JP2012038719A - Fuel cell structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a "horizontal-stripe" fuel cell structure which hardly causes a crack, etc. in an inclusion interposed in an area between adjacent fuel electrodes even when reduction contraction or oxidation expansion of the fuel electrodes occurs.SOLUTION: A plurality of power generation element parts A electrically connected in series with one another are arranged at predetermined intervals in a longitudinal direction on each of upper and lower surfaces of a flat plate-like support substrate 10 having a longitudinal direction and a fuel gas channel 11 formed in the inside. An "inclusion" (such as part of the support substrate 10) is interposed in an area between adjacent fuel electrodes 20, 20 which belong to the adjacent power generation element parts A, respectively. Gaps are formed between both of the adjacent fuel electrodes 20, 20 and the "inclusion." Because the "gap" functions as a "buffer area," the "inclusion" hardly receives tensile or compression stress from the fuel electrodes even when reduction contraction or oxidation expansion of the fuel electrodes occurs.

Description

  The present invention relates to a fuel cell structure.

  Conventionally, “a porous support substrate having a fuel gas flow path formed therein” and “a fuel electrode, a solid electrolyte, and an air electrode provided at a plurality of locations apart from each other on the outer surface of the support substrate. Are a plurality of power generation element portions stacked in this order ”and“ one fuel electrode and the other air of the adjacent power generation element portions provided respectively between one or a plurality of adjacent power generation element portions ”. One or a plurality of electrical connection portions that electrically connect the electrodes ”and“ a fuel gas that is provided between one or a plurality of adjacent power generation element portions and is supplied to the fuel electrode ” A structure of a solid oxide fuel cell including a gas seal portion made of a dense material that prevents mixing with oxygen-containing gas supplied to the air electrode is known (for example, Patent Document 1). 2). Such a configuration is also called a “horizontal stripe type”.

  Hereinafter, attention will be paid to the inclusions interposed in the region between the adjacent fuel electrodes respectively belonging to the adjacent power generation element portions. In the structure of the “horizontal stripe type” solid oxide fuel cell described in FIG. 1 of Patent Document 1, a part of the electrical connection portion (interconnector 5) is provided in the region between the adjacent fuel electrodes 2 and 2. And inclusions consisting of a part of the gas seal portion (solid electrolyte 3) are interposed without any gaps. In the structure of the “horizontal stripe type” solid oxide fuel cell described in FIG. 4 of Patent Document 1, a region between the adjacent fuel electrodes 13 and 13 is formed of a part of the support substrate (base tube 11). Inclusions are present without gaps. In the structure of the “horizontal stripe type” solid oxide fuel cell shown in FIG. 2 of Patent Document 2, a gas seal portion (solid electrolyte 33) is provided in a region between adjacent fuel electrodes (23 + 13a) and (23 + 13a). The inclusion which consists of a part of is interposed without a gap. Thus, in the structure described in the above-mentioned document, the inclusions are interposed in the region between adjacent fuel electrodes without a gap.

JP-A-8-106916 JP 2008-226789 A

  Incidentally, NiO-based cermet is usually used as a material for the fuel electrode. During the operation of the fuel cell, NiO is subjected to a reduction process using the reduction action of the fuel gas in order to impart conductivity and electrode activity to the fuel electrode. Thus, the fuel cell is operated with NiO reduced to Ni.

  On the other hand, when the operation of the fuel cell is suddenly stopped, a phenomenon such as a temporary flow of air into the fuel gas channel formed inside the support substrate may occur. In this case, a phenomenon may occur in which Ni in the fuel electrode is reoxidized to NiO due to the oxidizing action of oxygen contained in the air flowing into the fuel gas flow path.

  As described above, in the fuel electrode, a phenomenon in which NiO is reduced to Ni by the reducing action of the fuel gas and a phenomenon in which Ni is reoxidized to NiO by the oxidizing action of oxygen can occur. Here, when NiO is reduced to Ni, the fuel electrode contracts by so-called reduction contraction (the volume of the fuel electrode decreases). On the other hand, when Ni is reoxidized to NiO, the fuel electrode expands by so-called oxidative expansion (the volume of the fuel electrode increases).

  As in the structure described in the above document, when the inclusion is interposed in the region between adjacent fuel electrodes without a gap (that is, when the fuel electrode and the inclusion are in contact), Due to the influence of the contraction / expansion of the fuel electrode, the inclusion can receive tensile / compressive stress from the fuel electrode. As a result, cracks or the like may occur in the inclusions or in the vicinity of the interface between the inclusions such as the fuel electrode and the inclusions. As a result, the gas sealing function of the gas seal portion may be degraded, or the conductivity of the electrical connection portion may be degraded.

  The present invention is a “horizontal stripe type” fuel cell structure, and even if reduction contraction / oxidation expansion of a fuel electrode occurs, a crack or the like is generated in an inclusion interposed in a region between adjacent fuel electrodes. The purpose is to provide something difficult to do.

  The structure of the fuel cell according to the present invention includes a porous support substrate that does not have electron conductivity, in which a fuel gas flow path is formed, and a plurality of locations apart from each other on the outer surface of the support substrate. Provided, "a plurality of power generation element units in which at least a fuel electrode, a solid electrolyte, and an air electrode are laminated in this order" and one set or a plurality of sets of adjacent power generation element units, respectively, Between one or a plurality of electrical connection portions having electronic conductivity for electrically connecting one fuel electrode and the other air electrode of the power generation element portion and one set or a plurality of sets of the adjacent power generation element portions And a gas seal portion made of a dense material for preventing mixing of a fuel gas supplied to the fuel electrode and a gas containing oxygen supplied to the air electrode. That is, this structure is a “horizontal stripe type” fuel cell structure. The support substrate may be flat or cylindrical, and may have any shape as long as the fuel gas channel is formed inside.

  In the fuel cell structure according to the present invention, a part of the support substrate, a part of the electrical connection part, and the gas are provided in a region between the adjacent fuel electrodes respectively belonging to the adjacent power generation element parts. Inclusions consisting of any one or more of a part of the seal portion are interposed.

  The fuel cell structure according to the present invention is characterized by a gap between one or both of the adjacent fuel electrodes and the inclusion, or a high porosity having a larger porosity than the fuel electrode and the inclusion. The rate part is formed. In this case, it is more preferable that the gap or the high porosity portion is formed between both of the adjacent fuel electrodes and the inclusion.

  According to this, even if reduction contraction / oxidation expansion of the fuel electrode occurs due to the formation of the “gap” or “high porosity portion”, the inclusions are not easily subjected to tensile / compressive stress from the fuel electrode. In other words, “the gap” or “the high porosity portion” functions as the “buffer region”. As a result, even if reduction contraction / oxidation expansion of the fuel electrode occurs, cracks and the like are less likely to occur inside the inclusions. As a result, problems such as a decrease in the gas seal function of the gas seal portion and a decrease in the conductivity of the electrical connection portion are unlikely to occur.

1 is a perspective view showing a structure of a fuel cell according to the present invention. It is sectional drawing corresponding to the 2-2 line of the structure of the fuel cell shown in FIG. It is a figure for demonstrating the operating state of the structure of the fuel cell shown in FIG. It is a figure for demonstrating the flow of the electric current in the operating state of the structure of the fuel cell shown in FIG. It is a perspective view which shows the support substrate shown in FIG. FIG. 3 is a cross-sectional view corresponding to FIG. 2 in a first stage in the manufacturing process of the fuel cell structure shown in FIG. 1. FIG. 3 is a cross-sectional view corresponding to FIG. 2 in a second stage in the manufacturing process of the fuel cell structure shown in FIG. 1. FIG. 3 is a cross-sectional view corresponding to FIG. 2 in a third stage in the manufacturing process of the fuel cell structure shown in FIG. 1. FIG. 4 is a cross-sectional view corresponding to FIG. 2 in a fourth stage in the manufacturing process of the fuel cell structure shown in FIG. 1. FIG. 6 is a cross-sectional view corresponding to FIG. 2 in a fifth stage in the manufacturing process of the fuel cell structure shown in FIG. 1. FIG. 7 is a cross-sectional view corresponding to FIG. 2 in a sixth stage in the manufacturing process of the fuel cell structure shown in FIG. 1. FIG. 8 is a cross-sectional view corresponding to FIG. 2 in a seventh stage in the manufacturing process of the fuel cell structure shown in FIG. 1. It is sectional drawing corresponding to FIG. 2 of the 1st modification of the structure of the fuel cell concerning this invention. It is sectional drawing corresponding to FIG. 2 of the 2nd modification of the structure of the fuel cell concerning this invention. It is sectional drawing corresponding to FIG. 2 of the 3rd modification of the structure of the fuel cell concerning this invention. It is sectional drawing corresponding to FIG. 2 of the 4th modification of the structure of the fuel cell concerning this invention. It is the top view which showed the state of the fuel electrode and interconnector which were embed | buried under the recessed part of the support substrate shown in FIG. FIG. 10 is a cross-sectional view corresponding to FIG. 2 of a fifth modification of the fuel cell structure according to the present invention. It is sectional drawing corresponding to FIG. 14 of the 6th modification of the structure of the fuel cell concerning this invention. FIG. 16 is a cross-sectional view corresponding to FIG. 15 of a seventh modification of the fuel cell structure according to the present invention. It is sectional drawing corresponding to FIG. 16 of the 8th modification of the structure of the fuel cell concerning this invention.

(Constitution)
FIG. 1 shows a structure of a solid oxide fuel cell (SOFC) according to an embodiment of the present invention. This SOFC structure has a plurality (in this example, electrically connected in series to the upper and lower surfaces (main surfaces (planar surfaces) on both sides parallel to each other) of the flat support substrate 10 having a longitudinal direction. The four power generation element portions A having the same shape are arranged at predetermined intervals in the longitudinal direction and have a so-called “horizontal stripe type” configuration.

  The shape of the entire SOFC structure viewed from above is, for example, a rectangle having a side length of 5 to 50 cm in the longitudinal direction and a length of 1 to 10 cm in the width direction perpendicular to the longitudinal direction. The total thickness of the SOFC structure is 1 to 5 mm. The entire SOFC structure has a vertically symmetrical shape with respect to a plane passing through the center in the thickness direction and parallel to the main surface of the support substrate 10. Hereinafter, in addition to FIG. 1, the details of the SOFC structure will be described with reference to FIG. 2, which is a partial cross-sectional view of the SOFC structure corresponding to line 2-2 shown in FIG. 1. FIG. 2 is a partial cross-sectional view showing a configuration (part of) each of a typical pair of adjacent power generation element portions A and A and a configuration between the power generation element portions A and A. The configuration between the other power generation element portions A and A in other sets is the same as the configuration shown in FIG.

  The support substrate 10 is a flat plate-like fired body made of a porous material having no electronic conductivity. As shown in FIG. 5 described later, a plurality of (six in this example) fuel gas passages 11 (through holes) extending in the longitudinal direction are provided in the support substrate 10 at predetermined intervals in the width direction. Is formed. In this example, each recess 12 is a rectangular parallelepiped recess defined by four side walls closed in the circumferential direction and a bottom wall.

The support substrate 10 can be made of, for example, CSZ (calcia stabilized zirconia). Alternatively, it may be composed of NiO (nickel oxide) and YSZ (8YSZ) (yttria stabilized zirconia), NiO (nickel oxide) and Y ₂ O ₃ (yttria), or MgO. (Magnesium oxide) and MgAl ₂ O ₄ (magnesia alumina spinel) may be used. The thickness of the support substrate 10 is 1 to 5 mm. Hereinafter, only the configuration on the upper surface side of the support substrate 10 will be described in consideration of the fact that the shape of the structure is vertically symmetrical. The same applies to the configuration of the lower surface side of the support substrate 10.

  As shown in FIG. 2, in each recess 12 formed on the upper surface (upper main surface) of the support substrate 10, the entire rectangular parallelepiped fuel electrode 20 is formed between the side wall of the fuel electrode 20 and the side wall of the recess 12. It is buried so that a “gap” is formed between them (over the periphery of the fuel electrode 20). That is, in this example, “inclusions consisting of a part of the support substrate 10” are interposed in the region between the adjacent fuel electrodes 20 and 20, and both the adjacent fuel electrodes 20 and 20 are “inclusions”. A gap is formed between the two. The width L of the gap (see FIG. 2) is 0.5 to 100 μm. In this example, the “inclusion consisting of a part of the support substrate 10” corresponds to the protrusion between the adjacent recesses 12 and 12 in the support substrate 10.

  The fuel electrode 20 is a fired body made of a porous material having electron conductivity. The fuel electrode 20 includes a fuel electrode active part 22 that contacts a solid electrolyte membrane 40 described later, and a fuel electrode current collector 21 that is the remaining part other than the fuel electrode active part 22. The shape of the fuel electrode active portion 22 viewed from above is a rectangle extending in the width direction over the range where the recess 12 exists.

  The upper surface (outer surface) of the fuel electrode 20 and the main surface of the support substrate 10 constitute one plane (the same plane as the main surface of the support substrate 10 when the recess 12 is not formed). That is, no step is formed between the upper surface of the fuel electrode 20 and the main surface of the support substrate 10.

The fuel electrode active part 22 may be composed of, for example, NiO (nickel oxide) and YSZ (8YSZ) (yttria stabilized zirconia). Or you may comprise from NiO (nickel oxide) and GDC (gadolinium dope ceria). The fuel electrode current collector 21 can be composed of, for example, NiO (nickel oxide) and YSZ (8YSZ) (yttria stabilized zirconia). Alternatively, it may be composed of NiO (nickel oxide) and Y ₂ O ₃ (yttria), or may be composed of NiO (nickel oxide) and CSZ (calcia stabilized zirconia). The thickness of the anode active portion 22 is 5 to 30 μm, and the thickness of the anode current collecting portion 21 (that is, the depth of the recess 12) is 50 to 500 μm.

An interconnector 30 is formed at a predetermined location on the upper surface of each fuel electrode 20 (more specifically, each fuel electrode current collector 21). The interconnector 30 is a fired body made of a dense material having electronic conductivity. The shape of the interconnector 30 as viewed from above is a rectangle extending in the width direction over the range where the fuel electrode 20 exists. The interconnector 30 can be composed of, for example, LaCrO ₃ (lanthanum chromite). Alternatively, it may be composed of (Sr, La) TiO ₃ (strontium titanate). The thickness of the interconnector 30 is 10 to 100 μm.

  The entire surface of the support substrate 10 with the plurality of fuel electrodes 20 embedded therein, excluding the portion where the plurality of interconnectors 30 are formed on the outer peripheral surface extending in the longitudinal direction, is covered with the solid electrolyte membrane 40. The solid electrolyte membrane 40 is a fired body made of a dense material having ionic conductivity and not electron conductivity. The solid electrolyte membrane 40 can be made of, for example, YSZ (8YSZ) (yttria stabilized zirconia). Or you may comprise from LSGM (lantern gallate). The thickness of the solid electrolyte membrane 40 is 3 to 50 μm.

  That is, the entire outer peripheral surface extending in the longitudinal direction of the support substrate 10 in a state where the plurality of fuel electrodes 20 are embedded is covered with a dense layer composed of the interconnector 30 and the solid electrolyte membrane 40. This dense layer exhibits a gas sealing function that prevents mixing of the fuel gas flowing in the space inside the dense layer and the air flowing in the space outside the dense layer. Here, the “interconnector 30 and the solid electrolyte membrane 40” made of a dense material corresponds to the “gas seal portion”.

  As shown in FIG. 2, in this example, the solid electrolyte membrane 40 covers the upper surface of the fuel electrode 20 and the main surface of the support substrate 10. Here, as described above, no step is formed between the upper surface of the fuel electrode 20 and the main surface of the support substrate 10. Therefore, the solid electrolyte membrane 40 is flattened. As a result, compared with the case where a step is formed in the solid electrolyte membrane 40, the generation of cracks in the solid electrolyte membrane 40 due to stress concentration can be suppressed, and the gas sealing function of the solid electrolyte membrane 40 is reduced. Can be suppressed.

  An air electrode 60 is formed on the upper surface of a portion in contact with each fuel electrode active part 22 in the solid electrolyte membrane 40 via a reaction preventing film 50. The reaction preventing film 50 is a fired body made of a dense material, and the air electrode 60 is a fired body made of a porous material having electron conductivity. The shape of the reaction preventing film 50 and the air electrode 60 viewed from above is substantially the same rectangle as the fuel electrode active part 22.

The reaction preventing film 50 can be made of, for example, GDC = (Ce, Gd) O ₂ (gadolinium-doped ceria). The thickness of the reaction preventing film 50 is 3 to 50 μm. The air electrode 60 can be made of, for example, LSCF = (La, Sr) (Co, Fe) O ₃ (lanthanum strontium cobalt ferrite). Alternatively, from LSF = (La, Sr) FeO ₃ (lanthanum strontium ferrite), LNF = La (Ni, Fe) O ₃ (lanthanum nickel ferrite), LSC = (La, Sr) CoO ₃ (lanthanum strontium cobaltite), etc. It may be configured. Further, the air electrode 60 may be configured by two layers of a first layer (inner layer) made of LSCF and a second layer (outer layer) made of LSC. The thickness of the air electrode 60 is 10 to 100 μm.

  The reaction preventing film 50 is interposed because the YSZ in the solid electrolyte film 40 and the Sr in the air electrode 60 react with each other in the SOFC during the production or operation of the SOFC, and the solid electrolyte film 40 and the air electrode. This is to suppress the occurrence of a phenomenon in which a reaction layer having a large electric resistance is formed at the interface with the film.

  Here, the laminated body formed by laminating the fuel electrode 20, the solid electrolyte membrane 40, the reaction preventing membrane 50, and the air electrode 60 corresponds to the “power generation element portion A” (see FIG. 2). In other words, a plurality (four in this example) of power generating element portions A are arranged on the upper surface of the support substrate 10 at a predetermined interval in the longitudinal direction.

  For each pair of adjacent power generation element portions A and A, the air electrode 60 of one power generation element portion A (on the left side in FIG. 2) and the interconnector of the other power generation element portion A (on the right side in FIG. 2). The air electrode current collecting film 70 is formed on the upper surfaces of the air electrode 60, the solid electrolyte film 40, and the interconnector 30. The air electrode current collector film 70 is a fired body made of a porous material having electron conductivity. The shape of the air electrode current collector film 70 as viewed from above is a rectangle.

The air electrode current collector film 70 can be made of, for example, LSCF = (La, Sr) (Co, Fe) O ₃ (lanthanum strontium cobalt ferrite). Alternatively, LSC = (La, Sr) CoO ₃ (lanthanum strontium cobaltite) may be used. Or you may comprise from Ag (silver) and Ag-Pd (silver palladium alloy). The thickness of the air electrode current collector film 70 is 50 to 500 μm.

  By forming each air electrode current collecting film 70 in this way, for each pair of adjacent power generation element portions A and A, the air electrode 60 of one power generation element portion A (on the left side in FIG. 2), The other fuel electrode 20 (particularly, the fuel electrode current collector 21) of the power generating element part A (on the right side in FIG. 2) passes through the “air electrode current collector film 70 and interconnector 30” having electronic conductivity. Are electrically connected. As a result, a plurality (four in this example) of power generation element portions A arranged on the upper surface of the support substrate 10 are electrically connected in series. Here, the “air electrode current collector film 70 and the interconnector 30” having electronic conductivity correspond to “electrical connection portions”.

As shown in FIG. 3, the fuel gas (hydrogen gas or the like) flows through the fuel gas flow path 11 of the support substrate 10 with respect to the “horizontal stripe type” SOFC structure described above. By exposing the upper and lower surfaces (particularly, each air electrode current collecting film 70) to “gas containing oxygen” (air or the like) (or flowing a gas containing oxygen along the upper and lower surfaces of the support substrate 10), the solid electrolyte An electromotive force is generated by an oxygen partial pressure difference generated between both side surfaces of the film 40. Furthermore, when this structure is connected to an external load, chemical reactions shown in the following formulas (1) and (2) occur, and current flows (power generation state).
(1/2) · O ₂ + 2e ⁻ → O ²⁻ (where: air electrode 60) (1)
H ₂ + O ²⁻ → H ₂ O + 2e ⁻
(At: Fuel electrode 20) (2)

  In the power generation state, as shown in FIG. 4, current flows as indicated by an arrow in each pair of adjacent power generation element portions A and A. As a result, as shown in FIG. 3, the SOFC structure as a whole (specifically, the interconnector 30 of the power generating element portion A on the foremost side in FIG. 3 and the air electrode of the power generating element portion A on the farthest side in FIG. The power is extracted (via 60).

(Production method)
Next, an example of a manufacturing method of the “horizontal stripe type” SOFC structure shown in FIG. 1 will be briefly described with reference to FIGS. 5 to 12, “g” at the end of the reference numeral of each member indicates that the member is “before firing”.

  First, a support substrate molded body 10g having the shape shown in FIG. 5 is produced. The molded body 10g of the support substrate is manufactured by using a method such as extrusion molding or cutting using a slurry obtained by adding a binder or the like to the material of the support substrate 10 (for example, CSZ). obtain. Hereinafter, description will be continued with reference to FIGS. 6 to 12 showing partial cross sections corresponding to line 6-6 shown in FIG.

  As shown in FIG. 6, when the support substrate molded body 10g is manufactured, next, as shown in FIG. 7, the fuel electrode molded body (21g + 22g) is formed in each recess in the upper and lower surfaces of the support substrate molded body 10g. ) Is buried and formed. This molded body (21g + 22g) is embedded and formed so that a “gap” is formed between the side wall of the molded body and the side wall of the recess (over the periphery of the molded body). The molded body (21g + 22g) of each fuel electrode is embedded using, for example, a printing method using a slurry obtained by adding a binder or the like to the powder of the material of the fuel electrode 20 (for example, Ni and YSZ). It is formed.

Next, as shown in FIG. 8, a molded film 30g of the interconnector is formed at a predetermined location on the outer surface of the molded body 21g of each fuel electrode. The molded film 30g of each interconnector is formed by using a printing method or the like using a slurry obtained by adding a binder or the like to the powder of the material of the interconnector 30 (for example, LaCrO ₃ ).

  Next, as shown in FIG. 9, a plurality of interconnector molded bodies 30g on the outer peripheral surface extending in the longitudinal direction of the molded body 10g of the support substrate in a state where a plurality of molded fuel electrode bodies (21g + 22g) are embedded and formed. A solid electrolyte membrane molding film 40g is formed on the entire surface excluding the portion where is formed. The molded membrane 40g of the solid electrolyte membrane is formed using, for example, a printing method, a dipping method, etc., using a slurry obtained by adding a binder or the like to the powder of the material of the solid electrolyte membrane 40 (for example, YSZ). The

  Next, as shown in FIG. 10, a reaction preventing film forming film 50 g is formed on the outer surface of the solid electrolyte film forming body 40 g in contact with the fuel electrode forming body 22 g. The molded film 50g of each reaction preventing film is formed using a slurry obtained by adding a binder or the like to the powder of the material (for example, GDC) of the reaction preventing film 50, using a printing method or the like.

  Then, 10 g of the support substrate molded body in which various molded films are thus formed is fired in air at 1500 ° C. for 3 hours. As a result, a structure in which the air electrode 60 and the air electrode current collector film 70 are not formed in the SOFC structure shown in FIG. 1 is obtained.

  Next, as shown in FIG. 11, an air electrode forming film 60 g is formed on the outer surface of each reaction preventing film 50. The molded film 60g of each air electrode is formed using a slurry obtained by adding a binder or the like to the powder of the material of the air electrode 60 (for example, LSCF), using a printing method or the like.

  Next, as shown in FIG. 12, for each pair of adjacent power generation element portions, air is formed so as to straddle the air electrode forming film 60 g of one power generation element portion and the interconnector 30 of the other power generation element portion. On the outer surface of the electrode forming film 60g, the solid electrolyte film 40, and the interconnector 30, a formed film 70g of the air electrode current collecting film is formed. The forming film 70g of each air electrode current collector film is obtained by using a slurry obtained by adding a binder or the like to the powder of the material of the air electrode current collector film 70 (for example, LSCF), using a printing method or the like. It is formed.

  Then, the support substrate 10 in which the molded films 60g and 70g are thus formed is baked in air at 1050 ° C. for 3 hours. As a result, the SOFC structure shown in FIG. 1 is obtained. The example of the method for manufacturing the SOFC structure shown in FIG. 1 has been described above.

(Action / Effect)
As described above, in the “horizontal stripe type” SOFC structure according to the above-described embodiment of the present invention, the “inclusion consisting of a part of the support substrate 10” is formed in the region between the adjacent fuel electrodes 20, 20. (= Protrusions between adjacent recesses 12 and 12 in the support substrate 10) are interposed, and “gap” is formed between both of the adjacent fuel electrodes 20 and 20 and “inclusions”. . Here, “a gap” is formed means that the two are completely separated.

  According to this, even if reduction contraction / oxidation expansion occurs in the fuel electrode 20 (particularly in the direction along the extending direction of the main surface of the support substrate 10) due to the formation of the “gap”, the “inclusion” Is less susceptible to tensile and compressive stresses from the fuel electrode. In other words, the “gap” functions as a “buffer area”. As a result, due to the reduction contraction / oxidation expansion of the fuel electrode 20, it is difficult for a situation in which a crack or the like is generated near the interface between the solid electrolyte membrane 40 surrounding the “inclusions” and the “inclusions”. As a result, problems such as deterioration of the gas seal function of the gas seal portion (= solid electrolyte membrane 40 + interconnector 30) are less likely to occur.

  Further, in the above-described embodiment, a plurality of power generation element portions A are provided on each of the upper and lower surfaces of the flat support substrate 10. Thereby, compared with the case where a plurality of power generation element portions are provided only on one side surface of the support substrate, the number of power generation element portions in the structure can be increased, and the power generation output of the fuel cell can be increased.

  In the above embodiment, the solid electrolyte membrane 40 covers the outer surface of the fuel electrode 20 and the main surface of the support substrate 10. Here, no step is formed between the outer surface of the fuel electrode 20 and the main surface of the support substrate 10. Therefore, the solid electrolyte membrane 40 is flattened. As a result, compared with the case where a step is formed in the solid electrolyte membrane 40, the generation of cracks in the solid electrolyte membrane 40 due to stress concentration can be suppressed, and the gas sealing function of the solid electrolyte membrane 40 is reduced. Can be suppressed.

  In addition, this invention is not limited to the said embodiment, A various modification can be employ | adopted within the scope of the present invention. For example, in the above embodiment, as shown in FIG. 5 and the like, the planar shape of the recess 12 formed in the support substrate 10 (the shape when viewed from the direction perpendicular to the main surface of the support substrate 10) is a rectangle. For example, it may be a square, a circle, an ellipse, or the like.

  Moreover, in the said embodiment, although the several recessed part 12 is formed in each of the upper and lower surfaces of the flat support substrate 10, and the several electric power generation element part A is provided, as shown in FIG. A plurality of recesses 12 may be formed only on one side of the ten and a plurality of power generation element portions A may be provided. Further, in the above embodiment, the fuel electrode 20 is composed of two layers of the fuel electrode current collector 21 and the fuel electrode active portion 22, but the fuel electrode 20 is a single layer corresponding to the fuel electrode active portion 22. It may be configured.

  In the above embodiment, a “gap” is formed between both of the adjacent fuel electrodes 20 and 20 and “inclusions” (that is, both of the adjacent fuel electrodes 20 and 20 are “intervened”. However, a “gap” is formed only between one of the adjacent fuel electrodes 20 and 20 and “inclusions”, and the other of the adjacent fuel electrodes 20 and 20 and “inclusions”. No “gap” may be formed between the two. That is, one of the adjacent fuel electrodes 20 and 20 may not be in contact with the “inclusion”, and the other of the adjacent fuel electrodes 20 and 20 may be in contact with the “inclusion”.

  Further, in the above-described embodiment, “inclusions” that are part of the support substrate 10 (= adjacent recesses 12 in the support substrate 10) are used as “inclusions” interposed in the region between the adjacent fuel electrodes 20, 20. , 12), as shown in FIG. 14, “inclusions consisting of a part of the gas seal portion” may exist as “inclusions”. In the example shown in FIG. 14, “a dense membrane made of the same material as the solid electrolyte membrane 40” that is “a part of the gas seal portion” exists as “inclusions”, but “a part of the gas seal portion”. There may be a “dense membrane made of a material different from the solid electrolyte membrane 40”.

  Further, as shown in FIG. 15, “inclusions including a part of the gas seal part and a part of the electrical connection part” may exist as the “inclusions”. In the example shown in FIG. 15, “inclusions” are “a part of the gas seal part” “a dense film made of the same material as the solid electrolyte membrane 40” and “a part of the electrical connection part”. 30 is a “dense film made of the same material as that of 30”, but “a part of the gas seal part” is “a dense film made of a material different from the solid electrolyte film 40” and “a part of the electrical connection part”. “Dense film made of a material different from the interconnector 30” may exist.

  In the above embodiment, the interconnector 30 is formed (laminated) on the outer surface of the fuel electrode 20. However, as shown in FIGS. 16 and 17, the interconnector 30 is formed on the outer surface of the fuel electrode 20. It may be embedded in the recess. Hereinafter, main differences between the above-described embodiments and the modes illustrated in FIGS. 16 and 17 will be briefly described.

  In the form shown in FIGS. 16 and 17, a plurality of recesses 12 are formed on the main surface (upper and lower surfaces) of the support substrate 10 at predetermined intervals in the longitudinal direction. Each recess 12 has a bottom wall made of the material of the support substrate 10 and side walls closed in the circumferential direction made of the material of the support substrate 10 (two side walls along the longitudinal direction and two side walls along the width direction). ) And a rectangular parallelepiped depression defined by In each recess 12 formed on the upper surface (main surface) of the support substrate 10, the entire rectangular parallelepiped fuel electrode current collector 21 is located between the side wall of the fuel electrode current collector 21 and the side wall of the recess 12 ( It is embedded so that a “gap” is formed (around the anode current collector 21). In other words, an “inclusion comprising a part of the support substrate 10” is interposed in the region between the adjacent anode current collectors 21 and 21, and both the adjacent anode current collectors 21 and 21 Gaps are respectively formed between the “inclusions”. In this example, the “inclusion consisting of a part of the support substrate 10” corresponds to the protrusion between the adjacent recesses 12 and 12 in the support substrate 10.

  In this example, a “gap” is formed between both of the adjacent anode current collectors 21 and 21 and “inclusions” (= protrusions between adjacent recesses 12 and 12) ( That is, the “inclusion” is not in contact with any of the adjacent fuel electrodes 20, 20), but a “gap” is formed only between one of the adjacent fuel electrode current collectors 21, 21 and the “inclusion”. A “gap” may not be formed between the other of the fuel electrode current collectors 21, 21 that are formed and “inclusions”. That is, one of the adjacent anode current collectors 21 and 21 is not in contact with the “inclusion”, and the other of the adjacent anode current collectors 21 and 21 is in contact with the “inclusion”. Also good.

  A recess 21 a is formed on the upper surface (outer surface) of each fuel electrode current collector 21. Each recess 21a has a rectangular parallelepiped shape defined by a bottom wall made of the material of the fuel electrode current collector 21 and side walls closed in the circumferential direction (two side walls along the longitudinal direction and two side walls along the width direction). It is a depression. Of the side walls closed in the circumferential direction, two side walls along the longitudinal direction are made of the material of the support substrate 10, and two side walls along the width direction are made of the material of the fuel electrode current collector 21.

  The entire anode active portion 22 is embedded (filled) in each recess 21a. Accordingly, each fuel electrode active portion 22 has a rectangular parallelepiped shape. A fuel electrode 20 is configured by the fuel electrode current collector 21 and the fuel electrode active unit 22. The fuel electrode 20 (fuel electrode current collector 21 + fuel electrode active part 22) is a fired body made of a porous material having electron conductivity. The two side surfaces and the bottom surface along the width direction of each anode active portion 22 are in contact with the anode current collecting portion 21 in the recess 21a.

  A recess 21b is formed in a portion of the upper surface (outer surface) of each fuel electrode current collector 21 excluding the recess 21a. Each recess 21b includes a bottom wall made of a material of the fuel electrode current collector 21 and a circumferentially closed side wall made of the material of the fuel electrode current collector 21 (two side walls along the longitudinal direction). And two side walls along the width direction).

  An interconnector 30 is embedded (filled) in each recess 21b. Accordingly, each interconnector 30 has a rectangular parallelepiped shape. The interconnector 30 is a fired body made of a dense material having electronic conductivity. The four side walls (two side walls along the longitudinal direction and two side walls along the width direction) and the bottom surface of each interconnector 30 are in contact with the fuel electrode current collector 21 in the recess 21b.

  The upper surface (outer surface) of the fuel electrode 20 (the fuel electrode current collector 21 and the fuel electrode active unit 22), the upper surface (outer surface) of the interconnector 30, and the main surface of the support substrate 10 form one plane (recessed portion). The same plane as the main surface of the support substrate 10 when 12 is not formed) is formed. That is, no step is formed between the upper surface of the fuel electrode 20, the upper surface of the interconnector 30, and the main surface of the support substrate 10.

The fuel electrode active part 22 may be composed of, for example, NiO (nickel oxide) and YSZ (8YSZ) (yttria stabilized zirconia). Or you may comprise from NiO (nickel oxide) and GDC (gadolinium dope ceria). The fuel electrode current collector 21 can be composed of, for example, NiO (nickel oxide) and YSZ (8YSZ) (yttria stabilized zirconia). Alternatively, it may be composed of NiO (nickel oxide) and Y ₂ O ₃ (yttria), or may be composed of NiO (nickel oxide) and CSZ (calcia stabilized zirconia). The thickness of the anode active portion 22 is 5 to 30 μm, and the thickness of the anode current collecting portion 21 (that is, the depth of the recess 12) is 50 to 500 μm.

  As described above, the fuel electrode current collector 21 includes a substance having electronic conductivity. The fuel electrode active part 22 includes a substance having electron conductivity and a substance having oxidative ion (oxygen ion) conductivity. The “volume ratio of the substance having oxidative ion conductivity relative to the total volume excluding the pore portion” in the anode active portion 22 is “the oxidative ion conductivity relative to the entire volume excluding the pore portion” in the anode current collecting portion 21. Greater than the volume fraction of the substance having

The interconnector 30 can be composed of, for example, LaCrO ₃ (lanthanum chromite). Alternatively, it may be composed of (Sr, La) TiO ₃ (strontium titanate). The thickness of the interconnector 30 is 10 to 100 μm.

  The entire surface excluding the central portion in the longitudinal direction of each portion where the plurality of interconnectors 30 are formed on the outer peripheral surface extending in the longitudinal direction of the support substrate 10 in a state where the fuel electrode 20 and the interconnector 30 are embedded in the respective recesses 12. Is covered with a solid electrolyte membrane 40. The solid electrolyte membrane 40 is a fired body made of a dense material having ionic conductivity and not electron conductivity. The solid electrolyte membrane 40 can be made of, for example, YSZ (8YSZ) (yttria stabilized zirconia). Or you may comprise from LSGM (lantern gallate). The thickness of the solid electrolyte membrane 40 is 3 to 50 μm.

  That is, the entire outer peripheral surface extending in the longitudinal direction of the support substrate 10 in a state where the fuel electrode 20 is embedded in each recess 12 is covered with a dense layer composed of the interconnector 30 and the solid electrolyte membrane 40. This dense layer exhibits a gas sealing function that prevents mixing of the fuel gas flowing in the space inside the dense layer and the air flowing in the space outside the dense layer.

  As shown in FIG. 16, in this example, the solid electrolyte membrane 40 covers the upper surface of the fuel electrode 20, both side ends in the longitudinal direction on the upper surface of the interconnector 30, and the main surface of the support substrate 10. Here, as described above, no step is formed between the upper surface of the fuel electrode 20, the upper surface of the interconnector 30, and the main surface of the support substrate 10. Therefore, the solid electrolyte membrane 40 is flattened. As a result, compared with the case where a step is formed in the solid electrolyte membrane 40, the generation of cracks in the solid electrolyte membrane 40 due to stress concentration can be suppressed, and the gas sealing function of the solid electrolyte membrane 40 is reduced. Can be suppressed.

  An air electrode 60 is formed on the upper surface of a portion in contact with each fuel electrode active part 22 in the solid electrolyte membrane 40 via a reaction preventing film 50. The reaction preventing film 50 is a fired body made of a dense material, and the air electrode 60 is a fired body made of a porous material having electron conductivity. The shape of the reaction preventing film 50 and the air electrode 60 viewed from above is substantially the same rectangle as the fuel electrode active part 22.

The reaction preventing film 50 can be made of, for example, GDC = (Ce, Gd) O ₂ (gadolinium-doped ceria). The thickness of the reaction preventing film 50 is 3 to 50 μm. The air electrode 60 can be made of, for example, LSCF = (La, Sr) (Co, Fe) O ₃ (lanthanum strontium cobalt ferrite). Alternatively, from LSF = (La, Sr) FeO ₃ (lanthanum strontium ferrite), LNF = La (Ni, Fe) O ₃ (lanthanum nickel ferrite), LSC = (La, Sr) CoO ₃ (lanthanum strontium cobaltite), etc. It may be configured. Further, the air electrode 60 may be configured by two layers of a first layer (inner layer) made of LSCF and a second layer (outer layer) made of LSC. The thickness of the air electrode 60 is 10 to 100 μm.

  The reaction preventing film 50 is interposed because the YSZ in the solid electrolyte film 40 and the Sr in the air electrode 60 react with each other in the SOFC during the production or operation of the SOFC, and the solid electrolyte film 40 and the air electrode. This is to suppress the occurrence of a phenomenon in which a reaction layer having a large electric resistance is formed at the interface with the film.

  Here, the laminated body formed by laminating the fuel electrode 20, the solid electrolyte membrane 40, the reaction preventing membrane 50, and the air electrode 60 corresponds to the “power generation element portion A” (see FIG. 16). In other words, a plurality (four in this example) of power generating element portions A are arranged on the upper surface of the support substrate 10 at a predetermined interval in the longitudinal direction.

  For each pair of adjacent power generation element parts A and A, the air electrode 60 of one power generation element part A (on the left side in FIG. 16) and the interconnector of the other power generation element part A (on the right side in FIG. 16). The air electrode current collecting film 70 is formed on the upper surfaces of the air electrode 60, the solid electrolyte film 40, and the interconnector 30. The air electrode current collector film 70 is a fired body made of a porous material having electron conductivity. The shape of the air electrode current collector film 70 as viewed from above is a rectangle.

The air electrode current collector film 70 can be made of, for example, LSCF = (La, Sr) (Co, Fe) O ₃ (lanthanum strontium cobalt ferrite). Alternatively, LSC = (La, Sr) CoO ₃ (lanthanum strontium cobaltite) may be used. Or you may comprise from Ag (silver) and Ag-Pd (silver palladium alloy). The thickness of the air electrode current collector film 70 is 50 to 500 μm.

  By forming each air electrode current collecting film 70 in this way, the air electrode 60 of one power generation element part A (on the left side in FIG. 16) of each pair of adjacent power generation element parts A and A, The other fuel electrode 20 (in particular, the fuel electrode current collector 21) of the power generating element part A (on the right side in FIG. 16) is connected via the “air electrode current collector film 70 and interconnector 30” having electronic conductivity. Are electrically connected. As a result, a plurality (four in this example) of power generation element portions A arranged on the upper surface of the support substrate 10 are electrically connected in series. Here, the “air electrode current collector film 70 and the interconnector 30” having electronic conductivity correspond to the “electrical connection part”.

  The interconnector 30 corresponds to the “first portion made of a dense material” in the “electrical connection portion” and has a porosity of 10% or less. The air electrode current collecting film 70 corresponds to the “second portion made of a porous material” in the “electrical connection portion”, and has a porosity of 20 to 60%.

  As described above, in the form shown in FIGS. 16 and 17, the “gap” functions as the “buffer area” for the same reason as in the above embodiment. As a result, due to the reduction contraction / oxidation expansion of the fuel electrode 20, it is difficult for a situation in which a crack or the like is generated near the interface between the solid electrolyte membrane 40 surrounding the “inclusions” and the “inclusions”. As a result, problems such as deterioration of the gas seal function of the gas seal portion (= solid electrolyte membrane 40 + interconnector 30) are less likely to occur.

  Further, each of the plurality of recesses 12 for embedding the fuel electrode 20 has a side wall closed in the circumferential direction made of the material of the support substrate 10 over the entire circumference. In other words, the support body 10 is formed with a frame surrounding each recess 12. Therefore, this structure is not easily deformed when the support substrate 10 receives an external force.

  Further, the support substrate 10 and the embedded member are co-sintered in a state in which the members such as the fuel electrode 20 and the interconnector 30 are filled and embedded in the recesses 12 of the support substrate 10 without any gap. Therefore, a sintered body having high bondability between members and high reliability can be obtained.

  Further, the interconnector 30 is embedded in a recess 21b formed on the outer surface of the fuel electrode current collector 21, and as a result, the four sidewalls of the rectangular parallelepiped interconnector 30 (two sidewalls along the longitudinal direction, width) Two side walls along the direction) and the bottom face are in contact with the anode current collector 21 in the recess 21b. Therefore, the fuel electrode 20 (the current collector 21) and the interconnector 30 are compared to the case where a configuration in which the rectangular parallelepiped interconnector 30 is laminated (contacted) on the outer plane of the fuel electrode current collector 21 is employed. The area of the interface with can be increased. Therefore, the electronic conductivity between the fuel electrode 20 and the interconnector 30 can be increased, and as a result, the power generation output of the fuel cell can be increased.

  Further, in the above-described embodiment, a plurality of power generation element portions A are provided on each of the upper and lower surfaces of the flat support substrate 10. Thereby, compared with the case where a plurality of power generation element portions are provided only on one side surface of the support substrate, the number of power generation element portions in the structure can be increased, and the power generation output of the fuel cell can be increased.

  In the above embodiment, the solid electrolyte membrane 40 covers the outer surface of the fuel electrode 20, both end portions in the longitudinal direction of the outer surface of the interconnector 30, and the main surface of the support substrate 10. Here, no step is formed between the outer surface of the fuel electrode 20, the outer surface of the interconnector 30, and the main surface of the support substrate 10. Therefore, the solid electrolyte membrane 40 is flattened. As a result, compared with the case where a step is formed in the solid electrolyte membrane 40, the generation of cracks in the solid electrolyte membrane 40 due to stress concentration can be suppressed, and the gas sealing function of the solid electrolyte membrane 40 is reduced. Can be suppressed. In the above embodiment, the “inner electrode” and the “outer electrode” are the fuel electrode and the air electrode, respectively, but they may be reversed.

  Further, in each of the above-described embodiments shown in FIGS. 2, 14, 15, and 16, a “gap” is formed between the fuel electrode current collector 21 and the “inclusions”. In contrast, as shown in FIGS. 18, 19, 20, and 21 corresponding to FIGS. 2, 14, 15, and 16, respectively, the anode current collector 21 and the “inclusions” In the meantime, instead of “gap”, “high porosity portion B” may be formed. The high porosity portion B is a portion that is porous and has a larger porosity than the anode current collector 21 and the “inclusions”. Specifically, when the “inclusion” is porous (in the case of the protruding portion of the support substrate 10 shown in FIGS. 18 and 21), the porosity of the “inclusion” is 20 to 60%, and the fuel electrode assembly The porosity of the electric part 21 (inner electrode) is 25 to 50%, and the porosity of the high porosity part B is 25 to 80%.

  DESCRIPTION OF SYMBOLS 10 ... Support substrate, 11 ... Fuel gas flow path, 12 ... Recessed part, 20 ... Fuel electrode, 21 ... Fuel electrode current collecting part, 21a, 21b ... Recessed part, 22 ... Fuel electrode active part, 30 ... Interconnector, 40 ... Solid Electrolyte membrane, 50 ... reaction preventing membrane, 60 ... air electrode, 70 ... air electrode current collector membrane, A ... power generation element section

Claims (6)

A porous support substrate having a fuel gas passage formed therein;
A plurality of power generating element portions each provided at a plurality of locations apart from each other on the outer surface of the support substrate, wherein at least a fuel electrode, a solid electrolyte, and an air electrode are stacked in this order;
One or a plurality of electrical connections that are respectively provided between one or a plurality of adjacent power generation element portions and electrically connect one fuel electrode and the other air electrode of the adjacent power generation element portions. And
A dense material that is provided between one or a plurality of adjacent power generation element portions and prevents mixing of the fuel gas supplied to the fuel electrode and the gas containing oxygen supplied to the air electrode. A gas seal,
In a fuel cell structure comprising:
Any one of a part of the support substrate, a part of the electrical connection part, and a part of the gas seal part in a region between the adjacent fuel electrodes respectively belonging to the adjacent power generation element parts. Or one or both of the adjacent fuel electrodes and the inclusion has a gap or a porosity as compared with the fuel electrode and the inclusion. A fuel cell structure in which a large high porosity portion is formed. The fuel cell structure according to claim 1,
The fuel cell structure in which the gap or the high porosity portion is formed between both of the adjacent fuel electrodes and the inclusion. In the structure of the fuel cell according to claim 1 or 2,
The fuel electrode is a fuel having a small content ratio of a substance having oxidizing ion conductivity with respect to the fuel electrode active part that is in contact with the solid electrolyte and the fuel electrode active part that is the remaining part other than the fuel electrode active part. A fuel cell structure comprising an electrode current collector. A flat porous support substrate having a gas flow path formed therein;
A plurality of power generating element portions each provided at a plurality of positions separated from each other on the main surface of the flat support substrate, and a laminate of at least an inner electrode, a solid electrolyte, and an outer electrode;
One or a plurality of electrical connections that are respectively provided between one set or a plurality of sets of adjacent power generation element portions and electrically connect one inner electrode and the other outer electrode of the adjacent power generation element portions And
In a fuel cell structure comprising:
Each of the electrical connection portions includes a first portion made of a dense material, and a second portion made of a porous material connected to the first portion,
A first recess having a bottom wall made of the material of the support substrate and a side wall made of the material of the support substrate over the entire circumference at the plurality of locations on the main surface of the flat support substrate. Each formed,
In each of the first recesses, a corresponding inner electrode of the power generation element portion is embedded,
The first portion of the corresponding electrical connection portion is embedded in the second recess formed on the outer surface of each embedded inner electrode,
Each of the second recesses in which the corresponding first portion of the electrical connection portion is embedded is closed in the circumferential direction made of the material of the inner electrode and the bottom wall made of the material of the inner electrode. Having side walls,
A gap or the inner electrode between the protruding portion between the adjacent first recesses on the support substrate and one or both of the adjacent inner electrodes embedded in the adjacent first recesses, respectively. And the structure of the fuel cell in which the high porosity part whose porosity is large compared with the said protrusion part was formed. In the structure of the fuel cell according to any one of claims 1 to 4,
When the gap is formed, the fuel cell structure has a width of 0.5 to 100 μm. In the structure of the fuel cell according to any one of claims 1 to 4,
When the high porosity portion is formed, the inclusion or the protrusion has a porosity of 20 to 60%, the fuel electrode or the inner electrode has a porosity of 25 to 50%, and the high porosity A fuel cell structure having a porosity of 25 to 80%.

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