JP2017107662A - Fuel battery single cell and fuel battery cell stack - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel battery single cell and a fuel battery cell stack capable of efficiently discharging, to the outside of a cell, water vapor generated inside the cell.SOLUTION: A fuel battery single cell 1 comprises: a flat plate-shaped cell 2 having an anode 20, a solid electrolyte layer 21 and a cathode 22; and a metal frame 3 supporting the cell 2. The anode 20 comprises: a diffusion layer 201 which has a plurality of pores so as to diffuse introduced fuel gas F to a layer surface; and an active layer 202 which is arranged on the solid electrolyte layer 21 side of the diffusion layer 201 so as to serve as an anode reaction field. The diffusion layer 201 internally has a plurality of main gas passages 201a which is larger than a diameter of the pores. The main gas passages 201a come into contact with the active layer 202 and penetrate to the external surface of the diffusion layer 201.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a single fuel cell and a fuel cell stack.

  Conventionally, a flat plate fuel cell single cell having an anode, a solid electrolyte layer, and a cathode, and a fuel cell stack in which a plurality of fuel cell single cells are stacked via a separator are known.

  In the prior art document 1, in a fuel cell in which a plurality of supply gas passages and discharge gas passages are provided in a separator, the separator is made of a porous material, and moisture generated by the electrodes is sucked into the separator. Thus, a technique for suppressing the clogging of the electrode due to moisture is disclosed.

JP 2005-322595 A

  However, in the above fuel cell technology, in order to cause the separator to suck moisture, a process for discharging the moisture accumulated in the separator to the outside is separately required. Also, the introduction of fuel gas to the anode is hindered by the moisture moving from the electrode to the supply gas flow path. Therefore, even if the above technique is applied to a fuel cell that uses a solid electrolyte layer, it is difficult to efficiently discharge water vapor generated inside the cell to the outside of the cell. Moreover, since the amount of water vapor increases during high power generation, it becomes more difficult to discharge water vapor outside the cell.

  The present invention has been made in view of such problems, and is intended to provide a fuel cell single cell and a fuel cell stack that can efficiently discharge water vapor generated inside the cell to the outside of the cell. .

One aspect of the present invention includes a flat cell (2) including an anode (20), a solid electrolyte layer (21), and a cathode (22), and a metal frame (3) that supports the cell. A fuel cell single cell (1) comprising:
The anode has a large number of holes, and is disposed on the solid electrolyte layer side of the diffusion layer (201) for diffusing the introduced fuel gas (F) in the layer surface, and is used for the anode reaction. An active layer (202) to be
The diffusion layer includes a plurality of main gas passages (201a) larger than the diameter of the hole,
The main gas channel is in the fuel cell single cell (1) that is in contact with the active layer and penetrates the outer surface of the diffusion layer.

Another aspect of the present invention includes the fuel cell unit cell, a gas supply port (51) for supplying the fuel gas, and a gas discharge port (52) for discharging the fuel gas.
The main gas channel is in the fuel cell stack (5), which is in communication with the gas outlet and not in communication with the gas supply port.

  The fuel cell unit cell is in contact with the active layer and has a main gas flow path penetrating the outer surface of the diffusion layer. Therefore, the water vapor generated in the active layer by the anode reaction enters the main gas flow channel in contact with the active layer, and is discharged from the outer surface of the diffusion layer to the outside of the cell through the main gas flow channel. Therefore, according to the fuel cell single cell, water vapor generated inside the cell can be efficiently discharged outside the cell.

  In the fuel cell stack, the main gas flow path of the fuel cell single cell communicates with the gas discharge port and does not communicate with the gas supply port. Therefore, the fuel cell stack can prevent water vapor generated inside the cell from flowing back to the gas supply port. Therefore, the fuel cell stack can continue to introduce fresh fuel gas supplied from the gas supply port into the anode of the single fuel cell, and the water vapor discharged from the main gas flow path to the outside of the cell. Can be efficiently discharged through the gas discharge port.

  In addition, the code | symbol in the parenthesis described in the means to solve a claim and a subject shows the correspondence with the specific means as described in embodiment mentioned later, and limits the technical scope of this invention. It is not a thing.

FIG. 6 is an explanatory diagram schematically showing a cross section of a fuel cell single cell according to Embodiment 1 and a fuel cell stack according to Embodiment 5. It is the II-II sectional view taken on the line of FIG. It is the III-III sectional view taken on the line of FIG. FIG. 6 is an explanatory view schematically showing a cross section of a fuel cell unit cell of Embodiment 2 and a fuel cell stack of Embodiment 6. It is the VV sectional view taken on the line of FIG. It is the VI-VI sectional view taken on the line of FIG. 6 is an explanatory view schematically showing a part of a cross section of a single fuel cell according to Embodiment 3. FIG. FIG. 6 is an explanatory view schematically showing a part of a cross section of a fuel cell single cell according to a fourth embodiment.

(Embodiment 1)
The fuel cell single cell of Embodiment 1 is demonstrated using FIGS. 1-3. As illustrated in FIGS. 1 to 3, the fuel cell single cell 1 according to the present embodiment includes a flat cell 2 including an anode 20, a solid electrolyte layer 21, and a cathode 22, and a frame 3 that supports the cell 2. And have. The fuel cell using solid oxide ceramics as the solid electrolyte of the solid electrolyte layer 21 is referred to as a solid oxide fuel cell (SOFC).

  The cell 2 can further include an intermediate layer 23 between the solid electrolyte layer 21 and the cathode 22. The intermediate layer 23 is a layer mainly for suppressing the reaction between the solid electrolyte layer material and the cathode material. In the present embodiment, specifically, in the cell 2, the anode 20, the solid electrolyte layer 21, the intermediate layer 23, and the cathode 22 are laminated in this order and joined to each other. Specifically, the cell 2 can be an anode support type in which the anode 20 as an electrode is a support. In this case, since the anode 20 is sufficiently thicker than the other layers, the formability of a main gas channel 201a described later is excellent. In each figure, an example is shown in which the outer shape of the cell 2 has a rectangular shape. In addition, the outer shape of the cell 2 may be a circular shape or the like.

  The frame 3 is made of metal. In this specification, the metal includes an alloy. That is, the fuel cell single cell 1 has a ceramic cell 2 and a metal frame 3 and includes both ceramic and metal materials. Since the fuel cell single cell 1 uses a metal material, the degree of freedom of firing at the time of manufacture is higher than when all of the fuel cell is made of ceramics, and there is an advantage that it is easy to use a material advantageous in power generation characteristics. Specific examples of the metal constituting the frame 3 include stainless steel such as ferritic stainless steel, ferritic heat-resistant chromium alloy, and the like. Specifically, the frame 3 can be disposed on the outer periphery of the anode 20.

  The anode 20 has a diffusion layer 201 and an active layer 202. The diffusion layer 201 has a large number of holes and is a layer that diffuses the introduced fuel gas F in the layer surface. The active layer 202 is a layer that is disposed on the solid electrolyte layer 21 side of the diffusion layer 201 and serves as an anode reaction field. The diffusion layer 201 and the active layer 202 are joined to each other.

  In the present embodiment, the diffusion layer 201 serves as a support in the anode 20, and the thickness of the diffusion layer 201 is set larger than the thickness of the active layer 202. Further, the outer peripheral portion of the diffusion layer 201 of the anode 20 is supported by the frame 3. 1 shows an example in which the end surfaces of the solid electrolyte layer 21 and the active layer 202 are covered with a sealing material 4 such as a glass seal. In the fuel cell unit cell 1, the fuel gas F such as hydrogen and hydrocarbon introduced into the anode 20 and the oxidant gas (not shown) such as oxygen and air introduced into the cathode 22 are crossed by the sealing material 4. There are no leaks. Note that the seal material 4 also partially contacts the frame 3. 2 and 3, the frame 3 and the seal material 4 are omitted.

  The diffusion layer 201 includes a plurality of main gas flow paths 201a larger than the diameter of the hole. The fact that the main gas flow path 201a is larger than the diameter of the hole means that the hole provided in the porous diffusion layer 201 is different from the main gas flow path 201a. In addition, it can confirm that the magnitude | size of the main gas flow path 201a is larger than the diameter of a hole by observing the cross section of the anode 20 with a scanning electron microscope (SEM).

  The main gas channel 201 a is in contact with the active layer 202 and penetrates the outer surface of the diffusion layer 201. Specifically, the outer surface of the diffusion layer 201 can include an introduction surface 201c through which the fuel gas F is introduced and a lead-out surface 201d through which the fuel gas F is derived. In the present embodiment, the through-hole 201b of the main gas flow channel 201a is formed on the lead-out surface 201d of the outer surface of the diffusion layer 201. In this case, the fuel gas F introduced into the introduction surface 201 c of the diffusion layer 201 is diffused into the layer surface within the diffusion layer 201 and supplied to the active layer 202. In addition, the fuel gas F that has not been used for the anode reaction in the active layer 202 mainly flows along the main gas flow path 201a and is discharged from the through-hole 201b formed in the lead-out surface 201d of the diffusion layer 201. The During power generation of the single fuel cell 1, a flow of the fuel gas F in one direction toward the through hole 201b is generated in the main gas channel 201a. Then, water vapor (not shown) generated in the active layer 202 by the anode reaction enters the main gas flow path 201a in contact with the active layer 202 and diffuses along the flow of the fuel gas F in one direction toward the through-hole 201b. It is discharged to the outside of the cell 2 through the through hole 201b in the lead-out surface 201d of the layer 201. Therefore, in this case, it is possible to prevent water vapor generated inside the cell 2 from flowing backward with respect to the flow of the fuel gas F. Therefore, in this case, it is possible to obtain a single fuel cell 1 that easily discharges water vapor generated inside the cell 2 to the outside of the cell 2 efficiently.

  Specifically, the outer surface of the diffusion layer 201 includes a layer surface opposite to the solid electrolyte layer 21 side in the diffusion layer 201 and an end surface of the diffusion layer 201. In the present embodiment, the layer surface of the diffusion layer 201 is the fuel gas F introduction surface 201c. A part of the end surface of the diffusion layer 201 is a fuel gas F lead-out surface 201d. In this case, when the single fuel cell 1 is stacked, the layer surface of the diffusion layer 201 is communicated with the gas supply port 51 that supplies the fuel gas F, and the end surface of the diffusion layer 201 is a gas that discharges the fuel gas F. By communicating with the discharge port 52, a differential pressure is easily generated between the layer surface and the end surface of the diffusion layer 201. Therefore, in this case, the flow of the fuel gas F due to the differential pressure becomes a driving force, and the fuel cell unit cell 1 that easily discharges the water vapor generated inside the cell 2 to the outside of the cell 2 can be obtained.

  In the present embodiment, since the outer shape of the cell 2 is a square shape, there are four end faces of the diffusion layer 201, and one of the end faces serves as a fuel gas F lead-out face 201d. The remaining three end surfaces are different from the introduction surface 201c and the lead-out surface 201d. In the present embodiment, for example, when the fuel cell single cell 1 is stacked, a separator (not shown) is disposed on the opposite side of the diffusion layer 201 from the solid electrolyte layer 21 side, and gas is supplied through the gas supply channel 510. The fuel gas F supplied from the port 51 can be introduced into the introduction surface 201c.

  Specifically, the plurality of main gas flow paths 201a can be arranged along the anode surface direction in a state of being separated from each other. In this case, it is easy to form the through-hole 201b of the main gas channel 201a on the end surface of the diffusion layer 201. Therefore, the fuel cell single cell 1 in which the layer surface of the diffusion layer 201 opposite to the solid electrolyte layer 21 side is the introduction surface 201c, and a part of the end surface of the diffusion layer 201 is the lead-out surface 201d. It becomes easy to obtain. Moreover, the main gas flow path 201a arranged in the anode surface direction can be formed by using, for example, a disappearing agent paste that disappears by firing, and disappearing the disappearing agent paste simultaneously with firing of the anode 20. Therefore, in this case, the fuel cell single cell 1 excellent in formability of the main gas flow path 201a can be obtained.

  In the present embodiment, the main gas path 201 a is in contact with the active layer 202 at a portion on the solid electrolyte layer 21 side in the longitudinal wall surface. Note that the end of the main gas channel 201 a opposite to the through-hole 201 b side is disposed inside the diffusion layer 201.

  Each of the main gas flow paths 201a can be linear. In this case, compared to the case where the main gas flow path 201a is not linear, it is easy to reduce the resistance when water vapor flows, and the discharge of water vapor to the outside of the cell 2 is promoted. Therefore, in this case, it is possible to obtain a single fuel cell 1 that easily discharges water vapor generated inside the cell 2 to the outside of the cell 2 efficiently.

  In the above case, the average bending degree of the main gas channel 201a can be in the range of 1.0 to 2.0. In this case, the promotion of the discharge of water vapor to the outside of the cell 2 is ensured. The average bending degree of the main gas channel 201a is preferably 1.8 or less, more preferably 1.7 or less, still more preferably 1.6 or less, and even more preferably 1 from the viewpoint of ensuring the above effect. .5 or less.

The average bending degree of the main gas channel 201a is observed from a cross section parallel to the direction in which the main gas channel 201a is formed using a field emission scanning electron microscope (FE-SEM). Is the average value of each degree of bending calculated by the following formula.
Bending degree of main gas flow path 201a = (length of center line obtained by connecting the flow path centers of main gas flow path 201a) / (anode 20 in the flow direction in the portion where main gas flow path 201a is formed) Length)

  The flow path width of the main gas flow path 201a is preferably 20 μm or more, more preferably 100 μm or more, and even more preferably 400 μm or more, from the viewpoints of improving the discharge of water vapor, forming the flow path, and the like. In addition, the channel width of the main gas channel 201a is preferably 1500 μm or less, more preferably 800 μm or less, and even more preferably 500 μm or less, from the viewpoint of ensuring anode strength and the like. The channel pitch of the main gas channel 201a is preferably 20 μm or more, more preferably 100 μm or more, and still more preferably 400 μm from the viewpoints of suppressing strength deterioration due to short circuit between the channels and reducing the difficulty in manufacturing. This can be done. Further, the channel pitch of the main gas channel 201a is preferably 1000 μm or less, more preferably 800 μm or less, and even more preferably 500 μm or less, from the viewpoint of uniform discharge of water vapor in the anode surface.

  The diffusion layer 201 can further include a sub-gas channel 201e that is larger than the diameter of the hole and does not intersect with the main gas channel 201a in the layer surface. In this case, the fuel gas F introduced into the diffusion layer 201 is diffused in the layer surface not only by the hole portion of the diffusion layer 201 but also by the sub gas channel 201e. Therefore, according to this configuration, it is easy to diffuse the fuel gas F uniformly in the layer surface of the diffusion layer 201, and the fuel cell single cell 1 that can easily reduce the power generation distribution in the cell surface can be obtained. In the present embodiment, an example is shown in which the secondary gas flow path 201e is not in contact with the active layer 202 and does not penetrate the outer surface of the diffusion layer 201.

  There may be one sub-gas channel 201e or a plurality of sub-gas channels 201e. When the plurality of sub gas flow paths 201e are provided, the fuel gas F can be more uniformly diffused in the layer surface of the diffusion layer 201, so that the above effect can be easily obtained. Moreover, the sub gas flow path 201e can be made into linear form. In this case, compared with the case where the sub gas flow path 201e is not linear, the resistance when the fuel gas F flows can be easily reduced, and the fuel gas F can be more uniformly diffused in the layer surface of the diffusion layer 201. The above effect is easily obtained.

  In the present embodiment, an example is shown in which the diffusion layer 201 includes a plurality of sub gas flow paths 201e, and the sub gas flow paths 201e are arranged apart from each other. Moreover, the sub gas flow path 201e is arrange | positioned so that it may cross | intersect on the plane different from the main gas flow path 201a. More specifically, the sub gas channel 201e is specifically arranged on the plane different from the main gas channel 201a so as to intersect the main gas channel 201a at 90 °. The channel width and channel pitch of the sub gas channel 201e can be set in the same range as the main gas channel 201a.

  In the single fuel cell 1, the material of the solid electrolyte layer 21 is zirconium oxide-based oxidation such as yttria-stabilized zirconia (YSZ), scandia-stabilized zirconia (ScSZ), etc., from the viewpoint of excellent strength and thermal stability. A thing can be used conveniently. The material of the solid electrolyte layer 21 is preferably yttria-stabilized zirconia from the viewpoints of ion conductivity, mechanical stability, compatibility with other materials, and chemical stability from an air atmosphere to a fuel gas atmosphere. is there. In the present embodiment, specifically, yttria-stabilized zirconia can be used as the material of the solid electrolyte layer 21.

  The thickness of the solid electrolyte layer 21 is preferably 3 to 20 μm, more preferably 4 to 8 μm, from the viewpoint of reducing ohmic resistance. In the present embodiment, the thickness of the solid electrolyte layer 21 can be specifically 4 μm.

  In the single fuel cell 1, examples of the material of the diffusion layer 201 and the material of the active layer 202 include a mixture of a catalyst such as Ni or NiO and a solid electrolyte such as the above-described zirconium oxide oxide. it can. NiO becomes Ni in a reducing atmosphere during power generation. In this embodiment, as the material of the diffusion layer 201 and the material of the active layer 202, specifically, both Ni or a mixture of NiO and yttria stabilized zirconia can be used.

  In addition, the thickness of the diffusion layer 201 is preferably 100 μm or more, more preferably 200 μm or more, and more preferably 300 μm or more, from the viewpoint of securing strength as a support. The thickness of the diffusion layer 201 is preferably 800 μm or less, more preferably 700 μm or less, from the viewpoint of improving gas diffusibility. The thickness of the active layer 202 is preferably 10 μm or more, more preferably 15 μm or more, from the viewpoints of reaction persistence, handleability, workability, and the like. The thickness of the active layer 202 is preferably 30 μm or less, more preferably 25 μm or less, from the viewpoint of reducing electrode reaction resistance. In the present embodiment, the thickness of the diffusion layer 201 can be specifically 400 μm, and the thickness of the active layer 202 can be specifically 25 μm.

In the single fuel cell 1, the material of the intermediate layer 23 is, for example, CeO ₂ or CeO ₂ or one or two selected from Gd, Sm, Y, La, Nd, Yb, Ca, and Ho. Examples thereof include cerium oxide-based oxides such as ceria-based solid solutions doped with more than one element. These can be used alone or in combination of two or more. In the present embodiment, specifically, a ceria-based solid solution in which CeO ₂ is doped with Gd can be used as the material of the intermediate layer 23.

  In addition, the thickness of the intermediate layer 23 is preferably 1 to 20 μm, more preferably 2 to 5 μm, from the viewpoints of reducing ohmic resistance and suppressing element diffusion from the cathode. In the present embodiment, the thickness of the intermediate layer 23 can specifically be 3 μm.

In the single fuel cell 1, examples of the material of the cathode 22 include transition metal perovskite oxides. The transition metal perovskite oxide, specifically, for _{example, La x Sr 1-x CoO} 3 based _{oxide, La x Sr 1-x Co} y Fe 1-y O 3 based oxide, _Sm x Sr ₁ Examples include _-x CoO ₃ oxides (wherein 0 ≦ x ≦ 1, 0 ≦ y ≦ 1). These can be used alone or in combination of two or more. In this embodiment, specifically, a La _x Sr _1-x Co _y Fe _1-y O ₃ oxide (0 ≦ x ≦ 1, 0 ≦ y ≦ 1) is used as the material of the cathode 22. it can.

  The thickness of the cathode 22 is preferably 20 to 100 μm, more preferably 30 to 80 μm, from the viewpoints of gas diffusibility, electrode reaction resistance, current collection, and the like. In the present embodiment, specifically, the thickness of the cathode 22 can be set to 50 μm.

  The single fuel cell 1 has a main gas flow path 201 a that is in contact with the active layer 202 and penetrates the outer surface of the diffusion layer 201. Therefore, water vapor generated in the active layer 202 by the anodic reaction enters the main gas channel 201a in contact with the active layer 202, and is discharged from the outer surface of the diffusion layer 201 to the outside of the cell 2 through the main gas channel 201a. Therefore, according to the single fuel cell 1, water vapor generated inside the cell 2 can be efficiently discharged to the outside of the cell 2.

(Embodiment 2)
The fuel cell single cell of Embodiment 2 is demonstrated using FIGS. Of the reference numerals used in the second and subsequent embodiments, the same reference numerals as those used in the above-described embodiments represent the same components as those in the above-described embodiments unless otherwise indicated.

  As illustrated in FIGS. 4 to 6, in the single fuel cell 1 of the present embodiment, a part of the end surface of the diffusion layer 201 is the introduction surface 201 c of the fuel gas F. Further, the layer surface of the diffusion layer 201 opposite to the solid electrolyte layer 21 side is a fuel gas F lead-out surface 201d. And the through-hole 201b of the main gas flow path 201a is formed in this derivation | leading-out surface 201d.

  In this case, when the fuel cell single cell 1 is stacked, the end surface of the diffusion layer 201 is communicated with the gas supply port 51 for supplying the fuel gas F, and the layer surface of the diffusion layer 201 is discharged from the fuel gas F. By communicating with the discharge port 52, it becomes easy to generate a concentration gradient of water vapor between a portion of the main gas flow channel 201a in contact with the active layer 202 and a portion of the main gas flow channel 201a through the through port 201b. That is, water vapor is generated one after another in the portion in contact with the active layer 202 in the main gas channel 201a, and the concentration of water vapor is increased, while water vapor is present in the gas outlet 52 in the portion of the through port 201b in the main gas channel 201a. Since it is discharged, the concentration of water vapor is always low. Therefore, in this case, in addition to the flow of the fuel gas F in one direction toward the through-hole 201b, the concentration gradient of the water vapor becomes a driving force, and the water vapor generated inside the cell 2 is more easily discharged to the outside of the cell 2. A single fuel cell 1 is obtained. Further, in this case, since the water vapor moves in the anode thickness direction, the movement distance of the water vapor becomes shorter than that in the case where the water vapor moves in the anode surface direction. improves.

  In this embodiment, since the outer shape of the cell 2 is rectangular, there are four end faces of the diffusion layer 201, and one of the end faces is the introduction surface 201c of the fuel gas F. The remaining three end surfaces are different from the introduction surface 201c and the lead-out surface 201d. In the present embodiment, the fuel gas F can be introduced into the end face of the diffusion layer 201 through the gap 41 provided between the sealing material 4 and the frame 3.

  Specifically, the plurality of main gas flow paths F can be arranged along the anode thickness direction in a state of being separated from each other. In this case, it is easy to form the through-hole 201b of the main gas channel 201a on the layer surface of the diffusion layer 201. Therefore, a part of the end surface of the diffusion layer 201 is the introduction surface 201c, and it is easy to obtain the fuel cell single cell 1 in which the layer surface opposite to the solid electrolyte layer 2 side in the diffusion layer 201 is the lead-out surface 201d. Become. The main gas channel 201a arranged in the anode thickness direction includes, for example, a through-hole penetrating in the sheet thickness direction at a position corresponding to the sub-gas channel 201e, and a disappearing agent paste filled in the through-hole. It can be formed by laminating a plurality of unfired diffusion layer forming sheets (not shown) having sinter and firing them.

  In the present embodiment, in the main gas path 201 a, the end on the solid electrolyte layer 21 side is in contact with the active layer 202, and the end opposite to the solid electrolyte layer 21 side is in contact with the layer surface of the diffusion layer 201.

  Similar to the first embodiment, the diffusion layer 201 can further include a sub-gas channel 201e that is larger than the diameter of the hole and does not intersect with the main gas channel 201a in the layer surface. The sub gas flow channel 201e can be disposed closer to the active layer 202 side in the diffusion layer 201. In this case, the fuel gas F introduced into the diffusion layer 201 is easily diffused uniformly in the layer surface of the diffusion layer 201 relatively close to the active layer 202. More specifically, a layer including a hole may be present between the sub gas channel 201e and the active layer 202. In this case, the fuel gas F is not diffused directly from the sub gas path 201e to the active layer 202, and after the fuel gas F is reliably diffused by the layer including the hole, the fuel gas F is supplied to the active layer 202. The Therefore, in this case, the single fuel cell 1 that can easily reduce the power generation distribution in the cell plane is obtained. Other configurations and operational effects are the same as those of the first embodiment.

(Embodiment 3)
The fuel cell single cell of Embodiment 3 is demonstrated using FIG.

  As illustrated in FIG. 7, the fuel cell single cell 1 of the present embodiment has a dense layer 201 f that is denser than the hole formation site in the diffusion layer 201 on the wall surface of the main gas flow path 201 a. Yes. In this case, the water vapor flowing in the main gas flow channel 201a is hardly absorbed by the holes of the diffusion layer 201, and the discharge property of the water vapor to the outside of the cell 2 can be improved.

  In the present embodiment, specifically, the dense layer 201f can be configured to satisfy the relationship of porosity of the dense layer 201f <porosity of the hole forming portion in the diffusion layer 201. In this case, the above effect can be ensured. Further, the dense layer 201f can be specifically disposed on the wall surface on the diffusion layer 201 side among the wall surfaces in the main gas flow path 201a. In addition, the porosity said above is cross-sectional observation of the object part cross-sectioned using the ion milling method etc. by x10000 time using a scanning electron microscope (SEM), {(pore area) / (Observation area)} is a numerical value calculated by x100.

  For example, the dense layer 201f is formed by adding a sintering aid to the extinguishing agent paste when the extinguishing agent paste disappears during firing to form the main gas channel 201a. It can be formed by sintering the surroundings more than others. Examples of sintering aids include solid electrolyte nanopowder used for the diffusion layer 201. Other configurations and operational effects are the same as those of the first embodiment.

(Embodiment 4)
The fuel cell single cell of Embodiment 4 is demonstrated using FIG.

  As illustrated in FIG. 8, the fuel cell single cell 1 of the present embodiment has a dense layer 201 f that is denser than the hole forming portion of the diffusion layer 201 on the wall surface of the main gas flow path 201 a. Yes. In this case, the water vapor flowing in the main gas flow channel 201a is hardly absorbed by the holes of the diffusion layer 201, and the discharge property of the water vapor to the outside of the cell 2 can be improved.

  In the present embodiment, specifically, the dense layer 201f can be configured to satisfy the relationship of porosity of the dense layer 201f <porosity of the hole forming portion in the diffusion layer 201. In this case, the above effect can be ensured. Further, the dense layer 201f can be specifically disposed on the wall surface on the diffusion layer 201 side among the wall surfaces in the main gas flow path 201a.

  For example, when the main gas flow path 201a is formed using the extinguishing agent paste, the dense layer 201a is added around the wall surface of the main gas flow path 201a by adding a sintering aid to the extinction agent paste. It can be formed by sintering. Examples of sintering aids include solid electrolyte nanopowder used for the diffusion layer 201. Other configurations and operational effects are the same as those of the second embodiment.

(Embodiment 5)
A fuel cell stack according to Embodiment 5 will be described with reference to FIG. As shown in FIG. 1, the fuel cell stack 5 includes a single fuel cell 1, a gas supply port 51 that supplies the fuel gas F, and a gas discharge port 52 that discharges the fuel gas F. . In the present embodiment, the single fuel cell 1 of the first embodiment is used.

  The main gas flow path 201 a of the fuel cell single cell 1 communicates with the gas discharge port 52. That is, as illustrated in FIG. 1, the main gas flow path 201 a is spatially connected to the gas discharge port 52 without passing through the hole in the porous diffusion layer 201. On the other hand, the main gas flow path 201 a of the single fuel cell 1 does not communicate with the gas supply port 51. Here, as illustrated in FIG. 1, strictly speaking, it can be said that the main gas flow channel 201 a is spatially connected to the gas supply port 51 through a hole in the porous diffusion layer 201. However, such a connection is not suitable for the discharge of water vapor to the outside of the cell 2, and therefore, it is evaluated that the main gas flow path 201 a and the gas supply port 51 do not communicate with each other.

  According to the fuel cell stack 5, it is possible to prevent water vapor generated inside the cell 2 from flowing back to the gas supply port 51. Therefore, the fuel cell stack 5 can continue to introduce the fresh fuel gas F supplied from the gas supply port 51 into the anode 20 of the fuel cell single cell 1, and also from the main gas channel 201 a to the outside of the cell 2. The water vapor discharged to can be continuously discharged efficiently through the gas discharge port 52. Therefore, the fuel cell stack 5 can exhibit high power generation performance even during large power generation where the amount of water vapor increases.

  Specifically, the fuel cell stack 5 can have a stacked structure in which a plurality of fuel cell single cells 1 are stacked via separators (not shown). The separator is made of metal. Specific examples of the metal constituting the separator include stainless steel such as ferritic stainless steel, ferritic heat-resistant chromium alloy, and the like.

  In the present embodiment, more specifically, the gas supply flow path through which the fuel gas F supplied from the gas supply port 51 passes through the gap between the separator and the frame 3 disposed on the anode 20 side in the single fuel cell 1. 510, a gas discharge flow path 520 through which the water vapor discharged from the main gas flow path 201a and the fuel gas F pass can be used. In the present embodiment, the gas supply channel 510 is in contact with the layer surface of the diffusion layer 201. The gas discharge channel 520 is in contact with the end surface of the diffusion layer 201 through which the main gas channel 201a passes. Moreover, it can be set as the structure which has the flow path (not shown) through which oxidant gas passes in the clearance gap between the separator arrange | positioned at the cathode 22 side in the fuel cell single cell 1, and the flame | frame 3.

(Embodiment 6)
A fuel cell stack according to Embodiment 6 will be described with reference to FIG. As shown in FIG. 4, the fuel cell stack 5 of the present embodiment is different from the fuel cell stack 5 of Embodiment 5 in that the single fuel cell 1 of Embodiment 2 is used. . Further, in the fuel cell stack 5 of the present embodiment, the gas discharge channel 520 is in contact with the layer surface of the diffusion layer 201, the gas supply channel 510 is formed of the diffusion layer 201 through which the main gas channel 201a passes. The fuel cell stack 5 is different from the fuel cell stack 5 of the fifth embodiment in that it is in contact with the end face. Other configurations and operational effects are the same as those of the fifth embodiment.

(Experimental example)
Hereinafter, it demonstrates more concretely using an experiment example.
<Single fuel cell of sample 1>
-Material preparation-
NiO powder (average particle size: 1.0 μm), 8YSZ powder (average particle size: 0.5 μm), carbon (pore forming agent), polyvinyl butyral, isoamyl acetate and 1-butanol are mixed in a ball mill. A slurry was prepared. The mass ratio of NiO powder and 8YSZ powder is 65:35. Using the doctor blade method, the slurry was applied in layers on a resin sheet, dried, and then the resin sheet was peeled off to prepare a rectangular diffusion layer forming sheet A. The thickness of the diffusion layer forming sheet A was 110 μm. The average particle diameter is the particle diameter (diameter) d50 when the volume-based cumulative frequency distribution measured by the laser diffraction / scattering method shows 50% (hereinafter the same).

  Acrylic beads, ethyl cellulose, terpineol, a dispersant, a leveling agent, and an anti-settling agent were stirred with a planetary mixer, and then mixed with three rolls to prepare a quenching agent paste. The sheet A for diffusion layer formation was affixed on the surface of the slightly adhesive sheet | seat, and the vanishing agent paste was pattern-printed on the surface of the sheet | seat A for diffusion layer formation using the screen printing method. The printing pattern here is a linear pattern composed of 71 linear pastes arranged at equal intervals, and is for forming a sub-gas channel. The line width of each linear paste was 0.1 μm, the pitch between lines was 1.0 μm, and the line thickness was 55 μm. Further, both end portions of each linear paste are not in contact with the end face of the diffusion layer forming sheet A. After drying each linear paste, the diffusion layer forming sheet B was prepared by peeling off the slightly adhesive sheet.

  The diffusion layer forming sheet A was affixed to the surface of the slightly adhesive sheet, and the above-mentioned disappearant paste was pattern-printed on the surface of the diffusion layer forming sheet A using a screen printing method. The printing pattern here is a linear pattern composed of 71 linear pastes arranged at equal intervals, and is for forming a main gas flow path. The line width of each linear paste was 0.1 μm, the pitch between lines was 1.0 μm, and the line thickness was 55 μm. Further, one end of each linear paste is not in contact with the end face of the diffusion layer forming sheet A, and the other end of each linear paste is the end face opposite to the end face of the diffusion layer forming sheet A. Is in contact with After drying each linear paste, the diffusion layer forming sheet C was prepared by peeling off the slightly adhesive sheet.

  NiO powder (average particle size: 1.0 μm), 8YSZ powder (average particle size: 0.2 μm), carbon, polyvinyl butyral, isoamyl acetate and 1-butanol (mixed solvent) are mixed in a ball mill. A slurry was prepared. The mass ratio of NiO powder and 8YSZ powder is 65:35. Using the doctor blade method, the slurry was applied in layers on a resin sheet, dried, and then the resin sheet was peeled off to prepare a square active layer forming sheet. The thickness of the active layer forming sheet was 30 μm. The amount of carbon in the active layer forming sheet is smaller than that in the diffusion layer forming sheet A.

  A slurry was prepared by mixing 8YSZ powder (average particle size: 0.5 μm), polyvinyl butyral, isoamyl acetate and 1-butanol with a ball mill. Using the doctor blade method, the slurry was applied in layers on a resin sheet, dried, and then the resin sheet was peeled off to prepare a rectangular solid electrolyte layer forming sheet. The thickness of the solid electrolyte layer forming sheet was 5.0 μm.

A slurry was prepared by mixing CeO ₂ (10GDC) powder (average particle size: 0.3 μm) doped with 10 mol% Gd, polyvinyl butyral, isoamyl acetate, 2-butanol and ethanol with a ball mill. . Using the doctor blade method, the slurry was applied in layers on a resin sheet, dried, and then the resin sheet was peeled off to prepare a rectangular intermediate layer forming sheet. The thickness of the intermediate layer forming sheet is
The thickness was 4.0 μm.

A cathode forming paste was prepared by mixing LSC (La _0.6 Sr _0.4 CoO ₃ ) powder (average particle size: 2.0 μm), ethyl cellulose, and terpineol with three rolls.

  The diffusion layer forming sheet A, the diffusion layer forming sheet B, the diffusion layer forming sheet C, the active layer forming sheet, the solid electrolyte layer forming sheet, and the intermediate layer forming sheet are laminated in this order and pressure bonded. Thus, a laminate was obtained. In addition, the edge part of a linear paste is exposed to one of the four end surfaces of the sheet | seat C for diffusion layer formation in a laminated body. Here, at the time of the above lamination, the diffusion layer forming sheet B and the diffusion layer forming sheet C are a linear paste of the diffusion layer forming sheet B and a linear paste of the diffusion layer forming sheet C as viewed from the lamination direction. And are arranged so as to be orthogonal to each other. In addition, a CIP molding method was used for pressure bonding. The CIP molding conditions were a temperature of 80 ° C., a pressing force of 50 MPa, and a pressing time of 10 minutes. Moreover, the laminated body was degreased after the pressure bonding. In addition, a dimension adjustment can be implemented by cut | disconnecting the outer peripheral part of the laminated body after crimping | compression-bonding. In this case, the dimensional accuracy of the obtained cell can be improved. Furthermore, at the time of the cutting, by cutting the outer peripheral portion of the laminate so as to include the other end portion of the linear pattern in the diffusion layer forming sheet C, the end surface of the diffusion layer forming sheet C in the laminate The end of the paste can be surely exposed. In this case, the main gas channel can be surely penetrated to the end face.

  The laminate was fired at 1350 ° C. for 2 hours. As a result, a sintered body was obtained in which a diffusion layer (350 μm), an active layer (25 μm), a solid electrolyte layer (4.0 μm), and an intermediate layer (3.0 μm) were laminated in this order. In addition, each linear pattern lose | disappeared by the said baking, and the main gas flow path and subgas flow path as shown in FIG. 1 corresponding to each linear pattern were formed in the diffusion layer.

  A cathode forming paste was applied to the surface of the intermediate layer in the sintered body by a screen printing method, and baked at 950 ° C. for 2 hours to form a layered cathode (50 μm). Thereby, a flat cell was obtained.

  The outer periphery of the obtained cell is supported by a frame made of ferritic stainless steel, and the outer periphery of the solid electrolyte layer and the active layer is covered with a sealing material made of glass seal so that fuel gas does not leak to the cathode side. did. Thus, a fuel cell single cell of Sample 1 was obtained.

<Single fuel cell of sample 2>
In the same manner as Sample 1, a diffusion layer forming sheet A with a resin sheet was prepared. This was punched out using a mold to form a total of 8100 through holes arranged in 90 rows × 90 columns. In addition, the said through-hole is for comprising a part of linear main gas flow path. The diameter of the through holes is 100 μm, and the pitch between the through holes is 1.0 μm.

  The resin sheet with holes was peeled off, and a slightly adhesive sheet was attached instead. Next, the disappearant paste was filled into the through holes by screen printing and dried. Next, a diffusion layer forming sheet D was prepared by peeling off the slightly adhesive sheet. The thickness of the diffusion layer forming sheet D was 110 μm.

  A diffusion layer forming sheet D was affixed to the surface of the slightly adhesive sheet, and the extinction agent paste was pattern printed on the surface of the diffusion layer forming sheet D using a screen printing method. The printing pattern here is a linear pattern composed of 71 linear pastes arranged at equal intervals, and is for forming a sub-gas channel. In addition, each linear paste was arranged so that it might not overlap with each through-hole, and the line width of each linear paste was 0.1 μm, the pitch between lines was 1.0 μm, and the line thickness was 55 μm. Further, both end portions of each linear paste are not in contact with the end face of the diffusion layer forming sheet D. Then, the sheet | seat E for diffusion layer formation was prepared by peeling a slightly adhesive sheet.

  A diffusion layer forming sheet F having a thickness of 30 μm was prepared in the same manner as the diffusion layer forming sheet D.

  In the same manner as Sample 1, an active layer forming sheet, a solid electrolyte layer forming sheet, and an intermediate layer forming sheet were prepared.

  Diffusion layer forming sheet D, diffusion layer forming sheet E, diffusion layer forming sheet F, active layer forming sheet, solid electrolyte layer forming sheet, and intermediate layer forming sheet are laminated in this order, A laminated body was obtained by pressure bonding under the same pressure bonding conditions. Each diffusion layer forming sheet was laminated with the corresponding through holes positioned.

  Thereafter, a fuel cell single cell of Sample 2 was obtained in the same manner as Sample 1. In the diffusion layer of the fuel cell single cell of Sample 2, a main gas channel and a sub gas channel as shown in FIG. 4 were formed corresponding to the through hole pattern and the linear pattern.

<Single fuel cell of sample 3>
In the production of the fuel cell single cell of Sample 1, the same except that 8 YSZ nanopowder (average particle size: 15 nm) was added as a sintering aid to the extinguishing agent paste used when forming the diffusion layer forming sheet C. Thus, a fuel cell single cell of Sample 3 was obtained. When the cross section of the fuel cell single cell of Sample 3 was observed with a scanning electron microscope, a dense layer was confirmed on the wall surface of the main gas flow channel, which was denser than the formation site of the hole in the diffusion layer.

<Fuel cell single cell of sample 4>
In the production of the fuel cell single cell of Sample 2, 8YSZ nanopowder (average particle size: 15 nm) was added as a sintering aid to the extinguishing agent paste filled in the through-holes when forming the diffusion layer forming sheet D. A fuel cell unit cell of Sample 4 was obtained in the same manner except for the above point. When the cross section of the fuel cell single cell of Sample 4 was observed with a scanning electron microscope, a dense layer was confirmed on the wall surface of the main gas flow path, which was denser than the hole-forming portion of the diffusion layer.

  The present invention is not limited to the above embodiments, and can be applied to various embodiments without departing from the scope of the invention. For example, in the fifth embodiment, the single fuel cell of the third embodiment can be used instead of the single fuel cell of the first embodiment. In the sixth embodiment, the single fuel cell of the fourth embodiment can be used instead of the single fuel cell of the second embodiment.

DESCRIPTION OF SYMBOLS 1 Fuel cell single cell 2 Cell 20 Anode 201 Diffusion layer 201a Main gas flow path 202 Active layer 21 Solid electrolyte layer 22 Cathode 3 Frame 5 Fuel cell stack 51 Gas supply port 52 Gas discharge port F Fuel gas

Claims (11)

A fuel cell single cell (1) having a flat plate cell (2) having an anode (20), a solid electrolyte layer (21) and a cathode (22), and a metal frame (3) supporting the cell. ) And
The anode has a large number of holes, and is disposed on the solid electrolyte layer side of the diffusion layer (201) for diffusing the introduced fuel gas (F) in the layer surface, and is used for the anode reaction. An active layer (202) to be
The diffusion layer includes a plurality of main gas passages (201a) larger than the diameter of the hole,
The fuel cell single cell (1), wherein the main gas flow path is in contact with the active layer and penetrates the outer surface of the diffusion layer. The outer surface of the diffusion layer includes an introduction surface (201c) through which the fuel gas is introduced, and a lead-out surface (201d) from which the fuel gas is derived,
2. The fuel cell single cell according to claim 1, wherein a through-hole (201 b) of the main gas flow path is formed on the lead-out surface. The layer surface of the diffusion layer opposite to the solid electrolyte layer side is the introduction surface,
The fuel cell single cell according to claim 2, wherein a part of an end face of the diffusion layer is the lead-out face.   The fuel cell single cell according to claim 3, wherein the main gas flow paths are arranged along the anode surface direction in a state of being separated from each other. A part of the end surface of the diffusion layer is the introduction surface,
The layer surface opposite to the solid electrolyte layer side in the diffusion layer is the lead-out surface,
The fuel cell single cell according to claim 2.   The fuel cell single cell according to claim 5, wherein the main gas flow paths are disposed along the anode thickness direction in a state of being separated from each other.   The fuel cell single cell according to any one of claims 1 to 6, wherein the main gas flow path is linear.   8. The fuel cell single cell according to claim 7, wherein the average bending degree of the main gas channel is in a range of 1.0 to 2.0.   The diffusion layer according to any one of claims 1 to 8, further comprising a sub-gas channel (201e) that is larger than the diameter of the hole and does not intersect the main gas channel in the layer surface. The fuel cell unit cell described.   10. The fuel cell unit cell according to claim 1, further comprising a dense layer (201 f) that is denser than a portion where the hole is formed in the diffusion layer, on a wall surface of the main gas channel. 11. A fuel cell unit cell according to any one of claims 1 to 10, a gas supply port (51) for supplying the fuel gas, and a gas discharge port (52) for discharging the fuel gas. And
The fuel cell stack (5), wherein the main gas flow path communicates with the gas discharge port and does not communicate with the gas supply port.

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