electrolyte layer 33. In particular, an oxide containing at least one rare earth element selected from the group consisting of Sc, Y, Lu, Yb, Tm, Er, Ho, Dy, Gd, Sm, and Pr is used for the latter. Specific examples of such rare earth _{oxides, Sc 2 O 3, Y 2} O 3, Lu 2 O 3, Yb 2 O 3, Tm 2 O 3, Er 2 O 3, Ho 2 O 3, Dy 2 O ₃ , Gd ₂ O ₃ , Sm ₂ O ₃ , Pr ₂ O ₃ can be exemplified, and Y ₂ O ₃ , Yb ₂ O ₃ , and Y ₂ O ₃ are preferable in that they are particularly inexpensive. is there.

  The support substrate 31 may contain other metal components and oxide components as long as required characteristics are not impaired.

  The support substrate 31 as described above does not need to have fuel gas permeability as in the conventional case, but in this example, the support substrate 31 is porous having a predetermined porosity. Further, the conductivity of the support substrate 31 is preferably 300 S / cm or more, and particularly preferably 440 S / cm or more. In order to prevent leakage of the fuel gas from the support substrate 31, the outer surface of the support substrate 31 is covered with a dense layer (solid electrolyte 33 and interconnector 35).

  Further, the length of the flat portion A of the support substrate 31 is 20 to 35 mm, the length of the arc-shaped portion B (the length of the arc) is about 3 to 8 mm, and the thickness of the support substrate 31 is (of the flat portion A). The distance between both surfaces is preferably 2.5 to 8 mm.

(Fuel electrode layer 32)
In the present invention, the fuel electrode layer 32 causes the electrode reaction of the above-described formula (2), and is formed of a known porous conductive ceramic. For example, it is formed from ZrO ₂ in which a rare earth element is dissolved, and Ni and / or NiO. As ZrO ₂ (stabilized zirconia) in which the rare earth element is dissolved, the same one used for forming the solid electrolyte layer 33 described below is preferably used.

  The stabilized zirconia content in the fuel electrode layer 32 is preferably in the range of 35 to 65% by volume, and the Ni or NiO content is preferably 65 to 35% by volume. Further, the open porosity of the fuel electrode layer 32 is preferably 15% or more, particularly preferably in the range of 20 to 40%, and the thickness is preferably 1 to 30 μm. For example, if the thickness of the fuel electrode layer 32 is too thin, the performance may be deteriorated, and if it is too thick, there is a risk of peeling due to a difference in thermal expansion between the solid electrolyte layer 33 and the fuel electrode layer 32. .

  In the example of FIG. 1, the fuel electrode layer 32 extends to both sides of the interconnector 35, but is present at a position facing the oxygen electrode layer 34, in other words, only the portion of the power generation element 45 is fueled. Since the electrode only needs to be formed, for example, the fuel electrode layer 32 may be formed only in the flat portion A on the side where the oxygen electrode layer 34 is provided. Furthermore, the fuel electrode layer 32 can be formed over the entire circumference of the support substrate 31. In the present invention, it is preferable that the entire solid electrolyte layer 33 is formed on the fuel electrode layer 32 in order to increase the bonding strength between the solid electrolyte layer 33 and the support substrate 31.

  In order to sufficiently supply the fuel gas from the fuel gas passage 31 a to the solid electrolyte layer 33, the thickness of the fuel electrode layer 32 of the power generation element 45 is set to 0.5 to 2 mm, which is larger than the conventional one. It is desirable to allow the fuel gas to diffuse.

(Solid electrolyte layer 33)
The solid electrolyte layer 33 provided on the fuel electrode layer 32 is generally formed of a dense ceramic called ZrO ₂ (usually stabilized zirconia) in which 3 to 15 mol% of a rare earth element is dissolved. . Examples of rare earth elements include Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu, but they are inexpensive. From the point, Y and Yb are desirable.

  The stabilized zirconia ceramics forming the solid electrolyte layer 33 is desirably a dense material having a relative density (according to Archimedes method) of 93% or more, particularly 95% or more from the viewpoint of preventing gas permeation. It is desirable that the thickness is 10 to 100 μm. The solid electrolyte layer 33 may be composed of a lanthanum gallate perovskite type composition in addition to stabilized zirconia.

(Oxygen electrode layer 34)
The oxygen electrode layer 34 is formed of a conductive ceramic made of a so-called ABO ₃ type perovskite oxide. As such a perovskite oxide, at least one of transition metal perovskite oxides, particularly LaMnO ₃ oxides, LaFeO ₃ oxides, and LaCoO ₃ oxides having La at the A site is preferable. LaFeO ₃ -based oxides are particularly suitable because they have high electrical conductivity at an operating temperature of about 1000 ° C. In the perovskite oxide, Sr and the like may exist together with La at the A site, and Co and Mn may exist together with Fe at the B site.

  The oxygen electrode layer 34 must have gas permeability. Therefore, the conductive ceramic (perovskite oxide) forming the oxygen electrode layer 34 has an open porosity of 20% or more, particularly 30. It is desirable to be in the range of ˜50%.

  The thickness of the oxygen electrode layer 34 is preferably 30 to 100 μm from the viewpoint of current collection.

(Interconnector 35)
The interconnector 35 provided on the support substrate 31 at the position facing the oxygen electrode layer 34 is made of conductive ceramics, but is in contact with the fuel gas (hydrogen) and the oxygen-containing gas. It is necessary to have oxidation resistance. For this reason, lanthanum chromite perovskite oxides (LaCrO ₃ oxides) are generally used as the conductive ceramics. Further, in order to prevent leakage of the fuel gas passing through the fuel gas passage 31a and the oxygen-containing gas passing through the outside of the support substrate 31, such conductive ceramics must be dense, for example, 93% or more, particularly 95% or more. It is preferable to have a relative density of

  The interconnector 35 is desirably 10 to 200 μm from the viewpoint of preventing gas leakage and electrical resistance. That is, if the thickness is smaller than this range, gas leakage is likely to occur, and if the thickness is larger than this range, the electric resistance is large, and the current collecting function may be reduced due to a potential drop. . On the other hand, 100 μm or less is desirable from the viewpoint of warpage suppression.

Further, as is clear from FIG. 1, in order to prevent gas leakage, a dense solid electrolyte layer 33 is in close contact with both sides of the interconnector 35. _A bonding layer (not shown) made of ₂ O ₃ or the like can be provided between both side surfaces of the interconnector 35 and the solid electrolyte layer 33.

  A P-type semiconductor layer 39 is provided on the outer surface (upper surface) of the interconnector 35. By connecting the current collecting member 40 to the interconnector 35 via the P-type semiconductor layer 39, the contact between the two becomes an ohmic contact, the potential drop can be reduced, and the deterioration of the current collecting performance can be effectively avoided. Thus, for example, the current from the oxygen electrode layer 34 of one fuel battery cell 30 can be efficiently transmitted to the support substrate 31 of the other fuel battery cell 30. As such a P-type semiconductor, a transition metal perovskite oxide can be exemplified.

Specifically, those having higher electronic conductivity than LaCrO ₃ oxides constituting the interconnector 35, for example, LaMnO ₃ oxides and LaFeO ₃ oxides in which Mn, Fe, Co, etc. exist at the B site P-type semiconductor ceramics made of at least one of LaCoO ₃ -based oxides can be used. In general, the thickness of the P-type semiconductor layer 39 is preferably in the range of 30 to 100 μm.

  The interconnector 35 can also be provided directly on the flat portion A of the support substrate 31 on the side where the solid electrolyte layer 33 is not provided, but this portion is also provided with a fuel electrode material, and this fuel electrode material layer. An interconnector 35 is provided on 37. That is, the fuel electrode material is provided over the entire circumference of the support substrate 31, and the interconnector 35 is provided on the fuel electrode material layer 37. In this case, at the interface between the support substrate 31 and the interconnector 35. This is advantageous in that the potential drop can be suppressed.

(Manufacture of fuel cells)
The fuel battery cell having the above structure is manufactured as follows. First, an iron group metal such as Ni or its oxide powder, for example, Y ₂ O ₃ powder, an organic binder, and a solvent are mixed to prepare a clay, and by extrusion molding using this clay, A support substrate molding is produced and dried. The concave groove of the support substrate can be formed at the time of extrusion molding.

  Next, a fuel-side electrode forming material (Ni or NiO powder and stabilized zirconia powder), an organic binder and a solvent are mixed to prepare a slurry, and a sheet for the fuel-side electrode is prepared using this slurry.

  Further, a stabilized zirconia powder, an organic binder, and a solvent are mixed to prepare a slurry, and a solid electrolyte layer sheet is prepared using the slurry, and the fuel electrolyte electrode sheet is added to the solid electrolyte layer sheet. Then, this composite sheet is laminated so as to have a layer structure as shown in FIG. 1 and dried.

  In addition, when the concave groove 47 is large or the like, when it is difficult to laminate and form the composite sheet (when unevenness is formed on the surface of the composite sheet after lamination), the resin material scattered in the concave groove 47 during firing. May be filled.

The support substrate calcined body is composed of iron group metal such as Ni or oxide particles thereof and Y ₂ O ₃ particles, and the fuel side electrode calcined body is composed of Ni or NiO particles and stabilized zirconia particles. Thus, the solid electrolyte molded body is composed of a stabilized zirconia powder and an organic component.

Thereafter, the interconnector material (e.g., LaCrO ₃ based oxide powder), an organic binder and a solvent were mixed to prepare a slurry, to produce the interconnector sheet. This interconnector sheet is laminated at a position where the solid electrolyte layer of the laminate obtained above is not formed, to produce a laminate for firing.

Next, the above laminate for firing is subjected to a binder removal treatment, and co-fired at 1300 to 1600 ° C. in an oxygen-containing atmosphere, and an oxygen-side electrode forming material (for example, LaFeO) is placed at a predetermined position of the obtained sintered body. ₃ type oxide powder) and a paste containing a solvent, and if necessary, a paste containing a P-type semiconductor layer forming material (for example, LaFeO ₃ type oxide powder) and a solvent is applied by dipping or the like, and 1000-1300 By baking at a temperature of 0 ° C., the fuel cell 30 of the present invention having the structure shown in FIG. 1 can be manufactured.

  In the case where Ni alone is used to form the support substrate 31 and the fuel side electrode 32, Ni is oxidized to NiO by firing in an oxygen-containing atmosphere. , Ni can be returned.

(Cell stack)
As shown in FIG. 3, the cell stack includes a plurality of the fuel cells 30 described above, and a metal felt and / or between one fuel cell 30 and the other fuel cell 30 adjacent to each other in the vertical direction. A current collecting member 40 made of a metal plate is interposed, and both are connected in series with each other. In a state where the plurality of fuel cells 30 are stacked via the current collecting member 40, as shown in FIGS. 4A and 4B, the lower end portion is fixed to the fixed plate 61, and the upper surface of the fixed plate 61 is A cell stack in which a plurality of fuel cells 30 are erected on the manifold 65 is formed as an upper cover of the opened casing-like manifold body 63, and the fuel gas in the manifold 65 is fuel. The battery cell 30 is configured to pass through the gas passage 31a.

  That is, the support substrate 31 of one fuel cell 30 is electrically connected to the oxygen electrode layer 34 of the other fuel cell 30 via the interconnector 35, the P-type semiconductor layer 39, and the current collecting member 40. Yes. Such cell stacks are arranged side by side as shown in FIG. 3, and adjacent cell stacks are connected in series by a conductive member 42.

  The fuel cell of the present invention is configured by accommodating the cell stack of FIG. 3 in a storage container. The storage container is provided with an introduction pipe for introducing a fuel gas such as hydrogen into the fuel battery cell 30 from the outside, and an introduction pipe for introducing an oxygen-containing gas such as air into the external space of the fuel battery cell 30. The fuel cell is heated to a predetermined temperature (for example, 600 to 900 ° C.) to generate electric power, and the used fuel gas and oxygen-containing gas are discharged out of the storage container.

  In addition, this invention is not limited to the said form, A various change is possible in the range which does not change the summary of invention. For example, in the above embodiment, the case where the fuel electrode layer 32 is formed on the support substrate 31 has been described. However, an oxygen electrode layer, a solid electrolyte, and a fuel electrode layer may be formed on the support substrate.

  In the above embodiment, the case where the support substrate 31 is conductive has been described. However, when the support substrate 31 is insulative, a through-hole penetrating in the thickness direction is formed in the support substrate 31 as shown in FIG. The via hole conductor 51 can be formed by filling the through hole with a conductive material, and the fuel electrode layer 32 of the power generation element 45 and the interconnector 35 can be electrically connected by the via hole conductor 51. In this case, the support substrate material can be selected from various types of materials, and the support substrate can be made denser. The portions other than the power generation element 45 and the interconnector 35 can be made of a dense solid electrolyte layer. There is no need for coating, and manufacturing is facilitated.

The fuel cell of this invention is shown, (a) is a cross-sectional view, (b) is a longitudinal cross-sectional view which follows the XX line of (a). (A) is a cross-sectional perspective view of the fuel battery cell of this invention, (b) is a cross-sectional perspective view of a support substrate. It is a cross-sectional view showing a stack of fuel cells of the present invention. The fuel cell is shown in a standing state on the manifold, (a) is a perspective view showing a state where a fixing plate to which the fuel cell is fixed is fitted into the opening of the manifold body, and (b) is (a). (C) is a perspective view showing a state in which a fixing plate to which a fuel cell is fixed is fitted into an opening of a manifold body. The support substrate shows an insulating fuel cell, where (a) is a cross-sectional perspective view and (b) is a cross-sectional perspective view of the support substrate. It is a cross-sectional view showing a stack of conventional fuel cells. It is explanatory drawing which shows the relationship between the formation state of an interconnector, and a deformation | transformation.

Explanation of symbols

31 ... Support substrate (support)
31a ... Fuel gas passage 32 ... Fuel electrode layer (inner electrode)
33 ... Solid electrolyte 34 ... Oxygen electrode layer (outer electrode)
35 ... interconnector 40 ... current collecting member 45 ... power generation element 47 ... concave groove 51 ... via hole conductor 65 ... manifold

Claims (9)

A power generating element comprising a solid electrolyte sandwiched between an inner electrode and an outer electrode, and a support provided on the inner electrode side of the power generating element, and a groove on the outer surface of the support at a position where the power generating element is provided And a space between the groove and the inner electrode is used as a gas passage. The fuel cell according to claim 1, wherein the support has a plate shape, and the power generation element is provided on a main surface of the support. The fuel cell according to claim 1, wherein an interconnector is formed at a position of the support that faces the power generation element. The fuel cell according to any one of claims 1 to 3, wherein the support is conductive. An interconnector is formed at a position of the support facing the power generation element, the support is insulative, and a via-hole conductor provided on the support supports the inner electrode of the power generation element and the interconnect. The fuel cell according to claim 1, wherein the connector is electrically connected. The fuel cell according to any one of claims 1 to 5, wherein the support is dense. The fuel cell according to any one of claims 1 to 5, wherein the support is porous and a portion of the support other than the power generation element is covered with a dense layer. The fuel cell according to any one of claims 1 to 7, wherein the fuel cell is erected on a plurality of gas manifolds, and the gas in the gas manifold passes through a gas passage of the fuel cell, and the plurality of fuel cells. A cell stack, wherein the cells are electrically connected in series. 9. A fuel cell comprising the cell stack according to claim 8 housed in a housing container.

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