JP2009099308A - Solid oxide fuel cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a solid oxide fuel cell having less contact resistance and excellent durability even when used in a severe situation such as large changes in temperature and an oxidative atmosphere at high temperature. <P>SOLUTION: In an oxide fuel cell module 1, since a fine metal plate is used as an air electrode-side current collector 47, conductivity on an air electrode 43 side is excellent, and anti-oxidation performance at high temperature is also excellent. Moreover, since a conductive close-contact layer 85 for joining together the air electrode 43 and the air electrode-side current collector 47 is equipped between the air electrode 43 and the air electrode-side current collector 47, the contact resistance is small and the conductivity can be sufficiently ensured. Furthermore, since a fuel electrode 37 and a fuel electrode-side current collector 51 are slidable without joining each other, thermal stress accompanying on/off in operation can be relieved. Accordingly, battery performance can be prevented from being deteriorated due to breakage of the solid oxide fuel battery cell 3 and exfoliation of the air electrode-side current collector 47 from the air electrode 43. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a solid oxide fuel cell including a solid electrolyte body (solid oxide body) having a fuel electrode and an air electrode.

Conventionally, a solid oxide fuel cell (hereinafter also referred to as SOFC) including a solid electrolyte (solid oxide) is known as a fuel cell.
This SOFC uses, as a power generation unit, for example, a power generation cell in which a fuel electrode in contact with fuel gas is provided on one side of a layered solid electrolyte body and an air electrode in contact with air is provided on the other side. An SOFC in which a plurality of cells are stacked has been developed.

  As the above-described SOFC, generally, SOFCs such as a flat plate shape, a cylindrical shape, and a monolith shape are known. Among these, the flat SOFC has advantages such as high power generation efficiency due to low internal resistance and high output density per unit volume due to the lamination of thin power generation cells.

Furthermore, recently, in order to further improve the power density of the fuel cell, various methods aiming to reduce the contact resistance in each component of the stack have been disclosed.
For example, in Patent Document 1 described below, in a structure in which a porous cushion material is used for a current collector that is in contact with an electrode to collect current, the metal powder is scattered on the surface of the electrode, and the contact resistance between the electrode and the current collector We are trying to reduce it. Moreover, in the following Patent Document 2, a conductive paste is arranged between each electrode and each current collector made of metal felt, and each electrode and the current collector are connected by an adhesive layer formed by this conductive paste. A method of joining is disclosed.
JP 2003-7318 A JP 2006-12453 A

However, the technique of Patent Document 1 has a problem that since the current collector is porous, the contact area between the current collector and the electrode is small, and the contact resistance cannot be sufficiently reduced.
Further, in the technique of Patent Document 2, since both the air electrode and the fuel electrode are fixed to the current collector, the thermal stress caused by the temperature change when the fuel cell is turned on / off is caused by the metal felt. The current situation is that there is no good material because the current collector on the air electrode side is exposed to an oxidizing atmosphere at a high temperature.

  The present invention has been made to solve the above-described problems, and its purpose is that the temperature change is large, and even when it is used in a harsh situation of an oxidizing atmosphere at a high temperature, the contact resistance is low, The object is to provide a solid oxide fuel cell having excellent durability.

  (1) The invention of claim 1 is a solid electrolyte body, a fuel electrode provided on one surface of the solid electrolyte body and in contact with the fuel gas, and an air provided on the other surface of the solid electrolyte body and in contact with the oxidant gas. In the solid oxide fuel cell comprising the electrode, a fuel electrode side current collector electrically connected to the fuel electrode is provided on the opposite side of the fuel electrode to the solid electrolyte body side, and the air electrode An air electrode side current collector made of a metal plate electrically connected to the air electrode on the opposite side of the solid electrolyte body side, and further between the air electrode and the air electrode side current collector A conductive adhesive layer made of a material containing silver that joins the air electrode and the air electrode side current collector, and the fuel electrode and the fuel electrode side current collector are not joined. It is slidable.

  In the present invention, a dense (having high conductivity) metal plate is used as the air electrode side current collector instead of a conventional member such as a metal felt, so that the air electrode side has excellent conductivity. In addition, by using a metal plate, it is possible to improve the oxidation resistance performance at a high temperature as compared with a conventional metal felt or the like.

  Furthermore, in the present invention, a conductive adhesion layer (made of a material containing silver) that joins the air electrode and the air electrode side current collector is disposed between the air electrode and the air electrode side current collector. The contact resistance between the air electrode and the air electrode side current collector is small, and sufficient conductivity can be secured.

  Moreover, the temperature of the fuel cell changes greatly as the operation is turned on and off, and a large stress (for example, tensile stress) is applied to each current collector. However, in the present invention, the fuel electrode and the fuel electrode side current collector are applied. Since the electric body can be slid without being bonded with an adhesion layer like the air electrode side, the stress can be relieved. Therefore, damage to the fuel cell (cell) and separation of the current collector from the electrode can be suppressed, so that deterioration in battery performance can be prevented.

  That is, according to the present invention, even when used in a harsh situation where the temperature change is large and the oxidizing atmosphere is at a high temperature, there is a remarkable effect that the contact resistance is low and the durability is high.

(2) The invention of claim 2 is characterized in that the fuel electrode side current collector is made of a porous body mainly composed of nickel.
Since nickel (Ni) has a high thermal expansion coefficient, the fuel electrode side current collector itself expands when the fuel cell is operated at a high temperature without joining the fuel electrode and the fuel electrode side current collector. By doing so, the fuel electrode can be strongly contacted. For this reason, the contact resistance is small and sufficient conduction can be ensured.

  In addition, as content of nickel, 50 mol% or more is suitable. If it is 50 mol% or less, when the fuel cell is operated at a high temperature, the expansion of the fuel electrode side current collector itself is weak, and it cannot contact the fuel electrode strongly, and there is a possibility that sufficient conduction cannot be ensured.

  (3) In the invention of claim 3, the cell main body in which the solid electrolyte body, the fuel electrode and the air electrode are integrated is joined to a thin heat-resistant alloy plate capable of absorbing thermal stress. It is characterized by having.

  In the present invention, since the cell body is joined to a thin heat-resistant alloy plate (for example, a separator), the heat stress generated during the operation of the fuel cell can be absorbed by the heat-resistant alloy. Thereby, since the adhesiveness of an air electrode and an air electrode side collector is always maintained, the high electroconductivity mentioned above can be ensured.

(4) The invention of claim 4 is characterized in that the material containing silver is a silver palladium alloy.
The present invention exemplifies preferred materials for the adhesion layer. Silver-palladium alloy has high conductivity and is advantageous in terms of cost as compared with silver alone.

(5) In invention of Claim 5, content of palladium in the said silver palladium alloy is 1-10 mol%, It is characterized by the above-mentioned.
The present invention exemplifies a preferable content of palladium (Pd). For example, when the palladium content is less than 1 mol% (and therefore the silver content is 99 mol% or more), the fuel cell is operated along the air electrode (P1) as shown in FIG. When air flows, silver migration may occur over a long period of time and electrical leakage may occur between the separator (P2), but in the present invention, since the silver content is low, Such migration can be suppressed.

  On the other hand, if the content of palladium exceeds 10 mol%, the melting point of the alloy becomes high, the adhesion between the air electrode and the air electrode side current collector is impaired due to softening of the alloy due to high temperature during operation, and contact resistance However, in the present invention, since the palladium content is appropriate, such a problem does not occur.

(6) The invention of claim 6 is characterized in that a contact area between the air electrode and the adhesion layer is 10 to 60% of an area of the air electrode.
In the present invention, since the contact area between the air electrode and the adhesion layer is 10% or more of the area (surface area) of the air electrode, the current collection loss is small, and since it is 60% or less, the gas diffusion resistance is low. Few. Thus, high power generation performance can be ensured.

  Here, the solid electrolyte body (solid oxide body) moves, as ions, one part of the fuel gas introduced into the fuel electrode or the oxidant gas introduced into the air electrode during the operation of the battery. Have ionic conductivity. Examples of the ions include oxygen ions and hydrogen ions. Further, the fuel electrode comes into contact with the fuel gas that becomes the reducing agent and functions as a negative electrode in the cell. The air electrode is in contact with an oxidant gas serving as an oxidant and functions as a positive electrode in the cell.

Examples of the material of the solid electrolyte body (solid oxide body) include ZrO ₂ ceramics, LaGaO ₃ ceramics, BaCeO ₃ ceramics, SrCeO ₃ ceramics, SrZrO ₃ ceramics, and CaZrO ₃ ceramics.

As the material of the fuel electrode, for example, ZrO ₂ ceramics such as zirconia stabilized by at least one of metals such as Ni and Fe and rare earth elements such as Sc and Y, CeO ₂ ceramics, etc. The mixture with at least 1 sort (s) of ceramics etc. are mentioned. Moreover, metals, such as Pt, Au, Ag, Pd, Ir, Ru, Rh, Ni, and Fe, are mentioned. These metals may be used alone or in an alloy of two or more metals. Further, a mixture (including cermet) of these metals and / or alloys and at least one of each of the above ceramics may be mentioned. Moreover, the mixture of metal oxides, such as Ni and Fe, and at least 1 type of each of the said ceramic etc. are mentioned.

As the material for the air electrode, for example, various metals, metal oxides, metal double oxides, and the like can be used. Examples of the metal include metals such as Pt, Au, Ag, Pd, Ir, Ru, and Rh, or alloys containing two or more metals. Furthermore, examples of the metal oxide include oxides such as La, Sr, Ce, Co, Mn and Fe (La ₂ O ₃ , SrO, Ce ₂ O ₃ , Co ₂ O ₃ , MnO ₂ and FeO). It is done. As the double oxide, a double oxide containing at least La, Pr, Sm, Sr, Ba, Co, Fe, Mn, etc. (La _1-x Sr _x CoO ₃ -based double oxide, La _1-x Sr _x FeO ₃ -based double oxide, La _1-x Sr _x Co _1-y Fe _y O ₃ -based double oxide, La _1-x Sr _x MnO ₃ -based double oxide, Pr _1-x Ba _x CoO ₃ -based double oxide Oxide and Sm _1-x Sr _x CoO ₃ -based double oxide).

  -As the material of the heat-resistant alloy plate to be joined to the cell body, in addition to heat resistance, materials having excellent chemical stability, strength, etc. can be used. For example, heat resistance of stainless steel, nickel-base alloy, chromium-base alloy, etc. Examples include metal materials such as alloys.

Specifically, examples of stainless steel include ferritic stainless steel, martensitic stainless steel, and austenitic stainless steel. Examples of ferritic stainless steel include SUS430, SUS434, and SUS405. Examples of martensitic stainless steel include SUS403, SUS410, and SUS431. Examples of austenitic stainless steel include SUS201, SUS301, and SUS305. Further, examples of the nickel-based alloy include Inconel 600, Inconel 718, Incoloy 802, and the like. Examples of the chromium-based alloy include Ducrloy CRF (94Cr5Fe1Y ₂ O ₃ ).

-As a material of the air electrode side collector which is a metal plate, the material similar to the material of the said heat resistant alloy plate can be used, However, It is preferable to use a material with especially high electroconductivity. For example, a SUS430 ferrite alloy in which a small amount of La, Mn, Ti, Si, C, Ni, Al, Zr or the like is added to a metal interconnector material generally used in SOFC is suitable.
As the material for the fuel electrode side current collector, a porous body mainly composed of nickel is suitable, but other than that, for example, a SUS material similar to the above, an Ag-based alloy, or the like can be adopted.

-When generating power using a solid oxide fuel cell, a fuel gas is introduced to the fuel electrode side and an oxidant gas is introduced to the air electrode side.
Examples of the fuel gas include hydrogen, hydrocarbons, a mixed gas of hydrogen and hydrocarbons, a fuel gas obtained by passing these gases through water at a predetermined temperature and humidified, and a fuel gas obtained by mixing these gases with water vapor. It is done. The hydrocarbon is not particularly limited, and examples thereof include natural gas, naphtha, and coal gasification gas. The fuel gas is preferably hydrogen. These fuel gas may use only 1 type and can also use 2 or more types together. Moreover, you may contain inert gas, such as nitrogen and argon of 50 volume% or less.

  Examples of the oxidizing gas include a mixed gas of oxygen and another gas. Further, the mixed gas may contain 80% by volume or less of an inert gas such as nitrogen and argon. Of these oxidant gases, air (containing about 80% by volume of nitrogen) is preferred because it is safe and inexpensive.

  Next, an example (example) of the best mode of the present invention, that is, an example of a solid oxide fuel cell will be described.

a) First, the configuration of the solid oxide fuel cell module will be described.
As shown in FIG. 1, a solid oxide fuel cell module 1 is a device that generates power by receiving supply of a fuel gas (for example, hydrogen) and an oxidant gas (for example, air (specifically, oxygen in the air)). is there.

  The solid oxide fuel cell module 1 includes a solid oxide fuel cell stack 5 in which a plurality of (for example, 18) flat solid oxide fuel cell cells 3 are stacked, and a solid oxide fuel cell stack. First and second heat generators 7 and 9 stacked in close contact with both sides in the stacking direction (vertical direction in FIG. 1), and air preheat stacked in close contact with the upper side of the upper first heat generator 7 The first reformer 11, the fuel reformer 13 stacked in close contact with the lower side of the lower second heat generator 9, and the first to tenth fixing members 15 to penetrate the solid oxide fuel cell module 1 in the stacking direction. 33 etc. are provided.

The stacked body of the solid oxide fuel cell stack 5, the first and second heat generators 7 and 9, the air preheater 11, and the fuel reformer 13 is referred to as a module body 34.
As shown in the cross section along the air flow path in FIG. 2, the solid oxide fuel cell 3 is a so-called fuel electrode supporting membrane type cell, and a fuel electrode (anode) is disposed on the fuel gas flow path 35 side. ) 37 is disposed, and a thin solid electrolyte layer (solid oxide layer) 39 is formed on the upper surface of the fuel electrode 37 in the figure, and on the surface of the solid electrolyte layer 39 on the air flow path 41 side. An air electrode (cathode) 43 is formed.

  In addition, a metal plate is used between the air electrode 43 and the upper metal interconnector (a plate for ensuring conduction between the cells 3 and blocking the gas flow path) 45 in order to ensure the conduction. An air electrode side current collector 47 is disposed. On the other hand, a metal fuel electrode-side current collector 51 is also disposed between the fuel electrode 37 and the lower metal interconnector 49 in order to ensure electrical connection. The fuel electrode 37, the solid oxide layer 39, and the air electrode 43 are referred to as a cell body 53.

  More specifically, the solid oxide fuel cell 3 includes a ceramic insulating frame 55 and a metal air electrode frame 57 on the air flow path 41 side, and the air flow path 41, the fuel gas flow path 35, and the like. In addition, a separator 59, which is a metal thin plate capable of absorbing a thermal stress, is disposed between the cell main body 53 and the gas flow path, and a metal fuel electrode is provided on the fuel gas flow path 35 side. A frame 61 and a ceramic insulating frame 63 are provided.

  The interconnectors 45 and 49, the air electrode frame 57, the separator 59, and the fuel electrode frame 61 are made of a heat resistant alloy plate such as stainless steel, and the insulating frames 55 and 63 are made of alumina or the like. The air electrode side current collector 47 is made of a dense metal plate such as a SUS430 ferrite alloy to which a small amount of La, Mn, Ti, Si, C, Ni, Al, Zr or the like is added. The body 51 is made of, for example, a nickel porous body so that the fuel gas can pass therethrough.

  The frame portion 65 of the solid oxide fuel cell 3 is constituted by the interconnectors (outer peripheral edges) 45, 49, the insulating frames 55, 63, the air electrode frame 57, the separator 59, and the fuel electrode frame 61. The bolts 71 and 73 which comprise the 1st-10th fixing members 15-33 are penetrated by the through-holes 67 and 69 comprised so that this structure and the frame part 65 might be penetrated. FIG. 2 shows only some of the through holes and bolts.

  Further, the upper interconnector 45 is formed with first and second grooves 75 and 77 serving as air flow paths so as to communicate with the through holes 67 and 69. Therefore, air is introduced from one through hole 67 into the air flow path 41 in the cell via the first groove 75, and after the air contacts the air electrode 43, the other penetration is made via the second groove 77. It is discharged into the hole 69. In addition, the air (air residual gas) discharged from the through hole 69 reacts with the fuel gas (fuel residual gas) in the heat generators 9 and 7 and is discharged to the outside as exhaust gas.

  On the other hand, as shown in the cross-section along the flow path of the fuel gas in FIG. 3, the lower interconnector 49 is also connected to the through holes 79 and 81 (different from the air flow path) so as to communicate with the through holes 79 and 81. Third and fourth grooves 83 and 84 serving as gas flow paths are formed. Accordingly, the fuel gas is introduced from one through hole 81 into the fuel gas flow path 35 in the cell via the fourth groove 84, and after the fuel gas contacts the fuel electrode 37, the fuel gas is introduced via the third groove 83. It is discharged into the other through hole 79. The fuel gas (fuel residual gas) discharged from the through hole 79 reacts with air (residual air gas) in the heat generators 9 and 7 and is discharged outside as exhaust gas.

  In particular, in this embodiment, as shown in FIGS. 2 and 3, an adhesion layer 85 made of a silver palladium alloy (palladium content 1 to 10 mol%) is interposed between the air electrode 43 and the air electrode side current collector 47. Is formed.

  As will be described later, the adhesion layer 85 is formed by softening from a silver-palladium alloy conductive paste by heating at a high temperature during operation of the fuel cell, and the air electrode 43 and the air electrode side current collector are formed. While ensuring the electrical connection with the body 47, the air electrode 43 and the air electrode side collector 47 are joined.

  As shown in FIG. 4 except for the upper part of the solid oxide fuel cell 3 (interconnector 45, air electrode current collector 47, and insulating plate 55), the adhesion layer 85 is air surrounded by a separator 59. On the surface of the pole 43, while ensuring an air flow path, it is arranged in a grid pattern on the top, bottom, left and right of the figure. The contact area between the air electrode 43 and the adhesion layer 85 is 10 to 60% of the area of the air electrode 43 (the contact area between the air electrode side current collector 47 and the adhesion layer 85 is the same).

b) Next, a method for manufacturing the solid oxide fuel cell module 1 will be briefly described.
First, for example, a plate material made of SUS430 was punched out to produce interconnectors 45 and 49, an air electrode frame 57, a fuel electrode frame 61, and a separator 59. The thickness of the separator 59 is, for example, in the range of 10 to 300 μm so that thermal stress can be easily absorbed.

In addition, the insulating frames 55 and 63 were manufactured by forming a green sheet containing alumina as a main component into a predetermined shape and firing it by a conventional method.
Furthermore, the cell main body 53 of the solid oxide fuel cell 3 was manufactured according to a conventional method. Specifically, the material of the solid oxide layer 39 was printed on the green sheet of the fuel electrode 37, the material of the air electrode 43 was printed thereon, and then fired.

  The cell body 53 was fixed to the separator 59 by brazing. The air electrode side current collector 47 and the fuel electrode side current collector 51 were brazed and fixed to the adjacent upper interconnector 45 and lower interconnector 49, respectively.

On the other hand, Ag-Pd conductive paste was prepared by mixing three rolls of Ag-Pd powder (Pd: 1 mol%), ethyl cellulose, and an organic solvent.
Next, the conductive paste (which becomes the adhesion layer 85) is screen-printed on the surface of the air electrode current collector 47 (the surface which becomes the air electrode 43 side) in a lattice form as shown in FIG. Dried.

  The interconnectors 45 and 49, the air electrode frame 57, the insulating frames 55 and 63, the fuel electrode frame 61, the separator 59 to which the cell body 53 is brazed, and the air electrode side current collector (printed with conductive paste). 47, the fuel electrode side current collector 51 and the like are integrated as shown in FIG. 2, and each solid oxide fuel cell 3 is assembled, and each solid oxide fuel cell 3 is stacked to form a solid oxide. A physical fuel cell stack 5 was constructed.

  The first heat generator 7 and the air preheater 11 are stacked on one side of the solid oxide fuel cell stack 5, and the second heat generator 9 and the fuel reformer 13 are stacked on the other side. The module main body 34 was configured by arranging.

  Next, spacers (not shown) are arranged in the through holes 67, 69, 79, 81 of the module body 34, and the bolts 71, 73 of the first to tenth fixing members 15-33 are fitted, and nuts are attached to the tips thereof. 91 was screwed and the module body 34 was pressed and integrated to complete the solid oxide fuel cell module 1.

  In the conductive paste described above, at the operating temperature of the solid oxide fuel cell module 1 (for example, 700 ° C.), ethyl cellulose and the like are removed, and the Ag—Pd alloy is softened to cause the air electrode 43 or the air electrode side. The current collector 47 is in close contact with the current collector 47. When the operation is stopped, the adhesion layer 85 is firmly joined and integrated with the air electrode 43 and the air electrode side current collector 47.

  d) Thus, since the solid oxide fuel cell module 1 of the present embodiment uses a dense (having high conductivity) metal plate as the air electrode side current collector 47, the electric conductivity on the air electrode 43 side is used. It has excellent properties and has excellent oxidation resistance at high temperatures.

  Further, in this embodiment, since the conductive adhesion layer 85 for joining the air electrode 43 and the air electrode side current collector 47 is provided between the air electrode 43 and the air electrode side current collector 47, Contact resistance is low, and sufficient conductivity can be secured.

  Furthermore, in the present embodiment, the fuel electrode 37 and the fuel electrode side current collector 51 can slide without being joined, so that the thermal stress accompanying the on / off operation can be reduced. Therefore, it is possible to prevent the solid oxide fuel cell 3 from being damaged or the battery performance from being deteriorated due to the air electrode current collector 47 being peeled off from the air electrode 43.

  In addition, in this embodiment, the fuel electrode side current collector 51 is made of a nickel porous body, so that the fuel cell can be operated at a high temperature without joining the fuel electrode 37 and the fuel electrode side current collector 51. In this case, since the fuel electrode side current collector 51 itself expands and strongly contacts the fuel electrode 37, the contact resistance is small and sufficient conduction can be ensured.

  In this embodiment, since the cell body 53 is joined to the separator 59 which is a thin heat-resistant alloy plate, the separator 59 can absorb the thermal stress accompanying the operation of the fuel cell. Thereby, since the adhesiveness of the air electrode 43 and the air electrode side collector 47 is always maintained, the high electroconductivity mentioned above can be ensured.

  Furthermore, in this embodiment, a silver palladium alloy having a palladium content of 1 to 10 mol% is used as the material of the adhesion layer 85. Therefore, migration of silver can be suppressed, and adhesion (during operation) can be secured and contact resistance can be reduced.

  In addition, in this embodiment, the contact area between the air electrode 43 and the adhesion layer 85 is 10 to 60% of the area of the air electrode 43, so that the current collection loss is small and the gas diffusion resistance is small. Thus, high power generation performance can be ensured.

<Experimental example>
Next, experimental examples 1 and 2 performed for confirming the effect of the present invention will be described.
Here, a single-cell solid oxide fuel cell (experimental sample) was produced for experimentation. Specifically, a stainless steel plate having a thickness of 10 mm is arranged on both sides of a solid oxide fuel cell (see FIGS. 2 and 3) having the same configuration as in the above embodiment, and bolts are inserted into the through holes. The sample fixed integrally was produced.

a) Experimental Example 1
Experimental Example 1 is a study in which the power generation performance changes depending on the Pd content in the Ag—Pd alloy.

Here, six types of experimental samples (Sample Nos. 1 to 6) with different Pd contents in the Ag—Pd alloy were produced. In this experimental sample, the surface area of the air electrode was 100 cm ² , and the contact area between the air electrode and the air electrode side current collector was 10 cm ² .

  In this experiment, air and hydrogen are supplied to each experimental sample, and a power generation test is continuously performed at 0.7 V and 700 ° C. for 1000 hours, and the degree of deterioration of the power generation capacity (initial power generation capacity) The rate of decrease from The results are shown in Table 1 below.

この表１から明らかな様に、Ｐｄ含有量が、試料No．１の様に０ｍｏｌ％であっても、劣化率が−１．００と低く、Ｐｄ含有量が、試料No.３〜５の様に１〜１０ｍｏｌ％の場合には、更に劣化率が少なく好適である。

As is apparent from Table 1, the Pd content is determined according to the sample No. Even when it is 0 mol% as in 1, when the deterioration rate is as low as -1.00 and the Pd content is 1 to 10 mol% as in sample Nos. 3 to 5, the deterioration rate is further small and suitable. It is.

b) Experimental example 2
Experimental Example 2 is a study in which the power generation performance changes depending on the contact area between the air electrode and the air electrode side current collector, that is, the surface area (contact area) of the adhesion layer.

  Here, six types of samples (sample Nos. 7 to 12) were prepared in which the surface area of the adhesion layer (that is, the ratio of the surface area of the adhesion layer to the surface area of the air electrode) was different. In this experimental sample, the Pd content was 1 mol%.

  In this experiment, air and hydrogen were supplied to each experimental sample, and a power generation test was performed at 0.7 V and 700 ° C. to examine the power generation capacity. The results are shown in Table 2 below.

この表２から明らかな様に、接触面積の割合が、試料No.８〜１１の様に１０〜６０％の場合には、発電能力が高く好適である。これは、この範囲であれば、ガス拡散抵抗や電気の接触抵抗が共に少ないからと考えられる。

As is apparent from Table 2, when the ratio of the contact area is 10 to 60% as in Sample Nos. 8 to 11, the power generation capacity is high and suitable. This is considered to be because gas diffusion resistance and electrical contact resistance are both low within this range.

c) Experimental example 3
In Experimental Example 3, not only the air electrode and the air electrode side current collector are joined by the adhesion layer on the condition that the Pd content is 1.0 mol% and the contact area is 10%, but the fuel electrode and the fuel electrode assembly are the same. An experimental sample was prepared by bonding with an adhesion layer.

  Using this experimental sample, the device was repeatedly turned on and off five times under the same experimental conditions as in Experimental Example 1. As a result, cell cracking and air electrode peeling occurred, and power generation characteristics could not be evaluated. .

  Needless to say, the present invention is not limited to the above-described embodiments, and can be implemented in various modes without departing from the scope of the present invention.

1 is a perspective view showing a solid oxide fuel cell module of Example 1. FIG. It is explanatory drawing which fractured | ruptured the solid oxide fuel cell so that the flow path of air might be shown. It is explanatory drawing which fractured | ruptured the solid oxide fuel cell so that the flow path of fuel gas might be shown. It is explanatory drawing which shows the formation state of a contact | adherence layer except for the upper part of a solid oxide fuel cell. It is explanatory drawing which shows the problem at the time of using Ag single-piece | unit.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Solid oxide fuel cell module 3 ... Solid oxide fuel cell 5 ... Solid oxide fuel cell stack 37 ... Fuel electrode 39 ... Solid electrolyte layer 43 ... Air electrode 47 ... Air electrode side collector 51 ... Fuel electrode side current collector 85 ... adhesion layer

Claims (6)

A solid oxide body comprising: a solid electrolyte body; a fuel electrode provided on one surface of the solid electrolyte body and in contact with a fuel gas; and an air electrode provided on the other surface of the solid electrolyte body and in contact with an oxidant gas. In fuel cells,
A fuel electrode side current collector electrically connected to the fuel electrode is provided on the opposite side of the fuel electrode to the solid electrolyte body side, and the air electrode is provided on the opposite side of the air electrode to the solid electrolyte body side. It has an air electrode side current collector made of a metal plate that is electrically connected,
Furthermore, a conductive adhesive layer made of a material containing silver that joins the air electrode and the air electrode side current collector is provided between the air electrode and the air electrode side current collector,
A solid oxide fuel cell, wherein the fuel electrode and the fuel electrode side current collector are slidable without being joined.   2. The solid oxide fuel cell according to claim 1, wherein the fuel electrode side current collector is made of a porous body mainly composed of nickel.   The cell body in which the solid electrolyte body, the fuel electrode, and the air electrode are integrated has a structure joined to a thin heat-resistant alloy plate capable of absorbing thermal stress. Or a solid oxide fuel cell according to 2;   The solid oxide fuel cell according to any one of claims 1 to 3, wherein the material containing silver is a silver palladium alloy.   The solid oxide fuel cell according to claim 4, wherein a content of palladium in the silver-palladium alloy is 1 to 10 mol%.   The solid oxide fuel cell according to any one of claims 1 to 5, wherein a contact area between the air electrode and the adhesion layer is 10 to 60% of an area of the air electrode.

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