JP2006339035A - Flat plate type solid oxide fuel cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a flat plate type solid oxide fuel cell in which transmission loss of power at connection portion is reduced by increasing adhesion between each cells, and manifolds for performing supply and exhaust of the fuel gas and oxidizer gas to the unit cell can be securely sealed. <P>SOLUTION: An interconnector 12 which electrically connects the unit cells 3 and performs supply and exhaust of fuel gas and oxidizer gas to the unit cells 3 is pressed by a first pressure mechanism 4 and connects the cells 3 electrically. Manifolds M1-M4 which supply each gas to the interconnector 12 are respectively pressured by a second pressure mechanism 5. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a flat plate type solid oxide fuel cell having an electrolyte layer made of a flat plate type solid oxide, in particular, so that electrical connection of a single cell and sealing of a gas supply / exhaust pipe can be performed satisfactorily. The present invention relates to a flat plate type solid oxide fuel cell.

  A flat-type solid oxide fuel cell (SOFC) is composed of an electrolyte layer composed of a flat-plate type solid oxide, and an air electrode and a fuel electrode formed on the front and back surfaces of the electrolyte layer, respectively. A plurality of separators (hereinafter referred to as interconnectors) having passages for supplying and discharging fuel gas and oxidant gas to and from the fuel electrode and air electrode, respectively, and a plurality of the single cells are alternately stacked. By connecting them in series, a fuel cell stack (hereinafter referred to as a cell stack) is formed, and a fuel gas and an oxidant are supplied from the gas supply / exhaust passage (hereinafter referred to as a manifold) to each electrode of each single cell. The fuel cell is configured to generate power by supplying gas. Such a fuel cell has the advantages that the power generation efficiency is higher than that of other fuel cells and the operating temperature is high (700 ° to 1000 ° C.), so that high-temperature heat can be used.

  In order to increase the output voltage of the flat plate type solid oxide fuel cell, it is necessary to increase the adhesion between the cells and reduce the power transmission loss at the connection portion. Further, it is necessary to pressurize each single cell so as not to leak gas in a manifold for supplying and exhausting fuel gas and oxidant gas, and to seal the connection portion between the tubes.

  In order to manufacture a cell stack by stacking planar cells, it is necessary to electrically connect the electrode part of the cell so as not to disturb the gas supply and to supply gas to the electrode part of the cell from the outside. Manifold must be manufactured.

  Conventionally, when stacking planar cells, a manifold for supplying gas to each cell is formed by stacking cells and interconnectors and manufacturing the cell stack, and then placing the manifold over the manifold. Either a structure that seals the connection with the cell stack (external manifold type), or a structure that also has a manifold part on the interconnector, and also forms a manifold along with the stack of cells and interconnectors (internal manifold type) Things were used.

However, in the above-described external manifold type structure, it is very difficult to control the height of the stacked cell stack and seal the manifold and the cell stack, and it is difficult to design a highly reliable cell stack.
On the other hand, the internal manifold type structure has many difficulties such as ensuring insulation between each stacking stage and gas sealing within each stacking surface. Especially when using a fuel cell supported flat plate cell, it is reliable. It was difficult to realize a cell stack with high performance.

  The present invention has been made in order to solve the conventional problems inherent in the external manifold type and the internal manifold type described above. The purpose of the present invention is to increase the adhesion between the cells and increase the power at the connection portion. A flat solid oxide fuel that reduces gas transmission loss and reliably seals a manifold for supplying and exhausting fuel gas and oxidant gas to a single cell to prevent gas leakage To provide a battery.

  In order to achieve the above object, the present invention comprises a flat single cell formed of an electrolyte layer made of a flat solid oxide, an air electrode and a fuel electrode covering the front and back surfaces of the electrolyte layer, and an interconnector. A flat-plate solid oxide fuel cell for generating electric power, comprising a cell stack formed by alternately stacking a plurality of cells and a plurality of manifolds for supplying and exhausting fuel gas and oxidant gas to each single cell of the cell stack. The first pressurizing mechanism for pressurizing the cell stack and the second pressurizing mechanism for pressurizing the plurality of manifolds are provided.

  Further, according to the present invention, the electrical connection of the single cells of the cell stack and the interconnector for supplying and exhausting fuel gas and oxidant gas to each single cell and the manifold are connected to each single cell by a pipe. Is.

  In the present invention, the manifold is formed by alternately stacking a plurality of manifold connectors made of a metal manifold member and an insulating material.

  In the present invention, glass having a softening point not higher than the heat resistance temperature of the cell stack is interposed between the manifold member and the manifold connector.

  In the present invention, the manifold member and the manifold connector are joined by a brazing material having a melting point equal to or lower than a heat resistant temperature of the cell stack.

  In the present invention, the manifold connector is made of ceramics.

  In the present invention, the manifold connector is formed of an insulating plate whose main component is mica.

  Further, in the present invention, the first and second pressure mechanisms are each provided with a ceramic spring mainly composed of silicon nitride.

  In the present invention, since the cell stack is pressurized by the first pressurizing mechanism, the degree of adhesion between the cells can be increased and the transmission loss of power at the connection portion can be reduced. Further, since the manifold is pressurized by the second pressurizing mechanism, the sealing performance of the manifold is improved and gas leakage can be prevented.

  In the present invention, since glass (glass paste) having a softening point equal to or lower than the heat resistance temperature of the stack is interposed between the manifold member and the manifold connector, if the glass softens during heat treatment, the manifold member and the manifold connector To prevent gas leakage.

  In the present invention, since the manifold member and the manifold connector are joined by a brazing material having a melting point lower than the heat resistance temperature of the stack, if the brazing material is melted during heat treatment, the gap between the two members is closed to prevent gas leakage. To do.

  Furthermore, in the present invention, since the first and second pressurizing mechanisms are provided with ceramic springs mainly composed of silicon nitride, the heat resistance is excellent, and the pressurizing mechanism is at the same high temperature as the fuel cell. It can be installed in a rough environment.

Hereinafter, the present invention will be described in detail based on embodiments shown in the drawings.
FIG. 1 is a sectional view showing an embodiment of a flat plate type solid oxide fuel cell according to the present invention, FIG. 2 is a side view of a fuel electrode-supported solid oxide fuel cell, and FIG. 3 is a cell stack and a manifold. 4 is a cross-sectional view of the cell stack and the manifold showing the flow of the fuel gas, FIG. 5 is a cross-sectional view of the cell stack and the manifold showing the flow of the oxidizing gas, and FIG. 6 is a cross-sectional view of the cell stack and the manifold. FIG. 7 is an exploded perspective view showing another example of the seal structure, and FIG. 8 is a sectional view of the seal structure.

  1 to 6, a flat solid oxide fuel cell 1 according to the present invention includes a cell stack 2 and a single cell 3 (hereinafter also referred to as a cell) disposed around the cell stack 2. Four manifolds M1 to M4 for supplying and exhausting fuel gas and oxidant gas, the cell stack 2 is pressurized by the first pressurizing mechanism 4, and each manifold M1 to M4 is pressurized by the second pressurizing mechanism 5. It is comprised so that it may pressurize by.

  In FIG. 1, the cell stack 2 is formed by alternately stacking the required number of single cells 3 and interconnectors 12, and is installed on a heat insulating plate 13 via a pressing plate 14.

  Similarly, each of the manifolds M <b> 1 to M <b> 4 is installed on the heat insulating plate 13 via a pressing plate 15. The manifold M1 (FIGS. 1, 3, 4, and 6) constitutes a fuel gas supply manifold that supplies fuel gas to the cell stack 2, and the manifold M2 exhausts the exhaust gas of the fuel gas from the cell stack 2. The manifold M3 (FIGS. 5 and 6) constitutes an oxidant gas supply manifold that supplies oxidant gas to the cell stack 2, and the manifold M4 exhausts oxidant gas from the cell stack 2. An exhaust manifold for exhausting gas is configured.

  The first pressurizing mechanism 4 that pressurizes the cell stack 2 includes a compression spring 7 serving as a pressurizing unit installed on the cell stack 2 via a presser plate 16, and a plate installed on the compression spring 7. 17, four connecting rods 18 penetrating the plate 17, the heat insulating plate 13 and the pressing plate 14, and a nut 19 screwed to the rod 18.

  Similarly, the second pressurizing mechanism 5 for pressurizing each of the manifolds M1 to M4 includes a compression spring 8 installed on each of the manifolds M1 to M4, a plate 20 installed on the compression spring 8, and the plate. 20 and four connecting rods 21 penetrating the heat insulating plate 13, and a nut 22 screwed to the rod 21.

  The pressurization applied to the cell stack 2 and the manifolds M1 to M4 by the first and second pressurization mechanisms 4 and 5 tightens or loosens the nuts 19 and 22 screwed to the rods 18 and 21, respectively. Thus, it can be freely adjusted by changing the elastic force of the compression springs 7 and 8 respectively. As the compression springs 7 and 8, ceramic springs mainly composed of silicon nitride having excellent heat resistance and corrosion resistance are used. Thereby, the compression springs 7 and 8 can be placed in the same high temperature environment as the operating temperature of the fuel cell 1. Hereinafter, the structure of each part of the flat type solid oxide fuel cell 1 will be described in detail with reference to FIGS.

  2 and 3, a single cell 3 of the solid oxide fuel cell 1 includes a flat fuel electrode 25, an electrolyte layer 26 made of a flat solid oxide layered on the fuel electrode 25, and It is comprised with the air electrode 27, and the fuel electrode support type cell is comprised by this.

The constituent material of the single cell 3 can be applied to all material systems that are generally developed. For example, as the material of the electrolyte layer 26, a zirconia-based material such as stabilized ZrO ₂ (SASZ) or yttria stabilized zirconia (YSZ) added with Sc ₂ O ₃ and Al ₂ O ₃ is used as the material of the fuel electrode 25. Can use mixed cermets of these zirconia-based materials and nickel oxide, respectively.

  As a material of the air electrode 27, a general air electrode material such as lanthanum strontium manganite (LSM) can be used. In the present invention, from the viewpoint of using the interconnector 12 made of an alloy, the operating temperature of the fuel cell 1 is It is preferable that the temperature is 800 ° C. or lower. Therefore, it is preferable to use materials such as lanthanum nickel ferrite (LNF) and lanthanum strontium cobaltite (LSCo), which have better properties at low temperatures.

The thickness of the single cell 3 is about 1 mm. The area of the cell 3 is determined according to the required output, but is about 10 to 1000 cm ² . In this case, the average thermal expansion coefficient of the cell 3 from 800 ° C. to 1000 ° C. is about 10 to 11 × 10 ⁻⁶ / K.

  The electrical connection between the electrodes 26 and 27 of the cell 3 and the interconnector 12 is difficult to ensure the flatness of the respective surfaces of the interconnector 12, so that the deformable current collectors 28 and 29 (see FIG. 3 reference: circle 28: only 28 is shown in FIG. 6).

  As the current collector 28 on the fuel electrode 25 side, a porous body, a foam, a mesh, a nonwoven fabric, or the like made of a noble metal such as gold, silver, platinum, nickel, and various heat-resistant alloys such as stainless steel and inconel can be used.

  As the current collector 29 on the air electrode 27 side, a porous body, a foam, a mesh, a nonwoven fabric, or the like made of a noble metal such as gold, silver, or platinum, a heat-resistant alloy such as various stainless steels, and Inconel can be used. However, from the balance between oxidation resistance and economy, it is preferable to use a heat-resistant alloy such as silver or stainless steel in a deformable shape such as a porous body, foam, mesh, or nonwoven fabric.

  3 to 6, the interconnector 12 is formed in a disc shape and houses the single cell 3, the fuel electrode current collector 28, and the air electrode current collector 29, which are electrically connected in series, and The fuel gas and the oxidant gas can be supplied to the cell 3. For this reason, a recess 31 is formed on the upper surface side of the interconnector 12 to accommodate the single cell 3, the fuel electrode current collector 28, and the air electrode current collector 29. The single cell 3 is accommodated in the recess 31 with the fuel electrode 25 facing downward.

  Further, a convex portion 32 is integrally formed on the lower surface side of the interconnector 12, and the convex portion 32 includes gas supply passages 34a and 35a communicating with the manifolds M1 to M4, and a gas exhaust passage. 34b and 35b are formed, respectively. One end of each gas supply passage 34a, 35a communicates with the recess 31 of the interconnector 12, and the other end is connected to the manifolds M1, M3 via supply pipes 37a, 38a, respectively. One end of each gas exhaust passage 34b, 35b communicates with the concave portion 31 of the interconnector 12, and the other end is connected to each manifold M1, M3 at the outer edge of the convex portion 32 via exhaust pipes 37b, 38b. Yes. Such an interconnector 12 is stacked in a plurality of stages alternately with the single cells 3 and is pressurized by the first pressurizing mechanism 4, so that the convex portion 32 causes the air electrode current collector 29 to be connected to the lower single cell 3. Is pressed against the air electrode 27. The air supply pipes 37a and 38a and the exhaust pipes 37b and 38b are simply referred to as the pipe 37 and the pipe 38 when collectively referred to.

  The pressing plate 16 of the first pressurizing mechanism 4 is used as an interconnector because it is necessary to supply an oxidant gas to the uppermost unit cell 3. For this reason, a gas supply passage for oxidant gas and a gas exhaust passage (both not shown) are also formed in the holding plate 16, and an air supply pipe 38a (FIG. 1) and an exhaust pipe (see FIG. 1) are formed in these passages. Are not connected).

  The cells 3 are stacked by stacking a single cell 3 and current collectors 28 and 29 that are sealed in the recess 31 of the interconnector 12 and stacking the required number of stages in the stack. A good electrical connection between the cells 3 can be obtained by applying a predetermined load to the cell stack 2 by the first pressure mechanism 4. That is, when the cell stack 2 is manufactured by stacking the cell 3 and the interconnector 12, the interconnector cell 12, the fuel electrode current collector 28, the single cell 3, the air electrode current collector 29, and the interconnector cell 12 are sequentially provided. The cell stack 2 is manufactured by stacking. Then, such a cell stack 2 is pressurized by the first pressure mechanism 4 and a predetermined pressure is applied to each interconnector 12. When the cell stack 2 is pressurized by the first pressurizing mechanism 4, the convex portion 32 of the interconnector 12 presses the air electrode current collector 29 against the air electrode 27 of the single cell 3 on the lower stage side, and the fuel electrode 25 collects the fuel electrode. In order to press the electric material 28 against the bottom of the recess 31, the fuel electrode 25 and the fuel electrode current collector 28, and the air electrode 27 and the air electrode current collector 29 of each single cell 3 are in close contact with each other and electrically connected in series. Moreover, since all the unit cells 3 laminated | stacked by this are also connected in series, a high voltage is obtained at the time of electric power generation.

As the material of the interconnector 12, various heat-resistant metal materials including a ferritic stainless material such as SUS430 can be used. In particular, ferritic stainless steel containing 1% or more of Al is most preferable from the viewpoint of suitability of thermal properties. Among them, ferritic stainless steel containing Al in an amount of 1% or more and less than 10% is preferable because it has good mechanical properties. Also in this case, it is more preferable that Al is contained by 3% or more. Such metals include, for example, Nisshin Steel NCA-1 (Fe: 18%, Cr: 3%, Al). However, it is preferable that the electrical resistance of the oxide film formed on the surface of the refractory metal is as small as possible for electrical connection. A typical refractory metal material has a linear thermal expansion coefficient of about 11 to 16 × 10 ⁻⁶ / K, which is generally larger than the thermal expansion coefficient of the cell 3. Therefore, when gas-sealing the cell 3 and the interconnector 12, it is desirable to seal by a method that can absorb this difference in thermal expansion coefficient. For this reason, for example, the single cell 3 is disposed in the recess 31 of the interconnector 12, and the outer edge portion of the cell 3 and the interconnector 12 are connected by a sealing material 41 (see the top view of FIG. 3: not shown in FIG. 6). Gas seal. Such gas sealing by the sealing material 41 can be realized by using a glass material having a softening point lower than the operating temperature of the fuel cell 1 such as borosilicate glass.

  As the sealing material 41, it is preferable to use a glass material having a softening point lower than the operating temperature of the fuel cell, such as borosilicate glass as described above, but simply placing the sealing material 41 on the outer periphery of the cell 3 In some cases, sufficient reliability cannot be ensured. In such a case, as shown in FIGS. 7 and 8, ring-shaped sealing materials 41a and 41b mainly composed of a glass material are disposed on the outer periphery of the cell 3 and the upper surface of the electrolyte layer 26, respectively, and this electrolyte It is preferable to cover the sealing material 41 b and the interconnector 12 on the layer 26 with the cell cover 50.

  The cell cover 50 includes a cylindrical fitting portion 50a fitted to the outer periphery of the interconnector 12, and a ring-shaped cover portion 50b extending from the fitting portion 50a to the center in the radial direction. An opening 51 is formed in the center of 50b. The opening 51 has a size that allows the convex portion 32 of the interconnector 12 to enter. On the other hand, the cover portion 50b functions as a presser for the sealing material 41b.

  The material of the cell cover 50 is preferably a material that does not react with the sealing materials 41a and 41b at a high temperature. Moreover, since it covers the whole upper part of the interconnector 12, it is preferable to have electrical insulation in the meaning which prevents the short circuit between both electrodes of the single cell 3. FIG. Specifically, ceramic materials such as alumina, macerite, and zirconia can be used.

In addition, some heat resistant stainless steels and heat-resistant alloys containing Al of 1% or more and 25% or less, preferably 3% or more and 25% or less, are oxidized at a high temperature to have Al ₂ O on the surface. Some of them form an electrically insulating film composed mainly of ₃ . Such a material can be used as the cell cover 50. If the Al content exceeds 25%, the melting point of the alloy decreases and the function as a heat-resistant alloy is lost, which is not preferable. For example, MA47P (Ni: 2%, Cr: 4%, Al + α) can be used. By using a metal material, the cost of the cell cover 50 can be reduced.

  By using the sealing materials 41a and 41b and the cell cover 50 as described above, the unit cell 3 and the interconnector 12 can be more reliably sealed, and the reliability and durability of the cell stack 2 can be improved. It is possible to improve the power generation efficiency. Note that it is more effective to dispose a sealing material between the cell cover 50 and the interconnector 12 (fitting portion).

  The manifolds M1 to M4 have substantially the same structure, and are formed by alternately stacking a plurality of metal manifold members 44 and manifold connectors 45 made of an insulating material so that gas does not leak. The pressure is applied by the second pressure mechanism 5. The reason why each of the manifolds M1 to M4 is constructed by alternately stacking the metal manifold members 44 and the manifold connectors 45 made of an insulating material is that the cells 3 need to be insulated step by step. In the present embodiment, the number of manifolds M1 to M4 is one each. However, when the amount of fuel gas and oxidant gas required is large, two or more appropriate numbers can be provided.

  When constructing the manifolds M1 to M4, not only the manifold members 44 and the manifold connectors 45 are alternately stacked, but the softening point between the manifold members 44 and the manifold connectors 45 is lower than the heat resistant temperature of the cell stack 2 (for example, , 1000 ° C.) or glass (glass paste) may be interposed, or these may be joined by brazing. When the glass paste is interposed or brazed, the glass or brazing material is softened or melted during the heat treatment, so that the sealing function can be exhibited and the sealing performance can be further improved. As the brazing material, it is preferable to use a material having a melting point equal to or lower than the heat resistant temperature of the cell stack 2 (for example, 1000 ° C.).

  The manifold member 44 supplies and discharges fuel gas, and supplies and discharges oxidant gas. The manifold member 44 is formed in a hollow cylindrical shape as shown in FIGS. Alternatively, one end of the exhaust pipe 38 is connected. As the material of the manifold member 44, various heat resistant alloys are used similarly to the interconnector 12.

The pipes 37 and 38 that connect each interconnector 12 of the cell stack 2 and the gas manifold member 44 are also made of heat resistant stainless steel such as SUS310S, or heat resistant metal such as Inconel or Hastelloy. Further, since the pipes 37 and 38 do not need to be electrically conductive, an Fe—Cr—Al heat-resistant alloy that forms an Al ₂ O ₃ coating on the surface can be used. When a hydrocarbon-based fuel is used for direct introduction to the cell 3, the hydrocarbon fuel is supplied to the cell 3 in a stable state, particularly when a heat-resistant alloy that forms an Al ₂ O ₃ coating on the surface is used. This is preferable because it is possible.

Each of the pipes 37 and 38 is a thin one having a diameter of 1 to 5 mm, preferably about 2 to 3 mm, and can be deformed so that the mutual position can be changed. The pipes 37 and 38 are preferably thin if they are thin from the viewpoint of ease of deformation, but the fuel gas and oxidant gas that must be supplied to the single cell 3 have an electrode area of 10 cm ² or more. In some cases, since a flow rate of 100 ml / min or more is required, a diameter of 1 mm or more is required at least. Since the approximate 100cm ² ~400cm ² about as the size of the realistic cell 3, the flow rate required is about 1000 ml / min. In this case, a pipe having an outer diameter of 1.587 mm (1/16 inch) or a pipe having a diameter of 3.175 mm (1/8 inch) can be used. When the unit cell 3 having a larger area is used, it is preferable to increase the number of pipes 37 and 38 than to increase the diameter of the pipes 37 and 38.

As a material of the manifold connector 45, ceramics or mica (mica) is used. Actually, ceramics or composite ceramics mainly composed of alumina (Al ₂ O ₃ ), zirconia (ZrO ₂ ), calcia (CaO), magnesia (MgO), and silica (SiO ₂ , quartz) are used. However, oxygen ion conductors such as zirconia are not suitable for use as a manifold connector on the fuel electrode side because they may consume fuel due to their function as electrolytes. A typical example of the mixture is a machinable ceramic called macerite. In particular, when the manifold member 44 is a heat resistant stainless steel, magnesia is preferable, and a composite material using a matrix of other ceramics such as magnesia and alumina is also preferable. On the other hand, when the manifold member 44 is titanium or kovar, alumina is suitable.

  In the fuel cell 1 having such a structure, the air electrode 27 and the fuel electrode 25 are isolated via the electrolyte layer 26 ”, the oxidant gas is supplied to the air electrode 27, and the fuel electrode 25 is fueled. These are hydrogen and carbon monoxide. That is, the oxidant gas passes through the manifold member 44 of the supply manifold M3, the supply pipe 38a, and the gas supply passage 35a as shown in FIG. When supplied from above into the recess 31 of the connector 12, it contacts the air electrode 27 of the single cell 3. At the interface between the electrolyte layer 26 and the air electrode 27, a three-layer interface that contributes to the electrode reaction is formed. Oxygen ions react with oxygen in the oxidant gas by the air electrode reaction shown in the following formula (1). Changes to. The oxygen ions move inside the electrolyte layer 26 and reach the fuel electrode 25. The product gas and the unreacted fuel gas are discharged to the outside through the gas exhaust pipe 35b, the exhaust pipe 38b, and the exhaust manifold M4.

(Air electrode reaction)
1 / 2O ₂ + 2e ⁻ → O ²⁻ (1)

  On the other hand, the fuel gas supplied to the supply manifold M1 passes through the manifold member 44-supply pipe 37a-gas supply passage 34a as shown in FIGS. When supplied into the recess 31 of each interconnector 12 constituting the interconnector cell connecting portion 6, it contacts the fuel electrode 25 of the single cell 3. In the fuel electrode 25, oxygen ions that have moved from the air electrode 27 through the inside of the electrolyte layer 26 by the action of the fuel electrode 25 formed of Ni-YSZ cermet, Pt, and the like are expressed by the following equations (2) and (3). It reacts with hydrogen and carbon monoxide supplied to the fuel electrode 25 by the reaction shown in the formula, and water vapor or carbon dioxide and electrons are generated. The unreacted oxidant gas is exhausted to the outside through the gas exhaust passage 34b, the exhaust pipe 37b, and the exhaust manifold M2.

(Fuel electrode reaction)
H ₂ + O ²⁻ → H ₂ O + 2e ⁻ (2)
CO + O ²⁻ → CO ₂ + 2e ⁻ (3)

  Electrons generated at the fuel electrode 25 travel through an external circuit and reach the air electrode 27. The electrons that have reached the air electrode 27 react with oxygen by the air electrode reaction shown in the formula (1). Electric energy can be taken out as an output in the process in which the electrons move through the external circuit.

  As described above, in the present invention, the single cells 3 and the interconnectors 12 are alternately stacked, the fuel gas is supplied to the fuel electrode 25 of each cell 3, and the oxidant gas is supplied to the air electrode 27. And electrical connection with a gas supply system as shown in FIG. 5 is realized, whereby a high output solid oxide fuel cell 1 with low connection loss can be realized.

  In the present invention, each cell is configured so that a predetermined load is applied to each interconnector 12 and each of the manifolds M1 to M4 of the cell stack 2 by the independent first and second pressurizing mechanisms 4 and 5. It is possible to reduce the power transmission loss at the connecting portion by increasing the adhesion between the three, and to reliably seal the manifolds M1 to M4, and to prevent leakage of fuel gas and oxidant gas Can do.

  In particular, in the present invention, since two independent pressurizing mechanisms 4 and 5 are provided, there is an advantage that the weights for the cell stack 2 and the manifolds M1 to M4 can be adjusted to optimum loads, respectively.

  Since the first and second pressurizing mechanisms 4 and 5 are provided with compression springs 7 and 8 made of ceramics mainly composed of silicon nitride, the cell stack 2, in other words, the fuel cell 1 and the manifolds M1 to M4. The compression springs 7 and 8 are respectively disposed immediately above and can be placed in the same temperature environment as that of the fuel cell 1, thereby enabling downsizing of the apparatus.

  In the present invention, as the pressurizing means of the first and second pressurizing mechanisms 4 and 5, ceramic compression springs 7 and 8 mainly composed of silicon nitride, which is a material that can withstand high temperatures, are used. When using a spring made of a material that does not endure the operating temperature of the fuel cell, the spring may be disposed outside the heat insulating material 13.

  In addition, instead of the compression springs 7 and 8, an extension rod made of a material having a larger thermal expansion coefficient than that of the rods 18 and 21 can be disposed on the rod as the pressurizing means.

  In the above-described embodiment, there are four systems of manifolds, ie, fuel supply (M1), fuel exhaust (M2), and oxidant gas supply (M39 and oxidant gas exhaust (M4)). However, the oxidizing gas can be exhausted directly from the outer edge of the interconnector without passing through the manifold depending on the form of the stack 2. In this case, the M4 manifold is unnecessary.

  In addition, the present invention uses the fuel cell-supported single cell 3 but the electrolyte-supported single cell in which the fuel electrode and the air electrode are respectively disposed on the front and back surfaces of a flat solid electrolyte plate having sufficient strength. Can also be applied. In this case, it is not particularly necessary to seal the single cell 3 and the interconnector 12 unless the fuel gas needs to be recovered as a request on the system side. In this case, two manifolds can be used for supplying fuel gas and for supplying oxidant gas.

It is sectional drawing which shows one Embodiment of the flat type solid oxide fuel cell which concerns on this invention. It is a side view of a fuel electrode support type solid oxide fuel cell. It is a figure which shows schematic structure of a cell stack and a manifold. It is sectional drawing of the cell stack and manifold which show the flow of fuel gas. It is sectional drawing of the cell stack and manifold which show the flow of oxidant gas. It is a disassembled perspective view of a cell stack and a manifold. It is a disassembled perspective view which shows the other example of a seal structure. It is sectional drawing of the seal structure.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Solid oxide fuel cell, 2 ... Cell stack, 3 ... Single cell, 4 ... 1st pressurization mechanism, 5 ... 2nd pressurization mechanism, 7, 8 ... Compression spring, 12 ... Interconnector, 25 ... fuel electrode, 26 ... electrolyte layer, 27 ... air electrode, 28, 29 ... current collector, 34a, 35a ... gas supply passage, 34b, 35b ... gas exhaust passage, 37a, 38a ... supply pipe, 37b, 38b ... Exhaust pipe, 44 ... manifold member, 45 ... manifold connector, 41 ... sealing material, 50 ... cell cover, M1-M4 ... manifold.

Claims (8)

A cell stack formed by alternately laminating a plurality of flat single cells and interconnectors formed by an electrolyte layer made of a flat solid oxide and an air electrode and a fuel electrode covering the front and back surfaces of the electrolyte layer, respectively. And a flat solid oxide fuel cell that includes a plurality of manifolds for supplying and exhausting fuel gas and oxidant gas to each single cell of the cell stack, and generating power by supplying the fuel gas and oxidant gas. ,
A flat plate solid oxide fuel cell comprising a first pressurizing mechanism for pressurizing the cell stack and a second pressurizing mechanism for pressurizing the plurality of manifolds. The flat plate type solid oxide fuel cell according to claim 1,
A flat plate characterized in that an interconnector for electrically connecting single cells of the cell stack and supplying and exhausting fuel gas and oxidant gas to each single cell and the manifold are connected to each single cell by a pipe. Type solid oxide fuel cell. The flat plate type solid oxide fuel cell according to claim 1 or 2,
A flat solid oxide fuel cell, wherein the manifold is formed by alternately stacking a plurality of manifold connectors made of metal manifold members and insulating materials. The flat plate type solid oxide fuel cell according to claim 3,
A flat solid oxide fuel cell, wherein glass having a softening point not higher than a heat resistance temperature of the cell stack is interposed between the manifold member and the manifold connector. The flat plate type solid oxide fuel cell according to claim 3,
A flat plate solid oxide fuel cell, wherein the manifold member and the manifold connector are joined together by a brazing material having a melting point equal to or lower than a heat resistant temperature of the cell stack. The flat plate type solid oxide fuel cell according to any one of claims 3 to 5,
A flat plate solid oxide fuel cell, wherein the manifold connector is made of ceramics. The flat plate type solid oxide fuel cell according to any one of claims 3 to 5,
A flat plate solid oxide fuel cell, wherein the manifold connector is an insulating plate mainly composed of mica. The flat plate type solid oxide fuel cell according to any one of claims 1 to 7,
The flat solid oxide fuel cell, wherein each of the first and second pressurizing mechanisms includes a ceramic spring mainly composed of silicon nitride.

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