JP6743644B2 - Fuel cell - Google Patents

Description

The present invention relates to a solid oxide fuel cell having a solid electrolyte layer, an air electrode and a fuel electrode.

A solid oxide fuel cell having a solid electrolyte layer and an air electrode and a fuel electrode respectively formed on both surfaces of the solid electrolyte layer is known. An air electrode exposed to an oxidant gas such as air may be poisoned by a contaminant contained in the oxidant gas due to long-term use or the like, and its activity may be reduced.

For example, in Patent Document 1, in order to prevent poisoning of the air electrode, a pollutant trap layer that is disposed on the oxidant gas supply port side of the oxidant gas chamber and is formed separately from the air electrode and does not contribute to power generation is disclosed. A provided fuel cell is disclosed.

JP, 2005-90788, A

However, the contaminant trap layer formed separately from the air electrode cannot sufficiently prevent the contaminant from flying to the air electrode. As a result, the air electrode may be poisoned and deteriorated due to the pollutants, and the three-phase interface between the air electrode, the oxidant gas, and the solid electrolyte layer may be reduced to deteriorate the battery performance. Therefore, it is not possible to sufficiently secure the reliability of the fuel cell from the viewpoint of maintaining stable cell performance for a long period of time. Further, since the oxidant gas containing pollutants needs to pass through the pollutant trap layer with certainty before reaching the air electrode, it may be necessary to control the flow path of the oxidant gas.

The pollutant trap layer is a layer separately provided to prevent poisoning of pollutants, and is formed separately from the air electrode. Therefore, it is necessary not only to separately provide a step of forming a pollutant trap layer at the time of manufacturing a fuel cell, but also a space for forming the pollutant trap layer is required in terms of cell design. That is, the trap layer increases the manufacturing cost and hinders the degree of freedom in battery design.

The present invention has been made in view of such problems, and an object thereof is to provide a solid oxide fuel cell capable of preventing poisoning of an air electrode for a long period of time.

One aspect of the present invention is that a fuel electrode (2), a solid electrolyte layer (3), and an air electrode (4) are laminated in this order,
The air electrode includes an internal reaction layer (41) formed on the solid electrolyte layer side, and an external collection layer formed on the internal reaction layer and collecting contaminants in the oxidant gas (O). and (42), have a,
Furthermore, it has a current collecting plate (6) formed on the air electrode, and the current collecting plate comprises a current collecting substrate (61) and a plurality of projecting collectors extending from the current collecting substrate toward the air electrode. A solid oxide form having an electricity collecting portion (62) and having a thickness of the outer collection layer larger than that of the contact portion around the contact portion (47) of the air electrode with the current collecting portion. Located in the fuel cell (1).

In the fuel cell, the air electrode has an internal reaction layer formed on the solid electrolyte layer side and an external collection layer made of a conductive oxide that collects contaminants in the oxidant gas. Therefore, even if pollutants are contained in the oxidant gas, the pollutants are collected by the outer collection layer before reaching the inner reaction layer. Since the outer collection layer is formed on the inner reaction layer, the oxidant gas passes through the outer collection layer before reaching the inner reaction layer. As a result, the contaminants are reliably collected by the outer collection layer and the scattering of the contaminants into the inner reaction layer is suppressed, so that poisoning deterioration of the inner reaction layer can be sufficiently prevented. Therefore, the fuel cell can exhibit stable cell performance for a long period of time and has high reliability.

Further, in the above fuel cell, the outer collection layer is formed on the inner reaction layer. Therefore, the oxidant gas reaches the inner reaction layer after passing through the outer scavenging layer without controlling the flow path of the oxidant gas. Therefore, there is no need to control the flow path to collect the pollutants.

Further, in the above fuel cell, contaminants are collected in the outer collection layer of the air electrode. Therefore, another member is not required to collect the pollutants, and an increase in manufacturing cost due to an increase in members can be prevented.

Further, since the outer collection layer is formed on the inner reaction layer, it is not necessary to form the collection layer separately from the air electrode. Since the outer collection layer is laminated on the inner reaction layer, it is only necessary to change the thickness of the air electrode, and there is almost no need to change the design of the member dimensions. Since it is not necessary to secure a separate installation space in the fuel cell, it is possible to avoid increasing the size of the fuel cell.

As described above, according to the above aspect, it is possible to provide the solid oxide fuel cell capable of preventing the poisoning of the air electrode for a long period of time.
The reference numerals in parentheses described in the claims and the means for solving the problems indicate the corresponding relationship with the specific means described in the embodiments described later, and limit the technical scope of the present invention. Not a thing.

FIG. 3 is an explanatory view schematically showing a laminated structure of the fuel cell according to the first embodiment. FIG. 5 is an explanatory view schematically showing a laminated structure of the fuel cell according to the second embodiment. 6 is a cross-sectional view of an air electrode of a fuel cell according to Embodiment 3. FIG. FIG. 6 is an explanatory view schematically showing a laminated structure of the fuel cell according to the fourth embodiment. FIG. 5 is a sectional view taken along the line V-V in FIG. 4. FIG. 6 is an explanatory view showing a fuel cell in Embodiment 5 in the same arrow cross section as FIG. 5. FIG. 9 is an explanatory view schematically showing a laminated structure of a fuel cell in Embodiment 6. VIII-VIII sectional view taken on the line in FIG. FIG. 9A is an explanatory view showing the fuel cell of Modification 1 in the same arrow cross section as FIG. 8, and FIG. 8B is an explanatory view showing the fuel cell of Modification 2 in the same arrow cross section as in FIG. FIG. 5 is an explanatory view of a cross section in the interface direction between the current collector and the air electrode in the fuel cell of Example 1, observed from the current collector side. FIG. 3 is a diagram showing the relationship between the depth direction of the air electrode and the Cr content in the fuel cell of Example 1 and the fuel cell of Comparative Example. FIG. 3 is a diagram showing the relationship between the depth direction of the air electrode and the S content in the fuel cell of Example 1 and the fuel cell of Comparative Example. FIG. 5 is an explanatory view of a cross section in the interface direction between the current collector and the air electrode in the fuel cell of Example 2 as observed from the current collector side. 6 is a diagram showing the relationship between the depth direction of the air electrode and the Cr content in the fuel cell of Example 2. FIG. 6 is a diagram showing the relationship between the S electrode content and the depth direction of the air electrode in the fuel cell of Example 2. FIG. FIG. 3A is an explanatory view schematically showing the laminated structure of the fuel cell of Example 3, and FIG. 5B is an explanatory view of a cross section in the interface direction between the current collector and the air electrode in Example 3 observed from the current collector side. 6 is a diagram showing the relationship between the depth direction of the air electrode and the Cr content in the fuel cell of Example 3. FIG. 5 is a diagram showing the relationship between the S electrode content and the depth direction of the air electrode in the fuel cell of Example 3. FIG.

(Embodiment 1)
An embodiment relating to a solid oxide fuel cell will be described with reference to FIG. In addition, in this specification, Embodiments 1-5 are reference forms of this invention, and Example 1 and Example 2 are reference examples of this invention. The solid oxide fuel cell 1 is a fuel cell called SOFC and uses solid oxide ceramics as a solid electrolyte. As illustrated in FIG. 1, in the fuel cell 1, a fuel electrode 2, a solid electrolyte layer 3, and an air electrode 4 are laminated in this order. The fuel cell 1 may have a flat cell structure from the viewpoint of high power generation performance.

The solid electrolyte layer 3 may be composed of a single layer or plural layers. The thickness of the solid electrolyte layer 3 can be preferably 3 to 20 μm, and more preferably 5 to 15 μm from the viewpoint of reducing ohmic resistance.

As a material of the solid electrolyte layer 3, zirconium oxide-based oxides such as yttria-stabilized zirconia (that is, YSZ) and scandia-stabilized zirconia (that is, ScSZ) are preferable from the viewpoint of excellent strength and thermal stability. Can be used for. As the material of the solid electrolyte layer 3, yttria-stabilized zirconia is particularly preferable from the viewpoints of ionic conductivity, mechanical stability, compatibility with other materials, and chemical stability from the air atmosphere to the fuel gas atmosphere. Is.

The anode 2 as the anode and the cathode 4 as the cathode have gas permeability and are porous. The fuel electrode 2 side of the solid electrolyte layer 3 is exposed to the fuel gas atmosphere, and the air electrode 4 side of the solid electrolyte layer 3 is exposed to the oxidant gas.

The air electrode 4 and the solid electrolyte layer 3 may be in direct contact with each other, but as shown in FIG. 1, an intermediate layer 5 is formed between the air electrode 4 and the solid electrolyte layer 3. Is preferred. The intermediate layer 5 is a layer for suppressing the reaction between the solid electrolyte layer material of the solid electrolyte layer 3 and the air electrode material of the air electrode 3.

The thickness of the intermediate layer 5 can be preferably 1 to 20 μm from the viewpoint of reducing ohmic resistance, suppressing element diffusion from the air electrode 4, and the like.

As the material of the intermediate layer 5, for example, CeO ₂ or CeO ₂ is doped with at least one element selected from the group consisting of Gd, Sm, Y, La, Nd, Yb, Ca, and Ho. Examples thereof include cerium oxide-based oxides such as the ceria-based solid solution. These may be used alone or in combination of two or more.

The air electrode 4 has an internal reaction layer 41 formed on the solid electrolyte layer 3 side and an external collection layer 42 formed on the internal reaction layer 41. As illustrated in FIG. 1, the outer collection layer 42 can be the outermost layer of the air electrode 4.

When the air electrode 4 is formed on the intermediate layer 5 as illustrated in FIG. 1, a three-phase interface that contributes to power generation is formed by the internal reaction layer material, the intermediate layer material, and the pores. The external collection layer 42 does not necessarily have to contribute to the power generation reaction, has conductivity, and is a layer capable of collecting contaminants in the oxidant gas. The inner reaction layer 41 and the outer collection layer 42 are bonded to each other.

The inner reaction layer 41 and the outer collection layer 42 can be composed of transition metal perovskite type oxides having different compositions. The internal reaction layer 41 preferably contains a transition metal perovskite type oxide containing at least two elements selected from the group consisting of La, Sr, Sm, Co, Fe, Ni and Mn. In this case, the reactivity of the above three-phase interface can be further enhanced.

Transition metal perovskite oxide contained in the inside of the reaction layer _{41, La x Sr 1-x CoO} 3 based _{oxide, La x Sr 1-x Co} y Fe 1-y O 3 based oxide, and Sm _x Sr _{1 At} least one selected from _-x CoO ₃ -based oxides (where 0≦x≦1 and 0≦y≦1 in the above) is preferable. In this case, the reactivity of the three-phase interface can be further enhanced. From the viewpoint of further enhancing the reactivity of the three-phase interface, at least inside the reaction layer 41 is La _x Sr _1-x CoO ₃ based oxide and _{La x Sr 1-x Co y} Fe 1-y O 3 based oxide It is more preferable to contain one of them.

When the cathode 4 is formed on the intermediate layer 5 as illustrated in FIG. 1, the inner reaction layer 41 may further contain an intermediate layer material. That is, the internal reaction layer 41 can contain a composite material of a transition metal perovskite type oxide and an intermediate layer material. In this case, the three-phase interface that contributes to power generation can be further increased. Further, in this case, since the difference in linear thermal expansion coefficient between the inner reaction layer 41 and the intermediate layer 5 can be reduced, the bondability of the interface between the intermediate layer 5 and the inner reaction layer 41 can be improved. ..

When the internal reaction layer 41 contains the above-mentioned transition metal perovskite type oxide, the coefficient of linear thermal expansion of the internal reaction layer 41 is preferably 10×10 ⁻⁶ or more and less than 16×10 ⁻⁶ /K. .. The above-mentioned transition metal perovskite type oxide having a linear thermal expansion coefficient within the above range has higher electrochemical reactivity, so that the reactivity of the above-mentioned three-phase interface can be further improved. The linear thermal expansion coefficient of the inner reaction layer 41 is measured in the temperature range of 25° C. to 900° C. according to JIS R1618:2002. The same applies to the coefficient of linear thermal expansion of the external collection layer 42 described later.

The outer collection layer 42 preferably contains a transition metal perovskite type oxide containing at least two elements selected from the group consisting of La, Sr, Sm, and Co. In this case, the activity of the outer collection layer 42 is increased, and while exhibiting sufficient conductivity, at least one selected from S, B, Si, Cr, P, Cl and the like contained in the oxidant gas. It becomes possible to sufficiently collect the pollutants containing the element.

The external collection layer 42 preferably contains a transition metal perovskite type oxide containing at least Co and has a higher Co content than the internal reaction layer 41. In this case, the conductivity can be further improved while sufficiently securing the trapping property for the contaminants in the external trapping layer 42. The Co content in the inner reaction layer 41 and the outer scavenging layer 42 can be adjusted by adjusting the composition of the transition metal perovskite type oxide contained in each of them, or by including the intermediate layer material in the inner reaction layer 41. Can be adjusted.

The transition metal perovskite oxide outer trapping layer 42, specifically, for _{example, La x Sr 1-x CoO} 3 based _{oxide, Sm x Sr 1-x CoO} 3 based oxide (however, in the , 0≦x≦1) and the like. While more increased conductivity, from the viewpoint of enhancing the trapping capabilities, the external trapping layer 42 is more preferably made of La _x Sr _1-x CoO ₃ based oxide.

When the external collection layer 42 contains the above-mentioned transition metal perovskite type oxide, the linear thermal expansion coefficient of the external collection layer 42 is preferably 16×10 ⁻⁶ /K or more. The above-mentioned transition metal perovskite type oxide having a linear thermal expansion coefficient equal to or higher than the above predetermined value has high activity, and the outer scavenging layer 42 exhibits sufficient conductivity, while sufficiently suppressing contaminants contained in the oxidant gas. It becomes possible to collect in.

As in Embodiment 3 described later, the inner reaction layer and the outer collection layer may be constituted by a continuous layer whose composition continuously changes from the inner reaction layer to the outer collection layer, As illustrated in FIG. 1, the internal reaction layer 41 and the external collection layer 42 preferably have different compositions and have an interface between them. In this case, the internal reaction layer 41 and the external collection layer 42 can be easily formed by stacking sheets having different compositions and baking them.

The thickness of the internal reaction layer 41 is preferably 10 to 150 μm, more preferably 20 to 100 μm, from the viewpoint of gas diffusibility, electrode reaction resistance and the like. The thickness of the outer collection layer 42 is preferably ⅓ or more of that of the inner reaction layer 41 from the viewpoint of gas diffusibility, contaminant collection property, conductivity, and the like. Further, from the viewpoint of gas diffusibility, electrode reaction resistance, current collecting property, etc., the thickness of the entire air electrode is preferably 15 to 300 μm, more preferably 25 to 200 μm, and further preferably 30 to 150 μm.

The fuel electrode 2 may be composed of a single layer or plural layers. FIG. 1 illustrates the case where the fuel electrode 2 is composed of a single layer. When the fuel electrode 2 is composed of a plurality of layers, the fuel electrode 2 can be configured to have, for example, a diffusion layer and an active layer, although not shown. The diffusion layer is a layer capable of diffusing the fuel gas supplied to the fuel electrode within the layer surface. The active layer is a layer that is disposed on the solid electrolyte side of the diffusion layer and that contains the field of the anode reaction.

Examples of the material of the fuel electrode 2 include a mixture of a catalyst such as Ni or NiO and a solid electrolyte such as zirconia. Note that NiO becomes Ni in the reducing atmosphere during power generation.

The thickness of the fuel electrode 2 can be preferably 20 to 100 μm, and more preferably 30 to 80 μm from the viewpoint of gas diffusibility, electrode reaction resistance, current collecting property, and the like.

The fuel cell 1 can be, for example, an anode support type having an anode, which is the fuel electrode 2, as a support. In this case, as compared with the self-supporting membrane type in which the solid electrolyte layer 3 is used as a support, the resistance of the solid electrolyte layer 3 can be reduced and the ionic conductivity can be easily improved by making the solid electrolyte layer 3 thinner.

The fuel cell 1 of this embodiment can be manufactured, for example, as follows. First, a ceramic substrate in which the fuel electrode 2, the solid electrolyte layer 3, and the intermediate layer 5 are laminated in this order is prepared. The ceramic substrate can be prepared using, for example, a sheet forming process.

Next, the internal reaction layer forming paste is applied in layers on the intermediate layer 5 of the ceramic substrate by a screen printing method or the like, and baked by baking. The internal reaction layer forming paste can contain, for example, an internal reaction layer material, a binder, etc., and can be prepared into a paste by adding a binder and the like to the internal reaction layer material. Further, the firing temperature can be adjusted, for example, within a range of 900°C to 1100°C, and the firing time can be appropriately adjusted depending on the thickness, the amount of the binder, and the like.

The average particle diameter of the sintered particles in the inner reaction layer 41 is preferably 0.2 to 10 μm, more preferably 0.5 to 5 μm. In this case, the permeability of the oxidant gas can be maintained while sufficiently securing the three-phase interface. The average particle diameter of the sintered particles of the internal reaction layer 41 is obtained by, for example, observing the cross section of the internal reaction layer 41 with a scanning electron microscope and measuring the particle diameter of any 100 sintered particles to obtain the arithmetic average value thereof. It is calculated by As the scanning electron microscope, SU8200 manufactured by Nippon High Technologies Co., Ltd. is used, and the average particle diameter is determined from an SEM image at a magnification of 300 to 5000 times.

Next, the external collection layer forming paste is applied in layers on the internal reaction layer 41 by a screen printing method or the like, and baked by baking. The external trapping layer forming paste can include, for example, an external trapping layer material, a binder, and the like, and can be prepared into a paste by adding a binder and the like to the external trapping layer material. The firing temperature can be adjusted, for example, in the range of 900° C. to 1000° C., and the firing time can be appropriately adjusted depending on the thickness and the amount of binder.

The average particle size of the sintered particles in the outer collection layer 42 is preferably 0.3 to 15 μm, more preferably 0.8 to 8 μm. In this case, it is possible to maintain the permeability of the oxidant gas while sufficiently securing the trapping property for the contaminants. The average particle size of the sintered particles of the outer collection layer 42 can be measured by the same method as the average particle size of the inner reaction layer 41 described above. By increasing the surface area of the sintered particles in the outer trap layer 42, the outer trap layer 42 can be sufficiently trapped in the outer trap layer 42 before reaching the inner trap layer 41. The average particle diameter of the sintered particles of is preferably larger than the average particle diameter of the sintered particles of the internal collection layer 41.

Although not shown in FIG. 1, a current collector similar to that of Embodiment 3 described later can be arranged on the outer collection layer 42. As described above, the solid oxide fuel cell 1 can be manufactured.

In the fuel cell 1 of this embodiment, as illustrated in FIG. 1, a fuel electrode 2, a solid electrolyte layer 3, an intermediate layer 5, and an air electrode 4 are laminated in this order. Moreover, the air electrode 4 has an inner reaction layer 41 and an outer collection layer 42, and the inner collection layer 41 and the outer reaction layer 42 are laminated in this order from the intermediate layer 5 side. The oxidant gas O introduced to the air electrode 4 side of the solid electrolyte layer 3 reaches the inner reaction layer 41 through the outer collection layer 42 in the air electrode 4 having gas permeability. Therefore, even if the oxidant gas O contains contaminants, the contaminants are collected by the outer collection layer 42 before reaching the inner reaction layer 41. As a result, the contaminants are reliably collected by the outer collection layer 42, and the contaminants are prevented from flying to the inner reaction layer 41. Therefore, poisoning deterioration of the inner reaction layer 41 can be sufficiently prevented. .. Therefore, the fuel cell 1 can exhibit stable cell performance for a long period of time and has high reliability.

Further, in the fuel cell 1, since the contaminants are collected in the outer collection layer 42 of the air electrode 4, no other member is required for collecting the contaminants. Therefore, it is possible to prevent an increase in manufacturing cost due to an increase in members. Further, it is not necessary to separately form a member for collecting contaminants from the air electrode 4, and the outer collection layer 42 is laminated on the inner reaction layer 41 as illustrated in FIG. Therefore, it is only necessary to change the thickness of the air electrode 4, and there is almost no need to change the design of the dimensions of the members. Therefore, it is not necessary to separately secure an installation space for trapping pollutants in the fuel cell 1, and it is possible to prevent the fuel cell 1 from increasing in size.

As described above, according to this embodiment, it is possible to provide the solid oxide fuel cell 1 capable of preventing the poisoning of the air electrode for a long period of time.

(Embodiment 2)
The present embodiment is a fuel cell having no intermediate layer. In addition, among the reference numerals used in the present embodiment and subsequent ones, the same reference numerals as those used in the above-described embodiments and the like represent the same components and the like as those in the above-described embodiments and the like, unless otherwise specified.

As illustrated in FIG. 2, the fuel cell 1 may not have the intermediate layer, and the air electrode 4 may be formed on the solid electrolyte layer 3. In this case, the fuel electrode 2, the solid electrolyte layer 3, and the air electrode 4 are laminated in this order. The air electrode 4 has an internal reaction layer 41 formed on the solid electrolyte layer 3 and an external collection layer 42 formed on the internal reaction layer 41.

As illustrated in FIG. 2, when the air electrode 4 is formed on the solid electrolyte layer 3, the internal reaction layer 41 contributes to power generation by the internal reaction layer material, the solid electrolyte layer material, and the pores. A three-phase interface is formed.

Moreover, when the air electrode 4 is formed on the solid electrolyte layer 3, the internal reaction layer 41 can further contain a solid electrolyte layer material. That is, the internal reaction layer 41 can contain a composite material of a transition metal perovskite type oxide and a solid electrolyte layer material. In this case, the three-phase interface that contributes to power generation can be further increased. Further, in this case, since the difference in linear thermal expansion coefficient between the internal reaction layer 41 and the solid electrolyte layer 3 can be reduced, the bondability at the interface between the solid electrolyte layer 3 and the internal reaction layer 41 can be improved. You can As the solid electrolyte layer material, the same material as in Embodiment 1 is exemplified, and specifically, yttria-stabilized zirconia or the like can be used. Other configurations, functions and effects are similar to those of the first embodiment.

(Embodiment 3)
In this embodiment, a fuel cell in which the air electrode is formed by a continuous layer will be described.
As illustrated in FIG. 3, the air electrode 4 in the present embodiment does not have a clear interface between the inner reaction layer 41 and the outer collection layer 42, and thus the air collection from the inner reaction layer 41 to the outer collection layer 42 is prevented. The continuous layer 45 has a composition that continuously changes toward the layer 42. Also in this case, the outer collection layer 42 is formed on the surface layer side of the continuous layer 45, that is, on the surface layer side facing the oxidizing gas passage 10 into which the oxidizing gas O is introduced, and the internal reaction is formed on the intermediate layer 5 side. Layer 41 is formed.

The continuous layer 45 is made of a transition metal perovskite-type oxide containing Co and at least one element selected from the group consisting of La, Sr, Sm, Ni, and Mn. It is preferable that the Co content increases toward the collecting layer 42 side. In other words, in the transition metal perovskite type oxide forming the air electrode 4, the Co content increases from the intermediate layer 5 side of the air electrode 4 toward the surface layer side facing the oxidant gas flow channel 10. Is preferred. In this case, the internal reaction layer 41 is formed on the intermediate layer 5 side of the continuous layer 45, which requires the activity of the three-phase interface, and the internal reaction layer 41 can exhibit a good power generation reaction and trap contaminants. The outer collection layer 42 is formed on the surface layer side of the continuous layer 45 that requires collection and conductivity, and the outer collection layer 42 can exhibit good collection performance and conductivity. Other configurations, functions and effects are similar to those of the first embodiment.

The air electrode 4 including the continuous layer 45 can be formed, for example, as follows. On the inner reaction layer 41, a paste containing cobalt oxide or strontium cobalt oxide is applied in layers by a screen printing method or the like, and baked by baking. By burning the cobalt oxide layer on the internal reaction layer 41, cobalt is solid-diffused at the interface between the internal reaction layer and the cobalt oxide layer, and the continuous layer 45 having the Co content increased toward the surface is formed. .. At this time, the thickness of the cobalt oxide layer is preferably 1/2 or less of that of the internal reaction layer 41. The cobalt oxide paste can contain, for example, cobalt oxide and a binder, and can be prepared in a paste form by adding a binder and the like to cobalt oxide. The firing temperature can be adjusted, for example, in the range of 900° C. to 1100° C., and the firing time can be appropriately adjusted depending on the thickness and the amount of binder.

(Embodiment 4)
In the present embodiment, a fuel cell in which the oxidant gas introduction end surface of the air electrode is covered with an external collection layer will be described. As illustrated in FIG. 4, in the fuel cell 1, a current collector plate 6 is arranged on the air electrode 4 side, and an oxidant gas flow channel 10 is formed between the two. Although the specific configuration of the current collector plate 6 will be described later in the sixth embodiment, the current collector plate 6 can include, for example, a current collector substrate 61 and a large number of protruding current collectors 62.

As illustrated in FIG. 4, the oxidant gas O is introduced into the oxidant gas passage 10 from an oxidant gas inlet 11 formed on the side surface of the fuel cell 1, for example. As illustrated in FIGS. 4 and 5, the oxidant gas O introduced from the oxidant gas introduction port 11 collides with the oxidant gas O introduction end face 43 of the air electrode 4 in the oxidant gas flow passage 10. To do. The introduction end surface 43 is an end surface located on the side surface of the air electrode 4 and on the oxidant gas introduction port 11 side of the air electrode 4.

In the fuel cell 1 of this embodiment, the inner reaction layer 41 is covered with the outer collection layer 42 at the introduction end face 43. That is, in the introduction end face 43, the side end face 421 of the outer collection layer 42 extends to the oxidant gas introduction port 11 side more than the side end face 411 of the inner reaction layer 41, and the side end face 411 of the inner reaction layer 41. Is not exposed and is covered with the outer collection layer 42.

The air electrode 4 in this embodiment is formed as follows. First, similarly to Embodiment 1, the internal reaction layer forming paste is applied in layers on the intermediate layer 5 of the ceramic substrate by a screen printing method or the like, and baked by firing. Next, the external collection layer forming paste is applied in layers on the internal reaction layer 41 by a screen printing method or the like, and baked by baking. At this time, the introduction end face 43 is extended to the oxidant gas introduction port 11 side with respect to the side end face 411 of the internal reaction layer 41, and the external collection layer forming paste is applied. In this way, the inner collection layer 41 can be covered with the outer collection layer 42 at the introduction end face 43.

In the fuel cell 1 of the present embodiment, the outer collection layer 42 covers the inner reaction layer 41 even at the introduction end surface 43 of the oxidant gas O, so that the oxidant gas O is also collected outside at the introduction end surface 43. After passing through the layer 42, the inner reaction layer 41 is reached. As a result, even if the oxidant gas O contains a pollutant, the pollutant is reliably captured by the external trapping layer 42 even at the introduction end face 43. Therefore, since the contaminants are prevented from flying into the inner reaction layer 41, the deterioration of the inner reaction layer 41 due to poisoning can be more sufficiently prevented. That is, it is possible to prevent poisoning deterioration of the internal reaction layer 41 from the side surface of the air electrode 4. Therefore, the fuel cell 1 can exhibit stable cell performance for a longer period of time, and has higher reliability. Other configurations, functions and effects are similar to those of the first embodiment.

(Embodiment 5)
In the fourth embodiment, an example in which the inner reaction layer on the introduction end face is covered with the outer scavenging layer has been described, but in the present embodiment, as illustrated in FIG. 6, the end faces other than the introduction end face 43 of the air electrode 4 are illustrated. Also in the above, the form in which the inner reaction layer 41 is covered with the outer collection layer 42 will be described.

As illustrated in FIG. 6, in the fuel cell 1 of the present embodiment, the inner reaction layer 41 is covered with the outer collection layer 42 at the introduction end face 43, as in the fourth embodiment. Further, the inner reaction layer 41 is covered with the outer collection layer 42 also on the end faces 44 and 45 other than the introduction end face 43. Specifically, the inner reaction layer 41 is covered with the outer collection layer 42 at the side end faces 44 and 45 extending _in parallel with the inflow direction X _in of the oxidant gas O. The side end surfaces 44, 45 covered by the outer collection layer 42 do not need to be completely parallel to the inflow direction Xin, and even if they are partially or entirely inclined, the overall shape of each side end surface 44, 45. May be parallel to the inflow direction X _{in in} appearance.

The inner reaction layer 41 of the discharge end surface 46 from which the oxidant gas O is discharged from the fuel cell 1 is not covered with the outer collection layer 42, and the side end surface 411 of the inner reaction layer 41 is exposed. However, the inner reaction layer 41 may be covered with the outer collection layer 42 also on the discharge end surface 46.

When the inner reaction layer 41 is covered with the outer scavenging layer 42 on the end faces 44, 45 other than the introduction end face 43 as in the present embodiment, the oxidant gas O is also formed on these end faces 44, 45. Passes through the outer collection layer 42 and then reaches the inner reaction layer 41. Therefore, the poisoning deterioration of the internal reaction layer 41 can be prevented more reliably. Other configurations, functions and effects are similar to those of the first embodiment.

(Embodiment 6)
In the present embodiment, a fuel cell having a current collector plate having a projection-shaped current collector will be described. As illustrated in FIG. 7, in the fuel cell 1, the current collector plate 6 is arranged on the air electrode 4 side. The current collector plate 6 has conductivity and is made of metal, for example.

The current collector plate 6 has, for example, a plate-shaped or sheet-shaped current collector substrate 61, and a large number of protruding current collectors 62 extending from the current collector substrate 61 toward the air electrode 4. The shape of the projecting current collecting portion 62 is not particularly limited, and it is possible to form the pattern of comb teeth, brushes, or the like.

As illustrated in FIGS. 7 and 8, in the present embodiment, the shape of the current collector 62 is a rod shape or a needle shape extending from the current collector substrate 61, and the current collectors 62 are arranged in parallel with each other. In addition, the current collectors 62 adjacent to each other can be arranged at a predetermined interval. In other words, as illustrated in FIG. 8, _in the direction parallel to and perpendicular to the inflow direction X _in of the oxidant gas O into the fuel cell 1 and the discharge direction X _out of the oxidant gas O from the fuel cell 1. The current collectors 62 can be arranged at predetermined intervals. The inflow direction X _in and the discharge direction X _out are, for example, the same direction.

As illustrated in FIGS. 7 and 8, each current collector 62 is in contact with the outer surface of the air electrode 4, specifically, the outer collection layer 42. The current collector 62 is electrically connected to the air electrode 4, which is the cathode, at the contact portion 47 and collects current. Around the contact portion 47, that is, the non-contact portion 48, the thickness of the outer collection layer 42 of the air electrode 4 is larger than that of the contact portion 47, and a thick portion 481 is formed. In other words, in the contact portion 47, the thickness of the external collection layer 42 is smaller than that in the non-contact portion 48, and the thin portion 471 having a relatively smaller thickness than the thick portion 481 is formed. ing. As illustrated in FIG. 7, the outer trapping layer 42 has a thickness difference of ΔT between the contact portion 47 and the non-contact portion 48.

The external collection layers 42 having different thicknesses can be formed, for example, as follows. First, similarly to Embodiment 1, the internal reaction layer forming paste is applied in layers on the intermediate layer 5 of the ceramic substrate by a screen printing method or the like, and baked by firing. Next, the external collection layer forming paste is applied in layers on the internal reaction layer 41 by a screen printing method or the like, and baked by baking. Then, the area other than the contact portion 47 is further coated with the external collection layer forming paste and baked by baking. In this way, the external collection layer 42 having a larger thickness around the contact portion 47 than the contact portion 47 can be formed.

As described above, the fuel cell 1 of the present embodiment has the thin portion 471 at the contact portion 47 between the current collecting portion 62 and the external collection layer 42, and the periphery of the contact portion 47, that is, the current collecting portion 62. The non-contact portion 48 of the outer collection layer 42 has a thick portion 481. Therefore, in the contact portion 47 having a small thickness of the external collection layer 42, the electrical resistance of the external collection layer 42 is small, and the current collector 62 enables efficient current collection. On the other hand, in the non-contact portion 48 having a large thickness of the outer collection layer 42, the outer collection layer 42 enables sufficient collection of the contaminants in the oxidant gas O.

From the viewpoint of sufficiently obtaining the effect of improving the trapping performance of the pollutants by the thick portion 481, the thickness of the thick portion 481 is preferably 1.1 times or more, and 1.2 times or more of the thickness of the thin portion 471. More preferable. On the other hand, the thickness of the thin portion 471 is preferably ⅓ or more of the thickness of the inner collection layer 41, similarly to the thickness of the outer collection layer 42 described above, from the viewpoint of conductivity and the like. The other configurations and effects are similar to those of the fourth embodiment.

(Modification)
In this example, two modification examples in which the formation pattern of the current collector is different from that of the sixth embodiment will be described. Modification 1 is an example of a current collector that extends like a comb as illustrated in FIG. 9A. Each current collector 62 extends at a predetermined interval, for example, in a direction parallel to the inflow direction of the oxidant gas. In this case, a plurality of oxidant gas flow paths 10 that are parallel to each other are formed between the current collectors 62. Therefore, the flow direction of the oxidant gas O can be made uniform. The current collector 62 extending in a comb shape is in contact with the air electrode 4 at the contact portion 47.

In the fuel cell of Modification Example 1, as in the sixth embodiment, the thick portion 481 can be formed by increasing the thickness of the external collection layer 42 around the contact portion 47. In this case, the thickness of the external collection layer 42 facing the oxidant gas flow channel 10 extending in parallel to the inflow direction X becomes large. Therefore, in the thick portion 481 of the outer collection layer 42, the contaminants in the oxidant gas O can be sufficiently collected. Other configurations and operational effects are similar to those of the sixth embodiment.

Modification 2 is an example in which, as illustrated in FIG. 9B, a plurality of rod-shaped or needle-shaped current collectors 62 extending from the current collector substrate are arranged by shifting by half a pitch. That is, the current collectors 62 are arranged at predetermined intervals in a direction parallel to the inflow direction Xin of the oxidant gas O. The current collectors 62 arranged in the direction perpendicular to the inflow direction Xin are arranged so as to be offset by half a pitch in the inflow direction X. Therefore, the oxidant gas O flowing in the oxidant gas flow channel 10 is diffused in the flow channel 10 by the current collector 62. Therefore, power generation efficiency is further improved.

Further, the oxidant gas flow path 10 through which the diffused oxidant gas O flows is formed around the contact portion 47 between the current collector 62 and the air electrode 4, and in this periphery, the same as in the sixth embodiment. In addition, the thickness of the outer collection layer 42 can be increased to form the thick portion 481. Therefore, in the thick portion 481 of the outer collection layer 42, the contaminants in the oxidant gas O can be sufficiently collected. Other configurations and operational effects are similar to those of the sixth embodiment.

(Experimental example 1)
This example is an example in which the difference in the degree of infiltration of pollutants in the air electrode is compared between the air electrode having the outer collection layer and the air electrode not having the outer collection layer. First, a fuel cell having the same structure as that of the first embodiment was manufactured as follows.
<Material preparation>

A slurry was prepared by mixing NiO powder, yttria-stabilized zirconia powder containing 8 mol% Y ₂ O ₃ , carbon, polyvinyl butyral, isoamyl acetate, 2-butanol and ethanol in a ball mill. The yttria-stabilized zirconia containing 8 mol% Y ₂ O ₃ is hereinafter referred to as 8YSZ. The NiO powder has an average particle diameter of 1.0 μm, and the 8YSZ powder has an average particle diameter of 0.8 μm. The mass ratio of the NiO powder and the YSZ powder was 60:40. A sheet for fuel electrode formation was prepared by applying the above slurry in a layered manner on a plastic substrate using a doctor blade method and drying. The average particle diameter of the powder is the particle diameter d50 when the volume-based cumulative frequency distribution measured by the laser diffraction/scattering method shows 50%. The particle size is specifically a diameter. The same applies to the average particle diameter of the powder thereafter.

A slurry was prepared by mixing 8YSZ powder having an average particle diameter of 0.8 μm, polyvinyl butyral, isoamyl acetate, 2-butanol and ethanol in a ball mill. A sheet for forming a solid electrolyte layer was prepared by applying this slurry in layers on a plastic substrate using a doctor blade method and drying.

A slurry was prepared by mixing 10 mol% Gd-doped ceria powder, polyvinyl butyral, isoamyl acetate, 2-butanol, and ethanol in a ball mill. Ceria doped with 10 mol% of Gd is hereinafter referred to as “10GDC”. The average particle size of 10GDC powder is 0.8 μm. A sheet for forming an intermediate layer was prepared by applying the slurry in a layer form on a plastic substrate using a doctor blade method and drying.

A La _0.6 Sr _0.4 Co _0.2 Fe _0.8 O ₃ powder, ethyl cellulose, and terpineol were mixed in a ball mill to prepare an air electrode internal reaction layer forming paste. Hereinafter, La _0.6 Sr _0.4 Co _0.2 Fe _0.8 O ₃ is referred to as “LSCF”. The average particle size of the LSCF powder is 0.6 μm.

A La _0.6 Sr _0.4 CoO ₃ powder, ethyl cellulose, and terpineol were mixed in a ball mill to prepare a paste for forming an external collecting layer of an air electrode. Hereinafter, La _0.6 Sr _0.4 CoO ₃ is referred to as “LSC”. The LSC powder has an average particle size of 0.5 μm, and the 10GDC powder has an average particle size of 0.8 μm.

<Fabrication of fuel cell>
The fuel electrode forming sheet, the solid electrolyte layer forming sheet, and the intermediate layer forming sheet were laminated in this order to obtain a laminate. The obtained laminate was pressure-bonded and degreased using a hydrostatic press molding method. The hydrostatic press is also called CIP. The CIP molding conditions were a temperature of 80° C., a pressure of 50 MPa, and a pressurizing time of 10 minutes.

The laminate was fired at 1350° C. for 2 hours. As a result, a sintered body was obtained in which a fuel electrode having a thickness of 500 μm, a solid electrolyte layer having a thickness of 10 μm, and an intermediate layer having a thickness of 10 μm were laminated in this order.

Next, an internal reaction layer forming paste was applied to the surface of the intermediate layer in the above-mentioned sintered body by a screen printing method, and baked at 1000° C. for 2 hours to form an internal reaction layer having a thickness of 60 μm. The average particle size of the sintered particles in the inner reaction layer was 1.5 μm.

Next, the external collection layer forming paste was applied to the surface of the internal reaction layer in the above-mentioned sintered body by a screen printing method, and baked at 900° C. for 2 hours to form an external collection layer having a thickness of 20 μm. The average particle size of the sintered particles in the outer collection layer was 2.0 μm.

In this way, a fuel cell in which the fuel electrode, the solid electrolyte layer, the intermediate layer, the internal reaction layer, and the external collection layer were laminated in this order and joined together was obtained. A stack type fuel cell was manufactured by disposing a current collector plate on the air electrode side of this fuel cell as in the sixth embodiment and further stacking a plurality of fuel cells having a single cell structure by a known method. This fuel cell is referred to as Example 1.

In addition, in this example, a fuel cell for comparison was prepared. This fuel cell is the same fuel cell as in Example 1 except that it has no external collection layer. This fuel cell is referred to as Comparative Example 1.

Each of the fuel cells of Example 1 and Comparative Example 1 was used and driven under actual use conditions. Specifically, a mixed gas of H ₂ +N ₂ +H ₂ O was supplied to the fuel cell as a fuel gas and air was supplied to the fuel cell as an oxidant gas, and the fuel cell was driven in an environment of 700° C. The driving time was 5000 hours, and continuous driving was performed under constant conditions.

Next, the Cr content and the S content in the depth direction of the air electrode of the fuel cell after driving were examined by secondary ion mass spectrometry. Cr and S are pollutants contained in an oxidant gas such as air. Secondary ion mass spectrometry is also called SIMS. Specifically, SIMS was measured using a SIMS device “IMS” manufactured by Ametech Co., Ltd. under the conditions of primary ion species: Cs+, primary ion acceleration energy: 5 to 10 keV, and primary ion beam diameter: 100 to 300 nm. .. Note that FIG. 10 is a top view showing the fuel cell of Example 1 from the air electrode side, and the position of the SIMS analysis point P is shown in FIG. Also in the fuel cell of Comparative Example 1, the same position is the analysis point.

The analysis results are shown in FIGS. 11 and 12. 11 and 12, the horizontal axis represents the distance d (μm) in the depth direction from the surface of the air electrode. The vertical axis in FIG. 11 is the Cr content (wtppm). The vertical axis in FIG. 12 is the S content (wtppm).

As is known from FIGS. 11 and 12, in Example 1, it is more difficult for the pollutants Cr and S to reach the inside of the air electrode than in the comparative example. That is, in Example 1 having the external trapping layer, infiltration of the contaminants Cr and S into the air electrode was suppressed as compared with the comparative example not having the external trapping layer. As is known from FIGS. 11 and 12, in Example 1, most of Cr and S are trapped by the outer trapping layer having a thickness of 20 μm, and poisoning of the inner reaction layer is prevented.

In addition, in this example, a fuel cell manufactured in the same manner as in Example 1 was manufactured except that an internal reaction layer forming paste using LSC powder and 10 GDC powder was used in place of the LSCF powder. did. The average particle size of the sintered particles of the internal reaction layer produced using this internal reaction layer forming paste was 1.0 μm. Also for this fuel cell, as a result of examining the Cr content and the S content in the depth direction of the air electrode after driving, the same results as in Example 1 in this example were shown, and therefore, the illustration is omitted.

As described above, according to the present example, it is understood that the internal reaction layer can be prevented from being poisoned for a long period of time by stacking the external collection layer on the internal reaction layer of the air electrode.

(Experimental example 2)
This example is an example of analyzing the poisoning of the air electrode in the same manner as in Experimental Example 1 for the fuel cell having the same configuration as that of the fifth embodiment. In the fuel cell of this example, as in the fifth embodiment, the inner reaction layer 41 on the end faces 43, 44, 45 other than the discharge end face 46 of the air electrode 4 is covered with the outer collection layer 43 (see FIG. 13). .. This is Example 2. Since the outer collection layer 43 is laminated on the inner reaction layer 41, the inner reaction layer 41 is not originally shown in FIG. 13, but for convenience of description, the outer edge of the inner reaction layer 41 is indicated by a broken line. Show.

The fuel cell of Example 2 was manufactured as follows. First, in the same manner as in Example 1 except that an internal reaction layer forming paste using LSC powder and 10GDC powder was used in place of the LSCF powder, the internal reaction on the surface of the intermediate layer in the sintered body was performed. An internal reaction layer was formed by applying a layer-forming paste and baking it. The average particle size of the sintered particles in the inner reaction layer is 1.0 μm.

Next, the external collecting layer forming paste was applied from above the internal reaction layer by screen printing. At this time, on the end faces 43, 44, 45 other than the discharge end face 46, the external collecting layer forming paste was applied by extending by 2 mm from the side end face 411 of the internal reaction layer 41. Then, by firing at a temperature of 900° C. for 2 hours, the external collection layer 42 having a thickness of 20 μm was formed. The average particle diameter of the sintered particles of the outer collection layer is 1.5 μm. A fuel cell was manufactured in the same manner as in Example 1 except for the above.

As illustrated in FIG. 13, in the end faces 43, 44, 45 of the air electrode 4 of the fuel cell 1 of Example 2, the side end face 421 of the outer collection layer 42 is more than the side end face 411 of the inner reaction layer 41. It is extended, the side end surface 411 of the inner reaction layer 41 is not exposed, and is covered by the outer collection layer 42. In each of the end faces 43, 44, 45 except the discharge end face 46 of the oxidant gas, the outer collection layer 42 is formed to be 2 mm larger than the inner reaction layer, and ΔW=2 mm in FIG. 13.

Similar to Experimental Example 1, after driving the fuel cell of Example 2, the Cr content and the S content in the depth direction of the air electrode 4 were examined. The analysis point P is the same position as in Experimental Example 1, and is the position shown in FIG. The results are shown in FIGS. 14 and 15. The results of Example 1 are also shown in FIGS. 14 and 15 for comparison.

As is known from FIGS. 14 and 15, it can be seen that the fuel cell of Example 2 is further suppressed in poisoning of the air electrode as compared with Example 1. That is, it can be seen that by covering the side end surface 411 of the inner reaction layer 41 with the outer collection layer 42, poisoning of the inner reaction layer 41 is further suppressed. Further, as in the fourth embodiment, the side end surface 411 of the inner reaction layer 41 in the introduction end surface 41 of the oxidant gas O is covered with at least the outer collection layer 42, and the other side end surfaces 44, 45, 46 are exposed. The same analysis was performed on the fuel cell having the air electrode, but the same results as in Example 2 were shown, and therefore the illustration is omitted.

Therefore, when the inner reaction layer 41 is covered with the outer scavenging layer 42 even on the end face as in the fourth and fifth embodiments, the oxidant is also struck by the outer scavenging layer 42 on the end face of the air electrode 4. Pollutants in the gas can be collected. As a result, poisoning deterioration of the internal reaction layer 41 can be prevented more reliably, and the fuel cell 1 can exhibit stable cell performance for a longer period of time.

(Experimental example 3)
This example is an example of analyzing the poisoning of the air electrode in the same manner as in Experimental Example 1 for the fuel cell similar to that of the sixth embodiment. In the fuel cell 1 of this example, as illustrated in FIGS. 16A and 16B, the thin portion 471 is formed in the contact portion 47 between the current collecting portion 62 and the external collecting layer 42 as in the sixth embodiment. And has a thick portion 481 around the contact portion 47, that is, in the current collecting portion 62 and the non-contact portion 48 of the outer collection layer 42. The fuel cell 1 of this example is referred to as Example 3.

In the fuel cell of Example 3, the thin portion 471 of the outer collection layer 42 had a thickness of 20 μm, and the thick portion 481 had a thickness of 40 μm, as in the other examples. The inner reaction layer 41 of the air electrode 4 is covered with the outer collection layer 42 at the introduction end face 43.

The fuel cell of Example 3 was manufactured as follows. First, in the same manner as in Example 1 except that an internal reaction layer forming paste using LSC powder and 10GDC powder was used in place of the LSCF powder, the internal reaction on the surface of the intermediate layer in the sintered body was performed. An internal reaction layer was formed by applying a layer-forming paste and baking it. The average particle size of the sintered particles in the inner reaction layer is 1.0 μm.

Next, the external collecting layer forming paste was applied from above the internal reaction layer by screen printing. At this time, the introduction end face 43 was extended by 2 mm from the side end face 411 of the inner reaction layer 41, and the external scavenging layer forming paste was applied. Then, by firing at a temperature of 900° C. for 2 hours, the external collection layer 42 having a thickness of 20 μm was formed. The average particle diameter of the sintered particles of the outer collection layer is 1.5 μm.

Next, the external collecting layer forming paste was applied again by screen printing to the region of the current collector plate 6 other than the contact part 47 with the current collecting part 62, and was baked at a temperature of 900° C. for 2 hours. The average particle diameter of the sintered particles in the outer collection layer further laminated on the outer collection layer is 2.0 μm.

In this way, the external collection layer 42 having the thickness of the thick portion 481 of 40 μm and the thickness of the thin portion 471 of 20 μm was formed. A fuel cell 1 was manufactured in the same manner as in Example 1 except for the above.

Similar to Experimental Example 1, after driving the fuel cell 1 of Example 3, the Cr content and the S content in the depth direction of the air electrode 4 were examined. The analysis point P is the same position as in Experimental Example 1, and is the position of the contact portion 47 as shown in FIGS. 16(a) and 16(b). The results are shown in FIGS. 17 and 18. The results of Example 1 are also shown in FIGS. 17 and 18 for comparison.

As is known from FIGS. 17 and 18, it is understood that the fuel cell of Example 3 is further suppressed in poisoning of the air electrode 4 as compared with Example 1. That is, by increasing the thickness of the outer collection layer 42 around the contact portion 47, that is, the non-contact portion 48 to form the thick portion 481, the poisoning of the inner reaction layer 41 is further suppressed. I see that I can do it.

Therefore, as in the sixth embodiment, by increasing the thickness of the outer collection layer 42 around the contact portion 47, it is possible to further prevent poisoning deterioration of the inner reaction layer 41, and the fuel cell 1 The battery performance can be exhibited stably for a longer period of time.

The present invention is not limited to the above-described embodiments, but can be applied to various embodiments without departing from the spirit of the invention. For example, the configurations of the respective embodiments and examples can be combined with each other. The composition of the transition metal perovskite type oxide or the like in the outer collection layer 42 and the inner reaction layer 41 can be appropriately changed.

1 Solid Oxide Fuel Cell 2 Fuel Electrode 3 Solid Electrolyte Layer 4 Air Electrode 41 Internal Reaction Layer 42 External Collection Layer 5 Intermediate Layer 6 Current Collection Plate

Claims (16)

The fuel electrode (2), the solid electrolyte layer (3), and the air electrode (4) are laminated in this order,
The air electrode includes an internal reaction layer (41) formed on the solid electrolyte layer side, and an external collection layer formed on the internal reaction layer and collecting contaminants in the oxidant gas (O). and (42), have a,
Furthermore, it has a current collecting plate (6) formed on the air electrode, and the current collecting plate comprises a current collecting substrate (61) and a plurality of projecting collectors extending from the current collecting substrate toward the air electrode. A solid oxide form having an electricity collecting portion (62) and having a thickness of the outer collection layer larger than that of the contact portion around the contact portion (47) of the air electrode with the current collecting portion. Fuel cell (1). The solid oxide fuel cell according to claim 1, wherein the inner reaction layer and the outer collection layer contain transition metal perovskite oxides having different compositions. The solid oxidation according to claim 1 or 2, wherein the outer collection layer contains a transition metal perovskite type oxide containing at least two elements selected from the group consisting of La, Sr, Sm, and Co. Form fuel cell. The solid oxide according to any one of claims 1 to 3, wherein the outer collection layer contains a transition metal perovskite type oxide containing at least Co and has a higher Co content than the inner reaction layer. Type fuel cell. The solid oxide fuel cell according to claim 3 or 4, wherein the coefficient of linear thermal expansion of the outer collection layer is 16 × 10 ^-6 /K or more. The solid oxidation according to any one of claims 1 to 5, which has an intermediate layer (5) between the solid electrolyte layer and the air electrode, and the air electrode is formed on the intermediate layer. Form fuel cell. The internal reaction layer is a transition metal perovskite oxide containing at least two elements selected from the group consisting of La, Sr, Sm, Co, Fe, Ni, and Mn, or the transition metal perovskite oxide. The solid oxide fuel cell according to claim 6, which contains a composite material with a material forming the intermediate layer. The transition metal perovskite oxide contained in the inside of the reaction _{layer, La x Sr 1-x CoO} 3 based _{oxide, La x Sr 1-x Co} y Fe 1-y O 3 based oxide, and Sm _x The solid oxide form according to claim 7, which is at least one selected from the group consisting of Sr _1-x CoO ₃ -based oxides (wherein 0≦x≦1 and 0≦y≦1). Fuel cell. The solid oxide fuel cell according to claim 7, wherein the linear thermal expansion coefficient of the internal reaction layer is 10×10 ⁻⁶ or more and less than 16×10 ⁻⁶ /K. The solid oxide fuel cell according to claim 1, wherein the air electrode is formed on the solid electrolyte layer. The internal reaction layer is a transition metal perovskite oxide containing at least two elements selected from the group consisting of La, Sr, Sm, Co, Fe, Ni, and Mn, or the transition metal perovskite oxide. The solid oxide fuel cell according to claim 10, which contains a composite material with the material forming the solid electrolyte layer. The transition metal perovskite oxide contained in the inside of the reaction _{layer, La x Sr 1-x CoO} 3 based _{oxide, La x Sr 1-x Co} y Fe 1-y O 3 based oxide, and Sm _x The solid oxide form according to claim 11, which is at least one selected from the group consisting of Sr _1-x CoO ₃ -based oxides (wherein 0≦x≦1 and 0≦y≦1). Fuel cell. The solid oxide fuel cell according to claim 11 or 12, wherein the coefficient of linear thermal expansion of the internal reaction layer is 10×10 ⁻⁶ or more and less than 16×10 ⁻⁶ /K. The solid oxide form according to any one of claims 1 to 13, wherein the air electrode comprises a continuous layer (45) whose composition continuously changes from the inner reaction layer toward the outer collection layer. Fuel cell. The continuous layer is made of a transition metal perovskite-type oxide containing at least one element selected from the group consisting of La, Sr, Sm, Ni, and Mn, and Co. The solid oxide fuel cell according to claim 14, wherein the Co content increases toward the collection layer side. Furthermore, it has an oxidant gas inlet (111) formed on the side surface (11) of the solid oxide fuel cell, and the air electrode receives the oxidant gas supplied from the oxidant gas inlet. The solid oxide form according to any one of claims 1 to 15, wherein the solid oxide form has a collision end face (43), and the inner reaction layer is covered with the outer trapping layer at least at the introduction end face. Fuel cell.

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