JP2011165374A - Solid oxide fuel battery cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a solid oxide fuel battery cell with height of diffusion efficiency in a support body and height of electric conductivity of the support body taken heed of in good balance, in one with an electrode formed at least on one face side of the support body of a plate shape having fuel flow channels formed inside. <P>SOLUTION: On each of a top and a bottom faces of the conductive support body 10 having a plurality of fuel flow channels 11 formed inside, a fuel electrode 20, an electrolyte film 30, and an air electrode 40 are laminated. In the porous support body 10, a porosity of a whole of an area (a first area) among the plurality of fuel flow channels 11 is large, and that of an area (a second area) other than the first is small. As compared with a support body with a small porosity in a whole area, a diffusion efficiency of fuel gas in the support body is made higher, and, as compared with a support body with a large porosity in a whole area, electric conductivity of the support body is made higher. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a cell of a solid oxide fuel cell.

  Conventionally, an electrolyte membrane is provided on at least one of the upper surface and the lower surface of a plate-like support (conductor) that has a plurality of fuel flow paths for fuel gas and also serves as part or all of the fuel electrode. A cell (unit cell) of a solid oxide fuel cell (SOFC) formed by stacking a cathode and an air electrode is widely known (see, for example, Patent Document 1).

JP 2004-247248 A

  In general, the support is composed of a conductive porous fired body. The material constituting the support is required to have a function of passing electricity (electrons) and a function of passing fuel gas in addition to the function of ensuring the strength of the cell. The fuel gas moves through a number of pores present in the support. Electricity (electrons) moves through the part between the pores in the material constituting the support. In order to increase the power generation efficiency of the cell, it is desirable that the diffusion efficiency (ease of diffusion) of the fuel gas in the support body is high and the electrical conductivity of the support body is high.

  However, if the porosity of the support (the material constituting the support) is large, the passage through which the fuel gas passes becomes wider, so that the diffusion efficiency of the fuel gas increases, while the passage through which electricity (electrons) passes becomes smaller. The conductivity is lowered. On the contrary, if the porosity of the support is small, the diffusion efficiency of the fuel gas is lowered, while the electric conductivity is increased. That is, with respect to the porosity of the support, the fuel gas diffusion efficiency and the electrical conductivity are in a trade-off relationship.

  In view of the above, an object of the present invention is to provide an SOFC in which an electrolyte membrane and an air electrode are laminated on at least one of the upper and lower surfaces of a plate-like support having a fuel channel formed therein. It is an object of the present invention to provide a cell with a well-balanced consideration that the diffusion efficiency of the fuel gas in the support body is high and the electrical conductivity of the support body is high.

  The SOFC cell according to the present invention is a plate-like conductive support having a plurality of fuel gas flow paths formed therein, and is in contact with the fuel gas flowing through the plurality of fuel flow paths. A support that also serves as a part or all of the fuel electrode that reacts with the fuel gas, and one or a pair of solid electrolytes laminated on only one side or both sides of the upper surface and the lower surface of the support. The electrolyte membrane is laminated on the surface of the one electrolyte membrane opposite to the support, or is laminated on the surface of the pair of electrolyte membranes opposite to the support, and is in contact with a gas containing oxygen. And one or a pair of air electrodes for reacting the gas containing oxygen.

  Here, the support may include, for example, yttria-stabilized zirconia (YSZ) and nickel (Ni). The case where the support also serves as the entire fuel electrode refers to the case where an electrolyte membrane is directly formed on the support. On the other hand, the case where the support also serves as a part of the fuel electrode indicates a case where a fuel electrode active layer is interposed between the support and the electrolyte membrane. The anode active layer includes, for example, yttria-stabilized zirconia (YSZ) and nickel (Ni), and is configured to have a higher content of yttria-stabilized zirconia (YSZ) than the support. When an anode active layer is interposed between the support and the electrolyte membrane, the conductive support mainly functions as an anode current collecting layer.

  Hereinafter, for convenience of explanation, a structure in which an electrolyte membrane and an air electrode are laminated on only one side of the upper surface and the lower surface of the support is referred to as a “one-side electrode structure”, and the electrolyte is formed on both the upper and lower surfaces of the support. A structure in which a membrane and an air electrode are laminated is referred to as a “double-sided electrode structure”.

  The SOFC cell according to the present invention is characterized in that a first porosity, which is a porosity of at least a part of a first region, which is a region between the plurality of fuel flow paths in the support, is the support in the support. It exists in being larger than the 2nd porosity which is the porosity of 2nd area | regions other than 1st area | region. Here, for example, the first porosity is 30 to 70%, and the second porosity is 20 to 60%.

  The plurality of fuel flow paths may be formed to include, for example, portions (parallel portions) formed in parallel to each other along a planar direction (a planar direction perpendicular to the thickness direction) of the support. Within the “at least part of the first region” of the support having a porosity of the first porosity, the first porosity may be constant (uniform) or may vary depending on the location. . Similarly, in the second region, the second porosity may be constant (uniform) or may vary depending on the location. When the first and second porosity vary, the minimum value of the first porosity is larger than the maximum value of the second porosity.

  The fuel gas flowing through the fuel passage formed inside the support first enters the first region (region between the fuel passages) in the support from the inside of the fuel passage, and then the first region. Through the second region of the support (region other than the first region), and then moving toward the electrolyte membrane through the second region, and without passing through the first region from within the fuel flow path There are those that directly enter the second region and then move toward the electrolyte membrane through the second region (see FIGS. 13 and 18 to be described later).

  According to the said structure, the porosity of the material which comprises a support body can be designed so that a 1st porosity may be large and a 2nd porosity may become small. At least a part of the fuel gas moving through the first region passes through the “portion having a high porosity with the first porosity” in the support. Therefore, the diffusion efficiency of the fuel gas in the support body is higher than that of the second support having a small porosity in the entire region and a uniform support body. In addition, electricity (electrons) passing through the second region other than the first region passes through the “portion having the second porosity with a low porosity” in the support. Therefore, the electrical conductivity of the support is higher than that of a uniform support with a first porosity having a large porosity in the entire region. From the above, it is possible to provide an SOFC cell including a support that takes into consideration that the fuel gas diffusion efficiency in the support is high and the electrical conductivity of the support is high in balance.

  When the SOFC cell according to the present invention has a “both-side electrode structure”, it is preferable that the entire porosity of the first region is equal to the first porosity. In the case of the “both-side electrode structure”, the amount of fuel gas passing through the first region is larger than that in the “one-side electrode structure”. Therefore, from the viewpoint of increasing the diffusion efficiency of the fuel gas, it is preferable that the first porosity is designed so that the entire porosity of the first region is large. On the other hand, in the case of the “both-side electrode structure”, as will be described later, the SOFC cell can be designed so that electricity (electrons) hardly passes through the first region. In this case, most of the electricity (electrons) passes through the second region, that is, “the portion having the second porosity with a low porosity” in the support body. Therefore, the electrical conductivity of the support is increased. As described above, according to the above configuration, in the case of the “double-sided electrode structure”, it is possible to provide an SOFC cell in which the fuel gas diffusion efficiency is high and the electrical conductivity is considered in a very balanced manner.

  On the other hand, when the SOFC cell according to the present invention has a “one-side electrode structure”, a conductive current collecting member (interconnector) is laminated on the opposite side of the upper surface and the lower surface of the support to the one side. In this case, it is preferable that the porosity of a part of the first region is equal to the first porosity, and the porosity of the remaining portion of the first region is equal to the second porosity.

  In the case of the “one-sided electrode structure”, electricity (electrons) traverses in the thickness direction in the support body. That is, most of electricity (electrons) passes through the first region. Therefore, it is preferable that “a portion having a low porosity with a second porosity” exists in the first region. On the other hand, in the case of the “one-side electrode structure”, the amount of fuel gas passing through the first region (contributing to the reaction) is smaller than that in the “both-side electrode structure”. Therefore, the degree of demand for uniformly designing the entire porosity of the first region with a large first porosity is small. As described above, according to the above configuration, in the case of the “one-side electrode structure”, it is possible to provide an SOFC cell in which the fuel gas diffusion efficiency is high and the electric conductivity is considered in a very balanced manner.

It is a perspective view which shows the SOFC cell which concerns on embodiment of this invention. It is sectional drawing which shows the cross section obtained by cut | disconnecting the SOFC cell shown in FIG. 1 along a plane parallel to XY plane including 2-2 line. FIG. 3 is a cross-sectional view showing a cross section obtained by cutting the SOFC cell shown in FIG. 1 along a plane including a line 3-3 and parallel to the XZ plane. FIG. 4 is a cross-sectional view corresponding to FIG. 3 showing the distribution of porosity in the support shown in FIG. 1. It is a perspective view which shows a mode that the molded object of the several support body division body used in the process of manufacturing the support body shown in FIG. 1 is joined. It is a perspective view which shows the joined body before baking obtained by joining the molded object of several support body division body. It is a perspective view which shows the support body after baking obtained by baking the conjugate | zygote shown in FIG. It is sectional drawing which shows the cross section obtained by cut | disconnecting the support body shown in FIG. 7 along a plane parallel to XZ plane including 8-8 line. FIG. 9 is a cross-sectional view corresponding to FIG. 8 for an object in which fuel electrodes are respectively formed on the upper and lower surfaces of the support shown in FIG. 8. FIG. 10 is a cross-sectional view corresponding to FIG. 9 for an object in which electrolyte membranes are formed on the upper and lower surfaces and side surfaces of the object shown in FIG. It is sectional drawing corresponding to FIG. 10 in the object by which the air electrode was formed in the upper and lower surfaces of the object shown in FIG. FIG. 12 is a cross-sectional view corresponding to FIG. 11 in the SOFC cell completed by connecting interconnectors to the four corners of the upper surface of the object shown in FIG. 11. FIG. 13 is a cross-sectional view corresponding to FIG. 12 illustrating an example of a path through which fuel gas flows and a path through which electricity (electrons) flows in the support body of the SOFC cell illustrated in FIG. 1. It is a perspective view corresponding to FIG. 1 in the SOFC cell which concerns on the modification of embodiment of this invention. It is sectional drawing corresponding to FIG. 2 in the SOFC cell which concerns on the modification of embodiment of this invention. It is sectional drawing corresponding to FIG. 3 in the SOFC cell which concerns on the modification of embodiment of this invention. It is sectional drawing corresponding to FIG. 4 in the SOFC cell which concerns on the modification of embodiment of this invention. It is sectional drawing corresponding to FIG. 13 in the SOFC cell which concerns on the modification of embodiment of this invention.

(Configuration of SOFC cell)
1 to 4 show a SOFC cell A according to an embodiment of the present invention. The SOFC cell A generally has a rectangular parallelepiped shape (thin plate shape having a thickness direction in the Z-axis direction) having sides along the X-, Y-, and Z-axis directions. In this example, the shape (planar shape) viewed from above the SOFC cell A has a side (short side) length of 30 to 150 mm along the X-axis direction and a length (long side) along the Y-axis direction. Is a rectangle of 50 to 300 mm. The thickness of the SOFC cell A is 0.5 to 5 mm in this example. The planar shape may be a square having a side of 10 to 100 mm, a circle having a diameter of 5 to 100 mm, or the like. Each corner shown in FIGS. 1 to 4 may be subjected to R chamfering or C chamfering. Hereinafter, for convenience of explanation, the Z-axis positive direction may be referred to as the “up” direction, and the Z-axis negative direction may be referred to as the “down” direction.

  The SOFC cell A includes a support 10, a pair of fuel electrodes 20, 20, an electrolyte membrane 30, a pair of air electrodes 40, 40, and an interconnector 50. The support 10 is a porous plate-shaped (cuboid) fired body composed of nickel oxide NiO and / or nickel Ni and yttria-stabilized zirconia YSZ. The thickness T1 of the support 10 is 0.5 to 5.0 mm. Of the thicknesses of the constituent members of the SOFC cell A, the thickness of the support 10 is the largest. The volume ratio in the whole of Ni and / or NiO is 35-55 volume% in Ni conversion, and the volume ratio in the whole of YSZ is 45-65 volume%.

  As can be understood from FIGS. 2 and 3 (particularly, FIG. 3), a plurality of fuel flow paths 11 (in the support body 10 for flowing fuel gas along the Y-axis direction and parallel to each other) Cavity) is formed. A pair of openings 12, 12 that connect the outside and each fuel flow path 11 are formed. The cross-sectional shape in the thickness direction of each fuel flow path 11 is a rectangle in this example, but may be a square, a circle, an ellipse, or the like.

  As can be understood from FIG. 3, in this example, the position in the thickness direction (Z-axis direction) of the center of each fuel flow path 11 is equal to the center position in the thickness direction of the support 10. That is, the distance (first thickness) t1 between the upper surface of the support 10 and the upper surface side end of each fuel flow path 11, the lower surface of the support 10 and the lower surface side of each fuel flow path 11 Is equal to the distance (second thickness) t1 in the thickness direction (see FIG. 3). Note that the position in the thickness direction (Z-axis direction) of the center of each fuel flow path 11 may be offset in the thickness direction from the center position in the thickness direction of the support 10. In this example, t1 / T1 is 0.1 to 0.45. Moreover, the space | interval Z (refer FIG. 3) between the adjacent fuel flow paths 11 and 11 is 1-50 mm.

  In this example, the first thicknesses corresponding to the plurality of fuel flow paths 11 are all equal to t1, and the second thicknesses corresponding to the plurality of fuel flow paths 11 are all equal to t1. On the other hand, each 1st thickness corresponding to the some fuel flow path 11 may differ, and each 2nd thickness corresponding to the some fuel flow path 11 may differ.

  As will be described later (see FIG. 5), the support 10 is roughly formed of a support divided body having a shape obtained by dividing the support 10 into three in the thickness direction (Z-axis direction). 10d1g, 10d2g, 10d3g, and 10d4g (before firing) are joined and fired. The support 10 functions as a support substrate (a member having the highest rigidity) and also functions as a part of the fuel electrode (anode electrode).

  Further, as shown in FIG. 4, the entire porosity (first porosity) of the region (first region) between the plurality of fuel flow paths 11 in the support is a region other than the first region in the support ( It is larger than the porosity (second porosity) of the second region). In FIG. 4 (and the following figures), a portion indicated by fine dots corresponds to a portion corresponding to the first porosity (a portion having a high porosity). The first porosity is 30 to 70%, and the second porosity is 20 to 60%. The first porosity may be constant or may vary depending on the location. Similarly, the second porosity may be constant or may vary depending on the location. When the first and second porosity vary, the minimum value of the first porosity is larger than the maximum value of the second porosity.

  The fuel electrodes 20 and 20 (anode electrodes) are respectively formed on the upper surface and the lower surface of the support 10. The fuel electrodes 20 and 20 are porous thin plate-like fired bodies composed of nickel oxide NiO and / or nickel Ni and yttria-stabilized zirconia YSZ, like the support 10. The thickness T2 of each fuel electrode 20 is 5.0 to 30.0 μm. The volume ratio in the whole of Ni and / or NiO is 25-50 volume% in Ni conversion, and the volume ratio in the whole of YSZ is 50-75 volume%. Thus, in the fuel electrodes 20 and 20, the content ratio (volume%) of YSZ is larger than that of the support 10.

  The support 10 can be mainly used for taking out the electrons obtained by the reaction represented by the formula (3) described later in the fuel electrodes 20 and 20 to the outside via the interconnector 50. In this sense, the support 10 is also referred to as a “fuel electrode current collecting layer”. On the other hand, the fuel electrodes 20 are also referred to as “fuel electrode active layer”.

  The electrolyte membrane 30 is a thin film formed on the surface of the assembly so as to surround the periphery (upper and lower surfaces and side surfaces) of the assembly of the support 10 and the fuel electrodes 20 and 20. The electrolyte membrane 30 is a dense fired body made of YSZ. The thickness T3 of the electrolyte membrane 30 is 1.0 to 30.0 μm.

The air electrodes 40, 40 (cathode electrodes) are formed on the upper surface of “the portion formed on the upper surface of the upper fuel electrode 20” in the electrolyte membrane 30 and on the “lower surface of the lower fuel electrode 20” in the electrolyte membrane 30. It is formed on the lower surface of the “part”. The air electrodes 40 and 40 are porous thin plate-like fired bodies made of lanthanum strontium cobalt ferrite LSCF (La _0.6 Sr _0.4 Co _0.2 Fe _0.8 O ₃ ). The thickness T4 of each air electrode 40 is 5.0 to 50.0 μm.

  A phenomenon in which YSZ in the electrolyte membrane 30 and strontium in the air electrode 40 react with each other in the cell A during the cell fabrication or in the operation of the SOFC to increase the electrical resistance between the electrolyte membrane 30 and the air electrode 40. In order to suppress the generation of this, a reaction preventing layer may be interposed between the electrolyte membrane 30 and the air electrode 40. The reaction preventing layer is preferably a dense thin plate-like fired body made of ceria. Specific examples of ceria include GDC (gadolinium doped ceria) and SDC (samarium doped ceria).

  The interconnectors 50 are formed at the upper four corners of the SOFC cell A, respectively. Each interconnector 50 has a quadrangular prism shape, and a lower end portion is in contact with the support 10 and the fuel electrode 20, and an upper end portion is exposed from the upper surface of the upper air electrode 40. Each interconnector 50 is insulated from the electrolyte membrane 30 and the air electrode 40 by an insulating sealing material such as glass. Each interconnector 50 functions as a terminal electrode (current collecting member) on the fuel electrode side.

  The interconnector 50 is made of lanthanum chromite LC. The chemical formula of lanthanum chromite LC is represented by the following formula (1). In the following formula (1), AE is at least one element selected from Ca, Sr, and Ba. B is at least one element selected from Co, Ni, V, Mg, and Al. The range of x is 0 to 0.4, and more preferably 0.05 to 0.2. The range of y is 0 to 0.3, and more preferably 0.02 to 0.22. The range of z is 0 to 0.1, and more preferably 0.02 to 0.05. δ is a minute value including zero.

La _1-x AE _x Cr _{1-y + z} B _y O _3-δ (1)

  Note that lanthanum chromite LC is used as the material of the interconnector 50 on the fuel electrode side because the upper end of the interconnector 50 is exposed to an oxidizing atmosphere by contact with air, and the lower end of the interconnector 50 is fuel gas. Based on exposure to reducing atmosphere by contact with At present, lanthanum chromite LC is most suitable as a conductive ceramic that is stable in both oxidizing and reducing atmospheres and has low electric resistance. As described above, in the SOFC cell A, the electrodes are formed on both the upper and lower sides of the support 10. Therefore, the structure of the SOFC cell A is also called “both-side electrode structure”.

A fuel gas (hydrogen gas or the like) is supplied to the fuel flow path 11 inside the support 10 through the opening 12 with respect to the SOFC cell A that has been heated to the operating temperature (for example, 600 to 900 ° C.). At the same time, by supplying a gas (air or the like) containing oxygen to the air electrodes 40, 40, chemical reactions represented by the following formulas (2) and (3) occur. As a result, a potential difference is generated between the fuel electrodes 20 and 20 and the air electrodes 40 and 40.
(1/2) · O ₂ +2 ^e− → O ²⁻ (where: air electrode 40) (2)
H ₂ + O ²⁻ → H ₂ O + 2 ^e− (in the fuel electrode 20) (3)

  In the SOFC cell A, an air electrode side interconnector (not shown) is actually connected to the air electrodes 40, 40. Then, electric power based on the potential difference is taken out through the air electrode side interconnector and the fuel electrode side interconnector 50.

(SOFC cell manufacturing method)
Next, an example of a manufacturing method of the SOFC cell A shown in FIGS. 1 to 4 will be described. Hereinafter, the “molded body” means a state before firing. The symbol representing the “molded body” has “g” appended to the end of the symbol representing the fired body obtained by firing the “molded body”.

  In this example, when the support 10 (fired body) is manufactured, first, as shown in FIG. 5, “a plane along the XY plane including the upper edges of the plurality of fuel flow paths 11” and “a plurality of fuels”. The support 10 is divided into three in the thickness direction (Z-axis direction) so as to be divided into three in the thickness direction with the two planes “the plane along the XY plane including the lower edge of the flow path 11” as a boundary. 10d1g (1 sheet), 10d2g (2 sheets), 10d3g (5 sheets), 10d4g (1 sheet) having a shape obtained in this manner are produced.

  The compacts 10d3g (five) correspond to the region between the plurality of fuel flow paths 11 (that is, the first region), and the compacts 10d1g (one), 10d2g (two), 10d4g (one) Corresponds to a region other than the first region (that is, the second region). Therefore, the porosity of the fired body obtained by firing the molded body 10d3g (5 pieces) later corresponds to the first porosity (large porosity), and the molded bodies 10d1g (1 sheet), 10d2g (2 sheets), The porosity of the fired body obtained by subsequent firing of 10d4g (one sheet) corresponds to the second porosity (small porosity).

  Further, the molded body 10d1g (one sheet, a part of the second region) corresponds to the lower layer when the support body 10 is divided into three in the thickness direction (Z-axis direction), and the molded body 10d2g (two sheets) , A part of the second region), and the molded body 10d3g (5, all of the first region) correspond to the middle layer when the support 10 is divided into three in the thickness direction (Z-axis direction), The molded body 10d4g (one sheet, a part of the second region) corresponds to the upper layer when the support body 10 is divided into three in the thickness direction (Z-axis direction). These support body divided body molded bodies 10d1g (1 sheet), 10d2g (2 sheets), 10d3g (5 sheets), and 10d4g (1 sheet) are joined and fired to form the support body 10.

  The support divided body molded bodies 10d1g (1 sheet), 10d2g (2 sheets), 10d3g (5 sheets), and 10d4g (1 sheet) are produced by a so-called “gel cast method”. The gel casting method is a technique in which a ceramic slurry containing ceramic powder, a dispersion medium, and a gelling agent is molded using a mold, and the molded slurry is solidified and dried to obtain a molded body (before firing). For example, it is introduced in detail in, for example, WO 2004/035281. Therefore, detailed description of the gel casting method is omitted here.

  Each of the joint surfaces in the produced support divided body molded body 10d1g (1 sheet), 10d2g (2 sheets), 10d3g (5 sheets), 10d4g (1 sheet) (after solidification / drying and before firing) has a predetermined value. The bonding agent is applied. Then, as shown in FIG. 5, the surfaces on which the bonding agents in these divided support body molded bodies 10d1g (1 sheet), 10d2g (2 sheets), 10d3g (5 sheets), and 10d4g (1 sheet) are applied. It is pasted together. Thereby, as shown in FIG. 6, the joining molded object in which the fuel flow path 11 was formed is obtained.

  Next, this bonded molded body is subjected to firing. The firing conditions are, for example, a maximum temperature of 1400 ° C. × 1 hour. As a result, the compacts 10d1g (one sheet), 10d2g (two sheets), 10d3g (five sheets), and 10d4g (one sheet) constituting the bonded molded body are fired, and as shown in FIGS. A support 10 that is a fired body in which the fuel channel 11 is formed is obtained.

  Next, as shown in FIG. 9, YSZ—NiO paste films that will later become the fuel electrode 20 (fuel electrode active layer) are respectively formed on the upper and lower surfaces of the support 10. The formation of the YSZ-NiO paste film may be achieved by applying a paste to the upper and lower surfaces of the support 10 or may be achieved by attaching ceramic green sheets to the upper and lower surfaces of the support 10. Good.

  Next, as shown in FIG. 10, a YSZ paste film that will later become the electrolyte film 30 is formed around the support 10 on which the YSZ-NiO paste film is formed (upper and lower surfaces and side surfaces). The formation of the YSZ paste film may be achieved by applying the paste to the periphery (upper and lower surfaces and side surfaces) of the support 10 on which the YSZ-NiO paste film is formed, or the YSZ-NiO paste film is formed. Further, it may be achieved by covering the periphery (upper and lower surfaces and side surfaces) of the support 10 with a ceramic green sheet. Covering the support 10 on which the YSZ-NiO paste film is formed with the ceramic green sheet can be achieved by attaching the green sheet to the upper and lower surfaces, and bonding the green sheet to the side surface. Can be achieved. Further, a ceramic paste may be further applied to the side surface portion of the YSZ paste film where the thermal stress becomes high for reinforcement.

  Next, the object on which the YSZ-NiO paste film and the YSZ paste film are thus formed is fired at a predetermined temperature for a predetermined time (for example, 1400 ° C. for 1 hour). As a result, as shown in FIG. 10, the fuel electrodes 20 are formed on the upper and lower surfaces of the support body 10, and the electrolyte membrane 30 is formed around the support body 10 where the fuel electrodes 20, 20 are formed (upper and lower surfaces and side surfaces). It is formed.

  Further, as described above, when a reaction preventing layer made of ceria (CeO2) is interposed between the electrolyte membrane 30 and the air electrode 40, the entire surface (upper and lower surfaces and side surfaces) of the YSZ paste film is formed before the firing. ), A paste film that later becomes a reaction preventing layer is further formed. The formation of this film can also be achieved by applying a paste, using a ceramic green sheet, etc., as in the case of the YSZ paste film. This film and the YSZ paste film are both subjected to firing. Alternatively, after the YSZ paste film is baked, a paste film that later becomes a reaction preventing layer may be formed only on the upper and lower surfaces of the fired body by a printing method or the like, and then the film may be baked.

  In the above example, after the support 10 is formed by firing, the fuel electrodes 20 and 20 and the electrolyte membrane 30 are formed by firing. On the other hand, the support body 10, the fuel electrodes 20, 20, and the electrolyte membrane 30 may be fired simultaneously.

  Next, as shown in FIG. 11, a sheet that will later become the air electrode 40 is formed on the upper and lower surfaces of the fired body (that is, the upper surface of the upper electrolyte membrane 30 and the lower surface of the lower electrolyte membrane 30) by a printing method. Each is formed, and those sheets are fired at a predetermined temperature and a predetermined time (for example, 1000 ° C. for 1 hour). Thereby, the air electrode 40 is formed in the upper and lower surfaces of a sintered body, respectively. In addition, as mentioned above, the air electrodes 40 and 40 are fired only after that the firing temperature (1000 ° C.) of the air electrodes 40 and 40 is lower than the firing temperature (1400 ° C.) of other components. Based.

  Next, as shown in FIG. 12, the interconnectors 50 made of lanthanum chromite LC are in contact with the support 10 and the fuel electrode 20 at the upper four corners of the fired body, and the upper end is at the upper side. It is attached so as to protrude from the upper surface of the air electrode 40. A gap between each interconnector 50 and the electrolyte membrane 30 and the air electrode 40 is filled with an insulating sealing material such as glass. Thereby, each interconnector 50 is insulated from the electrolyte membrane 30 and the air electrode 40.

  All the above-described firing is performed in an oxidizing atmosphere. The support 10 and the fuel electrodes 20 and 20 need to have conductivity. Therefore, heat treatment (reduction treatment) for supplying a reducing gas to the fired support 10 and the fuel electrodes 20 and 20 at a high temperature by heating (for example, 800 ° C.) is performed thereafter. By this reduction treatment, NiO in the support 10 and the fuel electrodes 20 and 20 is reduced to Ni. The example of the method for manufacturing the SOFC cell A shown in FIGS. 1 to 4 has been described above.

(Operation and effect of the embodiment)
As described above, in the SOFC cell A according to the embodiment of the present invention having the “both-side electrode structure” described above, as shown in FIG. 4, the first region of the support 10 (the region between the plurality of fuel flow paths 11). The whole porosity is the first porosity (30 to 70%, large porosity), and the porosity of the second region (region other than the first region) of the support 10 is the second porosity (20 to 60%). , Small porosity). The action and effect of this will be described with reference to FIG. In FIG. 13, a solid line shows an example of a path through which fuel gas (for example, hydrogen gas) contributing to the reaction flows, and a broken line shows an example of a path through which electricity (electrons) flows.

  As shown by a solid line in FIG. 13, the fuel gas flowing through the fuel passage 11 first enters the first region (region with a high porosity) in the support 10 from the inside of the fuel passage 11, and then the first A first region that enters the second region (region with a low porosity) of the support, and then moves toward the upper and lower fuel electrodes 20 and 20 and the electrolyte membrane 30 through the second region, and the fuel flow There is one that directly enters the second region without passing through the first region from the inside of the path 11, and then moves toward the upper and lower fuel electrodes 20, 20 and the electrolyte membrane 30 through the second region.

  Therefore, the fuel gas moving through the first region passes through the “region of the first porosity having a large porosity” in the support 10 (see the dotted circle in FIG. 13). Therefore, the diffusion efficiency of the fuel gas in the support 10 is higher than that of the second support having a small porosity in the entire region and a uniform support.

  In addition, as indicated by broken lines in FIG. 13, electricity (electrons) hardly passes through the first region. That is, most of the electricity (electrons) passes through the second region, that is, “the region having the second porosity with a low porosity” in the support 10. Accordingly, the electric conductivity of the support 10 is higher than that of the first support having a large porosity in the entire region and a uniform support. As described above, according to the above embodiment, it is possible to provide an SOFC cell having a “both-side electrode structure” in which high diffusion efficiency of fuel gas and high electrical conductivity are considered in a well-balanced manner.

  In the above-described embodiment, a plurality of support body molded bodies 10d1g (1 sheet), 10d2g (2 sheets), 10d3g (5 sheets), and 10d4g (1 sheet) manufactured using the gel cast method are joined. The support 10 was formed by firing. Thereby, the porous support body 10 in which the porosity differs depending on the location was realized. As described above, it is very difficult to realize a porous support having different porosity depending on the location by using a so-called extrusion method or the like.

  The present invention is not limited to the above embodiment, and various modifications can be employed within the scope of the present invention. For example, in the above embodiment, the fuel electrodes 20 and 20 (fuel electrode active layer) are interposed between the support 10 and the electrolyte membrane 30. That is, the support 10 also serves as a part of the fuel electrode (= fuel electrode current collecting layer). On the other hand, when the support body 10 serves as all the fuel electrodes, the fuel electrodes 20 and 20 are omitted.

  In the above embodiment (“both-side electrode structure”), the entire porosity of the first region (region between the plurality of fuel flow paths 11) of the support 10 is the first porosity (large porosity). However, the porosity of a part of the first region of the support 10 is equal to the first porosity (large porosity), and the porosity of the remaining part of the first region is the second porosity (small porosity). May be equal.

  Moreover, in the said embodiment, although the "both-side electrode structure" is employ | adopted, like the modification of the said embodiment shown to FIGS. 14-17 corresponding to FIGS. 1-4, respectively, "one-sided electrode structure" May be adopted. In this modification, the same reference numerals as those in the above embodiment are assigned to the components corresponding to the members and the like in the above embodiment.

  In this modification, the thin plate-like fuel electrode 20 is formed only on the upper surface of the rectangular parallelepiped support body 10 and surrounds the periphery (the upper surface and the side surface excluding the lower surface) of the support body 10 and the fuel electrode 20. An electrolyte membrane 30 is formed. A thin plate-like air electrode 40 is formed only on the upper surface of the joined body (that is, the upper surface of the electrolyte membrane 30), and the thin plate-like interconnector 50 is formed on the lower surface of the joined body (that is, the lower surface of the support body 10). Is formed.

  The thickness T1 of the support 10 is 0.5 to 5.0 mm, the thickness T2 of the fuel electrode 20 is 5.0 to 30.0 μm, and the thickness T3 of the electrolyte membrane 30 is 1.0 to 30. The thickness T4 of the air electrode 40 is 5.0 to 50.0 μm, and the thickness T5 of the interconnector 50 is 1 to 300 μm. The material of each constituent member is the same as in the above embodiment.

  As shown in FIG. 17, in this modified example, the porosity of a part of the first region (the region between the plurality of fuel flow paths 11) is the first porosity (large porosity), and The porosity of the remaining portion is the second porosity (small porosity) equal to the porosity of the second region (region other than the first region). Specifically, the porosity of three locations (regions indicated by fine dots) in the first region (5 locations in FIG. 17) is the first porosity (large porosity), and the remaining in the first region The porosity at two locations is the second porosity (small porosity).

  Similar to the above embodiment, the first porosity is 30 to 70%, and the second porosity is 20 to 60%. The first porosity may be constant or may vary depending on the location. Similarly, the second porosity may be constant or may vary depending on the location. When the first and second porosity vary, the minimum value of the first porosity is larger than the maximum value of the second porosity.

(Operation and effect of the modified example)
Hereinafter, the operation and effect of the above modified example having the “one-side electrode structure” will be described with reference to FIG. As in FIG. 13, in FIG. 18, the solid line indicates an example of a path through which fuel gas (for example, hydrogen gas) contributing to the reaction flows, and the broken line indicates an example of a path through which electricity (electrons) flows.

  As indicated by a broken line in FIG. 18, in the above modification, electricity (electrons) traverses in the thickness direction in the support 10. That is, most of electricity (electrons) passes through the first region. Therefore, from the viewpoint of increasing the electrical conductivity, in the first region, as in the above-described modification, the first porosity has a large porosity in the entire first region as in the above embodiment. It is preferable that “a portion having a second porosity with a low porosity” exists.

  On the other hand, in the case of the above modification, the fuel gas contributing to the reaction flows from the fuel flow path 11 toward only the upper fuel electrode 20. Accordingly, the amount of fuel gas that passes through the first region (contributes to the reaction) as compared with the above-described embodiment in which the fuel gas that contributes to the reaction flows from the fuel flow path 11 toward the upper and lower fuel electrodes 20 and 20, respectively. Less is. As a result, as compared with the above-described embodiment, the degree of demand for uniformly designing the entire porosity of the first region with a large first porosity is small. As described above, according to the above modification, an SOFC cell having a “one-sided electrode structure” in which high diffusion efficiency of fuel gas and high electrical conductivity are considered in a well-balanced manner can be provided.

  In the above modification, the fuel electrode 20 (fuel electrode active layer) is interposed between the support 10 and the electrolyte membrane 30. That is, the support 10 also serves as a part of the fuel electrode (= fuel electrode current collecting layer). On the other hand, when the support body 10 serves as all of the fuel electrode, the fuel electrode 20 is omitted.

  In the above modification (“one-sided electrode structure”), the porosity of a part of the first region of the support 10 is equal to the first porosity (large porosity), and the porosity of the remaining part of the first region Is the second porosity (small porosity), but the entire porosity of the first region of the support 10 may be the first porosity (large porosity).

  DESCRIPTION OF SYMBOLS 10 ... Support body, 10d1g, 10d2g, 10d3g, 10d4g ... Support body division body molded body, 11 ... Fuel flow path, 20 ... Fuel electrode, 30 ... Electrolyte membrane, 40 ... Air electrode, 50 ... Interconnector

Claims (5)

A plate-like conductive support having a plurality of fuel flow paths for fuel gas formed therein, and a fuel electrode that reacts with the fuel gas in contact with the fuel gas flowing through the plurality of fuel flow paths A support that also serves as part or all of the support,
One or a pair of electrolyte membranes laminated on only one side of the upper surface and the lower surface of the support or laminated on both sides, and made of a solid electrolyte,
A gas that is laminated on the surface opposite to the support in the one electrolyte membrane or is laminated on a surface opposite to the support in the pair of electrolyte membranes, and that contains oxygen in contact with a gas containing oxygen One or a pair of air electrodes for reacting
A solid oxide fuel cell comprising:
The second region in which the first porosity, which is the porosity of at least a part of the first region that is the region between the plurality of fuel flow paths in the support, is a region other than the first region in the support. A cell of a solid oxide fuel cell that is larger than a second porosity that is the porosity of the solid oxide fuel cell. The cell of the solid oxide fuel cell according to claim 1,
The pair of electrolyte membranes are respectively laminated on both sides of the upper surface and the lower surface of the support, and the pair of air electrodes are respectively laminated on the surface of the pair of electrolyte membranes opposite to the support,
A cell of a solid oxide fuel cell, wherein the whole porosity of the first region is equal to the first porosity. The cell of the solid oxide fuel cell according to claim 1,
The one electrolyte membrane is laminated on only one side of the upper surface and the lower surface of the support, and the one air electrode is laminated on the surface of the one electrolyte membrane opposite to the support, and the support A conductive current collecting member is laminated on the side opposite to the one side of the upper surface and the lower surface in
A cell of a solid oxide fuel cell, wherein the porosity of a part of the first region is equal to the first porosity, and the porosity of the remaining portion of the first region is equal to the second porosity. In the cell of the solid oxide fuel cell according to any one of claims 1 to 3,
The cell of a solid oxide fuel cell, wherein the first porosity is 30 to 70% and the second porosity is 20 to 60%. In the cell of the solid oxide fuel cell according to any one of claims 1 to 4,
The support includes yttria stabilized zirconia (YSZ) and nickel (Ni),
The yttria stabilized zirconia (YSZ) and nickel (Ni) are included between the support and the one or the pair of electrolyte membranes, and the content ratio of yttria stabilized zirconia (YSZ) as compared with the support. A cell of a solid oxide fuel cell in which one or a pair of anode active layers having a large diameter is interposed.

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