JP2004281094A - Cell stack and fuel cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cell stack and a fuel cell capable of preventing deterioration with time of electrical connection between cells, and of keeping power generation performance over a long time. <P>SOLUTION: This cell stack 35 is so structured that a plurality of plate-like fuel cells 33 each having a gas circulation hole 34 in its inside, and an outside electrode 33d and an inter-connector 33e formed oppositely to each other are arranged; and the outside electrode 33d of each one-side fuel cell 33 is electrically connected to the inter-connecter 33e of the other-side fuel cell 33. The outside surfaces of the outside electrode 33d and/or the inter-connector 33e of the fuel cell 33 each have an irregular shape, and the irregular part(s) of the outside electrode 33d and/or the inter-connector 33d of the one-side fuel cell 33 is(are) directly connected to the inter-connector 33e and/or the outside electrode 33d of the other-side fuel cell 33. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a cell stack and a fuel cell, and more particularly to a cell stack and a fuel cell having a plurality of fuel cells having good current collection characteristics.
[0002]
[Prior art]
2. Description of the Related Art In recent years, various fuel cells in which a stack of fuel cells is housed in a housing container have been proposed as next-generation energy.
[0003]
A conventional solid oxide fuel cell has a structure in which a plurality of fuel cells are housed in a housing, and the fuel cells are electrically connected in series or in parallel by a current collecting member. It has been performed at a high temperature of about 1000 ° C. by supplying an oxygen-containing gas and a fuel gas to the cell.
[0004]
Conventionally, as a current collecting member for electrically connecting the fuel cells, a metal felt member in which fibrous metals are gathered has been used. A fuel cell using such a felt-shaped current collecting member has a plurality of fuel cells arranged in an array, for example, between an interconnector of one fuel cell and an outer electrode of the other fuel cell. A fuel cell is packed in series with a felt-shaped current collecting member to form a cell stack, and the cell stack is housed in a housing container (see Patent Document 1).
[0005]
[Patent Document 1]
JP-A-63-261678 [0006]
[Problems to be solved by the invention]
However, in the above-described fuel cell, since the felt-like current collecting member is made of a fibrous metal, when the oxygen-containing gas such as air is introduced between the fuel cells to generate power, the fibrous metal is used. Oxidized from the surface of the metal felt, the current collecting characteristics were reduced, the elasticity of the metal felt was reduced, and the characteristics deteriorated with time.
[0007]
An object of the present invention is to provide a cell stack and a fuel cell that can improve current collection characteristics between fuel cells.
[0008]
[Means for Solving the Problems]
The cell stack of the present invention has a gas flow hole inside, aligns a plurality of plate-shaped fuel cells provided with an outer electrode and an interconnector facing each other, the outer electrode of one fuel cell and the other electrode. A cell stack formed by electrically connecting interconnectors of a fuel cell, wherein an outer electrode of the fuel cell and / or an outer surface of the interconnector have an uneven shape, and an outer electrode and / or Alternatively, the uneven portion of the interconnector is connected to the interconnector and / or the outer electrode of the other fuel cell.
[0009]
In such a cell stack, the unevenness of the outer electrode and / or the interconnector of the fuel cell is connected to the interconnector and / or the outer electrode of the other fuel cell. Even when power is generated by flowing the oxygen-containing gas, the current collecting member is used without using a current collecting member, and since the outer electrode and the interconnector are formed of a material that is not deteriorated by the oxygen-containing gas. It is possible to eliminate the problem of deterioration of the current collecting characteristics due to oxidation of the metal and reduction in elasticity. Further, unlike the related art, there is no work of inserting and collecting the current collecting member between the fuel cells, and the cell stack can be easily manufactured.
[0010]
Further, the cell stack of the present invention is characterized in that a gas flow passage is formed by a concave portion of an outer electrode and / or an interconnector of one fuel cell and an interconnector and / or an outer electrode of the other fuel cell. And
[0011]
In such a cell stack, the space formed between the plurality of protrusions of the outer electrode and / or the interconnector of one fuel cell and the space between the interconnector and / or the outer electrode of the other fuel cell forms a fuel. Since it becomes a passage for the gas supplied to the outer electrode of the battery cell, gas flow is not hindered as compared with a case where a felt or the like is arranged between the fuel cells, and supply of gas to the outer electrode of the fuel cell is eliminated. Is done without delay.
[0012]
Further, in the cell stack of the present invention, the outer electrode of one fuel cell and / or the uneven portion of the interconnector are joined to the interconnector and / or the outer electrode of the other fuel cell by a conductive adhesive. It is characterized by.
[0013]
In such a cell stack, the connecting portion between the outer electrode and / or the interconnector of one fuel cell and the interconnector and / or the outer electrode of the other fuel cell is joined by a conductive adhesive. As a result, the conduction of the connection portion can be reliably ensured, the current collection characteristics can be improved, and the long-term connection reliability can be improved.
[0014]
The fuel cell of the present invention is characterized in that a plurality of the above-described cell stacks are stored in a storage container. In such a fuel cell, since the cell stack has good current collection characteristics, excellent power generation characteristics can be exhibited over a long period of time.
[0015]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 1 shows an embodiment of the fuel cell of the present invention, and reference numeral 31 denotes a storage container having a heat insulating structure. Inside the storage container 31, a cell stack 35 composed of a plurality of fuel cells 33, an oxygen-containing gas supply pipe 39 inserted between the fuel cells 33, and a fuel cell 33 are provided. A heat exchange section 41 is provided.
[0016]
The storage container 31 includes a frame 31a made of a heat-resistant metal and a heat insulating material 31b provided on an inner surface of the frame 31a.
[0017]
As shown in FIG. 2, the cell stack 35 in the storage container 31 is configured by directly connecting an interconnector 33e of one fuel cell 33 and an outer electrode 33d of the other fuel cell 33. 35 are arranged in three rows, the electrodes of the outermost fuel cells 33 of the adjacent cell stack 35 are connected to each other by a conductive member 42, whereby a plurality of fuel cells 33 arranged in three rows are electrically connected. Are serially connected. Here, a gas flow passage 43 for supplying gas to the outer electrode 33d is formed between the protrusions of the interconnector 33e of one fuel cell 33 and the outer electrode 33d of the other fuel cell 33. I have. FIG. 1 illustrates a state in which the fuel cells 33 are arranged in four rows.
[0018]
As shown in FIG. 3, the fuel cell 33 of the present invention has a plate-shaped cross section, and a porous fuel-side electrode 33b is formed on one main surface of a porous conductive support 33a having a columnar shape as a whole. , A dense solid electrolyte 33c and an oxygen-side electrode 33d made of porous conductive ceramics are sequentially laminated, and an intermediate film (not shown) is formed on the other main surface of the conductive support 33a on the side opposite to the oxygen-side electrode 33d. ), And an interconnector 33e made of a lanthanum-chromium-based oxide material is formed. A plurality of gas flow holes 34 are formed inside the support 33a.
[0019]
In the fuel cell 33, a plurality of uneven portions are formed on the other main surface of the conductive support 33a, and the intermediate film and the interconnector 33e are laminated on the uneven surface to form an outer surface of the interconnector 33e. Has an uneven shape.
[0020]
The outer surface of the interconnector 33e has a shape reflecting the shape of the conductive support 33a because the intermediate film has a substantially constant thickness. Note that a current collecting film (not shown) made of a P-type semiconductor material may be formed on the surface of the interconnector 33e, and in this case, the outer surface of the current collecting film also has an uneven shape.
[0021]
The fuel cell 33 is composed of arcuate portions provided at both ends in the width direction, a flat surface connecting these arcuate portions, and a surface on which a plurality of convex portions are formed, and these surfaces are substantially parallel to each other. Are located.
[0022]
As shown in FIG. 1, a fuel gas tank 45 for supplying a fuel gas to the fuel cell 33 is provided below the fuel cell 33. The fuel gas tank 45 is provided with a fuel gas tank from the outside. A fuel gas supply pipe 51 for supplying the fuel gas to the fuel cell 45 is connected.
[0023]
An attachment jig 53 attached to the lower end of the fuel cell 33 is screwed to the fuel gas tank 45, whereby the fuel cells 33 stand on the fuel gas tank 45, respectively. That is, the attachment jig 53 is connected to the cell end side attachment jig 53 a attached to the end of the fuel cell 33 and both ends are screwed to the cell end side attachment jig 53 a and the fuel gas tank 45, respectively. The connecting member 53b is formed with screw portions having opposite directions at both ends, and when the connecting member 53b is rotated to one side, the both ends are connected to the cell end side mounting jig 53a and The fuel gas tanks 45 are formed so as to be screwed respectively.
[0024]
A through hole is formed in the cell end side mounting jig 53 a and the connecting member 53 b so as to communicate with the fuel gas tank 45 and the gas flow hole 34 of the fuel cell 33.
[0025]
Further, as shown in FIG. 1, the tip of the oxygen-containing gas supply pipe 39 is located between the fuel cells 33.
[0026]
The heat exchange section 41 includes a heat exchanger 41a and an oxygen-containing gas storage chamber 41b provided to face the cell stack 35.
[0027]
The heat exchanger 41a has, for example, a plate fin structure in which flat plates and corrugated plates are alternately stacked.
[0028]
The combustion gas is introduced from the lower side surface of the heat exchanger 41a as shown by the dashed line in FIG. 1, and is discharged above the heat exchanger 41a, while the oxygen-containing gas is as shown by the broken line in FIG. Is introduced from the upper side surface of the heat exchanger 41a, is guided below the heat exchanger 41a, and is introduced into the oxygen-containing gas storage chamber 41b.
[0029]
The oxygen-containing gas storage chamber 41b is provided on the end face of the heat exchanger 41a on the side where the oxygen-containing gas is introduced, that is, on the end face on the side of the fuel cell 33, and the oxygen-containing gas that has passed through each passage of the corrugated plate is temporarily. It is to be accommodated.
[0030]
One ends of a plurality of oxygen-containing gas supply pipes 39 are open and communicate with the oxygen-containing gas storage chamber 41b.
[0031]
Further, as shown in FIG. 1, between the side surface of the oxygen-containing gas storage chamber 41b and the heat insulating material 31b, that is, around the oxygen-containing gas storage chamber 41b, the combustion gas is introduced to introduce the combustion gas into the heat exchanger 41a. The mouth 71 is provided. The combustion gas is led to the corrugated passage of the heat exchanger 41a through the combustion gas inlet 71.
[0032]
Here, a method of manufacturing the fuel cell 33 will be described with reference to an example of a method of manufacturing the fuel cell 33 having a protrusion on the interconnector 33e side.
[0033]
First, Ni and / or NiO powder and a rare earth oxide are mixed, and a pore agent, an organic binder made of a cellulose-based binder, and a solvent made of water are added to the mixture, and the mixed support material is extruded. Thus, a plate-shaped support molded body was produced. It should be noted that one side of the extrusion molding die has a shape that forms a projection.
[0034]
Next, an acrylic binder and toluene were added to 8YSZ powder (ZrO ₂ containing 8 mol of Y ₂ O ₃ ) to prepare a slurry to be a solid electrolyte 33c, and a sheet-like solid electrolyte formed body was formed by a doctor blade method. Produced.
[0035]
Next, Ni and / or NiO powder and 8YSZ powder (ZrO ₂ containing 8 mol of Y ₂ O ₃ ) were mixed, an acrylic binder and toluene were added, and a slurry to be the fuel electrode 33b was prepared. Screen printing was performed on one surface of the solid electrolyte molded body to produce a laminated molded body of the solid electrolyte molded body and the fuel-side electrode molded body.
[0036]
Next, the laminated molded body of the solid electrolyte molded body and the fuel-side electrode molded body abuts on the conductive support molded body, and the fuel-side electrode molded body abuts on the support molded body side. , And then wound so that the conductive support molded body on the surface having the convex portion on the other side was exposed, and dried.
[0037]
In addition, each may be made into a sheet-shaped molded body and laminated. This case is desirable because the time required for the process can be reduced and the cost can be reduced.
[0038]
Thereafter, Ni and / or NiO powder and 8YSZ powder (ZrO ₂ containing 8 mol of Y ₂ O ₃ ) are mixed, an acrylic binder and toluene are added, and a slurry for forming an intermediate film is prepared. Was applied to the surface of the molded body having the convex portions formed thereon.
[0039]
Further, a slurry adjusted with a LaCrO ₃ -based material, an organic binder, and a solvent was applied by dipping on the surface of the molded body to be an intermediate film, to form a molded body layer to be an interconnector 33e, and this was dried. Thus, a laminated molded body in which a molded body that becomes the fuel-side electrode 33b, a molded body that becomes the solid electrolyte 33c, a molded body that becomes the intermediate film, and a molded body that becomes the interconnector 33e are formed on the molded body that becomes the support 33a. did.
[0040]
Next, the laminated molded body was subjected to a binder removal treatment and fired at 1300 to 1600 ° C. in an oxygen-containing atmosphere. Next, a slurry composed of conductive ceramic fine particles made of a LaFeO ₃ -based material and a solvent such as IPA and water was prepared, and this slurry was sprayed by a spraying device (spray dry), and dried during dropping. While producing coarse particles having a particle size of 10 to 100 μm, the particles were deposited on the solid electrolyte surface of the above-mentioned laminated molded body.
[0041]
The coarse particles deposited on the surface of the solid electrolyte are heat-treated in the air at a temperature of 1000 to 1400 ° C. to become the oxygen-side electrode 33d formed on the surface of the solid electrolyte 33c.
[0042]
Since the support 33a is made of, for example, NiO by firing in an oxygen-containing atmosphere, the fuel cell 33 is subjected to a reduction treatment or exposed to a reducing atmosphere during power generation. Will be done.
[0043]
An Ag paste was applied to the protrusions of the fuel cell 33 manufactured in this manner, a plurality of the fuel cells 33 were overlapped and heat-treated, and one fuel cell 33 and the other fuel cell 33 were joined. .
[0044]
As described above, by bringing the interconnector 33e of the fuel cell 33 into direct contact with the oxygen-side electrode (outer electrode) 33d, the surface of the metal, which has been a problem when connecting via a metal current collector, is reduced. It is possible to prevent a problem that the current collecting characteristics are reduced due to the oxidation and the elastic force of the metal felt is reduced, and the characteristics are deteriorated with time.
[0045]
In the above-described example, the protrusions that are continuous in the axial direction of the fuel cell 33 are formed. However, the protrusions may be formed at predetermined intervals in the axial direction, that is, may be formed intermittently. good.
[0046]
In this case, the gas can be sufficiently introduced into the outer electrode 33d from the portion where the protrusion is cut off. Further, for example, by forming the protrusion in the width direction of the fuel cell 33 (the direction orthogonal to the axial length direction), gas introduction can be further promoted.
[0047]
In such a cell stack 35, a portion where the interconnector 33e of one fuel cell 33 and the oxygen-side electrode 33d of the other fuel cell 33 are connected was brought into contact without using Ag paste. Or a conductive adhesive or the like as described above. In this case, the conduction of the connection portion can be ensured, and the current collection characteristics can be improved. Ag paste or the like is suitably used as the conductive adhesive. Alternatively, a paste having the same composition as the oxygen-side electrode 33d and the interconnector 33e may be prepared and used as an adhesive.
[0048]
In the fuel cell of the present invention configured as described above, the oxygen-containing gas supplied from the oxygen-containing gas supply pipe 39 is the gas formed between the convex portions or the concave portions at the contact portions between the fuel cells 33. It is supplied to the oxygen-side electrode 33d through the flow passage 43. By forming the gas flow passage 43 with the protrusions or the recesses in this manner, the fuel cell 33 can be sufficiently supplied with the oxygen-containing gas required for power generation.
[0049]
Further, in such a fuel cell, surplus fuel gas and oxygen-containing gas that have not contributed to power generation are introduced above the fuel cell 33, react and burn above the fuel cell 33, and this combustion gas And an external oxygen-containing gas is introduced into the heat exchanger 41a, heat exchange is performed between the combustion gas and the oxygen-containing gas in the heat exchanger 41a, and the oxygen-containing gas can be preheated at the time of startup. Since the oxygen-containing gas in the oxygen-containing gas supply pipe 39 can be further heated by the combustion gas by inserting the gas-containing pipe 39 through the combustion section, the fuel cell 33 is indirectly heated by the heated oxygen-containing gas. The heating time before heating to substantially generate power can be shortened.
[0050]
Further, since the combustion section, the oxygen-containing gas storage chamber 41b, and the heat exchanger 41a are formed adjacent to the upper part of the fuel cell 33, the high-temperature combustion gas burned in the combustion section can be used without using piping or the like. It can be directly introduced into the heat exchanger 41a, and the preheating efficiency of the oxygen-containing gas can be increased with a simple structure.
[0051]
Further, since the combustion gas and the oxygen-containing gas can be heat-exchanged in the storage container 31, there is no need to separately provide a burner for preheating the oxygen-containing gas in the storage container 31, and the combustion gas can be reduced in size. Can be used effectively.
[0052]
Further, since the oxygen-containing gas storage chamber 41b is provided in the heat exchanger 41a, the connection between the heat exchanger 41a and the oxygen-containing gas supply pipe 39 can be performed through the oxygen-containing gas storage chamber 41b. The oxygen-containing gas from 41a can be reliably supplied to the fuel cell 33.
[0053]
In the above example, the unevenness is formed on the other main surface of the conductive support 33a, and the interconnector 33e is formed on the main surface to make the outer surface uneven, but from the viewpoint of increasing the power generation area. As shown in FIG. 4A, it is desirable that the outer surface of the outer electrode 33d be made uneven. In order to make the outer surface of the outer electrode 33d uneven, an uneven portion is formed on one main surface of the conductive support 33a, and the inner electrode 33b, the solid electrolyte 33c, and the outer electrode 33d having a certain thickness are formed thereon. Just fine.
[0054]
The plurality of protrusions may be formed by forming protrusions on one surface of the conductive support 33a as shown in FIGS. 3 and 4 (a), or as shown in FIG. 4 (b). Protrusions may be formed on both surfaces, that is, on the interconnector 33e and the oxygen-side electrode (outer electrode) 33d. In this case, in order to form the gas flow passage 43 large, it is desirable to form the convex portion on the interconnector 33e side and the convex portion on the oxygen side electrode (outer electrode) 33d at a position facing each other. In such a structure, the cross-sectional area of the gas flow passage 43 increases, and the oxygen-containing gas is more easily supplied to the fuel cell 33. Alternatively, as shown in FIG. 5, an interconnector 33e having a convex portion may be laminated on the outer surface of a flat conductive support 33a to form a plurality of convex portions. In this case, for example, the interconnector 33e having a complicated shape can be easily manufactured from the laminate of the sheet-shaped molded bodies.
[0055]
Further, for example, the convex portion on the interconnector 33e side and the concave portion between the convex portions on the oxygen-side electrode (outer electrode) 33d side may be located at corresponding positions. In this case, the height of the convex portion of the interconnector 33e is high. It is better that the depth of the concave portion between the convex portions on the oxygen-side electrode (outer electrode) 33d side is greater than that, and the difference forms the gas flow passage 43. In such a case, the positioning of the fuel cell 33 is facilitated, and the production of the cell stack 35 is facilitated.
[0056]
Further, as shown in FIG. 6, a concave portion may be formed in the conductive support 33a, and an interconnector 33e having a constant thickness may be laminated on a main surface of the concave portion, so that the outer shape of the interconnector 33e may be uneven.
[0057]
Note that the present invention is not limited to the above-described embodiment, and various changes can be made without changing the gist of the present invention. For example, the inner electrode 33b may be formed from the oxygen-side electrode 33b. Further, a reaction prevention layer may be formed between the oxygen-side electrode 33d and the solid electrolyte 33c. Further, the conductive support 33a and the inner electrode 33b may be formed with the same composition. For example, ZrO _{2 in} which Ni and Y ₂ O ₃ are dissolved may be used.
[0058]
That is, the conductive support 33a may also serve as the inner electrode 33b.
[0059]
Further, it goes without saying that various methods may be used for forming the oxygen-side electrode 33d and the current collecting film.
[0060]
In the above-described example, the production of the fuel cell 33 having the convex portion on the interconnector 33e side has been described as an example. However, when the convex portion is provided on the surface on which the oxygen-side electrode 33d is formed, the fuel-side electrode 33b is provided. The solid electrolyte 33c can be formed by the dipping method described in the formation of the interconnector 33e in the above embodiment.
[0061]
Similarly, when the interconnector 33e side is a flat portion, the interconnector 33e can be manufactured by laminating sheet moldings.
[0062]
【The invention's effect】
In the fuel cell of the present invention, a plurality of convex portions or concave portions are formed on the outer electrode and / or the interconnector, and the convex portion or concave portion of the outer electrode of one fuel cell and / or the interconnector is connected to the other fuel cell. Is directly connected to the interconnector and / or the outer electrode without using a metal current collecting member. Therefore, even when an oxygen-containing gas such as air is introduced between fuel cells to generate power, a conventional power generation method is used. As a result, the current collection characteristics are reduced due to the oxidation of the metal surface, and the elasticity of the metal felt is reduced.
[0063]
Further, since the gas can be sufficiently supplied to the inner electrode of the fuel cell, the power generation performance of the fuel cell can be improved, and the performance of the fuel cell can be improved.
[Brief description of the drawings]
FIG. 1 is a longitudinal sectional view showing a fuel cell of the present invention.
FIG. 2 is a cross-sectional view showing a cell stack of the present invention.
FIG. 3 is a sectional perspective view showing a fuel cell used in the cell stack of the present invention.
FIGS. 4A and 4B are cross-sectional perspective views of a fuel cell used in the cell stack of the present invention, in which FIG. 4A shows a configuration in which convex portions are provided on the outer electrode side, and FIG. Part is provided.
FIG. 5 is a cross-sectional perspective view of a fuel cell used in the cell stack of the present invention, in which a projection is formed by changing the thickness of an interconnector.
FIG. 6 is a cross-sectional perspective view of a fuel cell used in the cell stack of the present invention, in which a recess is provided on the interconnector side.
[Explanation of symbols]
33 ... fuel cell 33a ... conductive support 33b ... inner electrode, fuel side electrode 33c ... solid electrolyte 33d ... outer electrode, oxygen side electrode 33e ... interconnector 34 ...・ Gas circulation hole 35 ・ ・ ・ Cell stack

Claims (4)

A plurality of plate-shaped fuel cells having a gas flow hole therein and having an outer electrode and an interconnector opposed to each other are arranged, and an outer electrode of one fuel cell and an interconnector of the other fuel cell are arranged. An electrically connected cell stack, wherein the outer electrode of the fuel cell and / or the outer surface of the interconnector have an uneven shape, and the outer electrode of one fuel cell and / or the uneven portion of the interconnector have an uneven shape. A cell stack connected to an interconnector and / or an outer electrode of the other fuel cell. 2. The cell stack according to claim 1, wherein a gas flow passage is formed by a concave portion of an outer electrode and / or an interconnector of one fuel cell and an interconnector and / or an outer electrode of the other fuel cell. . The uneven portion of an outer electrode and / or an interconnector of one fuel cell is joined to an interconnector and / or an outer electrode of the other fuel cell by a conductive adhesive. 2. The cell stack according to 2. A fuel cell comprising a plurality of the cell stacks according to any one of claims 1 to 3 stored in a storage container.

Images