JP4889288B2 - Cell stack and fuel cell - Google Patents

Description

The present invention relates to a cell stack and a fuel cell, and in particular, a fuel having a solid electrolyte layer and an electrode layer on one flat portion of a flat support having a pair of flat portions and an interconnector on the other flat portion. The present invention relates to a cell stack and a fuel cell in which a plurality of battery cells are erected and arranged, and the plurality of fuel cells are electrically connected in series.

  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. 5 shows a conventional cell stack of a hollow plate type solid oxide fuel cell. This cell stack collects a plurality of fuel cells 13 (13a, 13b), A large number of current collecting members 15 made of metal felt or the like are interposed between the other fuel battery cell 13b, and an inner electrode (oxygen side electrode) 17 of one fuel battery cell 13a and an outer electrode of the other fuel battery cell 13b ( The fuel side electrode) 18 is electrically connected.

  The fuel cell 13 (13 a, 13 b) is configured by sequentially providing a solid electrolyte layer 19 and an outer electrode 18 on the outer peripheral surface of the flat inner electrode 17, and is exposed from the solid electrolyte layer 19 and the outer electrode 18. An interconnector 20 is provided on the inner electrode 17 so as not to be connected to the outer electrode 18. A plurality of gas passage holes 22 constituting a gas flow path 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 JP-A-2005-243334

  However, in the conventional fuel cell, since many current collecting members 15 are interposed between one fuel cell 13a and the other fuel cell 13b, gas enters between these fuel cells 13a and 13b. There is a problem that power generation performance is reduced. In addition, the current collecting member 15 has to use a large number of heat resistant alloys having excellent heat resistance, which increases the cost. In addition, a large number of current collecting members 15 must be arranged and joined between the fuel cells 13a and 13b, and it takes time to manufacture. Further, since there are many joints, there is a problem that joint failure tends to occur.

  An object of the present invention is to provide a cell stack and a fuel cell that can sufficiently supply gas between fuel cells and that can easily and inexpensively electrically connect the fuel cells.

The cell stack of the present invention, the gas flow path is formed in the axial direction on one flat portion of the plate-like support having a pair of flat portions, and having a solid electrolyte layer and electrode layers, of the support A cell stack in which a plurality of fuel cells having interconnectors are arranged upright on the other flat portion opposite to the one flat portion , and the plurality of fuel cells are electrically connected in series. Te, when viewed from the arrangement direction of the fuel cells, a portion of the flat portion of the fuel cell to neighboring set is, the right and left of the plurality of fuel cells in so that be superimposed along said axial direction The flat portions of the fuel cells in the overlapping portion are joined to each other in an overlapping manner.

In such a cell stack, a plurality of fuel cells are staggered so that a part of the flat portion of the adjacent fuel cells overlaps along the axial length direction when viewed from the arrangement direction of the fuel cells. Since they are arranged in a shape (alternately on the left and right), only the end of the flat part of the fuel cell overlaps and can be joined and fixed at this part, and a space is formed between the fuel cells. Gas (fuel gas or oxygen-containing gas) can be sufficiently supplied to the fuel cells through the space between the fuel cells. In addition, the joining location can be only the end portion of the flat portion of the fuel cell, even if a current collecting member made of a heat-resistant alloy can be used, the number thereof can be greatly reduced, and the joining location can be reduced. A cell stack can be produced easily and inexpensively.

  In addition, although the fuel cell can be mechanically fixed and electrically connected to each other by using the joint portion of the fuel battery cell, the fuel cell is mechanically fixed at the joint portion by other means. The fuel cells may be electrically connected. Furthermore, you may provide the junction location which performs mechanical fixation and electrical fixation between fuel cells separately, respectively.

The cell stack of the present invention, by joining a conductive material flat portions in the superposition portion of said fuel cell to neighboring set, and characterized in that mechanically bonded together to electrically connect To do. In such a cell stack, since a current collecting member made of a heat-resistant alloy is not used, the cell stack can be manufactured more inexpensively and easily.

Furthermore, in the cell stack of the present invention, a high conductivity layer having a higher conductivity than the electrode layer and the interconnector is provided on at least one of the electrode layer and the interconnector with a width toward the overlapping portion of the fuel cell. It is provided in the direction.

The interconnector is generally made of a conductive ceramic and has high resistance. Since the electrode of the fuel cell is porous for the purpose of supplying gas to the solid electrolyte, the resistance is high. , the generated electric current, the electrodes of the fuel cell, to flow in the width direction toward the superimposing unit of the fuel cell, current that is generated in one of the fuel cell, the electrode layers, through the interconnector, the other However, there is a possibility that the power generation performance may be reduced due to a large resistance to flow to the fuel cell of the battery. Since a high conductivity layer having a higher conductivity than the connector is provided, the current generated by one fuel cell flows to the other fuel cell via the high conductivity layer, and the resistance can be reduced. , It is possible to improve the power generation performance.

Further, in the cell stack of the present invention, the electrode is disposed along the electrode layer and the interconnector in the overlapping portion of the adjacent fuel cell, and in the direction along the gas flow path of the fuel cell. A high conductivity layer having a higher conductivity than those of the interconnector and the interconnector is provided, and flat portions of the fuel cells adjacent to each other are joined by the high conductivity layer.

  In such a cell stack, the resistance can be reduced by the high conductivity layer, and the fuel cell can be mechanically fixed.

  Furthermore, the fuel cell of the present invention is characterized in that the cell stack is housed in a housing container. In such a fuel cell, since gas can be sufficiently supplied between the fuel cells, the power generation performance is improved, and the fuel cells can be easily and inexpensively connected. Obtainable.

In the cell stack of the present invention, a space is formed between the fuel cells, and gas can be sufficiently supplied to the fuel cells through the space between the fuel cells, and the power generation performance can be improved. The joining location can be performed only at the end of the flat portion of the fuel cell, and even when a current collecting member made of a heat-resistant alloy is used, the number of the current collecting members can be greatly reduced and can be easily and inexpensively manufactured.

  In FIG. 1 showing a cross section of the fuel battery cell of the present invention, and in FIG. 2 showing a cross-sectional perspective view, the fuel battery cell generally indicated by 30 has a hollow flat plate shape, a flat cross section, and a rod shape as a whole. An elongated substrate-like porous support substrate (support) 31 is provided. Inside the support substrate 31, six fuel gas passages 31a (forming gas passages) are formed penetrating in the length direction (axial direction) at appropriate intervals. The support substrate 31 has a structure in which various members are provided. As shown in FIGS. 3 and 4, by arranging a plurality of such fuel battery cells 30 alternately in the left and right direction (staggered) and connecting them in series, a cell stack constituting the fuel battery can be formed. .

  As is understood from the shapes shown in FIGS. 1A and 2A, the support substrate 31 includes a flat portion A and arcuate portions B at both ends of the flat portion A. The flat portion A constitutes the main surface. Both main surfaces of the flat part A are formed substantially parallel to each other, and a fuel electrode layer 32 is provided so as to cover one main surface of the flat part A and the arcuate parts B on both sides, and further covers the fuel electrode layer 32. In this way, a dense solid electrolyte layer 33 is laminated, and on this solid electrolyte layer 33, an oxygen electrode layer 34 is formed on one main surface of the flat portion A so as to face the fuel electrode layer 32. Are stacked. The fuel electrode layer 32 and the solid electrolyte layer 33 are continuously formed on the main surface on one side of the flat portion A in the gas flow path forming direction G.

  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.

  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 31 a in the support substrate 31, and the oxygen electrode layer 34 is heated to a predetermined operating temperature. Then, an electrode reaction of the following formula (1) is generated, and power is generated by generating an electrode reaction of the following formula (2), for example, in the portion that becomes the fuel electrode of the fuel electrode layer 32.

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 the present invention, as shown in FIGS. 1 and 2, the oxygen electrode layer 34 and the interconnector 35 are formed with first high conductivity layers 38a and 38b in the length direction of the fuel cell, The first high conductivity layers 38a and 38b are connected to the side surfaces of the oxygen electrode layer 34 and the interconnector 35, respectively, and the oxygen electrode layer 34 and the interconnector 35 are electrically connected to the first high conductivity layers 38a and 38b, respectively. Is conducting. The first high conductivity layers 38 a and 38 b are formed at positions facing each other with the support substrate 31 therebetween.

  The first high conductivity layers 38a and 38b are formed on the surface of the solid electrolyte layer 33, and are made of, for example, a noble metal alloy such as Ag—Pd, conductive ceramics, or the like. By forming on the surface of the solid electrolyte layer 33, the bonding strength of the first high conductivity layers 38a, 38b to the fuel cells can be improved, and the bonding strength between the fuel cells described later can be improved.

Further, as shown in FIGS. 2B and 2C, the oxygen electrode layer 34 and the interconnector 35 have a fuel cell width direction (described later) so as to be orthogonal to the first high conductivity layers 38a and 38b. Second high-conductivity layers 39a and 39b are formed at the joining location (from the opposite side of the overlapping flat portion ) toward the joining location. These second high conductivity layers 39a and 39b are made of, for example, a noble metal alloy such as an Ag—Pd alloy, conductive ceramics, or the like.

  The first high conductivity layer 38a and the second high conductivity layer 39a have higher conductivity than the oxygen electrode layer 34, and are formed using a material different from the oxygen electrode layer 34 as described above. However, it can be formed, for example, by applying the oxygen electrode material again to the surface of the oxygen electrode layer 34 to form a denser film than the oxygen electrode layer 34. In this case, the first high conductivity layer can be formed. The rate layer 38a and the second high conductivity layer 39a can be easily formed. Alternatively, a noble metal alloy such as an Ag—Pd alloy can be formed on the oxygen electrode layer 34 by coating. Further, the oxygen electrode layer 34 may be formed by being divided, and a layer made of a material having a higher conductivity than that of the oxygen electrode layer 34 may be formed between the divided oxygen electrode layers. In this case, the bonding strength of the first high conductivity layer 38a and the second high conductivity layer 39a to the fuel cell can be improved. Whether or not the conductivity is high can be determined from the resistance value.

The first high conductivity layer 38b and the second high conductivity layer 39b that are electrically connected to the interconnector 35 have higher conductivity than the interconnector 35. For example, the surface of the interconnector 35 has a high conductivity. conductivity material can be more formed applying, also formed by dividing the interconnector 35, also it is formed by forming a layer made of a high conductivity material between these divided interconnector it can.

  Hereinafter, each member of the fuel cell will be described in detail.

(Support substrate 31)
In the fuel cell 30 having the above-described structure, the support substrate 31 is gas permeable so as to allow the fuel gas to permeate to the fuel electrode, and conductive for collecting current via the interconnector 35. It is required that the solid electrolyte layer does not crack or peel off due to the difference in thermal expansion during simultaneous firing, and at the same time, the volume expansion of the support substrate 31 in the reduction / oxidation cycle is satisfied. For the purpose of suppressing cracks in the solid electrolyte layer and the like caused by the above, it is an inorganic aggregate that does not generate a reaction product between the catalytic active metal and its oxide and the catalytic metal and its oxide, for example, a metal oxide A solid electrolyte or a rare earth element oxide containing at least one rare earth element is included.

  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.

  Since the support substrate 31 as described above needs to have fuel gas permeability, it is usually preferable that the open porosity is 30% or more, particularly 35 to 50%. Further, the conductivity of the support substrate 31 is preferably 300 S / cm or more, and particularly preferably 440 S / cm or more.

  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 from a known porous conductive cermet. 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. .

  Further, in the example of FIG. 1, the fuel electrode layer 32 extends to both sides of the interconnector 35, but it is sufficient that the fuel electrode is formed by being present at a position facing the oxygen electrode layer 34. 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.

(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 inside of the support substrate 31 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%. It is preferable to have the above relative density.

  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.

  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.

  Next, a fuel 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 electrode is prepared using this slurry. Further, instead of producing a sheet for the fuel electrode, a paste in which a material for forming a fuel electrode is dispersed in a solvent is applied to a predetermined position of the support substrate molded body formed as described above, and dried. A coating layer may be formed. This is calcined to produce a support substrate calcined body having a fuel electrode calcined body formed on the surface thereof. Thereafter, it is desirable to impregnate the open pores of the fuel electrode calcined body with a resin material. As the resin material, an acrylic resin or the like is used. For impregnation, the resin material may be immersed in an organic solvent in which the resin is dissolved. On the other hand, the portion where the interconnector is formed is masked so that the solid electrolyte is not formed.

Thereafter, a solid electrolyte is formed on the surface of the fuel electrode calcined body by a dip coating method. First, an immersion liquid containing a solid electrolyte material is prepared, and the support substrate calcined body is immersed in the immersion liquid. As the solid electrolyte material, for example, ZrO ₂ powder in which a rare earth element is dissolved is used, and in addition, an acrylic binder as an organic binder and toluene as a solvent are added and mixed in the immersion liquid. The immersion liquid has an organic component adjusted so as to have a predetermined viscosity.

  The dipping direction is preferably dipped in the width direction of the support substrate calcined body rather than dipping in the length direction of the support substrate calcined body in the dipping solution. After the immersion, when the substrate is pulled up, it can be attached to the fuel electrode calcined body of the support substrate calcined body to form a solid electrolyte molded body.

  A porous fuel electrode calcined body is formed on the surface of the porous support substrate calcined body, and the open pores of the fuel electrode calcined body are filled with a resin material, and the surface of the fuel electrode calcined body is solid. An electrolyte molded body is formed. The open pores of the fuel electrode calcined body are not impregnated with the solid electrolyte material.

The support substrate calcined body is composed of iron group metal such as Ni or its oxide particles and Y ₂ O ₃ particles, and the fuel electrode calcined body is composed of Ni or NiO particles and stabilized zirconia particles. The solid electrolyte compact 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 electrode forming material (for example, LaFeO ₃₎ is placed at a predetermined position of the obtained sintered body. A fuel cell 30 of the present invention having the structure shown in FIG. 1 is manufactured by applying a paste containing a system oxide powder) and a solvent and a paste containing the solvent by dipping or the like and baking at 1000 to 1300 ° C. Can do.

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

  In order to form the first high conductivity layer 38a and the second high conductivity layer 39a on the oxygen electrode layer 34, as described above, the oxygen electrode forming material is again applied to a predetermined position on the surface of the oxygen electrode layer 34. It can be formed by applying the paste containing, heat-treating again, and baking. Alternatively, a paste containing a noble metal alloy such as an Ag—Pd alloy may be applied to a predetermined position on the surface of the oxygen electrode layer 34 and then heat-treated and baked. Further, the oxygen electrode layer 34 may be formed by being divided, and a paste containing a material having a higher conductivity than that of the oxygen electrode layer 34 may be applied between these divided oxygen electrode layers, followed by heat treatment and baking. it can.

  In order to form the first high conductivity layer 38b and the second high conductivity layer 39b on the interconnector 35, a precious metal alloy such as an Ag—Pd alloy is included in a predetermined position on the surface after the interconnector 35 is formed. It can also be formed by applying a paste to be applied, heat-treating and baking. Alternatively, the interconnector 35 can be formed by being divided, and a paste containing a noble metal alloy such as an Ag—Pd alloy is applied between the divided interconnectors, followed by heat treatment and baking. The second high conductivity layer 38b is formed by applying a paste along the side surface of the interconnector 35 and baking it.

(Cell stack)
As shown in FIGS. 3 and 4, the cell stack is formed by arranging a plurality of the above-described fuel cells 30 in the left and right directions (staggered) and joining the flat portions of the fuel cells. That is, when viewed from the arrangement direction of a plurality of fuel cells, the flat portions of the adjacent fuel cells are arranged in a staggered manner so as to overlap (overlapping), The flat portions of the fuel cells are joined together to form a cell stack.

  3 and 4, the first high conductivity layers 38 a and 38 b of the adjacent fuel battery cells are joined and arranged, but the first high conductivity layers 38 a and 38 b of the adjacent fuel battery cells and A current collecting member made of a metal felt and / or a metal plate may be interposed between the two, and both may be connected in series.

  As shown in FIG. 3 (b), the cell stack includes a fuel cell in which the first high conductivity layer 38a is formed on the right side when the oxygen electrode layer 34 is viewed from the side, and the oxygen electrode layer 34 from the side. Two types of fuel cells in which the first high conductivity layer 38a is formed on the left side when viewed (the first high conductivity layer 38b is located at a position facing the first high conductivity layer 38a via the support substrate 31). The first high conductivity layer 38a electrically connected to the oxygen electrode layer 34 of one fuel cell is electrically connected to the interconnector 35 of the other fuel cell. The first high conductivity layer 38b is joined to the first high conductivity layer 38b. It is also possible to bond between the first high conductivity layer 38a and the first high conductivity layer 38b of the adjacent fuel cell by using a conductive bonding material such as an Ag—Pd alloy.

  As shown in FIG. 4, such a cell stack is formed upright on the gas manifold 55. The fuel cell of the present invention accommodates the cell stack of FIGS. 3 and 4 in a storage container. Composed. 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 the cell stack of the present invention, as shown in FIGS. 3 and 4, a plurality of fuel cells 30 are arranged in a staggered manner and the flat portions of these fuel cells are joined to each other. Thus, there is no current collecting member arranged between the fuel cells to obstruct gas supply. Therefore, the fuel gas, in this embodiment, oxygen-containing gas (air, etc.) can be sufficiently supplied between the fuel cells. And the power generation performance of the fuel cell can be sufficiently exhibited.

  In addition, since the cell stack can be configured without using an expensive current collecting member made of a heat resistant alloy or the like, the manufacturing cost can be reduced. Furthermore, since there is no need to join the fuel cells at multiple locations with a current collecting member made of a heat resistant alloy, connection reliability can be improved.

  Furthermore, in the cell stack of the present invention, the generated current flows through the oxygen electrode layer 34 and the second high conductivity layers 39a and 39b formed in the interconnector 35, so that the resistance is reduced and the fuel cell is formed. Power generation performance can be improved. Furthermore, since the generated current flows to the adjacent fuel cells by the first high conductivity layers 38a, 38b having a function of mechanically connecting the fuel cells, the resistance between the fuel cells can be reduced, Power generation performance as a cell stack can be improved.

  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, the support substrate itself is provided with a function as a fuel electrode, and a solid electrolyte and an oxygen electrode layer are formed on the support substrate. Also good. Moreover, although the case where the fuel electrode layer 32 was formed on the support substrate 31 was described in the above embodiment, the function as an oxygen electrode was added to the cell in which the oxygen electrode layer was formed on the support substrate or the support substrate itself, and the support substrate 31 was supported. A solid electrolyte and a fuel electrode layer may be formed on the substrate.

  In the above embodiment, the cell stack using the hollow flat plate fuel cell is described. However, the present invention is not limited to the above embodiment, and the cell stack using the cylindrical fuel cell is also used. Applicable.

  Further, in the above embodiment, the example in which the oxygen electrode layer 34 and the second high conductivity layer 39a, 39b are formed on the interconnector 35 has been described. However, the oxygen electrode layer 34 or the interconnector 35 has the second high conductivity layer formed thereon. The fuel gas can be supplied between the fuel cells without forming the second high conductivity layer.

BRIEF DESCRIPTION OF THE DRAWINGS 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 the cross-sectional perspective view of the fuel cell of this invention, (b) is the side view which looked at the fuel cell from the oxygen electrode layer side, (c) is the side view which looked at the fuel cell from the interconnector side is there. (A) is a top view which shows the cell stack of this invention, (b) is an enlarged plan view of (a) which shows a part typically. It is a perspective view which shows the state which stood the cell stack in the manifold. It is a cross-sectional view showing a conventional cell stack.

Explanation of symbols

31 ... Support substrate (support)
31a ... Fuel gas passage (gas passage)
32 ... Fuel electrode layer 33 ... Solid electrolyte 34 ... Oxygen electrode layer 35 ... Interconnectors 38a, 38b ... First high conductivity layers 39a, 39b ... Second high conductivity layers

Claims (5)

It is in the axial direction gas flow path formed on one of the flat portion of the plate-like support having a pair of flat portions, and having a solid electrolyte layer and electrode layers, opposed to the one flat portion of the support A cell stack comprising a plurality of fuel cells each having an interconnector arranged upright on the other flat portion , and the plurality of fuel cells connected electrically in series, when viewed from the arrangement direction, a portion of the flat portion of the fuel cell to neighboring set is alternately are arranged a plurality of fuel cells to the left and right in so that be superimposed along said axial direction, overlapping unit A cell stack formed by joining flat portions of the fuel cells in the above. By joining a conductive material flat portions in the superposition portion of said fuel cell to adjacent set, the cell stack according to claim 1, characterized in that mechanically bonded together to electrically connect. A high conductivity layer having a higher conductivity than the electrode layer and the interconnector is provided in at least one of the electrode layer and the interconnector in the width direction toward the overlapping portion of the fuel cell. The cell stack according to claim 1 or 2. Higher conductivity than the electrode layer and the interconnector in the direction along the electrode layer and the interconnector in the overlapping portion of the adjacent fuel cell and the gas flow path of the fuel cell. 4. The fuel cell according to claim 1, wherein high-conductivity layers each having a high conductivity are provided, and flat portions of the fuel cells adjacent to each other are joined by the high-conductivity layers. The cell stack described.   A fuel cell comprising the cell stack according to any one of claims 1 to 4 stored in a storage container.

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