JP5620785B2 - Fuel cell - Google Patents

Description

  The present invention relates to a fuel battery cell.

  Conventionally, “a flat porous support substrate having gas passages formed therein along the longitudinal direction” and “an inner electrode provided at a plurality of locations apart from each other on the main surface of the support substrate” , A plurality of power generating element portions in which a solid electrolyte and an outer electrode are laminated ”and“ inside one of the adjacent power generating element portions provided between one or a plurality of adjacent power generating element portions, respectively ” "One or more electrical connections for electrically connecting the electrode and the other outer electrode" and "dense to prevent mixing of the gas supplied to the inner electrode and the gas supplied to the outer electrode" There is known a fuel battery cell including a “gas seal portion made of a material” (for example, see Patent Document 1). Such a configuration is also called a “horizontal stripe type”. In the fuel battery cell described in this document, the gas seal portion is a dense insulator formed so as to cover the side end portion of the support substrate that extends along the longitudinal direction and has an outwardly convex curved shape. Have

  In such a fuel cell, by making the shape of the fuel cell flat (thin plate), the area of the power generation unit per fuel cell can be increased, and as a result, the power generation amount can be increased. Can do. However, if the shape of the fuel cell is flat, the curvature of the curved shape of the side end portion of the support substrate increases, and the curvature of the curved shape of the dense insulator covering the side end portion also increases. As a result, the stress acting on the insulator increases. As a result, there arises a problem that cracks are likely to occur in the insulator during the firing process performed in the manufacturing process of the fuel cell or during power generation of the fuel cell.

  If a crack occurs in the insulator, gas shutoff between the inside and outside of the fuel cell cannot be achieved, and the oxygen partial pressure difference between the inside and outside of the fuel cell decreases. As a result, the power generation performance of the fuel cell decreases. Therefore, it has been desired to suppress the occurrence of cracks in the insulator.

JP 2008-226789 A

  An object of the present invention is to provide a “horizontal stripe type” fuel cell that can suppress the occurrence of cracks in a dense insulator covering the side edge of a support substrate.

  The fuel cell according to the present invention includes a “flat porous support substrate having a gas flow path formed therein along a longitudinal direction” and “a plurality of locations separated from each other on the main surface of the support substrate”. Each of the plurality of power generation element portions formed by laminating at least the inner electrode, the solid electrolyte, and the outer electrode ”and“ one set or a plurality of sets of adjacent power generation element portions, respectively, “One or more electrical connection portions for electrically connecting one inner electrode and the other outer electrode of the power generation element portion”, “a gas supplied to the inner electrode and a gas supplied to the outer electrode” And a gas seal portion made of a dense material that prevents mixing with the gas. That is, this cell is a “horizontal stripe type” fuel cell. The gas seal portion includes a dense insulator formed so as to cover a side end portion extending along the longitudinal direction of the support substrate.

The fuel cell according to the present invention is characterized in that the thickness of the insulator corresponding to the end portion of the insulator in the plate thickness direction of the support substrate is T1, and the insulator corresponding to the side surface of the side end portion. When the maximum thickness of T2 is T2, the relationship 5.1 <T2 / T1 <300 is established. Here, when the insulator has a curved shape that protrudes outward in the width direction perpendicular to the longitudinal direction, the maximum thickness of the insulator corresponds to an end of the curved shape in the protruding direction. A thickness is preferred.

The present inventor found that if T2 / T1 <1 or T2 / T1> 300, cracks are likely to occur in the insulator, and if 1 ≦ T2 / T1 ≦ 300, cracks occur in the insulator. It has also been found that if 5.1 ≦ T2 / T1 ≦ 300, it is particularly difficult for the insulator to crack . This will be described later. Therefore, according to the above configuration, the generation of cracks in the insulator is suppressed, and the gas can be reliably shut off between the inside and outside of the fuel cell, and the degradation of the power generation performance of the fuel cell is reliably suppressed. be able to.

1 is a perspective view showing a fuel battery cell according to an embodiment of the present invention. It is sectional drawing corresponding to the 2-2 line of the fuel battery cell shown in FIG. It is a perspective view corresponding to Drawing 1 of a fuel cell concerning a modification of an embodiment of the present invention. It is a perspective view corresponding to FIG. 1 of the fuel battery cell which concerns on the other modification of embodiment of this invention. It is a figure for demonstrating the operation state of the fuel battery cell shown in FIG. It is a figure for demonstrating the flow of the electric current in the operating state of the fuel battery 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 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 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 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 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 shown in FIG. 1. FIG. 6 is a cross-sectional view corresponding to FIG. 2 in a sixth stage in the manufacturing process of the fuel cell 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 shown in FIG. 1. It is sectional drawing corresponding to FIG. 2 of the fuel cell concerning the other modification of embodiment of this invention.

(Constitution)
FIG. 1 shows a solid oxide fuel cell (SOFC) cell according to an embodiment of the present invention. This SOFC cell has a plurality (four in this example) electrically connected in series to the upper and lower surfaces (main surfaces (planes) on both sides parallel to each other) of the flat support substrate 10 having a longitudinal direction. ) Having the same shape, the so-called “horizontal stripe type” is disposed at predetermined intervals in the longitudinal direction.

  The shape of the entire SOFC cell 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 this SOFC cell is 1-5 mm. The entire SOFC cell preferably 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, but is not limited thereto. Hereinafter, in addition to FIG. 1, the details of the SOFC cell will be described with reference to FIG. 2, which is a partial cross-sectional view of the SOFC cell corresponding to line 2-2 shown in FIG. 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. The side end portion of the support substrate 10 has a curved surface that is convex outward (in the width direction). A plurality (six in this example) of fuel gas passages 11 (through holes) extending in the longitudinal direction are formed in the support substrate 10 at predetermined intervals in the width direction.

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 for simplification of description. The same applies to the configuration of the lower surface side of the support substrate 10.

  As shown in FIG. 2, a rectangular parallelepiped fuel electrode 20 is provided on the upper surface (upper main surface) of 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 anode active portion 22 viewed from above is a rectangle extending in the width direction over the range where the anode current collecting portion 21 exists.

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 outer surface of the support substrate 10 in the state where the plurality of fuel electrodes 20 are provided, excluding the portion where the plurality of interconnectors 30 are formed, 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 may be composed of, for example, YSZ (yttria stabilized zirconia) containing Y ₂ O ₃ (yttria). 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 provided 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”.

  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 substrate 60.

  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”.

  In this SOFC cell, a part of the solid electrolyte membrane 40 that is formed so as to cover the side end of the support substrate 10 (a part having a curved surface protruding outward) corresponds to the “insulator”. To do. That is, in this SOFC cell, the “insulator” consists only of the solid electrolyte membrane 40 layer. As shown in FIG. 1, the (layer) thickness of the “insulator” corresponding to the end portion (end portion in the vertical direction in the figure) of the “insulator” in the plate thickness direction (vertical direction in the figure) of the support substrate 10. When the thickness is T1 and the maximum thickness of the “insulator” (layer) corresponding to the side surface of the side end portion of the support substrate 10 is T2, the relationship 1 <T2 / T1 <300 is established. In this example, T2 is the thickness of the “insulator” corresponding to the end in the protruding direction (the end in the left-right direction in the figure) in the curved shape of the side end, but T2 is the curved surface of the side end. The thickness of the “insulator” corresponding to a portion other than the end in the protruding direction in the shape may be used.

  Specifically, in the form shown in FIG. 1, the end portion of the “insulator” in the vertical direction of the figure is composed only of the layer of the solid electrolyte membrane 40. Therefore, T1 is equal to the thickness of only the layer of the solid electrolyte membrane 40 in this portion. Further, the end portion of the “insulator” (the portion where the thickness of the “insulator” is maximized) in the left-right direction in the figure is also composed of only the solid electrolyte membrane 40 layer. Therefore, T2 is equal to the thickness of only the layer of the solid electrolyte membrane 40 in this portion.

  T1 is expressed as the thickness of the “insulator” corresponding to the edge in the thickness direction of the support substrate 10 in the range of the “insulator” that can be seen when the side surface of the fuel cell is viewed from the outside along the width direction. You can also. T1 is, for example, 20 to 40 μm.

In such a fuel cell, the dense “insulator” formed at the side end of the support substrate 10 does not need to be formed only from the solid electrolyte membrane 40. For example, as shown in FIG. 3, a laminate in which another dense insulator 80 is formed on the outer surface of the solid electrolyte membrane 40 may be used as the “insulator”. Although not shown, a laminate in which another dense insulator is formed on the inner surface of the solid electrolyte membrane 40 may be used. In this case, as another dense insulator, for example, another solid electrolyte such as 10Sc1CeZrO ₂ may be used, or a substance other than the solid electrolyte such as glass or ZrO ₂ may be used.

  Further, as shown in FIG. 4, the solid electrolyte membrane 40 (portion not corresponding to the “insulator”) formed on the main surface of the support substrate 10 is separated from the solid electrolyte membrane 40 in a dense manner. A simple insulator 80 may be formed at the side end of the support substrate 10. That is, in the embodiment shown in FIG. 4, the “insulator” is composed of only the insulator 80 layer.

  Also in the form shown in FIG. 3 or FIG. 4, the relationship 1 <T2 / T1 <300 is established as in the form shown in FIG. Specifically, in the form shown in FIG. 3, the end portion of the “insulator” in the vertical direction of the figure is composed of only the layer of the solid electrolyte membrane 40. Therefore, T1 is equal to the thickness of only the layer of the solid electrolyte membrane 40 in this portion. Further, the end portion of the “insulator” (the portion where the thickness of the “insulator” is maximized) in the left-right direction in the figure is a laminate of the solid electrolyte membrane 40 and the insulator 80. Therefore, T2 is the sum of the thickness of the solid electrolyte membrane 40 and the thickness of the insulator 80 in this portion.

  In the form shown in FIG. 4, the end portion of the “insulator” in the vertical direction of the figure consists only of the insulator 80 layer. Therefore, T1 is equal to the thickness of only the layer of the insulator 80 in this portion. Further, the end portion of the “insulator” (the portion where the thickness of the “insulator” is maximized) in the left-right direction in FIG. Therefore, T2 is equal to the thickness of only the layer of the insulator 80 in this portion.

As shown in FIG. 5, the fuel gas (hydrogen gas or the like) flows through the fuel gas flow path 11 of the support substrate 10 and the upper and lower surfaces of the support substrate 10 with respect to the “horizontal stripe type” SOFC cell described above. (In particular, each air electrode current collector film 70) is exposed to “a gas containing oxygen” (air or the like) (or a gas containing oxygen is allowed to flow along the upper and lower surfaces of the support substrate 10). An electromotive force is generated by a difference in oxygen partial pressure generated between the two side surfaces. 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 +2 ^e− → O ²⁻ (where: air electrode 60) (1)
H ₂ + O ²⁻ → H ₂ O + 2 ^e− (in the fuel electrode 20) (2)

  In the power generation state, as shown in FIG. 6, 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. 5, from the entire SOFC cell (specifically, in FIG. 5, the interconnector 30 of the power generating element portion A on the frontmost side and the air electrode 60 of the power generating element portion A on the farthest side in FIG. The power is removed.

(Production method)
Next, an example of a manufacturing method of the “horizontal stripe type” SOFC cell shown in FIG. 1 will be briefly described with reference to FIGS. 7 to 14, “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. 7 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, the description will be continued with reference to FIGS. 8 to 14 showing a partial cross section of the molded body 10g of the support substrate shown in FIG.

  As shown in FIG. 8, once the support substrate molded body 10g is manufactured, the fuel electrode molded body (21g + 22g) is then placed at a predetermined position on the upper and lower surfaces of the support substrate molded body 10g as shown in FIG. ) Is formed. The molded body (21 g + 22 g) of each fuel electrode 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 fuel electrode 20 (for example, Ni and YSZ). The

Next, as shown in FIG. 10, 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. 11, 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 which a plurality of molded fuel electrode bodies (21g + 22g) are embedded and formed. A molded membrane 40g of a solid electrolyte membrane is formed on the entire surface (including the surface of the side end portion of the molded body 10g of the support substrate) excluding the portion where the 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 Here, the portion formed on the side end of the molded body 10g of the support substrate in the molded membrane 40g of the solid electrolyte membrane corresponds to the molded film of the “insulator”. In the embodiment shown in FIG. 1, the formation of the molded film of the “insulator” is completed by this treatment.

  For example, in the embodiment shown in FIG. 3, after this processing, the above-mentioned “other dense parts” are further formed on the outer surface of the molded membrane 40 g of the solid electrolyte membrane formed at the side end of the molded body 10 g of the support substrate. A molded film of the insulator 80 ”is formed using a printing method, a dipping method, or the like. Further, in the embodiment shown in FIG. 4, the solid electrolyte membrane molded film 40 g is formed except for the side end portion of the support substrate molded body 10 g, and then, on the surface of the side end portion of the support substrate molded body 10 g, The molding film of the “other dense insulator 80” described above is formed using a printing method, a dipping method, or the like.

  Next, as shown in FIG. 12, a reaction prevention film molding film 50g is formed on the outer surface of the solid electrolyte membrane molding body 40g in contact with the fuel electrode molding body 22g. 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, the structure in which the air electrode 60 and the air electrode current collector film 70 are not formed in the SOFC cell shown in FIG. 1 is obtained.

  Next, as shown in FIG. 13, 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. 14, for each pair of adjacent power generation element portions, air is formed so as to straddle the air electrode molding 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 60 g, the solid electrolyte film 40, and the interconnector 30, the air electrode current collecting film forming film 70 g 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. Thereby, the SOFC cell shown in FIG. 1 is obtained. The example of the method for manufacturing the SOFC cell shown in FIG. 1 has been described above.

(Consideration of preferred range of T2 / T1)
Next, an experiment conducted in order to consider a preferable range of T2 / T1 regarding the thickness of the “insulator” layer formed on the side end portion of the support substrate 10 will be described. The fuel cell used in this experiment was manufactured using the above-described “manufacturing method”.

  The width dimension of the support substrate 10 is 26 mm, the dimension in the thickness direction is 3.5 mm, the thickness of the fuel electrode 20 is 50 μm, and the portion formed on the main surface of the support substrate 10 in the solid electrolyte membrane 40 (see “Insulation”). The thickness of the portion not corresponding to the “body” is 5 to 30 μm, and the thickness of the “insulator” (a part of the solid electrolyte membrane 40 or the insulator 80) formed on the side edge of the support substrate 10 is 3 to 3 μm. The thickness of the air electrode 60 was 1000 μm, the thickness of the interconnector 30 was 50 μm, and the thickness of the air electrode current collector film 70 was 50 μm.

  Next, hydrogen gas was allowed to flow inside the fuel cell, and the support substrate 10 and the fuel electrode 20 were reduced at 850 ° C.

  A fuel gas is circulated through the fuel gas flow path 11 of the obtained fuel cell, an oxygen-containing gas is circulated outside the fuel cell, the fuel cell is heated to 750 ° C. using a gas burner, and the fuel cell The cell was operated for a predetermined time.

  Thereafter, for the fuel cell, “while reducing gas is circulated in the fuel gas flow path 11, the ambient temperature is raised from room temperature to 750 ° C. in 60 minutes and then lowered from 750 ° C. to room temperature in 120 minutes. The thermal cycle test which repeats "pattern" 100 times was done. And the presence or absence of the crack was confirmed about the "insulator" (a part of the solid electrolyte membrane 40, or the insulator 80, a sintered body) formed in the side edge part of the support substrate 10. FIG. This confirmation was performed by visual observation and observation with a microscope.

  The above tests show various fuel cells in which the combinations of the thicknesses T1 and T2 of the “insulator” (fired body) formed on the side end portion of the support substrate 10 are different (thus, the ratio T2 / T1 is different). Made for each cell. Adjustment of T2 / T1 uses a pattern (printing method) when forming a molded film of “insulator” (before firing, that is, a molded film of the solid electrolyte film 40 or a molded film of the insulator 80). In some cases, the printing execution pattern was adjusted, and when the dipping method was used, the dipping execution pattern was adjusted. Table 1 shows the relationship between T2 / T1 and the presence or absence of cracks in this “insulator” (fired body). Note that 15 samples were prepared and evaluated for each level.

  According to Table 1, “T2 / T1 <1 or T2 / T1> 300 is likely to cause cracks in the insulator, and if 1 ≦ T2 / T1 ≦ 300, cracks are generated in the insulator. It ’s hard to do. ” In this case, if 1 ≦ T2 / T1 ≦ 300, the stress concentration at the end of the insulator is alleviated, and a structure in which stress is distributed so that excessive stress is not locally generated in the insulator is obtained. It is presumed that

  Further, the same test as described above was performed by changing the condition of the “thermal cycle test” to a condition in which cracks are more likely to occur in the insulator. Specifically, the heating time of the heat cycle test was changed from 60 minutes to 30 minutes (other conditions are the same). The results in this case are shown in Table 2.

According to Table 2, it was found that “if 5.1 ≦ T2 / T1 ≦ 300, it is particularly difficult for the insulator to crack.” Incidentally, Table 1, Table 2, but the material of the supporting substrate are shown the results of the case of _Ni-Y 2 _{O 3,} the material of the supporting substrate is _Ni-Y 2 _{O 3} other than the material, for example, Ni-YSZ It has been found that the same result can be obtained in the case of.

  As described above, according to the above experimental results, in order to suppress the occurrence of cracks in the “insulator”, it is preferable that 1 ≦ T2 / T1 ≦ 300, and particularly if 5.1 ≦ T2 / T1 ≦ 300. It turned out to be preferable. Thereby, the interruption | blocking of the gas between the inside and outside of a fuel cell can be achieved reliably, and the fall of the power generation performance of a fuel cell can be suppressed reliably.

  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, a plurality of power generation element portions A are provided on the upper and lower surfaces of the flat support substrate 10, but a plurality of power generation elements are provided only on one side of the support substrate 10 as shown in FIG. 15. The element part 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.

  DESCRIPTION OF SYMBOLS 10 ... Support substrate, 11 ... Fuel gas flow path, 20 ... Fuel electrode, 21 ... Fuel electrode current collector, 22 ... Fuel electrode active part, 30 ... Interconnector, 40 ... Solid electrolyte membrane, 50 ... Reaction prevention membrane, 60 ... Air electrode, 70 ... Air electrode current collector film, 80 ... Insulator, A ... Power generation element part

Claims (2)

A flat porous support substrate having a gas flow path formed therein along the longitudinal direction;
A plurality of power generation element portions each provided at a plurality of locations separated from each other on the main surface of the support substrate, and at least an inner electrode, a solid electrolyte, and an outer electrode are laminated;
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
A gas seal portion made of a dense material that prevents mixing of the gas supplied to the inner electrode and the gas supplied to the outer electrode;
A fuel cell comprising:
The side end portion extending along the longitudinal direction in the support substrate has a curved shape protruding outward in the width direction perpendicular to the longitudinal direction,
The gas seal portion is
A dense insulator that is formed so as to cover a side end portion of the support substrate and that has a curved shape protruding outward in the width direction ;
When the thickness of the insulator corresponding to the end portion of the insulator in the thickness direction of the support substrate is T1, and the maximum thickness of the insulator corresponding to the side surface of the side end portion is T2, 5 .1 ≦ T2 / T1 ≦ 300 The fuel battery cell is established. The fuel cell according to claim 1 ,
Before Symbol maximum thickness of the insulator, the thickness is the fuel cell corresponding to the end portion of the protruding direction of the curved surface shape.

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