JP2002329511A - Stack for solid electrolyte fuel cell and solid electrolyte fuel cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a stack for a solid electrolyte fuel cell and a solid electrolyte fuel cell using this reducing film resistance by providing an electrolyte layer as a thin film, capable of sufficiently securing an electrode reaction area, and having high reliability to a used state with frequent starts and stops. SOLUTION: In the stack, cell plates with an air electrode layer and a fuel electrode layer held between solid electrolyte layers are laminated. A cell plate 6 has a substrate having a recessed groove in a top face or a bottom face, and each layer laminated on a substrate face of a recessed groove side in order of the fuel electrode layer, the electrolyte layer and the air electrode layer by transferring a shape of the recessed groove. Plural pairs of the cell plate are laminated so as to oppositely join fuel electrode layers or air electrode layers. A tubular groove formed by the junction functions as a gas passage for fuel or air. Cell plate sets 8 are laminated to form the stack 11. Consequently, gas sealability of a gas introducing part is improved, and since no separators are used, high temperature durability is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solid electrolyte fuel cell which obtains electric energy by an electrochemical reaction using a solid electrolyte, and a stack used for the fuel cell.
In particular, the present invention relates to a structure of a cell plate on which an electrode and a solid electrolyte are formed and an improvement of a stack in which the cell plates are stacked.

[0002]

2. Description of the Related Art In recent years, fuel cells have attracted attention as clean energy sources that are capable of high energy conversion and are environmentally friendly. Among them, solid electrolyte type fuel cells are known to use oxidized fuel such as yttria-stabilized zirconia as an electrolyte. A battery in which a solid electrode is used to supply a fuel gas such as hydrogen or hydrocarbon to one side and air or oxygen gas to the other side, using a solid electrolyte as a partition, using a solid ion-conductive solid electrolyte. And is generally a fuel cell operating at about 1000 ° C.

It is known that the conductivity of such a solid electrolyte is about one digit lower than the conductivity of the electrolyte of a phosphoric acid fuel cell or a molten carbonate fuel cell. In general,
Since the electrical resistance of the electrolyte part results in power generation loss, it is important to reduce the film resistance as much as possible by making the solid electrolyte thinner in order to improve the power generation output density, but the electrolyte part has a function as a battery. In order to secure a certain amount of area, a solid electrolyte fuel cell adopts a cell structure (single cell structure) in which a solid electrolyte membrane is formed on a support having mechanical strength. ing. The following structure has been proposed as a specific structure of the fuel cell.

(1) Cylindrical type A cylindrical structure is used in which a cylindrical porous base tube is used as a support, and a fuel electrode layer, an electrolyte layer and an air electrode layer are laminated on the surface of the base tube. There are a cylindrical horizontal stripe type in which a plurality of single cell structures are arranged in one base tube, and a cylindrical vertical stripe type in which one single cell is formed in one base tube. In either case, a plurality of cylinders are electrically connected by an interconnector to form a battery, a fuel gas or air gas is introduced inside the base tube, and the other gas is introduced outside the base tube. Power is generated by introducing gas. In such a cylindrical solid electrolyte fuel cell, one of the fuel gas and the air flows into the base tube, and therefore, there is a feature that a seal is not particularly required between the fuel gas and the air. In addition, since it is cylindrical, it has the advantage of being resistant to thermal shock caused by starting and stopping the fuel cell, and it is possible to design a stack in which the manifold connected to the gas piping is kept at a relatively low temperature, and it has thermal durability. Is high.

(2) Flat plate type Basically, it has the same structure as that of phosphoric acid type or molten carbonate type. That is, a separator plate in which a fuel electrode plate having a fuel gas flow path formed on both surfaces of an interconnector flat plate and an air electrode plate having an air flow path formed thereon is bonded, and a fuel electrode layer and an air electrode layer are formed on both surfaces of a sheet electrolyte layer. Are stacked alternately on a planar cell plate in which the layers are laminated. It is considered important to reduce the thickness of the electrolyte layer in order to reduce the IR loss of the power generation output and improve the power density, and supports either the porous fuel electrode or the air electrode. A cell structure in which an electrolyte membrane and the other electrode layer are formed as a body has been proposed.
For example, a configuration is disclosed in which a 15 μm-thick electrolyte layer is formed on a 1.5-mm-thick Ni cermet fuel electrode layer by a vacuum slip casting method (Procee).
edings of The 3rd International
Tional Fuel Cell Conferen
ce, P349). In addition, in the flat plate type, the effective power generation cell area that can be installed per unit volume of the fuel cell can be increased as compared with the cylindrical type, so that the output density can be improved.

(3) Flat plate type In the flat plate type as described above, damage due to a difference in thermal expansion coefficient between a fuel electrode plate, an air electrode plate, and an interconnector plate which constitute a separator plate is prevented to endure heat. It is a major technical problem to improve the heat resistance or to improve the heat resistance of the interconnector flat plate to both fuel gas (reducing atmosphere) and air (oxidizing atmosphere). In order to improve this, the fuel electrodes and the air electrodes are stacked so as to face each other, the fuel gas flow path is formed between the fuel electrodes with the fuel electrode material, and the air flow is formed between the air electrodes with the air electrode material. A fuel cell stack having a configuration in which a passage is formed has been proposed (Japanese Patent Application Laid-Open No. 9-45355). According to this configuration, it is described that the separator can be omitted, so that the size can be further reduced and the heat durability can be improved.

(4) Monolith type The structure is similar to the flat type. That is, a fuel electrode layer having no gas flow path formed on both surfaces of the interconnector flat plate, a separator plate having an air electrode layer formed thereon, a corrugated fuel electrode layer, an electrolyte layer, and an air electrode layer. This is a structure in which cell films are alternately bonded. The flow path is formed by the corrugated cell plates, and the effective power generation cell area that can be installed per unit volume of the fuel cell stack can be increased, so that the output density can be improved.

[0008]

As described above, in order to reduce the size of the fuel cell stack and increase the power density, it is necessary to increase the effective cell area that can be installed per unit volume of the stack. It is important to increase the power generation output per cell area. However, the prior art (1) has a problem that it is generally difficult to increase the effective power generation cell area that can be installed per unit volume of the fuel cell stack. In particular, in order to mount the fuel cell on a moving body such as an automobile, it is important to reduce the size of the fuel cell stack. There is a problem in that it takes time to raise the temperature to a temperature at which power generation is possible, and the startability of the fuel cell stack deteriorates.

On the other hand, the prior art (2) generally has a configuration in which the effective cell area density can be easily increased. However, since one surface of the separator plate is exposed to the fuel gas and the other surface is exposed to the air, it is difficult to improve the heat durability against both gases, and there is a problem in improving the heat durability. In addition, the gas seal of the manifold connecting the stack composed mainly of the ceramic material and the gas pipe made of metal is not sufficient, and furthermore, since it includes a joint of different materials of ceramic and metal, it is weak in thermal shock resistance. There is also a problem.

In the prior art (3), by adopting a structure without using a separator, it is possible to improve the durability, which is a problem of the prior art (2), and to increase the effective cell area density per unit stack volume. Can be. However, as described above, there is a problem that the gas sealing property and the thermal shock resistance of the manifold portion are not sufficient. Further, in this configuration, since all the stacked cell plates are electrically connected in parallel, the fuel cell stack is a low-voltage high-current type, and when a high voltage is required, the power generation output of the stack is reduced. It is difficult to design, and there is a problem that a loss increases in a wiring portion when boosting or transmitting power.

Further, the prior art (4) employs a configuration in which a cell plate portion composed of an electrolyte layer and both electrode layers is formed in a wave shape to divide a gas flow path. Effective cell area density can be improved. However, there is a problem that the mechanical strength is not sufficient, and it is necessary to increase the thickness of the electrolyte in order to improve the strength. If the thickness is too large, the membrane resistance of oxygen ion conduction in the electrolyte portion increases. Therefore, there is a problem that the power generation output per unit cell area is reduced.

The present invention has been made in view of such problems of the prior art. It is an object of the present invention to reduce the film resistance by reducing the thickness of the electrolyte layer so that the electrode reaction area can be sufficiently increased. An object of the present invention is to provide a solid oxide fuel cell stack which can be ensured and has high reliability in a use mode in which starting and stopping frequently occur, and a solid oxide fuel cell using the same.

[0013]

Means for Solving the Problems The inventors of the present invention have made intensive studies to achieve the above object, and as a result, given a specific shape to an electrode layer or the like by using a predetermined substrate, and changed the lamination specification of each layer. It has been found that the above objects can be achieved by appropriate selection and the like, and the present invention has been completed.

That is, a first solid oxide fuel cell stack according to the present invention is a solid oxide fuel cell stack comprising a solid electrolyte layer and a cell plate having an air electrode layer and a fuel electrode layer sandwiched therebetween. A substrate in which the cell plate has a concave groove on an upper surface and / or a lower surface; and a fuel electrode layer, a solid electrolyte layer and an air electrode layer, or an air electrode layer, a solid electrolyte layer and a fuel on the substrate surface on the concave groove side. These layers are stacked in the order of the electrode layers and so as to substantially transfer the shape of the groove, and at least one pair of the cell plates causes the fuel electrode layers or the air electrode layers to face each other. The tubular grooves formed by joining the fuel electrode layers or the air electrode layers are stacked so as to join together, and function as a fuel or air gas flow path.

In a preferred embodiment of the first solid oxide fuel cell stack according to the present invention, the substrate is made of a porous material, and the gas flow channel has a polarity opposite to that of the gas flow channel served by the tubular groove. It is characterized by functioning as.

Further, in another preferred embodiment of the first solid oxide fuel cell stack, a penetrating opening is formed partially at the bottom of the concave groove, and the fuel electrode layer or the fuel electrode layer is formed through the opening. The air electrode layer is protruding.

Still another preferred embodiment of the first solid oxide fuel cell stack is a region other than the through-opening on the upper or lower surface of the substrate, or one of the region and the through-opening. In another embodiment, an insulating stress relaxation layer is added between the substrate and the air electrode layer or the fuel electrode layer.

On the other hand, the second solid oxide fuel cell stack according to the present invention is a solid oxide fuel cell stack comprising a solid electrolyte layer and a cell plate having an air electrode layer and a fuel electrode layer sandwiched therebetween. The solid electrolyte layer and the air electrode layer or the fuel electrode layer are arranged in this order on the fuel electrode layer or the air electrode layer, wherein the cell plate has a concave groove on the upper or lower surface and is made of a sintered body of a predetermined electrode material. And a laminated structure of fuel electrode layer-solid electrolyte layer-air electrode layer or air electrode layer-solid electrolyte layer-fuel electrode layer laminated so as to substantially transfer the shape of the concave groove, The pair of cell plates are stacked so that the fuel electrode layers or the air electrode layers face each other and are joined, and a tubular groove formed by joining the fuel electrode layers or the air electrode layers is formed of fuel or It functions as an air gas flow path.

Further, the solid oxide fuel cell of the present invention comprises:
A solid oxide fuel cell using the first or second fuel cell stack as described above, wherein a cell plate set including the pair of cell plates and a separator having a flow path are alternately stacked. It is characterized by comprising.

Further, another solid oxide fuel cell according to the present invention is a solid oxide fuel cell using the first or second fuel cell stack as described above, wherein the solid electrolyte fuel cell comprises a pair of cell plates. Between a cell plate set and an adjacent cell plate set,
It is characterized by being formed by interposing an electrical insulating layer.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, a stack for a solid oxide fuel cell and a solid oxide fuel cell according to the present invention will be described in detail. In addition, in this specification, "%" indicates a mass percentage unless otherwise specified. For convenience of explanation, one surface of each layer such as a substrate and an electrode layer is referred to as a “front surface”.
Or `` upper surface '', the other surface is `` back surface '' or `` lower surface '', and accordingly, the electrode layer such as the air electrode layer or the fuel electrode layer is `` front electrode '' or `` upper electrode '', `` back electrode '' or `` Although described as "lower electrode" and the like, these are equivalent elements, and a configuration in which they are replaced with each other is also included in the scope of the present invention.

As described above, the fuel cell stack of the present invention has a structure in which a solid electrolyte layer is sandwiched between an air electrode layer and a fuel electrode layer.
That is, the air electrode layer-solid electrolyte layer-fuel electrode layer, or the fuel electrode layer-solid electrolyte layer-in which the stacking order is reversed.
It is formed using a cell plate having a laminated structure of an air electrode layer.

Here, in the first stack, a concave groove is formed in a substrate functioning as a support of the above-mentioned laminated structure, and an electrode layer, a solid electrolyte layer and an electrode layer are sequentially laminated on the substrate with the concave groove. The groove shape of the substrate is substantially transferred to these layers, and a groove is also formed in the electrode layer located on the outermost surface, ie, the fuel electrode layer or the air electrode layer, to form a cell plate. Then, at least one pair of such cell plates is prepared, and the two cell plates are joined so that the concave grooves of both cell plates face each other to obtain a cell plate set. If necessary, a plurality of such cell plate sets are provided. Laminate to form a stack. As a result, in the cell plate set, a tubular groove is formed by the concave grooves, and the tubular groove is formed by the fuel electrode layers or the air electrode layers, and has the same polarity. No problem occurs even if is used as a fuel gas flow path or an air gas flow path.

The first stack of the present invention utilizes the above-described configuration, and does not require a separator as an essential component. In the present invention, by applying a semiconductor integrated technology as described later, it is possible to form a light, thin and short cell plate as compared with a conventional cell plate,
Further, as described later, a substrate having an opening penetrating the front and back surfaces (a substrate with an opening) can also be used, and these points are also different from the above-mentioned JP-A-9-45355.

On the other hand, according to the second stack of the present invention, a groove is formed in one or both of the air electrode layer and the fuel electrode layer, and a groove is formed on the electrode layer which is not located on the outermost surface. It also has a function as a support, and the formation of the tubular groove and the lamination of the cell plate set are the same as in the case of the first stack.

As described above, in the stack and the solid oxide fuel cell of the present invention, one of the fuel gas and the air, for example, the fuel gas is a tubular gas formed by joining the cell plates with the grooves. It is made to flow in a channel, and is isolated from air by a solid electrolyte layer. This allows
Since the fuel gas flows through a tubular flow path enclosed by the fuel electrode layer and the solid electrolyte layer, a separator that is exposed to both the fuel gas and air and requires high-temperature durability for both gases is required. Is not required.

In the present invention, the cross-sectional shape of the groove of the cell plate is not particularly limited as long as it can form a tubular flow path when the two grooves are joined. The shape may be a shape obtained by appropriately dividing an ellipse, a rectangle, and a polygon, typically a half circle, a half ellipse, a half of a rectangle or a polygon, or the like. When the electrode layers of each cell plate are joined with the concave grooves of the two cell plates facing each other, the purpose is to function as a joining material, to assist the current collecting function of the electrode layers, In order to alleviate this, an intermediate layer can be formed and laminated at a part between two electrode layers.

In the present invention, it is possible to use a porous substrate as the substrate of the cell plate. In this case, the substrate has a function of maintaining the strength of the cell plate, and a film having an electrode layer or a solid electrolyte layer. In addition to functioning as a support substrate during formation, it can also function as a gas flow path that does not flow through the tubular flow path, such as a gas flow path through which air flows when fuel gas flows through the tubular flow path. In this case, it is possible to form a stack having a high stacking density in which only the cell plate assemblies are stacked without using the separator plate in which the flow path is formed. Also,
When the porous substrate is electrically conductive, it can also have a function of collecting current generated by the cell.
Furthermore, in order to adjust the generated voltage to the required power generation value, an electric insulating layer may be inserted between adjacent cell plate assemblies and stacked, and the cell plate assemblies may be electrically connected in series. Since the same type of gas flows on both sides of the electric insulating layer in this case, a separator which also requires durability against both gases is not required.

On the other hand, when the substrate of the cell plate is porous and allows gas to permeate but has insufficient function as a gas flow path, or when a gas-impermeable substrate having an opening is used, The function of maintaining the strength of the cell plate and the function of supporting the electrode layer or the solid electrolyte layer film are excellent. In particular, there is an advantage that the solid electrolyte layer functioning as a gas partition can be easily formed into a dense and thin film. Further, there is an advantage that the substrate has an excellent function of transferring the heat energy heated at the time of starting.

When a stack is formed using such a substrate having gas impermeability and openings, a pair of cell plates (cell plate set) and a separator having a gas flow path can be alternately stacked. . In other words, the configuration is such that one separator is laminated for every two cell plates, and the lamination density of the portion having the power generation function can be improved as compared with the conventional configuration in which the separator is inserted for each cell plate. . If both sides of the separator in the stacking direction are electrically insulated,
The cell plate set above the separator and the cell plate set below can be electrically insulated, and the cell plates can be electrically connected in series. For example, the separator can be formed of insulating ceramics or the like, or can be formed by insulating a surface of a metal separator that is in contact with or in contact with at least one cell plate.

Further, as described above, in the second stack of the present invention, one of the air electrode and the fuel electrode layer can serve as the substrate of the cell plate. For the purpose of assisting the function of the gas flow path or controlling the generated voltage, a stack configuration in which a separator and an electrically insulating gas impermeable layer are inserted for each two-cell plate assembly can be provided.

Next, the materials of the solid electrolyte layer and the electrode layer in the stack and the solid oxide fuel cell of the present invention, and the method of manufacturing these will be described. In the present invention, the materials of the solid electrolyte layer and the electrode layer are not particularly limited, and known materials can be used. For example, as the fuel electrode material, known nickel, nickel cermet, platinum, and the like can be used. As the air electrode, for example, La _1-x Sr _x MnO ₃ , La
A perovskite-type oxide such as _1-x Sr _x CoO ₃ can be used. On the other hand, as the solid electrolyte layer,
Known Nd ₂ O ₃ , Sm ₂ O ₃ , Y ₂ O ₃ and Gd ₂ O
_For example, stabilized zirconia in which ₃ is dissolved, CeO ₂ -based solid solution, bismuth oxide, LaGaO _3, or the like can be used.

Examples of the method for forming the solid electrolyte layer and the electrode layer include a known film forming method such as an EVD method, a thermal spraying method, a sputtering method and a vapor deposition method, a tape casting method, a dipping method, a sol-gel method, a coating method, and the like. A spray method or the like can be applied. When one of the electrode layers is used as a substrate, a raw material powder formed by a known powder metallurgy technique is formed into a desired grooved substrate by an extrusion forming method or the like,
By sintering, a substrate / electrode layer having a concave groove can be manufactured.

Further, as described above, a porous substrate can be used in the present invention. As such a porous substrate, a porous metal or ceramic having gas permeability can be used. . For example, a known CaO
And ceramics sintered body such as 5mol added stabilized ZrO ₂ and _Al 2 _{O 3,} Ni, Ni alloy, SUS and Fe
A foamed metal such as an alloy, a sintered body alloy, a sintered body cermet, or the like can be used. Further, a porous substrate with a concave groove can also be manufactured by a known manufacturing method. For example, it can be manufactured by a method of extruding into a desired shape and then firing, or a method of manufacturing a known foamed metal. Further, the porous substrate has a relatively high porosity layer mainly serving as a gas passage and a relatively porous layer mainly serving as a support substrate when forming an electrode layer or a solid electrolyte layer. A substrate formed of at least two or more layers having a low ratio can also be used.

Further, in the substrate having an opening used in the present invention, a concave groove is formed on at least one of the upper surface and the lower surface of the substrate, and an opening penetrating from the upper surface of the substrate to the lower surface is partially formed in the concave groove. Is formed on the substrate, and either gas-permeable or impermeable can be used. For example, quartz, high melting point glass, alumina, magnesia, partially stabilized zirconia, silicon, Ni, Ni-based alloy, SU
S and Fe based alloys can be used.

In the case where the substrate is electrically conductive, the other portions than the substrate opening are provided for the purpose of electrically insulating the substrate and one electrode or for reducing the thermal stress between the substrate and the solid electrolyte layer or the electrode layer. Part or part of the substrate opening on at least one side,
A configuration in which an electric insulation / thermal stress relaxation layer is formed can be employed. In this case, it contains, for example, silicon oxide, silicon nitride, phosphosilicate glass (PSG), phosphoborosilicate glass (BPSG), alumina, titania, zirconia, ceria or MgO, and preferably any mixture thereof. A material serving as a main component can be used. Also, silicon, titanium, chromium, iron, cobalt,
Metals containing nickel, zirconium, molybdenum, tungsten or tantalum and mixed metals thereof as main components can be used.

[0037]

Hereinafter, the present invention will be described in more detail with reference to preferred embodiments, but the present invention is not limited to these embodiments.

Embodiment 1 FIG. 1 shows a manufacturing process of a cell plate used in this embodiment. The porous substrate 1 was formed on a mold 5 having a convex portion according to a known method for manufacturing a porous metal body. That is, a mixture mainly composed of a Ni raw material powder having an average particle size of 0.5 to 5 μm, together with an organic solvent, a water-soluble resin binder, a surfactant, a plasticizer and water, is applied on the convex 5 by a doctor blade method. By forming a relatively low porosity surface layer and then, by changing the mixing ratio of the organic solvent of the raw material mixture, the water-soluble resin binder and the surfactant,
Substrate layers having relatively high porosity were similarly overlapped to form a molded body. Further, a heat treatment including a bubble forming step, a degreasing step, and a sintering step is performed, and a relatively low porosity surface layer 1a having a porosity of 20% and a film thickness of 10 μm and a porosity of 80% and a film thickness at the thinnest portion are obtained. A porous substrate 1 comprising a porous substrate layer 1b having a concave groove of 500 μm was formed.

Next, the fuel electrode layer 2,
The electrolyte layer 3 and the air electrode layer 4 were formed by a known sputtering method. That is, the substrate 1 is placed in the RF magnetron sputtering apparatus.
First, the substrate is cleaned by reverse sputtering with an Ar ion beam for 5 minutes, and then, using a cermet target of Ni and yttria-stabilized zirconia, at an RF output of 300 W and a film forming pressure of 5 Pa, 5μ
m was formed. Next, the target was replaced with yttria-stabilized zirconia, and a film having a thickness of 2 μm was formed under the conditions of an RF output of 300 W and a pressure of 1 Pa. Further, the target was exchanged for LSM, and RF output was set to 300 W, film forming pressure was set to 5 Pa, and 5 μm.
The film was formed, and the cell plate 6 was formed.

Next, the stack of the present embodiment was prepared in the manner shown in FIG. Two cell plates 6 are laminated so that the grooves are opposed to each other (a and b), and a ribbon-shaped P
A joining layer 7 coated with an Ag-based brazing material capable of being baked at a low temperature was inserted and laminated on both surfaces of the t-line, and fired at 900 ° C. to form a cell plate set 8. A SUS gas introduction pipe 9 was inserted into a tubular gas flow path formed by the concave grooves of the two cell plates 6 and baked simultaneously (c). Next, a SUS end plate 10 having a thickness of 1 mm was placed at both ends of the three cell plate sets 8 stacked, and the SU
The S-made end plates 10 were mechanically fastened with bolts (not shown) to form a stack 11 (d).

With the obtained stack 11, the cell plate set 8
Air is introduced into a tubular flow path (X direction) provided with a SUS gas introduction pipe (not shown), and fuel hydrogen gas is introduced into the porous substrate 1 from a direction (Y direction) perpendicular to this. Was introduced, and the power generation characteristics were evaluated at 600 ° C. (e). Power generation of 0.1 W / cm ² was possible with respect to the cell effective area. In addition, as shown in FIG.
In the XY cross section, the portion where the cell plate lamination cross-sectional area for introducing the fuel is limited or the portion where the SUS gas introduction pipe is connected is
The stack temperature can be adjusted so that the temperature is relatively low and thermal stress is less likely to be applied to a rapid temperature rise.

According to the stack of the present embodiment as described above, one of the gases can be introduced into the tubular flow path formed by the cell plate assembly, so that the gas sealing property of the gas introduction portion is improved. At the same time, there is obtained an advantage that durability against high temperature or thermal shock is improved. Further, since a separator that is exposed to both fuel gas and air at a high temperature, which is one of the causes for lowering the durability, is not used, it is possible to obtain a solid oxide fuel cell having improved high-temperature durability. Furthermore, since no separator is used, the number of cell plates that can be stacked per unit length in the Z direction in FIG. 2E can be increased. As a result, the output density per stack capacity can be improved, and a small-sized fuel cell having excellent start-up properties can be manufactured.

(Embodiment 2) A manufacturing process of a cell plate used in this embodiment will be described with reference to FIG. FIG. 3 is a partial sectional view and a plan view of the cell plate in each manufacturing process. First, as shown in FIG. 3, an insulating stress relieving layer 22, for example, a silicon nitride film was formed on both surfaces of a Si substrate 21 by a low pressure CVD method at about 2000 ° (a). Next, a desired region of the silicon nitride film 22 on the back surface of the substrate was removed by photolithography and chemical dry etching using CF ₄ gas to form a silicon etching opening 26 (b). Next, silicon etching is performed at a temperature of about 80 ° C. using a silicon etchant, for example, hydrazine, to form a substrate opening 27 between the front surface and the back surface of the Si substrate 21 and to form a diaphragm 2 of the silicon nitride film 22.
9 was formed (c). Next, an electrolyte film 23 made of, for example, YSZ (yttria-stabilized zirconia) was formed to a thickness of about 2 μm in an area of 1.5 cm square so as to cover the diaphragm 29 by an RF sputtering method using an evaporation mask (d).

Next, as shown in FIG. 4, etching is again performed from the back surface of the Si substrate by chemical dry etching using CF ₄ gas to remove the silicon nitride film diaphragm 28 in contact with the back surface of the electrolyte film 23, and
3 was exposed. At the same time, the silicon nitride film on the back surface of the Si substrate 21 was also removed (e). Next, 1.8 cm of LSM was applied to the surface of the Si substrate by RF sputtering so as to cover the region where the electrolyte film 23 was formed using a deposition mask.
A film having a thickness of about 500 nm was formed in an m-square region to form a lower electrode layer 24 (f). Next, a Ni film is formed to a thickness of about 500 nm from the back surface of the Si substrate 21 by using the EB evaporation method to form an electrolyte film 2.
(3) The upper electrode 25 directly in contact with the back surface was formed, and a cell plate 29 in which the upper electrode 25 had a concave groove 25g was formed (g).

The obtained two cell plates 29 were stacked so that the concave grooves 25g formed by the substrate etching face each other as shown in FIG. 5 to obtain a cell plate set 29P. The cell plate set 29P and the separators 30 made of insulating ceramics and having flow paths formed thereon were alternately laminated by 10 layers to form a stack of this example (a). FIG. 5B shows an electric wiring diagram of the obtained stack, and FIG. 5C shows a perspective view. For this stack, fuel H ₂ gas was introduced into the tubular flow path formed by the cell plate groove, and air was introduced into the side of the separator.
Power generation characteristics were evaluated at 00 ° C. 11 V was obtained as the power generation voltage of the stack.

As described above, according to the stack of this embodiment, one of the gases can be introduced into the tubular flow path formed by the cell plate assembly, so that the gas sealing property is improved and the durability is improved. It is possible to form an excellent stack. In this embodiment, as compared with a stack in which a conventional cell plate and a separator are alternately stacked, the cell plate
Since the fuel cell and the separator can be alternately stacked, a fuel cell having a high stacking density can be manufactured. Further, in this embodiment, the separator is not exposed to both fuel and air at high temperature, so that a fuel cell having excellent durability can be obtained.

Further, by stacking the electrically insulating separators, it is possible to connect the cell plate sets electrically in series, and it becomes easy to perform high-voltage power generation according to the power generation request. Furthermore, since a cell plate having a high substrate density and good flatness can be used, a thinner and denser electrolyte layer can be formed, thereby reducing power generation loss. Therefore, it is possible to manufacture a fuel cell having a high output density, a small size, and an improved startability. When a gas-impermeable substrate is used, the gas can be separated without forming an electrolyte layer on the entire surface of the substrate. The effect that can be reduced is obtained.

As a modification of this embodiment, the structure of the cell plate can be as shown in FIG. In other words, the structure in which the electrolyte layer is formed from the surface of the substrate on which the groove is formed, or the purpose of increasing the groove by increasing the strength of the electrolyte layer, is to provide an insulating stress relaxation layer formed on one surface of the substrate with an electrolyte. A configuration in which the layers are reinforced can be employed.

(Embodiment 3) A manufacturing process of a cell plate used in this embodiment will be described with reference to FIG. Using the same mold 35 as in Example 1, a sintered body of the air electrode layer substrate 34 was formed by a known tape casting method and coating method. A mixture containing LSM having an average particle size of the raw material powder of 0.5 to 1 μm was prepared using a mold
5, and baked in the air at 1200 ° C. The film thickness was 200 μm at the thinnest portion of the concave portion and the porosity was 20%. An electrolyte layer 33 and a fuel electrode layer 32 were formed on the groove side in the same manner as in Example 1 to manufacture a cell plate 36. The obtained two cell plates 36 were stacked so as to face each other to form a cell plate set 37, and the cell plate set 37 and the separator 38 were alternately stacked to form a stack 39.
The power generation characteristics were evaluated in the same manner as in Example 2, and
15 W / cm ² was obtained.

According to the present embodiment, two cell plates having an air electrode substrate 34 having a concave groove and also serving as a substrate are laminated one on the other, and a tubular flow path is formed. A stack similar to the stack in which the tubular cells are arranged can be formed. On the other hand, there is an excellent advantage that the manufacturing process is simple and the manufacturing process according to the flat plate manufacturing method excellent in mass productivity can be adopted.

(Example 4) A stack of this example was prepared by alternately stacking 10 layers of cell plate assemblies manufactured in the same manner as in Example 1 with alumina-based insulating flat plates (FIG. 8). Example 1
The power generation characteristics were evaluated in the same manner as described above, and a power generation voltage of 8 V was obtained. As described above, by employing the structure of the cell plate and the stack of this embodiment, high-voltage power generation can be performed, and a small solid oxide fuel cell having a high cell plate stacking density can be manufactured. become.

Although the present invention has been described in detail with reference to some preferred embodiments, the present invention is not limited to these embodiments, and various modifications can be made within the scope of the present invention. For example, for the cell plate relating to the first stack, a cell plate having a groove only on one of the front surface and the back surface (upper surface or lower surface) is used, but the present invention is not limited to this, and both the front surface and the back surface are used. It is also possible to form the first stack using a cell plate having a concave groove.

[0053]

As described above, according to the present invention, a specific shape is given to an electrode layer or the like by using a predetermined substrate, and a lamination specification of each layer is appropriately selected. And a solid electrolyte fuel cell stack that has a high reliability with respect to a usage mode in which start-up and shutdown frequently occur. Type fuel cell can be provided. See attached bullet

[Brief description of the drawings]

FIG. 1 is an explanatory sectional view showing a manufacturing process of a cell plate used in one embodiment of a solid oxide fuel cell stack according to the present invention.

2 is a sectional view and a perspective view showing a stack using the cell plate shown in FIG. 1;

FIG. 3 is a partial cross-sectional view and a plan explanatory view showing a manufacturing process of a cell plate used in another embodiment of the stack of the present invention.

FIG. 4 is a partial cross-sectional view and a plan view showing a manufacturing process of a cell plate used in another embodiment of the stack of the present invention.

FIG. 5 is a cross-sectional, wiring, and perspective view showing a stack using the cell plate shown in FIG. 4;

FIG. 6 is a partial sectional view showing a modification of the cell plate shown in FIG.

FIG. 7 is a cross-sectional view showing a manufacturing process of a cell plate used in still another embodiment of the stack of the present invention and a stack using the same.

FIG. 8 is a wiring and sectional view showing another embodiment of the stack of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1, 21 Substrate 1a Substrate surface layer 1b Substrate layer 2, 32 Fuel electrode layer 3, 33 Electrolyte layer 4, 34 Air electrode layer 5, 35 Type 6, 36 Cell plate 7 Joining layer 8 Cell plate set 9 Gas introduction pipe 10 End Plates 11, 39 Stack 22 Insulating stress relieving layer 23 Electrolyte layer 24 Lower electrode layer 25 Upper electrode layer 25g Concave groove 26 Etching port 27 Opening 28 Diaphragm 29 Cell plate 29P Cell plate set 30, 38 Separator 37 Cell plate set

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H01M 8/24 H01M 8/24 ER (72) Inventor Shoji Hatano 2 Takaracho, Kanagawa-ku, Yokohama-shi, Kanagawa Nissan Inside the Automobile Co., Ltd. (72) Inventor Tatsuhiro Fukuzawa, 2 Takaracho, Kanagawa-ku, Yokohama, Kanagawa Pref. Nissan Motor Co., Ltd. (72) Inventor Naoki Hara 2 Takaracho, Kanagawa-ku, Yokohama, Kanagawa Pref. Nissan Motor Co., Ltd. (72) Invention Person Fumi Sato Nissan Motor Co., Ltd., 2 Takara-cho, Kanagawa-ku, Yokohama, Kanagawa Prefecture (72) Inventor Mitsugu Mitsuru Yamanaka 2 Nissan Motor Co., Ltd., Nissan Motor Co., Ltd. (72) Inventor Makoto Uchiyama, Kanagawa Yokohama, Kanagawa Prefecture 2 Takaracho, Ward Nissan Motor Co., Ltd. F-term (reference) 5H026 AA06 BB00 CC00 CC03 CV06 H H04

Claims (11)

[Claims] 1. A solid electrolyte fuel cell stack comprising a solid electrolyte layer and a cell plate having an air electrode layer and a fuel electrode layer sandwiched therebetween, wherein the cell plate has a concave groove on an upper surface and / or a lower surface. A substrate having a fuel electrode layer, a solid electrolyte layer and an air electrode layer, or an air electrode layer, a solid electrolyte layer and a fuel electrode layer, and the shape of the groove is substantially transferred onto the substrate surface on the groove side. At least one pair of the cell plates are laminated so that the fuel electrode layers or the air electrode layers face each other and are joined to each other, and the fuel electrode layers or the air A stack for a solid oxide fuel cell, wherein a tubular groove formed by joining the pole layers functions as a gas passage for fuel or air. 2. The solid electrolyte fuel according to claim 1, wherein the substrate is made of a porous material, and functions as a gas flow channel having a polarity opposite to that of the gas flow channel served by the tubular groove. Stack for batteries. 3. The fuel cell according to claim 1, wherein a through hole is partially formed at the bottom of the groove, and the fuel electrode layer or the air electrode layer protrudes from the opening. 5. The stack for a solid oxide fuel cell according to 4. 4. The fuel electrode layer or the air electrode layer, wherein the solid electrolyte layer and the air electrode layer or the fuel electrode layer are stacked so as to close the through opening from the substrate surface opposite to the groove side. Are laminated from the substrate surface on the concave groove side, and in the cross section of the through-opening, in order from the substrate surface on the concave groove side, the fuel electrode layer-solid electrolyte layer-air electrode layer, or air electrode layer-solid electrolyte layer 4. The solid oxide fuel cell stack according to claim 3, wherein the solid oxide fuel cell stack has a stacked structure of a fuel electrode layer. 5. The air electrode layer or the fuel electrode layer is stacked so as to close the through opening from the substrate surface opposite to the concave groove side, and the fuel electrode layer or the air electrode layer and the solid electrolyte layer are Are laminated from the substrate surface on the concave groove side, and in the cross section of the through-opening, in order from the substrate surface on the concave groove side, the fuel electrode layer-solid electrolyte layer-air electrode layer, or air electrode layer-solid electrolyte layer 4. The solid oxide fuel cell stack according to claim 3, wherein the solid oxide fuel cell stack has a stacked structure of a fuel electrode layer. 6. The substrate and the air electrode layer or the fuel electrode layer in a region other than the through-opening, or in this region and a part of the through-opening on the upper or lower surface of the substrate. The solid oxide fuel cell stack according to any one of claims 3 to 5, wherein an insulating stress relaxation layer is added between the stacks. 7. A porosity of the substrate made of the porous material, wherein a porosity near the substrate surface on the concave groove side is formed lower than a porosity inside the substrate in a cross section thereof. Item 7. The solid oxide fuel cell stack according to any one of Items 6 to 6. 8. A solid oxide fuel cell stack comprising a solid electrolyte layer and a cell plate having an air electrode layer and a fuel electrode layer sandwiched therebetween, wherein the cell plate has a concave groove on an upper surface or a lower surface. A solid electrolyte layer and an air electrode layer or a fuel electrode layer are laminated in this order on the fuel electrode layer or the air electrode layer made of a sintered body of a predetermined electrode material so as to substantially transfer the shape of the groove. Having a laminated structure of fuel electrode layer-solid electrolyte layer-air electrode layer, or air electrode layer-solid electrolyte layer-fuel electrode layer, wherein at least one pair of the cell plates is formed between the fuel electrode layers or the air electrode. The solid layer, wherein the layers are stacked so that the layers are opposed to each other, and the tubular groove formed by joining the fuel electrode layers or the air electrode layers functions as a fuel or air gas flow path. Stack for electrolyte fuel cell. 9. A solid oxide fuel cell comprising the fuel cell stack according to claim 1, wherein the fuel cell stack comprises a pair of cell plates, A solid oxide fuel cell comprising alternately stacked separators having passages. 10. A solid oxide fuel cell using the fuel cell stack according to any one of claims 1 to 8, wherein the fuel cell stack comprises a pair of cell plates and an adjacent cell plate set. A solid oxide fuel cell, comprising an electric insulating layer interposed between the solid electrolyte fuel cell and the cell plate set. 11. A solid oxide fuel cell using the fuel cell stack according to any one of claims 1 to 8, wherein the fuel cell stack comprises a pair of cell plates and an adjacent cell plate set. A solid oxide fuel cell, comprising a separator and an electrically insulating layer interposed between a cell plate set to be used.