JP5756591B2 - Fuel cell - Google Patents

Description

  The present invention relates to a fuel cell that obtains electric energy by electrochemical reaction of hydrogen and oxygen, and more particularly, to a fuel cell characterized by a junction structure between an electrode layer and a current collector.

  Conventionally, as one type of fuel cell, for example, a solid oxide fuel cell using a solid oxide in an electrolyte layer is known. A solid oxide fuel cell is generally provided with a solid electrolyte body made of a ceramic-based solid oxide having an ionic conductivity and a fuel gas (hydrogen, methane, methanol, etc.) provided on one side of the solid electrolyte body. A fuel electrode layer that is in contact, an air electrode layer that is provided on the other side of the solid electrolyte body and contacts an oxidant gas (air, oxygen, etc.), and an electrode layer such as the fuel electrode layer or the air electrode layer. And a current collector for taking out the electric energy generated by the electrochemical reaction of oxygen from the electrode layer to the outside (see Patent Document 1 and Patent Document 2).

  By the way, one of the factors that improve the power generation performance of the solid oxide fuel cell is to reduce the contact resistance between the electrode layer and the current collector. ing.

  Patent Document 1 proposes a configuration in which an exposed region is formed on the surface of the electrode layer on which the current collector is printed, and the electrode layer and the current collector are integrally sintered. This prevents contact between the electrode layer and the current collector, such as preventing cracking due to local stress concentration by forming the current collector on the entire surface of the electrode layer when the electrode layer and current collector are pressed. The increase in resistance is suppressed.

  In Patent Document 2, a current collector that is in contact with an air electrode that constitutes an electrode layer is composed of a composite layer of a metal felt layer and a metal powder sintered layer, and the metal powder sintered layer is used as an air electrode. Has been disclosed to stabilize the contact state between the electrode layer and the current collector based on the durability of the metal powder sintered layer and reduce the contact resistance between the electrode layer and the current collector. Yes.

JP 2006-139955 A JP 2002-298878 A

However, Patent Documents 1 and 2 have not yet been sufficiently studied for reducing the contact resistance between the electrode layer and the current collector.
In other words, the electrode layer is required to have electrical conductivity and fuel gas or oxidant gas permeability, whereas the current collector is required to have high current collecting performance. In general, electric bodies are formed using different materials, and their sintering temperature or thermal expansion coefficient is often different from each other.

  Therefore, in the fuel device described in Patent Document 1, even if the electrode layer and the current collector are integrally fired, the other is deformed so as to follow one warp or swell of the current collector and the electrode layer. As a result, the gap between the current collector and the electrode layer is likely to be irregularly formed. As a result, the contact area between the electrode layer and the current collector is decreased, and the contact resistance may be increased.

  In addition, for example, in an electrode layer made of a ceramic-based solid electrolyte body, a composite material obtained by mixing ceramic and metal powders and sintered, so-called cermet, etc., warping and undulation occur during sintering. In many cases, the surface of the electrode layer in contact with the current collector is not flat because the surface is curved or has uneven portions.

  Therefore, as described in Patent Document 2, even if the metal powder sintered layer is formed on the portion of the current collector that is in contact with the electrode layer (air electrode), the metal powder sintered layer is not flat. There is a problem that it is difficult to make contact with the surface while ensuring a large contact area, and it is difficult to reduce contact resistance.

  The present invention has been made in the background as described above, and the problem to be solved is that the contact area between the electrode layer and the current collector is ensured and the increase in contact resistance is suppressed. Accordingly, it is an object of the present invention to provide a fuel cell having a novel structure with improved power generation performance.

The invention according to claim 1, which has been made to solve such a problem, includes an electrolyte layer, electrode layers provided on both sides of the electrolyte layer and in contact with the fuel gas and the oxidant gas, and at least one of the electrode layers. A solid oxide fuel cell comprising a current collector that is connected to the electrode layer and extracts electricity from the electrode layer to the outside, and the electrode layer of the current collector at a junction between the current collector and the electrode layer The opposing surface is provided with a plurality of convex portions, and the surface of the electrode layer facing the current collector has a hardness that is greater than the hardness of the electrode layer, A crushing deformation part is formed in which at least a part of the tip of the convex part is inserted and crushed, and a crushing depth of the crushing deformation part by the convex part is 5 to 70 μm . The area of the portion facing the electrode layer at the tip is 0.2. It is a solid oxide fuel cell, which is a 13 mm ^2.

  In such a fuel cell of the present invention, when the electrode layer and the current collector are joined, a plurality of convex portions provided on the current collector are inserted into the crushed deformation portion of the electrode layer, For example, even when the opposing surfaces of the electrode layer and the current collector are difficult to be parallel to each other due to warpage or undulation on the surface of the electrode layer facing the current collector, the purpose of the electrode layer and the current collector A sufficient contact area is ensured.

That is, even when by two facing surfaces of the electrode layer and the current collector is less likely be parallel to each other hardly contact area is ensured by direct superposition of two facing surfaces, the insertion of the collapse deformation of the convex portion This increase in contact area eliminates an increase in contact resistance between the electrode layer and the current collector.

  In addition, the crushing deformed portion into which the convex portion of the current collector is inserted and crushed in this manner is specifically arranged at the joint portion of the electrode layer with the current collector, so that the portion other than the crushing deformed portion in the electrode layer Then, it is possible to appropriately increase the thickness dimension or to use a highly durable material. Thereby, the durability required for the entire electrode layer is sufficiently ensured, and desired conductive performance in the electrode layer is obtained.

Therefore, according to the fuel cell of the present invention, the durability of the electrode layer is ensured, and the contact resistance between the electrode layer and the current collector is reduced, thereby improving the power generation performance.
Moreover, in the fuel cell of the present invention, the crushing depth of the crushing deformed portion due to the convex portion is 5 to 70 μm.
When the crushing depth of the crushing deformation portion by the convex portion is less than 5 μm, it is difficult to ensure a sufficient contact area between the electrode layer and the current collector, and the contact resistance may increase. Moreover, when the crushing depth of the crushing deformation part by a convex part exceeds 70 micrometers, the ratio for which the crushing deformation part in an electrode layer accounts becomes high, and it may become difficult to ensure the durability of the whole electrode layer. Accordingly, the scope of the present invention is preferred.
The crushing depth is a depth dimension from the opening portion to the bottom of the electrode layer surface in the crushing deformation portion where the convex portion is inserted deepest in the crushing deformation portion where a plurality of convex portions are inserted.
And the area of the part which opposes the said electrode layer in the front-end | tip of the said convex part is 0.2-13 mm < ² > , It is characterized by the above-mentioned.
When the area of the portion facing the electrode layer at the tip of the convex portion is less than 0.2 mm ² , the contact area of the current collector with the electrode layer is reduced, and the contact resistance between the current collector and the electrode layer is increased. there is a possibility. Further, if the area of the portion facing the electrode layer at the tip of the convex portion exceeds 13 mm ² , stress concentration at the crushing deformed portion in contact with the tip of the convex portion is difficult to occur, and the convex portion is easily inserted into the crushing deformed portion. As a result, the contact area between the current collector and the electrode layer is reduced, which may increase the contact resistance, and it is difficult to ensure electrical contact. Accordingly, the scope of the present invention is preferred.
According to a second aspect of the present invention, the electrode layer having the crushing deformation portion includes a first electrode layer laminated on the electrolyte layer, and a position opposed to the current collector laminated on the first electrode layer. And a second electrode layer having a hardness lower than that of the first electrode layer, and the crushing deformation portion is formed on a surface of the second electrode layer facing the current collector. It is characterized by.

  In other words, reducing the durability of the electrode layer so that the crushing deformation portion is easily formed on the electrode layer and improving the durability to obtain the required strength of the electrode layer are contradictory acts. However, as described in claim 2, by forming the electrode layer as a laminated structure of the first electrode layer and the second electrode layer having different physical properties, it is easy to form a crushing deformed portion and durability of the electrode layer. Assured compatibility is achieved.

The invention according to claim 3 is characterized in that the electrode layer in which the crushing deformation portion is formed is an air electrode in contact with the oxidant gas.
The air electrode of the fuel cell is a cathode (positive electrode) and receives electrons to ionize oxygen, while the fuel electrode of the fuel cell is an anode (negative electrode) and oxygen ions and hydrogen that have passed through the electrolyte layer. The reaction generates water and emits electrons. In improving the power generation performance, it is preferable to reduce the internal resistance of the air electrode.

  Therefore, in the present invention, since the crushing deformation part is formed on the air electrode, the internal resistance of the air electrode and the contact resistance between the air electrode and the current collector are reduced, and the power generation performance Is further improved.

The invention according to claim 4 is characterized in that a thickness of the electrode layer in a direction facing the current collector is 100 to 300 μm.
If the thickness of the electrode layer in the direction facing the current collector is less than 100 μm, it becomes difficult to form the crushed deformation portion in the electrode layer while ensuring the durability of the electrode layer, and each convexity in the electrode layer There is a possibility that the current collection resistance in the lateral direction up to the current collector through the portion (the width direction orthogonal to the direction of the electrode layer facing the current collector) will increase. In addition, when the thickness of the electrode layer facing the current collector exceeds 300 μm, the internal resistance in the vertical direction of the electrode layer (direction facing the current collector of the electrode layer) increases, Durability may be difficult to ensure. Accordingly, the scope of the present invention is preferred.

The invention according to claim 5 is characterized in that a portion where the crushing deformation portion is formed in the electrode layer is formed by sintering a powder material having a particle diameter of 1 to 10 μm.
If the particle size of the powder material in the formation portion of the collapsed deformed portion of the electrode layer is less than 1 μm, sintering of the formed portion proceeds excessively and the bond strength of the particles increases, so that the convex portion is inserted into the deformed deformed portion. This may make it difficult to reduce the contact area between the electrode layer and the current collector. Moreover, when the particle diameter of the formation part of the crushing deformation part of an electrode layer exceeds 10 micrometers, the sintering of the said formation part becomes difficult to advance and the durability of an electrode layer may fall. Accordingly, the scope of the present invention is preferred. In addition, the said particle size is represented by the average value of the diameter of several particle | grains in the powder material which comprises the formation part of a crushing deformation part.

1 is a longitudinal sectional view schematically showing a main part of a solid oxide fuel cell as one embodiment of the present invention. The longitudinal cross-sectional view which shows one manufacturing process of the solid oxide fuel cell. The longitudinal cross-sectional view which expands and shows schematically the principal part of the solid oxide fuel cell.

  Hereinafter, a solid oxide fuel cell 10 as an embodiment relating to a fuel cell of the present invention will be described with reference to the drawings. The solid oxide fuel cell 10 is a device that generates power by being supplied with a fuel gas (for example, hydrogen) and an oxidant gas (for example, air), and has a substantially flat plate shape as shown in FIG. A plurality of cells 12 are stacked in the thickness direction (up and down in FIG. 1) to increase the voltage.

  The fuel cell 12 is a so-called fuel electrode supporting membrane type power generation unit, and a fuel electrode (anode) 14 as one electrode layer is used as a substrate, and a solid electrolyte layer 16 as an electrolyte layer is laminated on the surface of the fuel electrode 14. Further, an air electrode (cathode) 18 as the other electrode layer is laminated on the surface of the solid electrolyte layer 16. The solid electrolyte layer 16 may be composed of a single layer, but in the present embodiment, the solid electrolyte layer 16 is a plurality of layers including the electrolyte layer body 16a and the reaction prevention layer 16b, and the electrolyte layer body 16a and the air electrode 18 are the reaction prevention layer. It is laminated via 16b.

  The solid electrolyte layer 16, the fuel electrode 14, and the air electrode 18 are known materials as disclosed in JP 2006-172906 A, JP 2006-139955 A, JP 2002-298878 A, and the like. Can be adopted.

  The solid electrolyte layer 16 is made of a ceramic material having oxygen ion conductivity. Specifically, the electrolyte layer body 16a includes, for example, perovskite-based oxides including zirconia-based oxides (YSZ or ScSZ) stabilized with yttria, scandium, or the like, or lanthanum galade-based oxides doped with strontium or magnesium. An oxide is employed.

For the reaction preventing layer 16b, for example, each ceria-based oxide (SDC, GDC) doped with samarium, gadolinium or the like is employed. That is, the reaction preventing layer 16b is made of, for example, a material (SDC or the like) that does not generate a substance (La ₂ Zr ₂ O ₇ or the like) that remarkably increases electrical resistance even when the air electrode 18 containing La is directly baked. Thus, the formation reaction of La ₂ Zr ₂ O _{7 and the} like due to direct baking between the electrolyte layer body 16a made of zirconia-based oxide or the like and the air electrode 18 is prevented, and the electrical resistance is increased. It is suppressed.

As the fuel electrode 14, for example, a porous body made of a metal material such as Ni, Pt, or Ir, or a cermet made of a metal material and a ceramic material such as a zirconia-based oxide is used.
On the other hand, the air electrode 18 includes a first electrode layer 18a stacked on the reaction preventing layer 16b of the solid electrolyte layer 16 and a second electrode layer 18b stacked on the first electrode layer 18a.

  Each of the first electrode layer 18a and the second electrode layer 18b is made of a cermet made of a metal material such as Pt or Ni and a ceramic material such as a velovite oxide. The air electrode 18 composed of the laminated structure of the first and second electrode layers 18a and 18b is sintered by, for example, printing and forming a paste of powder material constituting the cermet of the first electrode layer 18a on the reaction preventing layer 16b. After that, the paste of the powder material constituting the cermet of the second electrode layer 18b is printed and formed on the first electrode layer 18a and sintered. Here, the particle size of the powder material of the second electrode layer 18b is 1 to 10 μm.

  In particular, at the stage before sintering, the particle size of the powder material of the first electrode layer 18a is made smaller than the particle size of the powder material of the second electrode layer 18b. As a result, the degree of sintering progress of the first electrode layer 18a is made larger than the degree of sintering progress of the second electrode layer 18b, and the density or particle bond strength in the first electrode layer 18a after sintering is the second. It is made larger than that of the electrode layer 18b.

  That is, the first electrode layer 18a and the second electrode layer 18b are formed using the same material, and the density of the first electrode layer 18a or the bond strength of the particles is larger than that of the second electrode layer 18b. Therefore, the hardness of the second electrode layer 18b is smaller than the hardness of the first electrode layer 18a.

  A region having a predetermined thickness from the upper surface to the lower side of the second electrode layer 18b in FIG. The thickness of the crushing deformable portion 20 is appropriately set according to various required characteristics such as a bonding state between a current collector 22 and a second electrode layer 18b, which will be described later, and durability of the second electrode layer 18b.

  The thickness of the second electrode layer 18b is larger than the thickness of the first electrode layer 18a. The thickness of the air electrode 18 including the first electrode layer 18a and the second electrode layer 18b is 100 to 300 μm.

  In addition, a current collector 22 is provided between the cells 12 in the stacking direction of the plurality of fuel cells 12 for the purpose of ensuring electrical connection between the cells 12. In the present embodiment, the current collector 22 is disposed only on the upper side of the air electrode 18 of each cell 12. However, instead of or in addition to the arrangement on the upper side of the air electrode 18, the current collector 22 is disposed on the fuel electrode 14. It is also possible to arrange it on the lower side.

  The current collector 22 has a substantially flat plate shape and faces the second electrode layer 18 b of the air electrode 18 in the thickness direction. A plurality of convex portions 24 are provided on the surface of the current collector 22 facing the crushing deformable portion 20.

  The convex portion 24 has a substantially cylindrical shape, and the plurality of convex portions 24 are arranged in the horizontal width direction (left and right in FIG. 1) and the vertical width direction (direction perpendicular to the paper surface in FIG. 1). ) At predetermined intervals (substantially equal intervals in the present embodiment).

Further, the area of the portion facing the air electrode 18 at the tip of each convex portion 24 (in other words, the size of the lower end surface of the convex portion 24 in FIGS. 1 to 3) is 0.2 to 13 mm ² . .
For example, a metal material such as Ni or Pt, cermet, or the like is employed as a material for forming the current collector 22 and the convex portion 24. The convex portion 24 may be formed integrally with the current collector 22, or may be fixed to the current collector 22 after being formed separately from the current collector 22.

The convex portions 24 and the current collectors 22 have substantially the same hardness, and are larger than the hardness of the second electrode layer 18b on which the crushing deformed portion 20 is formed.
In joining the current collector 22 having the plurality of convex portions 24 and the air electrode 18, first, as shown in FIG. 2, the surface of the current collector 22 on which the plurality of convex portions 24 are provided. Is superimposed on the upper surface of the second electrode layer 18b of the air electrode 18 on which the crushing deformation portion 20 is formed.

  Then, the current collector 22 is pressed toward the second electrode layer 18b in a state where the tip surfaces of the plurality of convex portions 24 of the current collector 22 and the upper surface of the second electrode layer 18b are overlapped with each other. Stress concentration occurs in the crushing deformed portion 20 where the convex portions 24 in the electrode layer 18b are overlapped, the crushing deformable portion 20 is brittlely broken, and the convex portions 22 are inserted into the crushing deformed portion 20 at a predetermined depth. Thereby, the current collector 22 is joined to the air electrode 18 via the convex portion 24.

  In particular, in this embodiment, a spacer (not shown) smaller than the height of the convex portion 24 is sandwiched between the opposing surfaces of the current collector 22 and the second electrode layer 18b, and the above-described convex portion 24 is deformed. By performing an insertion operation into the portion 20, an area portion having a predetermined height from the front end surface (the lower end surface in FIGS. 1 to 3) of the convex portion 24 is inserted into the crushing deformation portion 20. The crushing depth: ΔH of the crushing deformation portion 20 corresponding to the insertion depth of the convex portion 24 is set to 5 to 70 μm. The crushing depth: ΔH is the height (thickness) of the air electrode 18 in the convex part 24 that is inserted into the crushing deformed part 20 in the plurality of convex parts 24, and the tip surface and the air electrode of the convex part 24 from H1. Height between 18 lower end surfaces (thickness): Value obtained by subtracting H2: H1-H2.

  By the way, since the solid electrolyte layer 16 and the air electrode 18 are configured to include ceramics, the formation of the solid electrolyte layer 16 and the air electrode 18 causes some warping or undulation, and the collection of the air electrode 18. Although the surface facing the electric body 22 is shown flat in the drawing, strictly speaking, it has an uneven shape.

Therefore, at the stage where the plurality of protrusions 24 and the second electrode layer 18b are overlapped, not all the protrusions 24 may be overlapped on the second electrode layer 18b.
Therefore, in the present embodiment, in consideration of the displacement amount due to the pressing of the current collector 22 to the air electrode 18 into which all the convex portions 24 are inserted into the crushing deformable portion 20 having the concavo-convex shape, By setting the size and the like, all the convex portions 24 can be inserted into the collapsed deformable portion 20.

  As described above, in the solid oxide fuel cell 10 of the present embodiment, the plurality of convex portions 24 provided on the current collector 22 are inserted into the crushing deformation portion 20 of the air electrode 18, and the current collector 22 Since the air electrode 18 is joined, for example, even when the air electrode 18 is warped or undulated and the opposing surfaces of the current collector 22 and the air electrode 18 are difficult to be parallel to each other, the air electrode 18 and the current collector The contact area of the body 22 is ensured and the contact resistance is reduced.

  Moreover, since the front end side of each convex part 24 is inserted in the crushing deformation | transformation part 20, and it is not set as the structure which each protrusion 24 is inserted deeply over the whole, the crushing deformation | transformation part 20 in the air electrode 18 is carried out. There is little possibility that a crack will occur from the formation part to the whole.

  Moreover, in the air electrode 18, in addition to the fact that the entire thickness of the second electrode layer 18 b provided with the crushing deformation portion 20 is sufficiently larger than the thickness of the portion where the crushing deformation portion 20 is formed. The second electrode layer 18b and the first electrode layer 18a having higher hardness than the second electrode layer 18b have a two-layer structure. As a result, the durability required for the air electrode 18 as a whole is sufficiently ensured, and the air electrode 18 is thickened, and the current collection resistance in the width direction perpendicular to the thickness direction of the air electrode 18 is reduced. The current collecting performance of the air electrode 18 is improved.

  Therefore, in the solid oxide fuel cell 10 of the present embodiment, there is a remarkable effect that the electrical loss can be reduced and the power generation performance can be enhanced while the durability of the air electrode 18 is ensured.

  As mentioned above, although one embodiment of the present invention has been described in detail, the present invention is not limited in any way by the specific description in the embodiment, and various changes, modifications, and modifications based on the knowledge of those skilled in the art. The present invention can be implemented in a mode with improvements and the like. Further, it goes without saying that any such embodiments are included in the scope of the present invention as long as they do not depart from the spirit of the present invention.

  Specifically, in the above-described embodiment, after the air electrode 18 including the crushing deformable portion 20 and the current collector 22 including the convex portion 24 are separately formed, the convex portion 24 is inserted into the crushing deformable portion 20. However, for example, the paste of the powder material of the air electrode 18 is printed on the solid electrolyte layer 16 and dried, and the convex portion 24 of the current collector 22 is inserted into the crushed deformation portion 20, and then the air electrode 18 and the current collector 22 provided with the convex portions 24 may be integrally sintered.

  In the above-described embodiment, each of the plurality of convex portions 24 has a columnar shape having substantially the same size. For example, the convex portion has a rectangular shape, and the current collector 22 to the air electrode 18. It may have a sharpened shape or the like that tapers inward, and the shape and size of the plurality of convex portions 24 may be different from each other.

Further, the number and arrangement of the convex portions 24 in the current collector 22 are not limited to those illustrated, and for example, the convex portions 24 may be arranged at different intervals with respect to the current collector 22. .
Further, when the hardnesses of the first electrode layer 18a and the second electrode layer 18b are made different, in the above embodiment, the same powder material is used and the particle diameter of the powder material is made different. For example, it is possible to cope by adopting materials having different hardnesses in advance.

  Further, in the above embodiment, the current collector 22 having the convex portion 24 is laminated on the fuel electrode supporting membrane type fuel cell 12. However, instead of the fuel electrode, the air electrode is used as the base. Of course, it is possible to stack the fuel electrode and the air electrode on a normal type fuel cell in which the air electrode support membrane type or solid electrolyte layer is used as a base and the solid electrolyte layer supports the solid electrolyte layer.

  Further, the fuel cell of the present invention is not limited to the application to the solid oxide fuel cell as illustrated. For example, a solid polymer membrane (polymer) is used for the electrolyte and carbon is used for the electrode layer. The present invention can be applied to a polymer electrolyte fuel cell (PEFC) and other various fuel cells having a junction structure of an electrode layer and a current collector.

Next, an experiment conducted for confirming the effect of the fuel cell of the present invention will be described.
[Preparation of experimental samples]
First, GDC (gadolinium-added ceria) protection is applied to a substrate obtained by laminating a green sheet for a fuel electrode substrate made of a mixed powder of NiO and YSZ and a green sheet for a solid electrolyte membrane made of YSZ powder and then firing. Print and burn the film paste.

  In addition, an LSCF air electrode is baked on the sintered product of the GDC protective film paste to produce a fuel electrode support film type flat plate cell. When producing a plurality of such flat cells, the LSCF air electrode is composed of an upper layer made of a sintered powder material having a particle size of 1 to 10 μm or a particle size of less than 1 μm and a sintered material of a powder material having a particle size of 1 μm or less. A plurality of a two-layer structure with a lower layer and a single-layer structure made of a sintered powder material having a particle size of 1 to 10 μm or a particle size of less than 1 μm are prepared.

Furthermore, an air electrode current collector is obtained by projecting a plurality of cylindrical protrusions on one surface of a flat plate member made of a metal material such as ferritic stainless steel.
Then, each convex part of the air electrode current collector is pressed at a predetermined pressure against the upper end portion of the LSCF air electrode of each flat plate cell, and the contact state between the air electrode and the convex part is maintained, which becomes an experimental sample. A plurality of solid oxide fuel cells are produced.

In addition, the height dimension of the convex part corresponding to the protrusion dimension from the air electrode current collector of the convex part was 0.6 mm.
In this experimental sample, the ratio of the total area of the circular portion at the tip of each convex portion to the area of the surface on the side where the convex portion of the air electrode current collector is provided (hereinafter also referred to as area ratio) is 26 to Set to 27%. The number of convex portions provided on the air electrode current collector and the interval between the convex portions are determined based on the area of the circular portion at the tip of each convex portion (hereinafter also referred to as dot area) and the area ratio.

Specifically, when the dot area is set to 1.5 mm ² and the area ratio is set to 27%, the number of convex portions provided on the air electrode current collector is 1764, and the interval between the convex portions is 2.4 mm. become. When the dot area is 3.1 mm ² and the area ratio is set to 26%, the number of convex portions provided on the air electrode current collector is 841 and the convex interval is 3.5 mm. .
[Experiment contents]
In the plurality of experimental samples, a predetermined laser microscope was used to measure the air electrode recess amount (μm) when the convex portion was inserted into the air electrode. The air electrode dent amount corresponds to the crushing depth ΔH of the crushing deformed portion 20 by the convex portion 24 of the above embodiment: H1−H2.

  Here, the convex part is inserted into the air electrode and the air electrode dent amount of a predetermined size is expressed as Examples 1 to 14, while the convex part is not inserted into the air electrode, or the air electrode Since the state inserted in was not maintained, those in which the amount of air electrode dents did not appear were referred to as Comparative Examples 1 to 3 and Reference Example 1.

  Moreover, in the said experimental sample, each pressure is larger than a predetermined pressure for pressing each convex part of the air electrode current collector in Examples 1 to 14, Comparative Examples 1 to 3, and Reference Example 1 against the air electrode. The experimental sample in which the convex portion was pressed against the air electrode and the air electrode dent amount was expressed was referred to as Reference Example 2. The LSCF air electrode of Reference Example 2 has a two-layer structure of an upper layer made of a sintered material of a powder material having a particle size of 10 μm and a lower layer made of a sintered material of a powder material having a particle size of 1 μm.

In particular, in Examples 1 to 11, the following requirements (A) to (C) are all satisfied.
(A) The area of the circular portion at the tip of the convex portion pressed against the air electrode (in Table 1, the dot area) is 0.2 to 13 mm ² .
(B) The thickness of the air electrode composed of an upper layer and a lower layer or a single layer is 100 to 300 μm.
(C) The layer to which the convex portions of the current collector in the air electrode are pressed is formed by sintering a powder material having a particle diameter of 1 to 10 μm.

And in each experimental sample of an Example, a comparative example, and a reference example, oxidant gas (air) is supplied to the air electrode of each experimental sample, and fuel gas (hydrogen) is supplied to the fuel electrode made of a sintered product of the fuel electrode green sheet. Each experimental sample was set in a power generation evaluation apparatus (not shown) so that the gas was supplied, and a power generation test was performed at 700 ° C., and the voltage of each experimental sample was measured. The results are shown in Table 1. In each example of Table 1 or each comparative example, one of the upper layer thickness (μm) and the lower layer thickness (μm) indicated as “0” is a lamination of one of the layers. This indicates that the air electrode has a single-layer structure of only the other layer.
[Experimental result]

表１に示される結果からも、実施例１〜１４によれば、何れも、集電体の凸部が所定の深さで空気極に差し込まれており、比較例１〜３に比して、高電圧が得られることが認められる。

Also from the result shown in Table 1, according to Examples 1-14, the convex part of an electrical power collector is inserted in the air electrode by the predetermined | prescribed depth, and compared with Comparative Examples 1-3. It can be seen that a high voltage is obtained.

  Further, in Examples 1 to 11 and Example 14, the thickness of the air electrode is set to 100 μm or more, and the thickness of the air electrode is less than 100 μm. The current collecting resistance in the lateral direction is reduced. As a result, the voltages of Examples 1 to 11 and 14 are considered to be larger than those of Example 12.

  On the other hand, when the total thickness of the air electrode exceeds 300 μm as in Comparative Example 2, it is difficult to ensure the support stability of the air electrode with respect to the substrate of the flat plate cell. It becomes impossible to measure the air electrode dent amount and voltage.

  In Comparative Examples 1 and 3, the tip area of the convex portion pressed against the air electrode is larger than in Examples 5, 6, and 14, but the convex portion is made of a powder material having a particle size of less than 1 μm. By being pressed against the hard air electrode made of a sintered product, the collapsed deformed portion is not formed on the air electrode. As a result, the voltage is lower than in the example.

From this, it can be seen that the formation of the crushing deformation portion is more important for reducing the contact resistance between the current collector and the air electrode than increasing the tip area of the convex portion.
Further, as in Example 14, when the tip area of the convex portion pressed against the air electrode is less than 0.2 mm ² , stress concentration tends to occur in the portion where the convex portion of the air electrode is pressed, Although the air electrode dent amount is sufficiently secured, it is recognized that the voltage does not increase as much as in Examples 1-11. This is because the portion of the convex portion inserted into the crushing deformable portion that makes positive contact with the air electrode is the tip portion rather than the peripheral wall portion of the convex portion, and ensuring the area of the tip portion is the contact between the air electrode and the current collector. This is thought to be because it contributes greatly to the increase in area.

However, as in Reference Example 1, when the tip end area of the convex portion is excessively 13 mm ² or more, stress is not easily concentrated on the pressing portion of the convex portion of the air electrode, and the convex portion is not inserted into the air electrode. The air electrode is not crushed and deformed. For this reason, in Reference Example 1, a predetermined voltage is secured based on the large area of the tip portion of the convex portion, but it is recognized that the voltage does not increase as much as in Examples 1-11.

Therefore, it is desirable that the tip area of the convex portion is increased within a range in which the crushing deformed portion is formed on the air electrode.
Also, from the results of Examples 1 to 14, Comparative Examples 1 to 3, and Reference Example 1, it is recognized that the voltage is suitably secured if the air electrode dent amount is practically 5 μm or more. .

  On the other hand, as in Reference Example 2, when the pressing force against the air electrode of the plurality of convex portions is increased and the convex portion is crushed and the air electrode dent amount of the portion inserted into the deformed portion is 80 μm, the air electrode is included, Cracks are confirmed in some flat plate cells such as electrolyte layers (green sheets for solid electrolyte membranes or GDC protective film pastes) and fuel electrodes (sintered green sheets for fuel electrode substrates). . This crack is different from the dent or the like of the portion where the convex portion is inserted in the collapsed deformed portion of the air electrode.

  The occurrence of the crack is caused by the fact that the surface of the air electrode into which the convex portion is inserted is not flat due to swell or warping when the air electrode is sintered, and therefore, the tip surface of each convex portion and the surface of the air electrode This is considered to be caused by variations in the distance between them.

  Therefore, in the air electrode dent amount, that is, the crushing depth of the crushed deformation portion due to the convex portion, some errors are allowed depending on the setting of the size of the convex portion, the undulation amount of the air electrode, etc. In consideration of the range in which a suitable voltage can be obtained without taking into account the size of the protrusions used in a typical fuel cell and the normal amount of swell of the air electrode, which may affect the strength of the cell In this case, the thickness is preferably 5 to 70 μm.

  Therefore, according to the fuel cell having any one of the configurations of Examples 1 to 14, the current collector is based on ensuring a suitable thickness of the air electrode and forming the crushing deformation portion by inserting the convex portion into the air electrode. Electrical loss due to contact between the body and the air electrode is reduced, and power generation performance is improved. In addition, in the fuel cells of Examples 1 to 11 having the above requirements (A) to (C), the power generation performance can be further improved.

DESCRIPTION OF SYMBOLS 10 ... Solid oxide fuel cell, 12 ... Fuel cell, 14 ... Fuel electrode, 16 ... Solid electrolyte layer, 18 ... Air electrode, 20 ... Collapse deformation part, 22 ... Current collector, 24 ... Convex part

Claims (5)

An electrolyte layer; an electrode layer provided on both sides of the electrolyte layer and in contact with the fuel gas and the oxidant gas; and a current collector that joins at least one of the electrode layers and extracts electricity from the electrode layer. In the solid oxide fuel cell provided,
A plurality of convex portions are provided on the surface of the current collector that faces the electrode layer at the junction between the current collector and the electrode layer,
On the surface of the electrode layer facing the current collector, the hardness of the convex portion is larger than the hardness of the electrode layer, so that at least a part of the tip of the convex portion is inserted and crushed. A deformation part is formed,
And, the collapse depth of the crush deformation portion by the convex portion, with a 5 to 70 m, the area of the portion facing the electrode layer at the tip of the convex portion is 0.2～13Mm ² A solid oxide fuel cell. The electrode layer having the crushing deformable portion includes a first electrode layer laminated on the electrolyte layer, a layer laminated on the first electrode layer and facing the current collector, and the hardness is the first electrode. And a second electrode layer that is smaller than the first electrode layer, wherein the crushing deformation portion is formed on a surface of the second electrode layer facing the current collector. 2. The solid oxide fuel cell according to 1. 3. The solid oxide fuel cell according to claim 1, wherein the electrode layer in which the crushing deformation portion is formed is an air electrode in contact with the oxidant gas. 4. 4. The solid oxide fuel cell according to claim 1, wherein a thickness of the electrode layer in a direction facing the current collector is 100 to 300 μm . 5. Forming part of the crushing deformation portion of the electrode layer, the particle size is according to any one of claims 1 to 4, characterized that you have been formed by sintering 1~10μm powder material Solid oxide fuel cell.

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