JP3740342B2 - Solid oxide fuel cell - Google Patents

Description

【００５８】
この表１より、空気極におけるｓ／ｔが１．０の試料Ｎo.１では固体電解質と空気極の間で剥離した。また。空気極におけるｓ／ｔが１未満で、集電体におけるｘ＋ｕの値が１．０１の試料Ｎo.２の場合には、導電率が０．０３Ｓ／ｃｍと低いことが判る。
【００５９】
これに対して、空気極におけるｓ／ｔが１未満で、かつ集電体におけるｘ＋ｕの値が１．０１６以上の本発明の試料では、導電率が０．０８Ｓ／ｃｍ以上と高いことが判る。特に、ｓ／ｔが０．９５〜０．９９８の範囲で、かつ１．５１５−ｓ／２ｔ≦ｘ＋ｕ≦１．５６−ｓ／２ｔの関係式を満足する本発明の試料Ｎo.３、４、６〜１８では、導電率が０．１０Ｓ／ｃｍ以上と高いことが判る。
【００６０】
【発明の効果】
本発明の固体電解質型燃料電池セルでは、空気極に含まれるＲとＭｎとの比率ｓ／ｔ、即ちＡサイトとＢサイトの比が１未満である場合に、集電体のＬａの含有率を増加して最適化することにより、空気極から集電体にＭｎが拡散し、集電体中のＬａと反応してＬａＭｎＯ₃ を生成したとしても、Ｌａ量が充分に存在しているため、Ｃｒに対するＬａ量が相対的に少なくなることを防止でき、ランタンクロマイト系複合酸化物粒子からのＣｒの蒸発を防止でき、ランタンクロマイト系複合酸化物粒子のネック部における酸化クロムの凝集堆積を防止できる。これにより、集電体の焼結性を確保して磁器を緻密にし、導電性を確保できる。
【図面の簡単な説明】
【図１】本発明の固体電解質型燃料電池セルを示す断面図である。
【図２】従来の固体電解質型燃料電池セルを示す斜視図である。
【符号の説明】
３１・・・固体電解質
３２・・・空気極
３３・・・燃料極
３５・・・集電体[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a solid oxide fuel cell, and a current collector formed by forming a porous air electrode on one surface of a solid electrolyte and a porous fuel electrode on the other surface and electrically connected to the air electrode. The present invention relates to a solid oxide fuel cell.
[0002]
[Prior art]
The solid oxide fuel cell has a high power generation efficiency because its operating temperature is as high as 900 to 1050 ° C., and is expected as a third generation power generation system.
[0003]
Generally, cylindrical and flat plate types are known as solid oxide fuel cells. Flat-type solid oxide fuel cells have a feature of high power density per unit volume of power generation, but there are problems such as imperfect gas seal and non-uniform temperature distribution in the cell for practical application . On the other hand, the cylindrical solid oxide fuel cell has the characteristics that the mechanical strength of the cell is high and the temperature in the cell can be kept uniform although the output density is low. Both types of solid oxide fuel cells have been actively researched and developed taking advantage of their characteristics.
[0004]
As shown in FIG. 2, the cylindrical solid oxide fuel cell has a porous air electrode 2 made of a LaMnO ₃ material having an open porosity of about 30 to 40%, and the surface thereof contains Y ₂ O _3. The solid electrolyte 3 made of ZrO ₂ is coated, and a porous Ni-zirconia fuel electrode 4 is provided on the surface. In the fuel cell module, each single cell is connected via a LaCrO _{3 current} collector (interconnector) 5. Power generation is performed at a temperature of 950 to 1050 ° C. with air 6 (oxygen) flowing inside the air electrode 2 and fuel 7 (hydrogen) flowing outside.
[0005]
Power generation is performed at a temperature of about 1000 ° C., and the air electrode side is exposed to an oxidizing atmosphere and the fuel electrode side is exposed to a reducing atmosphere.
[0006]
Since the anode (air electrode) and cathode (fuel electrode) of a fuel cell must be exposed to an atmosphere having different oxygen partial pressure ratios during power generation, the anode and cathode of a plurality of fuel cells cannot be connected in series. . For this reason, lanthanum chromite oxide, which is chemically stable and highly conductive even in atmospheres with different oxygen partial pressure ratios, is used as a current collector material, and this current collector is electrically connected to the air electrode. By electrically connecting the body to the fuel electrode of another fuel cell, electrical connection is possible between a plurality of cells.
[0007]
As a method for producing a cylindrical solid oxide fuel cell as described above, in recent years, in order to simplify the production process and reduce the production cost, at least two of the constituent materials are simultaneously fired. A so-called co-sintering method has been proposed. In this co-sintering method, for example, a solid electrolyte molded body and a current collector molded body are wound into a roll shape around a cylindrical air electrode molded body and co-fired, and then a fuel electrode is formed on the surface of the solid electrolyte. Is the method.
[0008]
For example, in Japanese Patent Laid-Open No. 9-129245, after a solid electrolyte sheet-shaped molded body is wound around the surface of a cylindrical air electrode molded body (including a calcined body), an end of the solid electrolyte sheet-shaped molded body is disclosed. After polishing the open part (notch part) to make it flat, the sheet-shaped molded body of the current collector is laminated and pressed, fired, and then a slurry containing metal is applied to the surface of the solid electrolyte Thus, a cylindrical solid oxide fuel cell having a fuel electrode is disclosed.
[0009]
This co-sintering method is a very simple process and has a small number of manufacturing steps, and is advantageous in improving the yield during manufacturing of cells and reducing costs. In such a fuel cell by the co-sintering method, a solid electrolyte composed of Y ₂ O ₃ stabilized or partially stabilized ZrO ₂ is used, and the thermal expansion coefficient is matched with this solid electrolyte. , A part of La of the perovskite complex oxide composed of LaMnO ₃ is substituted with at least one of Y and Ca, and the current collector material is excellent in chemical stability at high temperature, Because of its high electrical conductivity, lanthanum chromite complex oxides are used, and those with MgO added to match the thermal expansion coefficient with the solid electrolyte.
[0010]
[Problems to be solved by the invention]
As described above, when the air electrode and the current collector are simultaneously fired, the Mn element contained in the air electrode diffuses into the current collector during the firing process, and Mn diffused in the current collector and the current collector La reacts to produce LaMnO _3, and the amount of La forming the lanthanum chromite complex oxide in the current collector is reduced. Therefore, Cr in the current collector is easily evaporated and aggregated, and Cr ₂ O ₃ accumulates at the neck of the lanthanum chromite complex oxide particles, impairing the sintering of the current collector, resulting in insufficient density of the current collector porcelain, and oxidizing and reducing atmosphere inside and outside the fuel cell. There is a problem that it is impossible to shut off the light and the conductivity is lowered.
[0011]
An object of the present invention is to provide a solid oxide fuel cell capable of densifying a current collector and improving the conductivity of the current collector even when Mn diffuses from the air electrode.
[0012]
[Means for Solving the Problems]
The solid electrolyte fuel cell of the present invention is a solid electrolyte type battery comprising a current collector formed by forming an air electrode on one side of the solid electrolyte and a fuel electrode on the other side, and electrically connected to the air electrode. in the fuel cell, the current collector is a perovskite-type crystal phase containing at least La, Cr and Mg as the metal element, _La 2 _{O 3} phase, wherein the MgO phase, formula composition by atomic ratio of the metal elements La _{( x + u)} Mg _{(y + v)} Cr _z (x + y + z = 2), and the air electrode is composed of a perovskite-type crystal phase containing at least La and Mn as metal elements, and the composition formula according to the atomic ratio of the metal elements is R _s Mn _t (R is La, or La and a rare earth element other than La and at least one element of Ca), and the ratio of R to Mn in the composition formula of the air electrode The s / t is less than 1, x + u in the composition formula of the current collector is 1.016 or more , and v is 0.4 to 0.8 .
[0013]
Thus, when the ratio of R and Mn contained in the air electrode, that is, the ratio s / t between the A site and the B site is less than 1, the La content of the current collector is increased and optimized. Thus, even if Mn diffuses from the air electrode to the current collector and reacts with La in the current collector to produce LaMnO ₃ , the amount of La relative to Cr is relatively Can be prevented, Cr can be prevented from evaporating from the lanthanum chromite complex oxide particles, and aggregation of chromium oxide at the neck portion of the lanthanum chromite complex oxide particles can be prevented. Thereby, the sinterability of the current collector can be secured, the porcelain can be made dense, and the conductivity can be improved.
[0014]
That is, for example, when a cell is co-sintered using a cylindrical air electrode material made of a perovskite complex oxide containing La, Ca, Y, and Mn, each component element constituting the air electrode at the time of co-sintering Among them, the diffusion of Mn element (evaporation and diffusion in the solid phase) is particularly fast. Therefore, in order to reduce the diffusion of Mn element, a composition region in which free MnO-based oxide (second phase) does not exist, that is, a perovskite (LaMnO ₃ ) phase is stable as a single phase (A / It is preferable to use a material having a B ratio of 1). When a Mn-rich non-stoichiometric composition side, that is, a material having a small A / B site ratio (s / t) is used, a MnO-based oxide as a second phase is generated in addition to the perovskite phase. The diffusion amount of is abnormally high compared to the former.
[0015]
On the other hand, when an air electrode material having a stoichiometric composition (A / B ratio is 1) is used, reaction products and decomposition products of CaZrO ₃ and Y ₂ O ₃ are formed between the air electrode and the solid electrolyte during co-sintering. As a result, the separation of the interface proceeds with time, and the output is also abruptly deteriorated in performance. For this reason, the ratio s / t (A / B ratio) of R (where R is La, or La, a rare earth element other than La, and at least one element of Ca) and Mn in the composition formula of the air electrode is less than 1. It is desirable that the composition is as close to the stoichiometric composition as possible, for example, 0.95 ≦ s / t ≦ 0.998.
[0016]
Thus, by setting s / t to less than 1 and bringing it closer to the stoichiometric composition side, the content of free MnO-based oxide (second phase) can be reduced, and Mn diffusion can be reduced. Reactions and decomposition products that increase polarization resistance are not generated at the interface with the solid electrolyte. On the other hand, the diffusion of Mn occurs more remarkably in a high temperature region of 1400 ° C. or higher. Therefore, by reducing the temperature during co-sintering and reducing the holding time during firing as much as possible, The amount of Mn can be reduced. Furthermore, it is an effective means to prevent the gas generated from the air electrode during firing from approaching the current collector.
[0017]
However, even when the s / t in the air electrode is set to 0.95 to 0.998 in this way, in particular, the smaller the s / t, that is, the greater the amount of Mn, the more Mn diffuses into the current collector. In order to increase, the amount of La in the current collector must be increased. Therefore, considering the amount of diffusion of Mn that diffuse, as the La in Mn a current collector that diffuse is even produced a compound consisting of LaMnO _3, does not generate the Cr ₂ O _3, collecting The La amount in the composition formula of the electric body is excessive, and the amount x + u is 1.016 or more. However, if La in the current collector is excessive, conversely, generation of voids may be promoted and the density of the porcelain may decrease. Therefore, x + u in the composition formula of the current collector is set to 1.515-s. /2t≦x+u≦1.56-s/2t was satisfied.
[0018]
Moreover, by satisfying v in the composition formula of the current collector from 0.4 to 0.8, the firing shrinkage behavior and thermal expansion coefficient of the current collector can be brought close to those of the solid electrolyte, and the destruction of the porcelain due to internal stress. Can be prevented.
[0019]
Furthermore, by setting the thickness of the air electrode to 1 mm or more, the cylindrical shape can be maintained, and by setting the current collector thickness to 50 to 200 μm, sufficient airtightness can be secured, and the potential drop of the current collector can be reduced. Can be small.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
As shown in FIG. 1, the cylindrical solid electrolyte fuel cell of the present invention has a cell main body 34 formed by forming an air electrode 32 on the inner surface of a cylindrical solid electrolyte 31 and a fuel electrode 33 on the outer surface. A current collector 35 that is electrically connected to the air electrode 32 is formed on the outer surface of the cell body 34.
[0021]
That is, a notch 36 is formed in a part of the solid electrolyte 31, and a part of the air electrode 32 formed on the inner surface of the solid electrolyte 31 is exposed, and the solid electrolyte in the vicinity of the exposed surface 37 and the notch 36. The surface of both ends of 31 is covered with a current collector 35, and the current collector 35 is joined to the surface of both ends of the solid electrolyte 31 and the surface of the air electrode 32 exposed from the notch 36 of the solid electrolyte 31.
[0022]
A current collector 35 that is electrically connected to the air electrode 32 is formed on the outer surface of the cell body 34, and is formed so as to cover a continuous identical surface 39 having almost no step, and is electrically connected to the fuel electrode 33. Not. When the current collectors 35 are connected to each other, the current collectors 35 are electrically connected to the fuel electrodes of other cells via Ni felts, thereby forming a fuel cell module. The continuous coplanar surface 39 is formed by polishing between both end portions of the solid electrolyte molded body until both end portions of the solid electrolyte molded body and a part of the air electrode molded body are substantially the same continuous surface.
[0023]
The solid electrolyte 31 is partially stabilized or stabilized ZrO ₂ containing, for example, 3 to 20 mol% of Y ₂ O ₃ or Yb ₂ O _{3. The} fuel electrode 33 is, for example, 50 to 80 wt% Ni. ZrO ₂ containing (containing Y ₂ O ₃ ) is used.
[0024]
Air electrode 32 consists of at least La and perovskite type crystal phase containing Mn as metallic elements, the atomic composition formula R _s Mn _t (R by ratio of the metal elements La, or a La, a rare earth element other than La and, And at least one element of Ca). Ca is preferably 8 to 10% by weight in terms of oxide, and at least one of the rare earth elements is preferably contained in an amount of 10 to 20% by weight in terms of oxide.
[0025]
Examples of rare earth elements include Y, Nd, Dy, Er, Yb, etc. Among these, Y is desirable.
[0026]
The current collector 35 has a perovskite-type crystal containing La, Cr, and Mg as metal elements as a main crystal, includes a La ₂ O ₃ phase and an MgO phase, and a composition formula based on the atomic ratio of the metal elements is La _{(x + u)} Mg _{(y + v)} Cr _z Oα (x + y + z = 2, α is an atomic ratio of oxygen). The current collector 35 may contain a rare earth element or an alkaline earth metal element.
[0027]
In the solid oxide fuel cell of the present invention, the ratio s / t of R and Mn in the composition formula of the air electrode 32 is less than 1, and x + u in the composition formula of the current collector 35 is 1.016 or more. It is characterized by being.
[0028]
When s / t is 1 or more, the reaction product and decomposition product of CaZrO ₃ and Y ₂ O ₃ are interposed between the air electrode and the solid electrolyte when co-sintering. This is because, as a result, the separation of the interface progresses with time, and the output is abruptly deteriorated in performance. Therefore, although s / t is set to less than 1, as a result, Mn in the air electrode diffuses into the current collector, so that x + u indicating the amount of La in the current collector is increased and Cr ₂ O ₃ is precipitated. In order to suppress this, x + u is set to 1.016 or more. Therefore, when x + u is smaller than 1.016, the rate at which Mn diffuses into the current collector is greater than the increase in the amount of La in the current collector, and Cr ₂ O ₃ is precipitated and burned. This is because the connectivity is lowered and the electrical conductivity of the current collector is lowered.
[0029]
Moreover, it is desirable that s / t is 0.95 to 0.998. Within this range, the reaction products and decomposition products of CaZrO ₃ and Y ₂ O ₃ are not generated between the air electrode and the solid electrolyte, and the amount of diffused Mn can be reduced. On the other hand, when s / t is smaller than 0.95, the amount of Mn diffused increases, and when s / t becomes larger than 0.998, CaZrO ₃ , Y ₂ O is interposed between the air electrode and the solid electrolyte. _{This is because} the reaction product ₃ and decomposition product ₃ are easily generated. It is desirable that s / t is 0.96 to 0.99.
[0030]
Furthermore, it is desirable that x + u in the composition formula of the current collector satisfy 1.515-s / 2t to 1.56-s / 2t. Within this range, La in the current collector is increased corresponding to the amount of Mn in the air electrode, and the optimum amount of La that does not generate Cr ₂ O ₃ can be obtained.
[0031]
Moreover, it is desirable that v in the composition formula of the current collector satisfies 0.4 to 0.8. Within this range, the amount of MgO phase is optimal, and the firing shrinkage behavior and thermal expansion coefficient of the current collector can be brought close to those of the solid electrolyte, and the destruction of the porcelain due to internal stress can be prevented.
[0032]
Furthermore, it is desirable that the thickness of the air electrode is 1 mm or more and the thickness of the current collector is 50 to 200 μm. Thereby, while being able to hold | maintain a cylindrical shape, sufficient airtightness of a collector can be ensured and the electrical potential drop of a collector can be made small. The thickness of the current collector is desirably 75 to 150 μm.
[0033]
In the manufacturing method of the solid oxide fuel cell configured as described above, first, a cylindrical air electrode molded body is formed. In this cylindrical air electrode molded body, for example, raw materials of La ₂ O ₃ , Y ₂ O ₃ , CaCO ₃ , and MnO ₂ are weighed and mixed according to a predetermined composition. At this time, it is necessary to weigh so that the s / t ratio of the perovskite complex oxide constituting the air electrode molded body satisfies 0.95 to 0.998.
[0034]
Then, for example, it is calcined at a temperature of about 1500 ° C. for 2 to 10 hours, and then pulverized to a particle size of 4 to 8 μm. The prepared powder is mixed and kneaded with a binder to produce a cylindrical air electrode molded body by extrusion molding. Further, the binder is debindered and calcined at 1200 to 1250 ° C. A fired body is produced. Since Mn diffusion is significant at 1400 ° C. or higher, Mn hardly diffuses at the calcining temperature of the air electrode molded body.
[0035]
As a sheet-like first solid electrolyte molded body, a slurry obtained by adding toluene, a binder, and a commercially available dispersant to a predetermined powder and molding it into a thickness of, for example, 100 to 120 μm by a method such as a doctor blade is used. The first solid electrolyte formed body is attached to the surface of the cylindrical air electrode calcined body and calcined to form the first solid electrolyte calcined body on the surface of the air electrode calcined body.
[0036]
Next, a sheet-shaped fuel electrode molded body is produced. First, for example, a slurry obtained by adding toluene and a binder to Ni / YSZ mixed powder prepared at a predetermined ratio is prepared. Similarly to the production of the first solid electrolyte molded body, the molded and dried mold is formed to form a sheet-like second solid electrolyte molded body having a thickness of 15 μm, for example.
[0037]
After the fuel electrode layer molded body is printed and dried on the second solid electrolyte molded body, the second solid electrolyte molded body on which the fuel electrode layer molded body is formed is formed on the first solid electrolyte calcined body. The solid electrolyte calcined body is wound and laminated so that the second solid electrolyte molded body comes into contact therewith.
[0038]
The Ni / YSZ mixed powder constituting the fuel electrode layer molded body is a raw material powder having an average particle diameter of Ni powder of 0.2 to 0.4 μm and an average particle diameter of YSZ powder of 0.4 to 0.8 μm. In order to increase the dispersibility after blending to a predetermined ratio, wet pulverization mixing is performed using ZrO ₂ balls.
[0039]
Next, for example, after raw materials of La ₂ O ₃ , MgO, and Cr ₂ O ₃ are weighed and mixed to become La (MgCr) O ₃ , for example, at a temperature of about 1400 to 1550 ° C. for 2 to 5 hours It is formed by calcining and then pulverizing to about 2 to 3 μm and further adding predetermined amounts of La ₂ O ₃ and MgO. In this case, the composition formula of the powder is expressed by La _{(x + u)} Mg _{(y + v)} Cr _z Oα (x + y + z = 2), and the powder is prepared so that x + u is 1.016 or more. Using this powder, as in the preparation of the solid electrolyte compact, a current collector compact is produced by molding to a thickness of 100 to 120 μm, and this current collector compact is affixed to a predetermined location.
[0040]
Thereafter, the laminated body of the cylindrical air electrode calcined body, the first solid electrolyte calcined body, the second solid electrolyte molded body, the fuel electrode molded body and the current collector molded body is, for example, 1400 to 1550 ° C. in the atmosphere. At the temperature, four layers are cofired simultaneously.
[0041]
Since the diffusion of Mn affects the firing temperature and holding time, the amount of Mn can be further reduced by reducing the firing temperature as much as possible and shortening the firing time as much as possible.
[0042]
The fuel electrode layer molded body has a thickness of 9 to 60 μm. When the thickness of the fuel electrode layer compact is less than 9 μm, the firing shrinkage difference is promoted as the Ni grains grow. On the other hand, when the thickness is greater than 60 μm, the fuel electrode has a thermal expansion coefficient mismatch with the solid electrolyte. It becomes easy to peel. From this point, the thickness of the fuel electrode molded body is particularly preferably 25 to 40 μm.
[0043]
In such a production method, the s / t ratio of the air electrode is set to 0.95 to 0.998, and the content of free MnO-based oxide (second phase) is reduced by bringing the ratio close to the stoichiometric composition side. Diffusion to the current collector due to evaporation of Mn can be reduced.
[0044]
In addition, since the s / t of the air electrode is smaller than 1, no reaction and decomposition products that increase the polarization resistance are generated at the interface between the air electrode and the solid electrolyte, and no peeling occurs at the interface, which is high. The power density can be maintained for a long time.
[0045]
Furthermore, since the s / t (A / B ratio) of the air electrode is less than 1 and x + u indicating the La amount of the current collector is 1.016 or more, the s / t is particularly 0.95 to 0.998. X + u satisfies the relational expression of 1.515−s / 2t ≦ s / t ≦ 1.56-s / 2t, so that even if Mn in the air electrode diffuses into the current collector, Precipitation of Cr ₂ O _{3 in} the body can be prevented, densification of the current collector can be promoted, and the electrical conductivity of the current collector can be improved.
[0046]
In the above example, the cylindrical solid electrolyte fuel cell has been described. However, the present invention is not limited to the above example, and can be applied to a flat plate fuel cell.
[0047]
Also in a cylindrical solid electrolyte fuel cell, it is sufficient that an air electrode is formed on one side of the solid electrolyte and a fuel electrode is formed on the other side, and the structure is not limited to that shown in FIG.
[0048]
Furthermore, although the example which formed the air electrode calcined body and the 1st solid electrolyte calcined body was demonstrated in the said example, these may be an air electrode molded object and a 1st solid electrolyte molded object.
[0049]
【Example】
In order to produce a cylindrical solid electrolyte fuel cell by a co-sintering method, a cylindrical air electrode calcined body was first produced by the following procedure. Commercial purity of 99.9% or higher _{La 2 O 3, Y 2 O} 3, the CaCO _3, Mn ₂ O ₃ as starting material, the _{(La 0.56 Y 0.14 Ca 0.3)} s Mn t O 3 of s / t, That is, the A / B ratio was weighed so as to have the value shown in Table 1, and using this, after extrusion, it was deburied and calcined at 1250 ° C. to produce an air electrode calcined body.
[0050]
Next, a slurry was prepared using a ZrO ₂ powder having an average particle diameter of 1 to ₂ μm containing Y ₂ O ₃ at a ratio of 8 mol%, and the first and the first 100 μm and 15 μm thick first and A sheet as a two-solid electrolyte molded body was produced.
[0051]
Next, a ZrO ₂ powder containing 8 mol% of Y ₂ O ₃ having an average particle diameter of 0.6 μm with respect to Ni powder having an average particle diameter of 0.4 μm was prepared, and the Ni / YSZ ratio (weight) The mixture was prepared so as to have a ratio of 65/35, pulverized and mixed, and slurried. The prepared slurry was printed on the entire surface of the second solid electrolyte molded body to produce a fuel electrode molded body.
[0052]
Next, commercially available La ₂ O ₃ , Cr ₂ O ₃ and MgO having a purity of 99.9% or more are used as starting materials, and this is weighed and mixed so as to be La (MgCr) O _3, and then at 3500C. After calcining for a time, La ₂ O ₃ and MgO were added thereto. Composition formula of the _{powder, La (x + u) Mg} (y + v) Cr z Oα (x + y + z = 2, x + u, y + z + v, u, v are the values shown in Table 1) is prepared to have a. A slurry was prepared using this powder, and a current collector molded body having a thickness of 100 μm was prepared by a doctor blade method.
[0053]
First, the first solid electrolyte compact was wound around the air electrode calcined body in a roll shape so that both ends thereof were opened, and calcined at 1150 ° C. for 5 hours. After the calcination, the first solid electrolyte calcined body was polished flat so as to expose the air electrode calcined body and processed so as to form a continuous same surface.
[0054]
Next, the second solid electrolyte molded body on which the fuel electrode molded body is formed is laminated on the surface of the first solid electrolyte calcined body so that the first solid electrolyte calcined body and the second solid electrolyte molded body are in contact with each other. After drying, the current collector molded body is pasted on the same continuous surface, and then co-sintered at 1500 ° C. in the atmosphere for 6 hours to produce a co-sintered body, and the thickness of the air electrode The thickness of the current collector was set to the thickness shown in Table 1.
[0055]
Next, in order to produce a cylindrical cell for power generation using the co-sintered body, a sealing member was joined to one end of the co-sintered body. The sealing member was joined by the following procedure. A slurry is prepared by adding water as a solvent to a ZrO ₂ powder containing Y ₂ O ₃ at a ratio of 8 mol% and having an average particle diameter of 1 μm, and one end of the co-sintered body is immersed in this slurry, It was applied to the outer peripheral surface of one end so as to be 100 μm and dried. The molded body having a cap shape as a sealing member was subjected to isostatic pressing (rubber press) using a powder having the same composition as the slurry composition and cut. Thereafter, the end portion of the co-sintered body coated with the slurry was inserted into a molded body for a sealing member, and baked at a temperature of 1300 ° C. in the atmosphere for 1 hour.
[0056]
The produced cell was heated to 1000 ° C. with the air atmosphere inside and the Fo gas atmosphere outside, the current was passed between the air electrode and the current collector, and the voltage at the current collector portion was measured to measure the electrical conductivity. The measurement results are shown in Table 1. Sample No. 18 used La _0.99 MnO ₃ as the air electrode material.
[0057]
[Table 1]

[0058]
From Table 1, sample No. 1 having an s / t of 1.0 at the air electrode peeled between the solid electrolyte and the air electrode. Also. In the case of sample No. 2 in which the s / t at the air electrode is less than 1 and the value of x + u in the current collector is 1.01, it can be seen that the conductivity is as low as 0.03 S / cm.
[0059]
On the other hand, in the sample of the present invention in which s / t in the air electrode is less than 1 and the value of x + u in the current collector is 1.016 or more, it can be seen that the conductivity is as high as 0.08 S / cm or more. . In particular, the samples No. 3, 4 of the present invention satisfying the relational expression of s / t in the range of 0.95 to 0.998 and 1.515−s / 2t ≦ x + u ≦ 1.56-s / 2t. 6-18, it turns out that electrical conductivity is as high as 0.10 S / cm or more.
[0060]
【The invention's effect】
In the solid oxide fuel cell of the present invention, when the ratio s / t of R and Mn contained in the air electrode, that is, the ratio of A site to B site is less than 1, the La content of the current collector Even if Mn diffuses from the air electrode to the current collector and reacts with La in the current collector to produce LaMnO ₃ , the amount of La is sufficient. The amount of La relative to Cr can be prevented from becoming relatively small, the evaporation of Cr from the lanthanum chromite complex oxide particles can be prevented, and the aggregation of chromium oxide at the neck portion of the lanthanum chromite complex oxide particles can be prevented. it can. Thereby, the sinterability of the current collector can be secured, the porcelain can be made dense, and the conductivity can be secured.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a solid oxide fuel cell of the present invention.
FIG. 2 is a perspective view showing a conventional solid oxide fuel cell.
[Explanation of symbols]
31 ... Solid electrolyte 32 ... Air electrode 33 ... Fuel electrode 35 ... Current collector

Claims (3)

In a solid oxide fuel cell comprising a current collector formed by forming an air electrode on one side of a solid electrolyte and a fuel electrode on the other side, and electrically connected to the air electrode, the current collector comprises: It includes a perovskite crystal phase containing at least La, Cr and Mg as a metal element, a La ₂ O ₃ phase, and an MgO phase, and the composition formula according to the atomic ratio of the metal element is La _{(x + u)} Mg _{(y + v)} Cr _z (x + y + z = 2),
The air electrode is composed of a perovskite-type crystal phase containing at least La and Mn as metal elements, and the composition formula according to the atomic ratio of the metal elements is R _s Mn _t (R is La, or La and rare earth elements other than La and At least one element of Ca), the ratio s / t of R and Mn in the composition formula of the air electrode is less than 1, and x + u in the composition formula of the current collector is 1.016 or more , v Is 0.4 to 0.8 , a solid oxide fuel cell. The solid oxide fuel cell according to claim 1, wherein the ratio s / t of R and Mn in the composition formula of the air electrode is 0.95 to 0.998. 3. The solid oxide fuel cell according to claim 1, wherein x + u in the composition formula of the current collector satisfies a relational expression of 1.515−s / 2t ≦ x + u ≦ 1.56-s / 2t. cell.

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