JP4154748B2 - Method for manufacturing cell for solid oxide fuel cell - Google Patents

Description

【００４２】
上記表１に示す結果から明らかなように、電解質スラリーを塗布した段階で、電解質スラリーと平衡状態にある雰囲気中で緩速に乾燥した後に焼成して形成した各実施例に係る電池用セルにおいては、電解質スラリーの粘度の大小、またはスラリー塗膜厚の大小に関係なく、焼成後において割れや剥離などの不良の発生率が極めて少なく、高品質の電池用セルが高い歩留りで量産できた。
【００４３】
上記割れや剥離などの不良発生率を大幅に低減できる機構は必ずしも明確ではないが、スラリー塗膜形成段階で電解質スラリーと平衡状態にある雰囲気中、すなわち塗付した電解質スラリーの溶媒の蒸気圧と等しい蒸気圧を有する雰囲気中において所定時間保持することにより、スラリー塗膜の外表面から溶媒が急激に揮散することが防止でき、塗膜の内外における歪みの発生がなくなり、焼成工程においてもその歪みが拡大することがないため、割れや剥離が効果的に防止できるためと考えられる。
【００４４】
一方、スラリー塗膜を大気中で保持した比較例１〜５の場合には、塗膜の最外表面から溶媒が急激に揮散して塗膜の内外部において溶媒の蒸発速度に差を生じて内部歪みが発生し、その内部歪みが焼成時に拡大されるため、割れや剥離が急増する結果、良質の電解膜が形成できないものと考えられる。
【００４５】
また、本実施例によれば電解質スラリーの濃度（粘度）が大きく、またはスラリー塗膜の厚さが厚い場合においても、スラリーの塗布回数および焼成回数が１回で済み、電池用セルの製造工数を大幅に削減でき、燃料電池の低コスト化に優れた効果を発揮できた。
【００４６】
さらに各実施例に係る燃料電池用セルを使用して燃料電池を組み立て、そのＩ−Ｖ特性を測定したところ、いずれも図４に示すような良好なＩ−Ｖ特性が得られた。すなわち、電解質膜に割れや剥離がないため、燃料ガスの短絡などが一切なく、各電流値において十分な電位差が得られ、特性が良好な燃料電池が得られることが判明した。
【００４７】
なお、各実施例に係る電池用セルに対して、室温から動作温度（１０００℃）まで加熱した後に室温まで冷却するヒートサイクルを少なくとも１０回作用させた場合においても、電解質膜に割れや剥離は発生せず、優れた耐久性を有することが確認されている。
【００４８】
また本実施例においては電解質スラリーの調製時に特定の溶媒、分散剤や可塑剤を使用しており、またスラリーについてもＹＳＺスラリーを使用して電解質膜を形成する例で示しているが、他の溶媒、分散剤や可塑剤、または他のセラミックススラリーを使用した場合においても、同様に、割れや剥離がないセラミックス薄膜を効率的に製造できることが確認されている。さらに薄膜を形成する本体の材質，形状，および厚さに対する制約もないため、本実施例方法は、電解質膜を形成する場合のみならず、多層構造の燃料極を形成する場合にも同様に適用することが可能である。
【００４９】
【発明の効果】
以上説明の通り本発明に係る固体電解質型燃料電池用セルの製造方法によれば、電解質スラリーと平衡状態にある雰囲気中、すなわち塗付した電解質スラリーの溶媒の蒸気圧と等しい蒸気圧を有する雰囲気中に、スラリー塗膜を形成した円筒状空気極を保持しているため、スラリー塗膜の外表面から溶媒が急激に揮散することが効果的に防止でき、塗膜の内外における歪みの発生が防止できる。そのため、乾燥・焼成工程においても塗膜の歪みが拡大することなく、割れの発生が少ない電解質膜を高い歩留りで製造することができる。
【００５０】
また、焼成前の段階において、スラリー塗膜の内部歪みが低減されているため、焼成処理において高い昇降温速度を作用させた場合においても、塗膜に割れが発生せず、優れた耐久性を有する電解質膜を効率的に製造することができる。
【００５１】
さらに、高粘度の電解質スラリーを塗布した場合においても、焼成時に割れや剥離を発生することが少ないため、所定厚さの電解質膜を１回のスラリー塗布操作および１回の焼成操作によって形成することが可能であり、従来の１０数回に及ぶ塗布・焼成操作を繰り返していた従来方法と比較して、電池用セルの製造工数を大幅に低減でき、燃料電池の低コスト化に大きな効果を発揮することができる。
【図面の簡単な説明】
【図１】 本発明に係る固体電解質型燃料電池用セルの製造方法を実施するための製造装置の構成例を示す断面図。
【図２】 図１に示す装置を使用して浸漬処理を実施する状態を示す断面図。
【図３】 図１に示す装置を使用して電池用セルを保持した状態を示す断面図。
【図４】 実施例で作成した燃料電池用セルを使用した電池のＩ−Ｖ特性を示すグラフ。
【符号の説明】
１ 電解質スラリー
２ スラリー貯槽
３ シール容器
４ シール用媒体（液体パラフィン）
５ 外気遮断槽
６ ガス圧力調整槽
７ セル支持棒
８ 円筒状空気極（円筒形電池用セル本体）
９ スラリー塗膜[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method for manufacturing a cell for a solid oxide fuel cell, and in particular, the manufacturing yield and reliability of a fuel cell can be greatly increased with less occurrence of cracks in an electrolyte membrane formed by a firing method, and The present invention relates to a method for manufacturing a cell for a solid oxide fuel cell that can greatly reduce the number of manufacturing steps.
[0002]
[Prior art]
Various fuel cells have been developed and put into practical use as direct current power generators that allow a fuel such as hydrogen and an oxidant such as oxygen in the air to react electrochemically and directly extract the reaction energy as electricity. In this fuel cell, a pair of porous electrodes (fuel electrode, air electrode) are usually arranged with an electrolyte layer interposed therebetween, and a fuel gas such as hydrogen, methane gas, or coal gasification gas is disposed on the back surface of one electrode (fuel electrode). In addition, an oxidant gas such as air or oxygen is brought into contact with the back surface of the other electrode (air electrode), and electric energy is taken out between the electrodes by utilizing an electrochemical reaction generated at this time. It is a thing. In the fuel cell configured as described above, as long as the fuel gas and the oxidant gas are supplied, electric energy can be extracted with high conversion efficiency.
[0003]
Depending on the type of electrolyte used and the operating temperature, the fuel cell has been put into practical use, such as a phosphoric acid fuel cell (PAFC), a molten carbonate fuel cell (MCFC), and a high temperature solid electrolyte fuel cell (SOFC). In particular, a solid oxide fuel cell (SOFC) using a solid metal oxide such as stabilized zirconia (ZrO ₂ ) as an electrolyte has few restrictions on the shape of the battery. It is the present condition which is spreading widely as a cell.
[0004]
A battery cell which is a constituent element of a conventional solid oxide fuel cell has been manufactured through the following processes, for example. That is, it has been formed by a wet method or a chemical vapor deposition method (CVD method) in which a step of applying a slurry to the surface of a battery cell body (for example, a cylindrical air electrode) and a step of drying and baking are repeated.
[0005]
[Problems to be solved by the invention]
However, in the case of forming an electrolyte membrane by the above CVD method, the manufacturing cost increases, and complicated operation and high skill are required to strictly control the film formation conditions. It has been difficult to produce battery cells.
[0006]
On the other hand, in the method of firing after applying the electrolyte slurry by a wet method, if a thin film is formed on each surface of the electrolyte, the air electrode, and the fuel electrode, cracks are likely to occur during firing, and the thin film is likely to peel off. Furthermore, there is a problem that the film is not uniformly formed and the thickness is likely to vary, and in any case, it is difficult to manufacture battery cells having high characteristics at a high manufacturing yield.
[0007]
In order to cope with the above problems, for example, an electrolyte sheet before firing is attached to the electrode support tube in the initial stage of the film forming process and then sintered, and thereafter, the film formation with the electrolyte slurry is performed repeatedly on the surface of the electrolyte sheet. A method for manufacturing a sintered solid oxide fuel cell is also being tried.
[0008]
According to the above manufacturing method, the electrolyte membrane for the thickness of the electrolyte sheet is uniformly formed, and the electrolyte slurry applied afterwards enters the cracks generated during the firing of the electrolyte sheet, so that the crack portion is blocked, It is described that an effect of forming a dense electrolyte film with little variation can be obtained.
[0009]
However, the above-described conventional method requires a step of separately preparing an electrolyte sheet and a step of repeatedly applying and baking the electrolyte slurry, and for attracting and adhering electrolyte particles to the surface of the electrolyte sheet. A suction pump or the like is indispensable, and manufacturing equipment becomes large. In any case, it is difficult to manufacture battery cells at low cost.
[0010]
In addition, in the conventional battery cell manufacturing method using a wet method, when a highly viscous electrolyte slurry is applied and fired, there is a difference in shrinkage between the battery cell body (for example, a cylindrical air electrode) and the electrolyte slurry during firing. There is a problem that stress strain is easily generated in the film, and fine cracks and peeling are easily generated in the film after firing.
[0011]
Therefore, it has been forced to manufacture an electrolyte membrane having a predetermined thickness by repeatedly applying and baking an electrolyte slurry having a low concentration and low viscosity. That is, the amount of slurry applied at one time is reduced to reduce the effect of thermal shrinkage as much as possible, and the slurry is further applied to the cracked portion and dried and fired repeatedly to obtain an electrolyte membrane having a predetermined thickness. Formed.
[0012]
However, according to the above-described conventional manufacturing method, it is necessary to repeat the slurry application, drying, and firing processes as many as 10 times, so that the number of battery cell manufacturing steps becomes enormous, and the manufacturing cost of the fuel cell increases. There was a problem that it increased significantly.
[0013]
The present invention has been made to solve the above-described problems, it is less likely to cause cracks in the electrolyte membrane formed by the firing method, and can greatly increase the production yield and reliability of the fuel cell, Moreover, it aims at providing the manufacturing method of the cell for solid oxide fuel cells which can also reduce manufacturing man-hours significantly.
[0014]
[Means for Solving the Problems]
In order to achieve the above object, the present inventor has conducted various studies on method conditions that can effectively prevent the occurrence of cracks, particularly when an electrolyte membrane is formed by a wet method. As a result, a cylindrical air electrode coated with electrolyte slurry is held for a specified time in an atmosphere in equilibrium with the electrolyte slurry for a predetermined period of time, and then dried and fired to integrally form an electrolyte membrane with less cracking. The knowledge that the battery cell obtained efficiently was obtained for the first time was acquired. The present invention has been completed based on the above findings.
[0015]
That is, in the method for manufacturing a solid oxide fuel cell according to the present invention, a fuel electrode and an air electrode, which are a pair of porous electrodes, are arranged with an electrolyte membrane interposed therebetween, and a fuel gas is disposed on the back surface of one fuel electrode. And an oxidant gas in contact with the back surface of the other air electrode, and utilizing the electrochemical reaction generated at this time, a solid oxide fuel configured to take out electrical energy from between the electrodes the method of manufacturing a battery cell, in the space in the closed container which stores the electrolyte slurry in the bottom, and houses a cylindrical air electrode for applying an electrolyte slurry, pulled up by immersing the cylindrical cathode to the electrolyte slurry equal a step of applying an electrolyte slurry into the cylindrical air electrode surface, a cylindrical air electrode coated with the electrolyte slurry, and the vapor pressure of the solvent of the applied electrolyte slurry by A step of holding a predetermined time in an atmosphere having a pressure after drying a cylindrical air electrode coated with the electrolyte slurry and baking and forming the electrolyte film having a predetermined thickness, the electrolyte slurry application step And the atmospheric pressure in the airtight container in the holding process of the cylindrical air electrode is maintained constant.
[0016]
Moreover, it is preferable that the viscosity of the electrolyte slurry stored at the bottom of the sealed container is 2000 to 3000 cP. Furthermore, the thickness of the electrolyte membrane formed on the cylindrical air electrode surface is preferably set in the range of 10 to 50 μm. Moreover, it is preferable to hold | maintain the cylindrical air electrode which apply | coated electrolyte slurry in the atmosphere which has a vapor pressure equal to the vapor pressure of the solvent of the apply | coated electrolyte slurry for 10 minutes or more .
[0017]
Here, the electrolyte slurry used in the method of the present invention is not particularly limited, and a raw material powder forming a film such as nickel oxide, zirconia (ZrO ₂ ) or a mixed powder thereof is used as a binder (binder). ), A plasticizer and a dispersing agent and a homogeneously dispersed mixture in a solvent are used. The raw material powder is dried at 105 ° C. for about 24 hours in order to reduce moisture.
[0018]
The solvent is not particularly limited, and for example, isopropyl alcohol, ethanol, acetone, or a mixed solution thereof can be used. A binder (binder) is added to maintain the shape of the applied slurry. For example, carboxymethyl cellulose, polyvinyl ether, polyvinyl butyral resin, ethyl cellulose, acetyl cellulose, etc. can be used. About 2 to 10 g is added to 100 g. As the plasticizer, for example, diethyl phthalate (DEP), dibutyl phthalate (DBP), di-n-butyl phthalate, dioctyl phthalate (DOP) or the like can be used, and 10 to 40 ml is added per 100 g of slurry raw material powder. Furthermore, as a dispersing agent, for example, diethylamine, triethylamine, OP-83RAT, etc. can be used, and it is added at a rate of 2 to 10 ml per 100 g of slurry raw material powder.
[0019]
As described above, the dried raw material powder is added to a solvent together with a binder, a plasticizer, and a dispersant, and after sufficient mixing, defoamed to prepare an electrolyte slurry. It is preferable to adjust the viscosity of the electrolyte slurry to a range of 2000 to 3000 cP. When the viscosity of the electrolyte slurry is as low as less than 2000 cP, the film thickness of the slurry in one slurry application process becomes too small. In order to form an electrolyte film having a predetermined thickness, a plurality of slurry application processes are required. This is necessary and the number of manufacturing steps increases. On the other hand, if the viscosity of the slurry exceeds 3000 cP, the coating thickness of the slurry becomes excessive, and cracks are likely to occur during firing.
[0020]
Construction material of the cylindrical air electrode, the shape is not subject to particular limitation on the thickness, for example LaSrMnO _3, you can use the one formed in a cylindrical shape with a material which does not heat shrinkable, such as LaMnO _3.
[0021]
In the method for manufacturing a solid oxide fuel cell according to the present invention, first, the step of applying the electrolyte slurry to the surface of the cylindrical air electrode by immersing the cylindrical air electrode prepared as described above in the electrolyte slurry. Have. Here, the immersion speed of the cylindrical air electrode in the electrolyte slurry is set in the range of 20 to 40 mm / min in order to prevent the surrounding bubbles from being involved, and the immersion time is set to about 3 to 6 minutes. Moreover, the taking-out speed of the cylindrical air electrode after the immersion is preferably in the range of 3 to 6 mm / min.
[0022]
In addition, the slurry application thickness corresponding to the thickness of the electrolyte membrane finally formed is adjusted by the viscosity of the slurry and the take-out speed of the cylindrical air electrode .
[0023]
Next, the cylindrical air electrode to which the electrolyte slurry is applied is held for a predetermined time in an atmosphere in equilibrium with the electrolyte slurry. That is, by holding the cylindrical air electrode in an atmosphere in equilibrium with the volatile components in the electrolyte slurry, particularly the solvent, it is possible to prevent the solvent from rapidly evaporating from the outermost surface of the coating film of the electrolyte slurry, It is considered that the difference in the evaporation rate of the solvent between the inner and outer surfaces of the coating film does not increase, and the occurrence of distortion inside and outside the coating film is reduced. That is, since the internal distortion of the slurry coating film is reduced before firing, the distortion of the coating film does not expand even during the drying and firing of the post process, and the electrolyte membrane with less cracking is high. It is thought that the effect of being formed by the yield can be obtained.
[0024]
In the atmosphere in equilibrium with the electrolyte slurry, that is, in the atmosphere having a vapor pressure equal to the vapor pressure of the solvent of the applied electrolyte slurry, the time for holding the cylindrical air electrode is the coating film of the applied electrolyte slurry. The time until the gloss disappears on the surface is sufficient, and it is desirable to keep it for at least 10 minutes. However, considering the production efficiency of the battery cell, about 10 to 20 minutes is preferable.
[0025]
The cylindrical air electrode having the slurry coating film with reduced internal strain as described above is dried in the temperature range of about 80 to 100 ° C. and then baked in the temperature range of 1100 to 1600 ° C. for 2 to 5 hours. Thus, a battery cell in which an electrolyte membrane having a predetermined thickness of about 10 to 50 μm is integrally formed is manufactured.
[0026]
In addition, since the internal strain of the slurry coating film is reduced in the stage before firing, even when a high heating / cooling rate of about 100 ° C./Hr is applied during firing, cracks do not occur in the coating film, An electrolyte membrane having excellent durability can be efficiently produced.
[0027]
According to the method for manufacturing a cell for a solid oxide fuel cell having the above-described structure, slurry application is performed in an atmosphere in equilibrium with the electrolyte slurry, that is, in an atmosphere having a vapor pressure equal to the vapor pressure of the solvent of the applied electrolyte slurry. Since the cylindrical air electrode on which the film is formed is held, it is possible to effectively prevent the solvent from rapidly evaporating from the outer surface of the slurry coating film, and to prevent the occurrence of distortion inside and outside the coating film. Therefore, an electrolyte membrane with less cracking can be produced with a high yield without increasing the distortion of the coating film even in the drying / firing process.
[0028]
In addition, since the internal strain of the slurry coating is reduced in the stage before firing, even when a high heating / cooling rate is applied during firing, the coating does not crack and has excellent durability. It is possible to efficiently produce an electrolyte membrane having the same.
[0029]
Furthermore, even when a high-viscosity electrolyte slurry is applied, cracks and peeling are less likely to occur during firing, so an electrolyte film having a predetermined thickness is formed by one slurry application operation and one firing operation. Compared to the conventional method where the coating and baking operations are repeated 10 times or more, the number of manufacturing steps for battery cells can be greatly reduced, and the effect of reducing the cost of the fuel cell is significant. can do.
[0030]
DETAILED DESCRIPTION OF THE INVENTION
Next, embodiments of the present invention will be specifically described with reference to the accompanying drawings. FIG. 1 is a cross-sectional view showing an example of a manufacturing apparatus for carrying out the method for manufacturing a solid oxide fuel cell according to the present invention.
[0031]
The manufacturing apparatus shown in FIG. 1 includes a slurry storage tank 2 storing an electrolyte slurry 1 such as a YSZ slurry, a seal container 3 disposed outside the slurry storage tank 2, and liquid paraffin stored in the seal container 3 Gas for adjusting the gas pressure in the internal space by containing and discharging the sealing medium 4, the outside air blocking tank 5 that blocks the upper space of the slurry storage tank 2 from the outside air, and the atmospheric gas existing in the inside space of the outside air blocking tank 5 A pressure adjusting tank 6, a cell support bar 7 made of Teflon (registered trademark) disposed so as to protrude from the top of the outside air blocking tank 5, and a cylindrical shape suspended from the lower end of the cell support bar 7 Battery cell main body ( cylindrical air electrode) 8.
[0032]
The outside air blocking tank 5 provided with the cell support rod 7 is arranged so as to be movable up and down in the direction of the slurry storage tank 2, and the atmosphere in the outside air blocking tank 5 is blocked from the outside air by the sealing medium 4 during this up and down movement. Even if the outside air blocking tank 5 moves up and down, the internal atmosphere is accommodated in or discharged from the gas pressure adjusting tank 6 composed of a plastic bag, The internal atmospheric pressure is always maintained at a constant value.
[0033]
(Examples 1-5)
A large number of fuel cell main bodies ( cylindrical air electrodes) made of LaMnO ₃ and having an outer diameter of 14 mm were prepared. On the other hand, yttria-stabilized zirconium (YSZ: 5% Y ₂ O ₃ —ZrO ₂ ) raw material powder for forming an electrolyte membrane was prepared, heat-treated at 105 ° C. for 24 hours, and dried.
[0034]
Next, to 50 g of the dried zirconia raw material powder, 5 g of carboxymethyl cellulose as a binder, 10 ml of diethyl phthalate as a plasticizer, and 2 ml of diethylamine as a dispersant are added, and the blending amount of isopropyl alcohol as a solvent is further increased. Five types of electrolyte slurries for Examples 1 to 5 having the slurry viscosities shown in Table 1 were finally prepared by adjusting and blending, thoroughly mixing and defoaming.
[0035]
Next, as shown in FIG. 1, each electrolyte slurry is filled in the slurry storage tank 2, while the upper end portion of the cylindrical air electrode 8 is fixed to the lower end portion of the cell support rod 7 with a sealing tape, thereby providing an electrolyte. The slurry 1 was suspended in the upper space. Then, the gas pressure adjusting tank 6 was connected when the upper space of the electrolyte slurry 1, that is, the atmosphere in the outside air blocking tank 5 was in an equilibrium state with the electrolyte slurry 1 and became constant.
[0036]
Next, as shown in FIG. 2, a dipping process is performed in which the outside air blocking tank 5 holding the cylindrical air electrode 8 is lowered at the insertion speed shown in Table 1 and the cylindrical air electrode 8 is immersed in the electrolyte slurry 1. did. At this time, a part of the atmosphere in the outside air blocking tank 5 is discharged to the gas pressure adjusting tank 6 so that the atmospheric pressure in the upper space of the electrolyte slurry is kept constant. After elapse of the immersion time shown in Table 1, the outside air blocking tank 5 was raised at the take-out speed shown in Table 1, and the cylindrical air electrode 8 was pulled up. At this time, the atmospheric gas stored in the gas pressure adjusting tank 6 returns to the inside of the outside air blocking tank 5 so that the atmospheric gas pressure is kept constant.
[0037]
Next, as shown in FIG. 3, the cylindrical air electrode 8 on which the slurry coating film 9 having a predetermined thickness is formed is equal to the vapor pressure of the solvent of the applied electrolyte slurry in an atmosphere in equilibrium with the electrolyte slurry 1. It was kept in an atmosphere having a vapor pressure for the time shown in Table 1 (10 minutes). That is, after leaving the gloss of the YSZ slurry coating formed on the surface of the cylindrical air electrode 8 to disappear, the outlet of the gas pressure adjusting tank 6 was opened to gradually dry the slurry coating.
[0038]
Next, the cylindrical air electrode 8 having a dried slurry coating film was taken out from the outside air blocking tank 5 and subjected to a firing treatment. The firing treatment was performed in a nitrogen gas atmosphere at a heating rate of 100 ° C./Hr, held at a firing temperature of 1300 ° C. for 5 hours, and then cooled at a cooling rate of 100 ° C./Hr to obtain the thicknesses shown in Table 1, respectively. Fuel cell cells according to Examples 1 to 5 in which an electrolyte membrane having a thickness was integrally formed were prepared.
[0039]
(Comparative Examples 1-5)
On the other hand, in Examples 1-5, the apparatus which does not have an outside air blocking tank was used, and the cylindrical air electrode was pulled up from the electrolyte slurry, and was held and dried in contact with the atmosphere. By carrying out an immersion treatment and a firing treatment under various conditions, fuel cell cells according to Comparative Examples 1 to 5 were prepared. However, it was confirmed that the electrolyte membrane of the fuel cell according to each comparative example was cracked or peeled at a rate of almost 100%, and it was difficult to put it to practical use.
[0040]
On the other hand, the electrolyte membrane of the cell for fuel cells according to each of the obtained examples was observed and the rate of occurrence of defects such as cracking and peeling was measured to obtain the results shown in Table 1 below.
[0041]
[Table 1]

[0042]
As apparent from the results shown in Table 1 above, in the battery cell according to each of the examples formed by baking after slowly drying in an atmosphere in equilibrium with the electrolyte slurry at the stage of applying the electrolyte slurry. Regardless of the viscosity of the electrolyte slurry or the thickness of the slurry coating film, the occurrence rate of defects such as cracking and peeling after firing was extremely small, and high-quality battery cells could be mass-produced with a high yield.
[0043]
The mechanism that can greatly reduce the incidence of defects such as cracks and peeling is not necessarily clear, but in an atmosphere that is in equilibrium with the electrolyte slurry in the slurry coating formation stage, that is, the vapor pressure of the solvent of the applied electrolyte slurry By holding for a predetermined time in an atmosphere having an equal vapor pressure, the solvent can be prevented from abruptly evaporating from the outer surface of the slurry coating film, and the occurrence of distortion inside and outside the coating film is eliminated, and the distortion is also caused in the firing process. This is probably because cracking and peeling can be effectively prevented.
[0044]
On the other hand, in the case of Comparative Examples 1 to 5 in which the slurry coating film was held in the air, the solvent abruptly evaporated from the outermost surface of the coating film, resulting in a difference in the evaporation rate of the solvent inside and outside the coating film. Since internal strain is generated and the internal strain is enlarged at the time of firing, it is considered that a high-quality electrolytic film cannot be formed as a result of rapid increase in cracking and peeling.
[0045]
Further, according to this example, even when the concentration (viscosity) of the electrolyte slurry is large or the thickness of the slurry coating is thick, the number of times of applying and firing the slurry is only one, and the number of manufacturing steps of the battery cell is increased. Can be drastically reduced, and an excellent effect on cost reduction of the fuel cell can be exhibited.
[0046]
Furthermore, when the fuel cell was assembled using the fuel cell according to each example and the IV characteristics thereof were measured, good IV characteristics as shown in FIG. 4 were obtained. That is, it has been found that since the electrolyte membrane is not cracked or peeled off, there is no short circuit of the fuel gas, a sufficient potential difference is obtained at each current value, and a fuel cell with good characteristics can be obtained.
[0047]
Even when the battery cell according to each example was subjected to at least 10 heat cycles of heating from room temperature to operating temperature (1000 ° C.) and then cooling to room temperature, the electrolyte membrane was not cracked or peeled off. It does not occur and has been confirmed to have excellent durability.
[0048]
Further, in this example, a specific solvent, a dispersing agent and a plasticizer are used at the time of preparing the electrolyte slurry, and an example is shown in which an electrolyte membrane is formed using a YSZ slurry. Similarly, it has been confirmed that even when a solvent, a dispersant, a plasticizer, or other ceramic slurry is used, it is possible to efficiently produce a ceramic thin film without cracking or peeling. Furthermore, since there are no restrictions on the material, shape, and thickness of the main body that forms the thin film, the method of this embodiment is applied not only to the formation of an electrolyte membrane but also to the formation of a fuel electrode having a multilayer structure. Is possible.
[0049]
【The invention's effect】
As described above, according to the method for manufacturing a cell for a solid oxide fuel cell according to the present invention, in an atmosphere in equilibrium with the electrolyte slurry, that is, an atmosphere having a vapor pressure equal to the vapor pressure of the solvent of the applied electrolyte slurry. Since the cylindrical air electrode on which the slurry coating film is formed is held inside, the solvent can be effectively prevented from abruptly evaporating from the outer surface of the slurry coating film, and distortion can be generated inside and outside the coating film. Can be prevented. Therefore, an electrolyte membrane with less cracking can be produced with a high yield without increasing the distortion of the coating film even in the drying / firing process.
[0050]
In addition, since the internal strain of the slurry coating is reduced in the stage before firing, even when a high heating / cooling rate is applied during firing, the coating does not crack and has excellent durability. It is possible to efficiently produce an electrolyte membrane having the same.
[0051]
Furthermore, even when a high-viscosity electrolyte slurry is applied, cracks and peeling are less likely to occur during firing, so an electrolyte film having a predetermined thickness is formed by one slurry application operation and one firing operation. Compared to the conventional method where the coating and baking operations are repeated 10 times or more, the number of manufacturing steps for battery cells can be greatly reduced, and the effect of reducing the cost of the fuel cell is significant. can do.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a configuration example of a production apparatus for carrying out a method for producing a solid oxide fuel cell according to the present invention.
FIG. 2 is a cross-sectional view showing a state in which an immersion process is performed using the apparatus shown in FIG.
3 is a cross-sectional view showing a state in which a battery cell is held using the apparatus shown in FIG.
FIG. 4 is a graph showing IV characteristics of a battery using a fuel cell produced in an example.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Electrolyte slurry 2 Slurry storage tank 3 Seal container 4 Sealing medium (liquid paraffin)
5 Outside air blocking tank 6 Gas pressure adjusting tank 7 Cell support rod 8 Cylindrical air electrode ( cylindrical battery cell body)
9 Slurry coating

Claims (4)

A fuel electrode and an air electrode, which are a pair of porous electrodes, are arranged with an electrolyte membrane in between, a fuel gas is brought into contact with the back surface of one fuel electrode, and an oxidant gas is brought into contact with the back surface of the other air electrode. In the method for producing a cell for a solid oxide fuel cell configured to take out electrical energy from between the electrodes using an electrochemical reaction generated at this time,
A cylindrical air electrode on which electrolyte slurry is applied is accommodated in a space in an airtight container in which electrolyte slurry is stored at the bottom, and the cylindrical air electrode is immersed in the electrolyte slurry and pulled up to form a cylindrical air electrode surface. Applying an electrolyte slurry; and
Holding the cylindrical air electrode coated with the electrolyte slurry in an atmosphere having a vapor pressure equal to the vapor pressure of the solvent of the coated electrolyte slurry for a predetermined time;
And drying the cylindrical air electrode coated with the electrolyte slurry to form an electrolyte membrane having a predetermined thickness, and in the sealed container in the electrolyte slurry coating step and the cylindrical air electrode holding step. A method for producing a cell for a solid oxide fuel cell, wherein the atmospheric pressure is maintained constant.   The method for producing a cell for a solid oxide fuel cell according to claim 1, wherein the viscosity of the electrolyte slurry stored in the bottom of the sealed container is 2000 to 3000 cP. 2. The method for producing a solid oxide fuel cell according to claim 1, wherein the thickness of the electrolyte membrane formed on the surface of the cylindrical air electrode is set in a range of 10 to 50 [mu] m. 2. The solid oxide fuel cell according to claim 1, wherein the cylindrical air electrode coated with the electrolyte slurry is held in an atmosphere having a vapor pressure equal to the vapor pressure of the solvent of the coated electrolyte slurry for 10 minutes or more. Cell manufacturing method.

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