JP5484155B2 - ELECTROLYTE SHEET FOR SOLID OXIDE FUEL CELL, METHOD FOR PRODUCING THE SAME, AND CELL FOR SOLID OXIDE FUEL CELL USING THE SAME - Google Patents

Description

  The present invention relates to an electrolyte sheet for a solid oxide fuel cell (hereinafter referred to as SOFC), a method for producing the same, and a cell for a solid oxide fuel cell using the same. In particular, the present invention relates to an oxygen ion conductive solid electrolyte sheet excellent in sealing properties, a method for producing the same, and an electrolyte-supported cell (hereinafter referred to as ESC) using the electrolyte sheet.

  Ceramics are used in many fields because they have excellent electrical and magnetic properties in addition to mechanical properties such as heat resistance and wear resistance. Among them, ceramic sheets mainly composed of zirconia have excellent oxygen ion conductivity and toughness in addition to them, so that they are solid electrolytes for sensor components such as oxygen sensors and humidity sensors, and also solids for fuel cells. It is used as an electrolyte.

  As an electrolyte sheet for the SOFC cell, in addition to increasing the strength of the thin film, in order to increase the effective area of the electrochemical reaction and improve the power generation performance, the electrolyte sheet and the fuel electrode and air electrode formed on both sides thereof It is required to increase the contact area. In addition, in order to obtain stable power generation performance, it is required to prevent the fuel electrode and the air electrode from peeling off from the solid electrolyte during operation of the fuel cell and during temperature rise and fall. Therefore, the present inventors focused on the surface roughness of the electrolyte sheet and studied a wide range of surface roughness. As a result, the SOFC single cell using the electrolyte sheet having a specific surface roughness satisfies these requirements. As disclosed in Patent Documents 1 to 3.

  The SOFC is a battery that supplies two types of gas, a fuel and an oxidant, to a fuel electrode and an air electrode separated by an electrolyte sheet, respectively, and causes an electrochemical reaction at each electrode to extract electric power to the outside. Even if the electrolyte sheet has the specific surface roughness, the voltage of the single cell is as low as about 1V. Therefore, when operating as an actual fuel cell, it is necessary to stack single cells and connect them in series (stacked) in order to obtain a practically sufficient amount of power generation. At this time, the adjacent unit cells are electrically connected, and at the same time, the fuel gas and the oxidant gas are properly distributed, supplied and discharged to the fuel electrode and the air electrode through the manifold. A separator made of metal or ceramic is disposed on the surface. The separator is also called an interconnector.

  In the SOFC stack, during operation at a high temperature of approximately 600 ° C. to 950 ° C. or during a heat cycle by repeated heating and cooling between normal temperature and 600 ° C. to 950 ° C. as the SOFC is started / stopped, It is necessary to prevent leakage of oxidant gas.

  Therefore, a melt sealing method using low-melting glass as a sealing material, a cooling / curing solid sealing method using a heat-resistant sealing material, and a heat-curing solid sealing method using a heat-resistant inorganic adhesive or a heat-resistant inorganic coating agent have been studied. ing. For example, in the melt sealing method, paying attention to the consistency of thermal expansion coefficient with the adherend, etc., a high temperature adhesive in which ceramic particles such as alumina, silica, magnesia, zirconia are dispersed in water glass, Various glass powder sealing materials that ensure sealing properties by softening have been proposed (see, for example, Patent Document 4). Further, a seal structure has been proposed in which the air electrode side gas seal area of the sealing material is made larger than the fuel electrode side gas seal area (see, for example, Patent Document 5).

  However, it is difficult to completely prevent gas leakage with only the sealing material and the sealing structure. For this reason, the adherend (that is, the electrolyte sheet) to which the sealing material is bonded needs to be designed to be suitable for bonding the sealing material, but the surface state of the electrolyte sheet that is the adherend is preferably sealed. However, few technologies have been disclosed that focus on the ability to do this.

  The present invention has been made in consideration of such circumstances, and has excellent cell adhesion performance between the electrolyte sheet and the electrode, and also provides fuel cell and / or fuel gas from between the electrolyte sheet and the separator portion of the stack. Alternatively, an object of the present invention is to provide a solid electrolyte sheet having a suitable surface state in which leakage of oxidant gas is suppressed as much as possible to maintain high power generation performance and various SOFC sealing materials can be selected, and a method for manufacturing the same.

JP 2000-281438 A International Republication No. 2004-34492 JP 2007-323899 A JP 2007-149430 A JP 2007-287585 A

  The present invention has been made paying attention to the above-mentioned circumstances, and the object thereof is directed to an electrolyte sheet for a solid oxide fuel cell, and in the peripheral region thereof, fuel gas and / or oxidant gas is used. In addition to excellent sealing performance to prevent leaks, it is possible to strongly bond electrodes with high adhesion in areas other than the peripheral area, and stably achieve excellent performance without degrading power generation characteristics due to peeling. It is to provide an electrolyte sheet that can be exhibited, and to establish a technique that can efficiently produce such a high-performance electrolyte sheet.

  The electrolyte sheet for a solid oxide fuel cell according to the present invention that has solved the above problems is different in the sheet surface roughness (Ra) in the peripheral area of at least one surface and the area other than the peripheral area. The sheet surface roughness in the peripheral region obtained by measuring the sheet with a laser optical non-contact three-dimensional shape measuring device is more than 3.0 μm and 10 μm or less in Ra, other than the peripheral portion The sheet surface roughness in the region is characterized in that Ra is 0.3 μm or more and 3.0 μm or less.

  In addition, the sheet surface roughness in the peripheral region obtained by measuring the electrolyte sheet with a laser optical non-contact three-dimensional shape measuring apparatus is 4.0 μm or more and 20 μm or less in Rz. In addition, the average crest / valley interval of the electrolyte in the peripheral region obtained by measuring the sheet with a laser optical non-contact three-dimensional shape measuring apparatus is 0.1 μm or more and 20 μm or less in Sm. have. In the above, Ra (arithmetic average roughness) and Rz (maximum roughness) are based on the German standard “DIN-4768”, and Sm (average length of roughness curve elements) is the German standard “DIN”. This is a roughness parameter determined in accordance with “−4287” and is a value measured on one or both surfaces of the electrolyte sheet.

  In the electrolyte sheet of the present invention, by setting Ra, Ra and Rz and / or Sm in a specific range as described above, power generation characteristics and electrode adhesion when the electrolyte sheet is used as a cell. -The peel resistance can be improved, and further, the deterioration of the power generation performance due to gas leakage when the cells are stacked and the damage due to local heat generation can be prevented, and favorable characteristics as an electrolyte for SOFC can be secured.

The electrolyte sheet preferably contains at least one selected from the group consisting of zirconia-based oxides, LaGaO ₃ -based oxides, and ceria-based oxides, and most preferably scandium and yttrium. Further, it is a zirconia-based oxide which is selected from the group consisting of cerium and ytterbium and which is stabilized with an oxide of one element with at least a small surface roughness.

The electrolyte sheet referred to in the present invention is an electrolyte sheet for a solid oxide fuel cell comprising a dense sintered body having a thickness of 50 μm to 400 μm and a sheet plane area of 50 cm ^{2 to} 900 cm ² . It is preferably used for an electrolyte-supported cell (ESC).

  The method for producing an electrolyte sheet for a solid oxide fuel cell according to the present invention is mainly positioned as a method capable of reliably obtaining an electrolyte sheet satisfying the above-mentioned specific surface properties, and its configuration is untreated for electrolyte. Including a step of pressurizing at least one surface of the green sheet with a roughening die having a roughened surface, the die being a peripheral region measured by a laser optical non-contact three-dimensional shape measuring device The mold surface roughness of Ra exceeds 3.0 μm and 20 μm or less, and the mold surface roughness of the region other than the peripheral edge is 0.3 μm or more and 10 μm or less of Ra. However, the present invention has a gist where the mold surface roughness of the peripheral area> the mold surface roughness of the area other than the peripheral area.

  Since the electrolyte sheet having different surface roughness in the peripheral region of at least one surface of the present invention and the region other than the peripheral portion is excellent in gas sealability as well as adhesion with the electrode, a cell using the electrolyte sheet is used. The electrode is less likely to be peeled even during a thermal cycle due to long-term thermal history at the SOFC operating temperature (600 ° C. to 950 ° C.) and repeated raising and lowering temperatures between the normal temperature and the operating temperature with the start / stop of the SOFC. ing. Furthermore, the stack using the cell can be a SOFC having stable power generation performance by preventing loss due to leakage of fuel gas and / or oxidant gas and cell damage due to local heat generation due to fuel gas leakage. become.

It is a conceptual diagram of the cross section which shows the structure of a single cell stack power generation test apparatus.

1: Electrolyte sheet 2: Fuel electrode 3: Air electrode
4: Cell 5: Fuel gas seal part 6: Fuel electrode side metal separator 7: Fuel gas introduction pipe 8: Fuel gas discharge pipe 9: Air seal part 10: Air electrode side metal separator 11: Air introduction pipe 12: Air discharge pipe

  Under the above-described problems, the present inventors have described in detail the manufacturing conditions of the electrolyte sheet and the physical properties of the electrolyte sheet (particularly the surface roughness and power generation characteristics of the electrolyte sheet) that vary depending on the factors of the manufacturing conditions. I have been researching. As a result, by adopting the electrolyte sheet of the present invention, which will be described in detail later, by determining a specific surface roughness, it has been found that the gas leakage resistance is excellent while maintaining the adhesion and power generation characteristics of the electrode, Was able to specify the production conditions for stably obtaining the target product having the physical properties. As will be described in detail below, the surface roughness of the electrolyte sheet is classified into the surface roughness in the peripheral area where the sealing material is applied and the surface roughness in the area other than the peripheral area where the electrode is formed, for each function. By designing optimally, we succeeded in establishing a simple manufacturing technology that makes it easy to secure gas leak resistance and does not impair the adhesion to the electrodes and the power generation characteristics.

  Moreover, if the production method of the present invention is adopted, the target product can be obtained more reliably. However, since the index for obtaining the target product has been clarified in the present invention, the production method can be used in addition to the production method defined in the present invention. If the conditions are variously devised, it is of course possible to obtain an electrolyte that meets the object of the present invention. Hereinafter, a specific configuration of the present invention will be described in detail.

  First, the inventors of the present invention have a general SOFC electrolyte sheet surface in which a gas seal layer is formed along the peripheral edge with a width of 1 to 8 mm from the peripheral edge of the electrolyte sheet. An electrode layer is formed in a region other than the peripheral portion, and the periphery of the electrolyte sheet is convinced that the gas seal layer has a suitable surface roughness different from the surface roughness suitable for electrode formation. Research has been conducted on the surface roughness of parts. As a result, the surface roughness of the electrolyte sheet is different in the sheet surface roughness (Ra) in the peripheral region of at least one surface and the region other than the peripheral region, and the electrolyte sheet is made into a laser optical non-contact three-dimensional shape. It was confirmed that the sheet surface roughness in the peripheral region obtained by measurement with a measuring device was adjusted to Ra and exceeded 3.0 μm to 10 μm or less and showed excellent gas sealing properties.

  Preferably, the sheet surface roughness is more than 3.5 μm and 9.0 μm or less in Ra, more preferably more than 4.0 μm and 8.0 μm or less.

  Incidentally, when the electrolyte sheet surface in the peripheral region is too flat, specifically, when Ra is 3.0 μm or less, the anchor effect on the sealing material is weak and the gas sealing performance is insufficient. On the pole side, fuel gas leaks, and on the air electrode side, air leaks easily occur, causing a problem that the fuel utilization rate and the air amount utilization rate decrease. In particular, if the fuel gas leaks on the fuel electrode side, the fuel gas directly burns in contact with air, so the temperature rises only at the location where the gas seal is poor, causing local thermal stress and cracking in the cell. There is a concern that the power generation performance may be deteriorated due to generation or volume change of the metal component (for example, metallic nickel) of the fuel electrode due to oxidation and collapse of the electrode structure.

  On the other hand, when the electrolyte sheet surface in the peripheral region is too rough, specifically, when the Ra exceeds 10 μm, the peripheral portion is used when stacking the manufactured cells, such as electrode printing and firing. Cracks and cracks are likely to occur from the region, and gas leaks occur from there and become a problem.

  Furthermore, in the electrolyte sheet of the present invention, Rz and Sm on the sheet surface are important control factors for sealing properties.

  That is, the sheet surface roughness in the peripheral region is 4.0 to 20 μm in Rz, more preferably 5.0 to 18 μm, and particularly preferably 6.0 to 15 μm. Those adjusted to m or less were confirmed to exhibit particularly excellent gas sealing properties. If the Rz is less than 4.0 μm, the anchoring effect on the sealing material is weak, so that the gas sealability is further insufficient. If the Rz is more than 20 μm, cracks and cracks are further generated from the peripheral region. It tends to occur and becomes a problem.

In the present invention, in particular, the Sm (average length of roughness curve element) of the electrolyte sheet in the peripheral region specifying the peak-valley average interval that is the shape in the planar direction of the electrolyte sheet is It is a control factor that greatly affects the filling properties and the denseness of the formed sealing layer, and Sm is 0.1 to 20 μm, more preferably 0.3 to 18 μm, particularly preferably It was confirmed that those adjusted to 0.5 μm or more and 15 μm or less also showed particularly excellent gas sealing properties.
Therefore, Ra and Rz specify the shape of the electrolyte sheet in the thickness direction, and in addition to this, by specifying the average interval between the peaks and valleys of the electrolyte sheet in the peripheral region, the three-dimensional shape of the peripheral region of the electrolyte sheet is determined. The relationship between the rough shape and the sealing performance was clarified.

  Incidentally, when the interval between the peaks and valleys on the surface of the electrolyte sheet in the peripheral region is too narrow, specifically, when the Sm is less than 0.1 μm, the filling property of the sealing material is deteriorated, and bubble marks are formed in the formed sealing layer. Presence of sealing performance decreases. On the contrary, when the interval between the peaks and valleys on the surface of the electrolyte sheet is too wide, specifically, when the Sm exceeds 20 μm, the seal durability when repeatedly raising and lowering the temperature is further problematic.

  In the electrolyte sheet of the present invention, the surface roughness in the region other than the peripheral portion is specified together with the surface roughness in the peripheral region. That is, since the region other than the peripheral portion is substantially the same as the region where the electrode is formed, the sheet surface roughness of the region other than the peripheral portion is set to 0.3 to 3.0 μm in Ra. Even if the same electrolyte material or the same electrode material is used, the adjusted material is excellent in electrode formation and maintains an electrochemical reaction field (three-phase interface) with the electrode, and exhibits excellent power generation characteristics and adhesion. It was also confirmed that it exhibits excellent and stable power generation characteristics.

  By the way, when Ra is less than 0.3 μm, the effective contact area that becomes the three-phase interface of the solid electrolyte-electrode-pores constituting the electrode reaction field is reduced. Therefore, not only the power generation performance as a battery, that is, the amount of power generation per unit area of the electrode is reduced, but also when it is exposed to high temperatures for a long time during sintering or use after electrode formation, or between room temperature and high temperature. When the thermal history is repeatedly received, peeling between the electrolyte sheet surface and the electrode layer is likely to occur.

  Therefore, in order to avoid such problems, it is necessary to roughen the electrolyte sheet surface prior to electrode formation. However, when the surface roughness of the electrolyte sheet is too large, specifically, when Ra exceeds 3.0 μm, the workability of electrode formation and the stability of the formed electrode layer are reduced, resulting in power generation performance. It becomes difficult to form an electrode having a uniform thickness that contributes to the improvement of the thickness, and further, not only the adhesion of the electrode layer is lowered, but also the strength of the electrolyte sheet itself is weakened.

  In the present invention, the sheet surface roughness means a value measured in accordance with the measurement of the electrical contact roughness parameters Ra and Rz of the German standard “DIN-4768” revised in May 1990, and is Sm (roughness). The average length of the curve element is a value measured according to the German standard “DIN-4287”. In addition, the average value which measured arbitrary four places in a peripheral part area | region, and the average value which measured arbitrary nine places in areas other than a peripheral part were calculated, and it was set as each Ra, Rz, and Sm.

  As the measuring device, a laser optical non-contact three-dimensional shape measuring device for measuring in a non-contact state on the electrolyte surface was used. The main measurement principle of this device is to focus a diameter of 1 μm on the sample surface (that is, the electrolyte sheet surface) from a semiconductor laser light source of 780 nm through a movable objective lens. At this time, specularly reflected light returns to the beam path through the same optical path. Since the images are evenly imaged on the four photodiodes via the liter, the measurement surface with the unevenness is displaced, resulting in non-uniformity in the image, and a signal is immediately generated to cancel the focus of the objective lens. The light barrier measurement mechanism detects the amount of movement when the lens is controlled so that it always matches the surface of the object to be measured, and the specifications are for a spot diameter of 1 μm and the resolution is the measurement range. 0.01% (maximum 0.01 micrometer).

  The German standards “DIN-4768” and “DIN-4287” stipulate the measurement of Ra, Rz, Sm by the electric contact type roughness parameter. The Ra, Rz, Sm defined in the present invention are measured by this measurement. It is determined in accordance with “DIN-4768” and “DIN-4287” from the Ra, Rz, Sm measurement method attached to the apparatus and the Ra, Rz, Sm calculation analysis program.

  In general, the surface roughness is evaluated by a contact-type surface roughness measuring apparatus that measures a diamond probe or the like by contacting the surface of the object to be measured and converting the phase difference of the surface into an electrical signal. However, the probe diameter is at least 2 μm, which is larger than that of laser optics, and the surface roughness required by the contact-type surface roughness measuring device may be due to the occurrence of the probe at the concave or convex portions. There is a tendency to be difficult to appear as a large difference in performance. However, it is expected that the laser optical non-contact measurement method can grasp the surface shape and roughness more accurately than the contact measurement device as described above. Therefore, in the present invention, the surface roughness measurement value measured by the laser optical non-contact measuring device is the surface roughness of the electrolyte sheet.

The type of ceramic constituting the electrolyte sheet of the present invention is preferably a solid ceramic that contains at least one selected from the group consisting of zirconia-based oxides, LaGaO ₃ -based oxides, and ceria-based oxides. The electrolyte is exemplified.

Preferred zirconia-based oxides include oxides of alkaline earth metals such as MgO, CaO, SrO and BaO as stabilizers, Y ₂ O ₃ , La ₂ O ₃ , CeO ₂ , Pr ₂ O ₃ and Nd ₂ O. ₃ , oxides of rare earth elements such as Sm ₂ O ₃ , Eu ₂ O ₃ , Gd ₂ O ₃ , Tb ₂ O ₃ , Dy ₂ O ₃ , Ho ₂ O ₃ , Er ₂ O ₃ , Yb ₂ O ₃ , Sc One or two or more oxides selected from ₂ O ₃ , Bi ₂ O ₃ , In ₂ O ₃ , or the like, or Al ₂ O ₃ , TiO ₂ , Ta as a dispersion strengthener Examples thereof include dispersion strengthened zirconia to which ₂ O ₅ , Nb ₂ O _{5 and the} like are added. Particularly preferred is a zirconia-based oxide stabilized with an oxide of at least one element selected from the group consisting of scandium, yttrium, cerium and ytterbium.

The LaGaO ₃ -based oxide is a composite oxide having a perovskite crystal structure, in which a part of La and Ga is substituted and dissolved by Sr, Y, Mg, etc. having a lower valence than each atom. , or for example for _{La 0.9 Sr 0.1 Ga 0.8 Mg 0.2} La 1-x , such as _{O 3 Sr x Ga 1-y} Mg y O 3, La 1-x Sr x Ga 1-y Examples include Mg _y Co ₂ O ₃ , La _1-x Sr _x Ga _1-y Fe _y O ₃ , La _1-x Sr _x Ga _1-y Ni _y O _{3, and the} like.

Preferred ceria-based oxides include CaO, SrO, BaO, Ti ₂ O ₃ , Y ₂ O ₃ , La ₂ O ₃ , Pr ₂ O ₃ , Nd ₂ O ₃ , Sm ₂ O ₃ , Eu ₂ O ₃ , _{gd 2 O 3, Tb 2 O} 3, Dy 2 O 3, Er 2 O 3, Tm 2 O 3, Yb 2 O 3, PbO, WO 3, MoO 3, V 2 O 5, Ta 2 O 5, Nb 2 Examples thereof include ceria-based oxides doped with one or more of O ₅ .

  These oxides can be used alone or in combination of two or more as required. Among those exemplified above, in order to obtain an electrolyte sheet having higher thermal, mechanical, chemical properties, and oxygen ion conductivity properties, it was stabilized with 3 to 10 mol% yttrium oxide. Particularly preferred are tetragonal and / or cubic zirconium oxides stabilized with ˜12 mol% scandium oxide or stabilized with 4-15 mol% ytterbium oxide. Among these, zirconia stabilized with 8 to 10 mol% yttrium oxide (8YSZ to 10YSZ), zirconia stabilized with 10 mol% scandium oxide and 1 to 2 mol% ceria (10Sc1CeSZ to 10Sc2CeSZ), 10 Zirconia (10Sc1AlSZ) stabilized with mol% scandium oxide and 1 mol% alumina is optimal.

The form of the electrolyte sheet of the present invention is not particularly limited, and examples thereof include a flat plate shape, a curved shape, a membrane shape, a cylindrical shape, a cylindrical flat plate shape, and a honeycomb shape. As an electrolyte sheet for a solid oxide fuel cell, Saga 50 micro m to 400 micro m or less, it is preferable and more preferably electrolyte sheet plane area below 100 micro m to 300 micro m consisting 50 cm ² or more 900 cm ² or less dense sintered body as the electrolyte of the ESC .

In the case of the electrolyte sheet, the shape of the sheet may be any of a circle, an ellipse, a square with a round shape, and the like, a hole with a similar circle, ellipse, square with R, etc. in these sheets. You may have one or two or more. The sheet area is preferably 80 cm ² or more, more preferably 100 cm ² or more. In addition, this area means the area enclosed by the outer periphery including the area of the said hole, when there exists a hole in a sheet | seat. As a matter of course, the peripheral portion of the hole is also included in the peripheral region of the electrolyte referred to in the present invention.

In another preferable form and shape of the electrolyte sheet, one surface of the electrolyte sheet is bonded to the fuel electrode, and the sheet thickness is 5 μm or more and less than 50 μm, more preferably 10 μm or more and 30 μm or less. in surface area of the electrolyte sheet consisting of 50 cm ² or more 900 cm ² or less of membrane dense sintered body, which is suitable as an electrolyte for ASC. The electrolyte sheet may be bonded to a fuel electrode substrate that also functions as a fuel electrode.

  In order to efficiently produce the electrolyte sheet having the surface roughness intended in the present invention, at least one surface of the untreated green sheet for electrolyte has a surface roughness (Ra) in a peripheral region and a region other than the peripheral portion. Including a step of pressurizing with a different roughening mold, and the mold surface roughness of the peripheral region measured by a laser optical non-contact three-dimensional shape measuring apparatus is 3.0 as Ra. The surface roughness of the mold in the region other than the peripheral portion exceeds 0.3 μm and is 10 μm or less (provided that the mold surface roughness in the peripheral region> This is a method using the mold surface roughness of the region other than the peripheral portion. By using the mold, the portion corresponding to the peripheral region of the electrolyte sheet on the surface of the untreated green sheet for electrolyte and the portion corresponding to the region other than the peripheral portion of the electrolyte sheet are roughened to different predetermined roughness at the same time or with a time difference. .

  Generally used as a method for producing the above-mentioned untreated green sheet for electrolyte is a slurry containing an electrolyte raw material powder and an organic binder, a dispersant, a solvent, and a plasticizer or an antifoaming agent as necessary. It is a method of spreading on a release polymer film by a doctor blade method, calendar method, extrusion method, etc., forming into a sheet shape, drying this and volatilizing the dispersion medium to obtain an untreated green sheet for electrolyte .

  There is no particular limitation on the type of binder used in the production of the untreated green sheet for electrolyte, and a conventionally known organic binder can be appropriately selected and used. Examples of organic binders include ethylene copolymers, styrene copolymers, acrylate and methacrylate copolymers, vinyl acetate copolymers, maleic acid copolymers, vinyl butyral resins, and vinyl acetal resins. And vinyl formal resins, vinyl alcohol resins, waxes, celluloses such as ethyl cellulose, and the like.

  Among these, from the point of moldability and strength of the green sheet, thermal decomposability at the time of firing, etc., carbon number 10 such as methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, isobutyl acrylate, cyclohexyl acrylate, 2-ethylhexyl acrylate, etc. Alkyl acrylates having the following alkyl groups; and alkyls having 20 or less carbon atoms such as methyl methacrylate, ethyl methacrylate, butyl methacrylate, isobutyl methacrylate, octyl methacrylate, 2-ethylhexyl methacrylate, decyl methacrylate, dodecyl methacrylate, lauryl methacrylate, cyclohexyl methacrylate and the like. Alkyl methacrylates having a group; hydroxyethyl acrylate, hydroxypropyl Hydroxyalkyl acrylates or hydroxyalkyl methacrylates having a hydroxyalkyl group such as acrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate; aminoalkyl acrylates or aminoalkyl methacrylates such as dimethylaminoethyl acrylate and dimethylaminoethyl methacrylate; acrylic acid and methacrylic acid And a number average molecular weight of 20,000 to 250,000 obtained by polymerizing or copolymerizing at least one selected from carboxyl group-containing monomers such as maleic acid and maleic acid half esters such as monoisopropylmalate More preferably, 50,000 to 200,000 (meth) acrylate copolymers are recommended as preferred.

  These organic binders can be used alone or in combination of two or more as necessary. Particularly preferred is a monomer polymer containing 60% by mass or more of isobutyl methacrylate and / or 2-ethylhexyl methacrylate.

  The use ratio of the raw material powder and the binder is preferably in the range of 5 to 30 parts by weight, more preferably 10 to 20 parts by weight with respect to the former 100 parts by weight. Insufficient strength and flexibility make it impossible to sufficiently roughen to the desired surface roughness. On the other hand, if the amount is too large, it is difficult not only to adjust the viscosity of the slurry, but also to decompose the binder component during firing. The release becomes large and intense, making it difficult to obtain a flat ceramic sheet.

  The solvent used for the production of the green sheet includes alcohols such as water, methanol, ethanol, 2-propanol, 1-butanol and 1-hexanol; ketones such as acetone and 2-butanone; pentane, hexane and butane. Aliphatic hydrocarbons such as benzene, toluene, xylene, ethylbenzene, and the like; and acetates such as methyl acetate, ethyl acetate, and butyl acetate are appropriately selected and used. These solvents can also be used alone, or two or more of them can be used in combination as appropriate. The amount of these solvents used should be appropriately adjusted in consideration of the viscosity of the slurry at the time of forming the green sheet, and preferably the slurry viscosity is in the range of 1 to 50 Pa · s, more preferably 2 to 20 Pa · s. It is better to make adjustments.

  In the preparation of the slurry, in order to promote peptization and dispersion of the raw material powder, polymer electrolytes such as polyacrylic acid and ammonium polyacrylate; organic acids such as citric acid and tartaric acid; isobutylene or styrene and maleic anhydride Copolymers, ammonium salts and amine salts thereof; dispersants such as copolymers of butadiene and maleic anhydride and ammonium salts thereof; and dibutyl phthalate and phthalic acid for imparting flexibility to green sheets Phthalic acid esters such as dioctyl; glycols such as propylene glycol and glycol ethers; polyester plasticizers such as phthalic polyester, adipic acid polyester, and sebacic acid polyester; and surfactants and antifoams An agent or the like can be added as necessary.

  A slurry composed of the above raw material blend is formed by the method described above, dried to obtain an electrolyte green sheet, and then cut into a predetermined shape and size. The forming method is not particularly limited, and a sheet having an appropriate thickness is obtained using a conventional method such as a doctor blade method or an extrusion method. Then, it is set as the unprocessed green sheet for electrolytes by drying. Drying conditions are not particularly limited, and for example, drying may be performed at a constant temperature of room temperature to 150 ° C., or heating may be performed by successively raising the temperature in the order of 50 ° C., 80 ° C., and 120 ° C.

  Note that “untreated” in the untreated green sheet means that a special treatment for roughening the surface is not performed.

  Another form of the electrolyte sheet for a solid oxide fuel cell of the present invention is an electrolyte membrane in an ASC half cell in which an electrolyte and a fuel electrode are joined and integrated. The untreated electrolyte green sheet for producing the electrolyte membrane is formed into a membrane by applying an electrolyte paste having the above composition to the fuel electrode green sheet by a screen printing method, a coating method, etc., and then drying it. There are a method of volatilizing the dispersion medium, a method of laminating the fuel electrode green sheet and the electrolyte green sheet, and a pressure treatment to obtain an untreated green sheet for electrolyte. Here, it is also possible to use a fuel electrode substrate green sheet instead of the fuel electrode green sheet.

  Next, if necessary, the green sheet is subjected to pressure treatment with a roughing mold having a surface roughened by making an untreated green body of an appropriate size by cutting, punching or the like. This treatment attaches the roughening die up and down to the press machine, or attaches only to one of the upper and lower sides, and pressurizes the unprocessed green sheet for electrolyte obtained as described above, The roughness of the mold is transferred to the surface of the green sheet and moderately roughened within the surface roughness range of the present invention. In addition, the surface roughness of the green sheet can be easily adjusted by the roughness of the surface roughening mold to be used, the pressing pressure, the pressing time, and the like in the pressurizing process. Such roughness can be adjusted by controlling the temperature during pressurization according to the binder added to the raw slurry.

  Here, in order for the roughness of the mold to be accurately transferred to the surface of the green sheet and roughened to the roughness within the surface roughness range of the present invention, the tensile fracture elongation in the tensile test of the green sheet is 5%. Preferably, the tensile yield strength is 2.0 MPa or more and 20 MPa or less. More preferably, the tensile elongation at break is 8% to 30% and the tensile yield strength is 3.0 MPa to 15 MPa.

  Incidentally, when the tensile fracture elongation is less than 5% and the tensile yield strength exceeds 20 MPa, the roughness of the mold is not sufficiently transferred to the green sheet, resulting in insufficient roughening. Conversely, the tensile fracture elongation is 50%. When the upper tensile yield strength is less than 2.0 MPa, there arises a problem that it becomes difficult to peel off the green sheet from the mold.

  The tensile fracture elongation and the tensile yield strength are measured according to the plastic tensile test method of JIS K-7113. Specifically, using a universal material testing machine (model 4301 manufactured by Instron Japan Co., Ltd.), a green sheet cut into a No. 2 type test piece shape, while holding both ends of the test piece with a jig The test piece was pulled at a tensile rate of 100 mm / min, and the tensile elongation at break and the tensile yield strength were measured.

  The roughening mold used in the pressure treatment of the present invention is particularly suitable if the surface is moderately roughened and has a strength and flexibility that can sufficiently peel the green sheet after the pressure treatment. Not limited. For example, examples of the material include cemented carbide tungsten, stainless steel, die steel, stellite, special steel, and cemented carbide, all of which can be used. However, a mold made of a cemented carbide such as cemented tungsten is preferably used because of its excellent wear resistance, hardness, electric discharge machinability, and the like.

  The method for roughening the surface of the mold is not particularly limited, and a conventionally known method such as blasting, grinding, electric discharge machining, or etching may be used. However, in order to produce a uniformly rough ceramic green body, it is necessary to uniformly rough the mold. As a method for uniformly roughing the mold, it is preferable to perform electric discharge machining. In the electric discharge machining process, the degree of roughening can be adjusted by the current intensity and the processing time.

The uniformity of the surface roughness of the roughening mold in the present invention is determined by measuring R _a (arithmetic roughness intermediate value) in the mold at a plurality of locations in the mold peripheral area and areas other than the peripheral area. In this case, the roughness is expressed as at least one standard deviation. More specifically, in the roughening mold, the roughness is measured by a laser optical non-contact three-dimensional shape measuring device at four places in the peripheral area of the mold and at nine places other than the peripheral area. The standard deviation may be calculated. The uniformity, that is, the standard deviation is preferably 0.3 or less.

  As a rough indication of the roughness of the roughening mold to be used, the surface roughness of the peripheral edge area of the mold is more than 4.0 μm and 18 μm or less in Ra, and the surface of the area other than the peripheral edge area. The roughness is more preferably 0.4 μm or more and 8 μm or less in terms of Ra. As for Rz, the surface roughness of the peripheral edge region of the mold is 4.0 μm or more and 40 μm or less in Rz, and more preferably 5.0 μm or more and 30 μm or less. Furthermore, regarding Sm, the surface roughness of the peripheral edge region of the mold is 0.1 μm or more and 30 μm or less in Sm, and more preferably 0.3 μm or more and 25 μm or less.

  The press pressure in the pressure treatment is about 1.96 MPa to 58.8 MPa, preferably about 2.94 MPa to 49.0 MPa. The pressurization time is 0.1 second to 600 seconds, preferably 1 second to 300 seconds. According to such conditions, the untreated green sheet for electrolyte is appropriately roughened in accordance with the roughness of the mold, and the electrolyte having the surface roughness specified in the present invention can be reliably produced. In the pressure treatment, since it is necessary to transfer different roughness to the untreated green sheet for electrolyte, a shim (spacer) or a buffer material sheet is further inserted between the mold and the base plate to which the mold is attached. By supplementarily attaching a roughening sheet or the like, the electrolyte having the surface roughness specified in the present invention can be produced more reliably.

  Further, after the pressure treatment step, in order to efficiently peel the roughened electrolyte green body from the roughening die, one or more air ejection holes are provided in the die, and the air ejection is performed after the pressure treatment. It is preferable to feed air from the hole. According to this aspect, it is possible to peel the roughened electrolyte green sheet in a short time without damaging it.

  The diameter of the air ejection hole provided in the mold is preferably about 0.1 mm or more and 1 mm or less. Since the electrolyte green body is not roughened at the locations where the air ejection holes are provided, the air ejection holes should be smaller. On the other hand, if the air ejection hole is too small, the mold and the green sheet may not be peeled off satisfactorily, so the diameter is preferably 0.1 mm or more. The same applies to the number of air ejection holes, and the smaller the number, the better for roughening the electrolyte green sheet, but the larger the number for efficient peeling. Accordingly, the number of air ejection holes is preferably 2 or more and 80 or less, more preferably 4 or more and 60 or less, although it depends on the area of the electrolyte to be produced.

  The electrolyte green sheet having a roughened surface through the pressure treatment step is fired to obtain the electrolyte sheet of the present invention. Specific firing conditions are not particularly limited, and may be based on a conventional method. For example, in order to remove organic components such as a binder and a plasticizer from the surface roughened electrolyte green sheet, the treatment is performed at 150 to 600 ° C., preferably 250 to 500 ° C. for about 5 to 80 hours. Subsequently, the surface roughening electrolyte of this invention is obtained by carrying out holding | maintenance baking at 1000-1600 degreeC, Preferably 1200-1500 degreeC for 2 to 10 hours.

  The surface roughness electrolyte sheet surface roughness of the present invention obtained above is approximately 70 to 90% with respect to the surface roughness of the electrolyte green sheet. Therefore, in order to obtain an electrolyte sheet having a desired surface roughness, the conditions of the pressure treatment step may be adjusted so that a similar surface-roughened electrolyte green sheet can be obtained.

  The solid oxide fuel cell of the present invention is characterized by using the surface roughened electrolyte sheet. The electrolyte sheet having a different surface roughness (Ra) in the peripheral region of at least one surface of the present invention and the region other than the peripheral region is an electrolyte sheet having the same surface roughness in the peripheral region and the region other than the peripheral portion. Compared to the electrolyte sheet that has not been surface roughened, the peripheral area has a higher degree of roughness, so the adhesion to the sealing material is improved and gas sealing is improved, and the adhesion to the electrode is also improved, resulting in improved power generation efficiency. Also gets higher. Therefore, the solid oxide fuel cell of the present invention enables efficient power generation and stable power generation over a long period of time.

  The solid oxide fuel cell has a fuel electrode formed on one surface of the electrolyte sheet of the present invention and an air electrode formed on the other surface by screen printing or the like. Here, the order of formation of the fuel electrode and the air electrode is not particularly limited, but an electrode having a low necessary firing temperature is first formed on the electrolyte sheet and then fired, or the fuel electrode and the air electrode may be fired simultaneously. Good. Further, an intermediate layer as a barrier layer may be formed between the electrolyte sheet and the air electrode layer in order to prevent generation of a high resistance component due to a solid phase reaction between the electrolyte and the air electrode. In this case, the fuel electrode is formed on the surface on which the intermediate layer is formed or the surface opposite to the surface to be formed, and the air electrode is formed on the intermediate layer. Here, the order of formation of the intermediate layer and the fuel electrode is not particularly limited, and the intermediate layer and the fuel electrode are formed by applying and drying the intermediate layer paste and the fuel electrode paste on each surface of the electrolyte sheet, respectively, and then firing the respective layers. May be formed by firing at the same time.

  The material for the fuel electrode and the air electrode, further the intermediate layer material, and the paste application method, drying conditions, and firing conditions for forming them can be implemented in accordance with conventionally known methods.

  The electrolyte sheet according to the cell of the present invention in which the fuel electrode and the air electrode are formed, or the electrolyte sheet according to the cell of the present invention in which the fuel electrode and the air electrode and the intermediate layer are formed has a peripheral portion such as fuel gas or air. The surface roughness is extremely suitable for the gas seal, and the contact area between the electrolyte and the electrode or intermediate layer is large, so that the durability and power generation performance are excellent. Therefore, the method of the present invention can be used to produce a surface roughened electrolyte sheet that can be used as an electrolyte for a solid oxide fuel cell having excellent performance and a surface roughened electrolyte green sheet that is a precursor thereof. Can contribute.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited by the following examples, but may be appropriately modified within a range that can meet the purpose described above and below. It is also possible to implement, and they are all included in the technical scope of the present invention.

Example 1
(1) 10 mol% scandium oxide 1 mol% cerium oxide stabilized zirconia powder (trade name “10Sc1CeSZ”, d ₅₀ ; 0.6, manufactured by Daiichi Elemental Chemical Co., Ltd.) Microm) 16 parts by mass of a methacrylic copolymer binder (number average molecular weight; 100,000, glass transition temperature; −8 ° C.) in terms of solid content, and sorbitan acid trioleate as a dispersant, per 100 parts by mass 2 parts by mass, 3 parts by mass of dibutyl phthalate as a plasticizer, and 50 parts by mass of a mixed solvent of toluene / isopropanol (mass ratio = 3/2) as a solvent are placed in a nylon mill charged with zirconia balls and milled for 40 hours. A slurry was prepared. The obtained slurry was transferred to a jacketed round bottom cylindrical vacuum degassing vessel equipped with a bowl-shaped stirrer and having an internal volume of 50 L. While rotating the stirrer at a speed of 30 rpm, the jacket temperature was reduced to 40 ° C. (about 4 ° C.). -21 kPa) under reduced pressure, adjusted to a viscosity of 3 Pa · s at 25 ° C., and continuously applied onto a polyethylene terephthalate (PET) film by the doctor blade method as a coating slurry, It was dried at 40 ° C., 80 ° C., and 110 ° C. to obtain a long untreated green body (green sheet) for solid electrolyte, cut into a circle of about 160 mmφ, and peeled from the PET film.

(2) Surface roughening mold Of the circular tungsten carbide mold of about 160 mmφ, the peripheral region having a width of about 6.7 mm from the periphery and the other region (center portion) were subjected to electric discharge machining treatment under different conditions. When an electric discharge machined mold is measured with a laser optical non-contact three-dimensional shape measuring device (manufactured by UBM, Micro Focus Expert, model “UBM-14”), the average of any four locations in the peripheral region is Ra. Was 4.1 μm, Rz was 10.9 μm, Sm was 2.0 μm, and Ra was 0.7 μm on the average of any 10 locations in the region other than the peripheral portion.

(3) Roughening of green sheet The green sheet roughening mold of (2) above was attached to a compression molding machine (model “S-37.5”, manufactured by Shin-Fuji Metal Industry Co., Ltd.) up and down. The 10Sc1CeSZ green sheet produced in (1) above was placed on the lower mold. The green sheet is slowly sandwiched by lowering the upper roughing mold, pressurizing at a press pressure of 9.8 MPa for 1 second, and then the upper roughening mold is slowly raised to remove the roughened green sheet. Peeled from the mold.

(4) Firing of roughened green sheet Next, the upper and lower sides of the roughened green sheet obtained in (3) above were 99.5% alumina porous plates (porosity: 30%) having a maximum undulation height of 10 μm. After sandwiching and degreasing, it was heated and fired at 1420 ° C. for 3 hours to obtain a 10Sc1CeSZ electrolyte sheet having a thickness of about 120 mmΦ and a thickness of 0.28 mm. The surface roughness of this electrolyte sheet was measured in the same manner as (2) above. In an average of four arbitrary positions in the area of the width of the sheet around 5 mm, Ra is 3.3 μm, Rz is 8.2 μm, and Sm is 1.6 μm. In an average of arbitrary 10 positions, Ra was 0.5 μm.
that's all

(5) Production of Solid Oxide Fuel Cell Cell A solid oxide fuel cell was produced by forming a fuel electrode and an air electrode on both sides of the 10Sc1CeSZ electrolyte sheet. Specifically, 70 parts by mass of nickel oxide powder (d ₅₀ : 0.9 μm) obtained by thermally decomposing basic nickel carbonate in an area of about 110 mmφ excluding the area of 5 mm width at the peripheral part of the 10Sc1CeSZ electrolyte sheet, A fuel electrode paste composed of ceria particles and zirconia particles is formed by screen printing, and an intermediate layer paste composed of 20 mol% samarium-doped ceria is screened on the opposite surface in the same manner except for a region having a width of 5 mm. A fuel electrode and an intermediate layer were formed on the electrolyte by printing and baking at 1300 ° C.

Next, on the intermediate layer, 80 parts by mass of commercially available strontium-doped lanthanum iron cobaltate (La _0.6 Sr _0.4 Fe _0.8 Co _0.2 O ₃ ) powder and a commercially available 20 mol% gadolinia-doped ceria powder An air electrode paste composed of 20 parts by mass was formed by screen printing and baked at 950 ° C. to obtain a cell having a four-layer structure.

(Example 2)
For the untreated green sheet for a solid electrolyte obtained in Example 1, the average of four arbitrary positions in the peripheral region was such that Ra was 9.0 μm, Rz was 17.5 μm, and Sm was 5.9 μm. The roughened electrolyte sheet was the same as in Example 1 except that it was roughened using a roughening mold with an Ra of 0.8 μm in the average of any 10 locations in the region other than the peripheral portion. And the cell using the said electrolyte sheet was produced. The results are shown in Table 1.

(Example 3)
For the untreated green sheet for solid electrolyte obtained in Example 1, the average of four arbitrary positions in the peripheral region was such that Ra was 12.8 μm, Rz was 27.5 μm, and Sm was 13.7 μm. The roughened electrolyte sheet in the same manner as in Example 1 except that the average of arbitrary 10 locations in the region other than the peripheral portion was roughened by using a roughening mold having a Ra of 0.6 μm. And the cell using the said electrolyte sheet was produced. The results are shown in Table 1.

(Comparative Example 1)
For the untreated green sheet for solid electrolyte obtained in Example 1, the average of four arbitrary locations in the peripheral region was such that Ra was 0.3 μm, Rz was 1.6 μm, and Sm was 0.09 μm. The roughened electrolyte sheet in the same manner as in Example 1 except that the average of arbitrary 10 locations in the region other than the peripheral portion was roughened by using a roughening die having a Ra of 0.7 μm. And the cell using the said electrolyte sheet was produced. The results are shown in Table 1.

(Comparative Example 2)
As for the untreated green sheet for solid electrolyte obtained in Example 1, the average of arbitrary four locations in the peripheral region was such that Ra was 21.2 μm, Rz was 47.4 μm, and Sm was 30.7 μm. The roughened electrolyte sheet is the same as in Example 1 except that the average of any nine locations in the region other than the peripheral portion is roughened by using a roughening die having a Ra of 0.6 μm. And the cell using the said electrolyte sheet was produced. The results are shown in Table 1.

(Example 4)
(Gas leak test)
As in the single cell stack power generation test apparatus of FIG. 1, the electrolyte sheets, sealing materials and metal separators obtained in Examples 1 to 3 and Comparative Examples 1 and 2 are placed in an electric furnace and heated to 950 ° C. Then, the peripheral portion of the electrolyte sheet 1 was joined to the fuel electrode side metal separator 6 and the air electrode side metal separator 10 to produce each SOFC single cell stack.

The sealing material used is a sheet molded body of silica-alumina-potassium oxide glass, and the composition is SiO ₂ (50 mass%)-Al ₂ O ₃ (18 mass%)-K ₂ O (12 mass%)-ZnO ( 12% by mass) -Na ₂ O (8% by mass) and formed into a sheet by a doctor blade method using a slurry obtained by mixing glass powder having an average particle diameter of 20 μm with a PVA aqueous solution. . This glass has a thermal expansion coefficient of 10.3 × 10 ⁻⁶ K ⁻¹ and a softening point of 885 ° C.

  The fuel gas introduction pipe 7 and the fuel gas discharge pipe 8 of each SOFC single cell stack in the electric furnace are connected to the fuel gas circulation system, and the air introduction pipe 11 and the air discharge pipe 12 are connected to the air circulation system. The rate was increased at a rate of ° C / hr. After reaching the predetermined temperature, hold it for 1 hour while introducing air into both the fuel gas flow system and the air flow system, then lower the temperature at a rate of 200 ° C./hr and take the temperature lower than 200 ° C. over 12 hours. The furnace was cooled. This unit was set as 1 heat cycle, and it implemented repeatedly. The introduction air flow rate is 2NLM (Normal Liter Per Minute), and the fuel electrode side exhaust air flow rate and the air electrode side exhaust air flow rate after 1 heat cycle, 10 heat cycles, and 30 heat cycles are measured, and the gas leak rate is calculated. Calculated. The results are shown in Table 1.

In any cell using the electrolyte sheet of the present invention, the gas leak rate after 30 thermal cycles was 0%, but the cell or surface using the electrolyte sheet of Comparative Example 1 having a smaller surface roughness than the electrolyte sheet of the present invention The cell using the electrolyte sheet of Comparative Example 2 having a large roughness has a gas leak rate of 3 to 8% after 30 heat cycles, and both of them are inferior in sealing properties (Example 5)
(Cell power generation performance test)
Using the cells produced in Example 1 and Comparative Example 2, a continuous power generation test was performed at 750 ° C. using the single cell power generator shown in FIG. 1, and the IV curve was measured. Note that 3% humidified hydrogen was used as the fuel gas, and air was used as the oxidant. Moreover, the product name “R8240” manufactured by Advantest Corporation was used for the current measuring device, and the product name “R6240” manufactured by Advantest Corp. was used for the current-voltage generator. The maximum output density (W / cm ² ) at the start of the power generation test and after 200 hours was determined, and the results are shown in Table 1.

  Comparing the maximum power density after the elapse of 200 hours, the cell of Example 1 using the electrolyte sheet of the present invention is more than the cell using the electrolyte sheet of Comparative Example 2 having a larger surface roughness than the electrolyte sheet of the present invention. It is 14% higher and it can be seen that the gas sealability is excellent.

  The present invention relates to an electrolyte sheet for a solid oxide fuel cell and a cell using the electrolyte sheet, and can contribute to a solid oxide fuel cell that can improve power generation performance and maintain high power generation performance. .

Claims (8)

An electrolyte sheet for a solid oxide fuel cell,
In at least one surface , the electrolyte sheet surface roughness (Ra) in the peripheral region and the region other than the peripheral portion is different,
The sheet surface roughness in the peripheral region obtained by measuring the electrolyte sheet with a laser optical non-contact three-dimensional shape measuring apparatus is more than 3.0 μm and 10.0 μm or less in Ra, and the region other than the peripheral region The sheet surface roughness in Ra is 0.3 μm or more and 3.0 μm or less, and the average of the peaks and valleys in the peripheral region obtained by measuring the electrolyte sheet with a laser optical non-contact three-dimensional shape measuring device The electrolyte sheet for a solid oxide fuel cell, wherein the interval is 0.1 μm or more and 20 μm or less in Sm.
Here, the surface roughness Ra (arithmetic average roughness) is a surface roughness parameter determined in accordance with the German standard “DIN-4768”, and the mean valley interval Sm (average length of roughness curve elements) is Germany. This is an average interval parameter determined in accordance with the standard “DIN-4287”. An electrolyte sheet for a solid oxide fuel cell according to claim 1,
Further, the electrolyte for a solid oxide fuel cell, in which the sheet surface roughness in the peripheral region obtained by measuring the electrolyte sheet with a laser optical non-contact three-dimensional shape measuring apparatus is 4.0 μm or more and 20 μm or less in Rz. Sheet.
Here, the surface roughness Rz (maximum roughness) is a surface roughness parameter determined in accordance with the German standard “DIN-4768”. 3. The electrolyte sheet for a solid oxide fuel cell according to claim 1, wherein the electrolyte sheet is selected from the group consisting of a zirconia-based oxide, a LaGaO ₃ -based oxide, and a ceria-based oxide. An electrolyte sheet for a solid oxide fuel cell containing at least one kind. The solid oxide fuel cell according to claim 3, wherein the zirconia-based oxide is zirconia stabilized with an oxide of at least one element selected from the group consisting of scandium, yttrium, cerium, and ytterbium. Electrolyte sheet. An electrolyte sheet for a solid oxide fuel cell according to any one of claims 1 to 4,
An electrolyte sheet for a solid oxide fuel cell comprising a dense sintered body having a thickness of 50 μm to 400 μm and a sheet area of 50 cm ^{2 to} 900 cm ² . A method for producing an electrolyte sheet for a solid oxide fuel cell in which the sheet surface roughness is different in a peripheral area of at least one surface of the electrolyte sheet for a solid oxide fuel cell and a region other than the peripheral area,
Including a step of pressurizing at least one surface of the untreated green sheet for electrolyte with a roughening mold whose surface is roughened, and the mold is measured by a laser optical non-contact three-dimensional shape measuring device The mold surface roughness of the peripheral edge region is more than 3.0 μm and 20 μm or less in Ra, and the mold surface roughness of the region other than the peripheral edge is 0.3 μm or more and 10 μm in Ra.
The following (however, the mold surface roughness of the peripheral area> the mold surface roughness of the area other than the peripheral area)
The method for producing an electrolyte sheet for a solid oxide fuel cell according to any one of claims 1 to 5.     A single cell for a solid oxide fuel cell, wherein the electrolyte sheet for a solid oxide fuel cell according to any one of claims 1 to 6 is used.   A solid oxide fuel cell comprising the single cell for a solid oxide fuel cell according to claim 7.

Images