JP2017037838A - Stack structure of fuel battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a stack structure 1 in which gas leak occurs hardly.SOLUTION: A stack structure 1 includes a cell 100, a manifold 200, and a bonding material 300. The manifold 200 has a cell support hole 221 into which the cell 100 is inserted. The bonding material 300 bonds the cell 100 and the manifold 200. The bonding material 300 has a filling portion 301 arranged in a gap between the cell 100 and the cell support hole 221, and a pool portion 302 arranged outside the filling portion 301. In the cross section perpendicular to the outer surface of the cell 100, the rate of the second contact length C2 between the pool portion 302 and the cell 100 to the first contact length C1 between the filling portion 301 and the cell 100 ranges from not less than 0.25 to not more than 29.80.SELECTED DRAWING: Figure 6

Description

  The present invention relates to a fuel cell stack structure.

  A conventional stack structure of a fuel cell includes a fuel cell, a manifold, and a bonding material (seal material) (see Patent Document 1). The manifold has a cell support hole (through hole) into which the fuel cell is inserted. The bonding material bonds the support substrate and the cell support hole.

  In this stack structure, the bonding material divides the internal space of the manifold (space exposed to the fuel gas) and the external space of the stack structure (space exposed to air), so that the fuel gas and the air To prevent mixing. That is, the bonding material functions as a sealing material.

JP 2005-1000068 A

  In the stack structure, during operation, thermal stress due to thermal expansion and contraction is generated in the fuel cell and the manifold. Then, this thermal stress may cause a crack locally in the bonding material. Here, when a locally generated crack further grows due to thermal stress, this crack becomes a passage connecting the internal space of the manifold and the external space of the manifold, and the fuel gas introduced into the internal space is discharged from the internal space. There is a risk of leaking into the external space. For this reason, various attempts have been made to suppress the occurrence of gas leaks due to cracks, and a technique for solving this problem is expected.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a stack structure in which gas leakage is unlikely to occur.

  The stack structure of a fuel cell according to the present invention includes a fuel cell, a manifold, and a bonding material. The manifold has a cell support hole into which the fuel cell is inserted. The joining material joins the fuel cell and the manifold. The bonding material has a filling portion disposed in a gap between the fuel battery cell and the cell support hole and a pool portion disposed outside the filling portion. In the cross section perpendicular to the outer surface of the fuel cell, the ratio of the second contact length between the reservoir and the fuel cell to the first contact length between the filling portion and the fuel cell is 0.25 or more and 29.80. It is as follows.

  According to the present invention, it is possible to provide a stack structure in which gas leakage is unlikely to occur.

1 is an overall perspective view of a stack structure of a fuel cell according to an embodiment of the present invention. It is a whole perspective view of a cell. It is a whole perspective view of a manifold. It is a partial expanded sectional view of a cell and a manifold. It is an enlarged view of the insertion hole formed in the support plate of a manifold. It is an expanded sectional view of the portion where a bonding material is arranged. FIG. 3 is an enlarged cross-sectional view of a portion where a bonding material is disposed in a fuel cell stack structure.

<Structure of stack structure>
Here, an embodiment of a stack structure according to the present invention will be described with reference to the drawings.

  The stack structure 1 is a structure used for a solid oxide fuel cell (SOFC). In the present embodiment, an x, y, z coordinate system is set as shown in FIG.

  The stack structure 1 includes a plurality of cells 100, a manifold 200, and a bonding material 300.

<Cell>
Each cell 100 is a fuel cell. As shown in FIG. 1, each cell 100 is provided in a manifold 200. The cells 100 are arranged at intervals from each other. As shown in FIGS. 2 and 4, the end portion 10 a (inflow side end portion) on the side where the fuel gas flows in the x-axis direction (longitudinal direction) of the cell 100 is joined to the manifold 200 by the joining material 300. An end 10b (discharge side end) on the side where the fuel gas is discharged in the x-axis direction of the cell 100 is a free end. The stack structure in which the support substrate 10 is arranged in the manifold 200 is generally expressed as a “cantilever stack structure”.

  As shown in FIG. 2, the cell 100 is substantially formed in a flat plate shape. The longitudinal direction, the lateral direction, and the thickness direction of the cell 100 correspond to the x-axis direction, the y-axis direction, and the z-axis direction, respectively.

  The cell 100 is formed such that the length L1 in the x-axis direction is longer than the length L2 in the y-axis direction. The length L1 in the x-axis direction is not particularly limited, but can be set within a range of 50 mm or more and 500 mm or less. The length L2 in the y-axis direction is not particularly limited, but can be set within a range of 10 mm or more and 100 mm or less. The length L3 in the z-axis direction is not particularly limited, but can be set within a range of 1 mm or more and 5 mm or less.

  As shown in FIG. 2, each cell 100 includes a plurality of power generation element portions A, a support substrate 10, and a seal film 20.

Each power generation element part A has a fuel electrode, a solid electrolyte membrane, and an air electrode. Each power generating element portion A is a laminated fired body in which a fuel electrode, a solid electrolyte membrane, and an air electrode are laminated in this order. Here, the fuel electrode is composed of, for example, NiO (nickel oxide) and YSZ (8YSZ; yttria stabilized zirconia). The solid electrolyte membrane is made of, for example, YSZ (8YSZ; yttria stabilized zirconia). The air electrode is made of, for example, LSCF = (La, Sr) (Co, Fe) O ₃ (lanthanum strontium cobalt ferrite).

  The plurality of power generation element portions A are provided on the support substrate 10. A plurality of (for example, four) power generation element portions A are electrically connected in series.

  The support substrate 10 is a fired body made of a porous material having no electronic conductivity. The support substrate 10 is made of CSZ (calcia stabilized zirconia), for example.

  The support substrate 10 supports the power generation element portion A. Specifically, a plurality of power generation element portions A are provided on both main surfaces of the support substrate 10 at a predetermined interval in the x-axis direction.

  A plurality (for example, six) of fuel gas passages 11 (through holes) are formed inside the support substrate 10. Each fuel gas channel 11 extends in the x-axis direction. Each fuel gas channel 11 is formed at a predetermined interval in the y-axis direction (width direction).

  The seal film 20 covers the outer surface of the support substrate 10. The sealing film 20 can be composed of a dense material. Examples of the dense material include YSZ, ScSZ, glass, and spinel oxide. The seal film 20 may be made of the same material as that of the solid electrolyte film of each power generating element portion A. In this case, the seal film 20 may be formed integrally with the solid electrolyte film of each power generating element portion A.

<Manifold>
The manifold 200 is for supplying fuel gas to each of the plurality of cells 100. As shown in FIGS. 3 and 4, the manifold 200 is a substantially rectangular parallelepiped housing. In the manifold 200, the height direction (upward), the lateral direction (width direction), and the longitudinal direction correspond to the x-axis direction, the y-axis direction, and the z-axis direction, respectively.

  As shown in FIGS. 3 and 4, the manifold 200 includes a base 210 and a support plate 220 (upper wall). The base 210 is made of a metal such as stainless steel. The base part 210 has a bottom part and a side wall surrounding the bottom part. An opening that opens upward is formed by the bottom and the side wall.

  The support plate 220 is made of a metal such as stainless steel. The support plate 220 is disposed on the base 210. Specifically, the support plate 220 is disposed at the front end portion of the side wall of the base 210 and closes the opening of the base 210. In this manner, the support plate 220 closes the opening of the base portion 210, whereby an internal space S1 is formed in the manifold 200 (see FIG. 4). That is, the internal space S <b> 1 is configured by the base portion 210 (bottom portion and wall portion) and the support plate 220. Fuel gas is introduced into the internal space S1.

  The fuel gas is introduced from the outside into the internal space S1 through the introduction pipe 230. The introduction pipe 230 is made of a metal such as stainless steel. The introduction pipe 230 is joined and fixed to the support plate 220 of the manifold 200. Specifically, the introduction pipe 230 is welded to the support plate 220 while being inserted into a through hole (not shown) formed in the support plate 220.

  The manifold 200 having the above configuration supports a plurality of cells 100 as shown in FIGS. 3, 4, and 5. Specifically, the support plate 220 of the manifold 200 has a plurality of cell support holes 221. Each cell support hole 221 is formed in the support plate 220 so as to communicate the outside (external space) of the manifold 200 and the internal space S1. More specifically, each cell support hole 221 passes through the support plate 220 in the x-axis direction (height direction) (see FIG. 4). Each cell support hole 221 is formed at a predetermined interval in the z-axis direction (longitudinal direction) (see FIGS. 3 and 5). Each cell support hole 221 is also formed at a predetermined interval in the y-axis direction (short direction) (see FIG. 3).

  As shown in FIG. 4, each cell 100 is disposed in each cell support hole 221. Specifically, the inflow side end portion 10a of each cell 100 is inserted into each cell support hole 221 so that the fuel gas flow path 11 of each cell 100 communicates with the internal space S1.

  As shown in FIG. 5, when each cell support hole 221 is viewed from the outside (external space) of the manifold 200 (when viewed along the x axis), each cell support hole 221 is formed long in one direction, In addition, both end portions are formed in an arc shape. That is, each cell support hole 221 is formed in an oval shape. Each cell support hole 221 is formed such that the length L4 in the y-axis direction (length in the longitudinal direction) is longer than the length L5 in the z-axis direction (length in the lateral direction / length in the width direction). ing.

  The length L4 in the y-axis direction in each cell support hole 221 is larger than the length L2 in the y-axis direction on the outer surface of the inflow side end 10a of each cell 100. The difference between the length L4 of each cell support hole 221 in the y-axis direction and the length L2 of each cell 100 in the y-axis direction is, for example, in the range of 0.1 mm or more and 1.0 mm or less.

  In addition, the length L5 in the z-axis direction of each cell support hole 221 is larger than the length L3 in the z-axis direction on the side surface of the inflow side end 10a of each cell 100. The difference between the length L5 of each cell support hole 221 in the z-axis direction and the length L3 of each cell 100 in the z-axis direction is, for example, in the range of 0.1 mm or more and 1.0 mm or less.

  That is, as shown in FIG. 5, in the state where the inflow side end portion 10 a of each cell 100 is inserted into each cell support hole 221, the inner surface of each cell support hole 221 and the inflow side end portion 10 a of each cell 100. A gap G is formed between the outer surface. The gap G is formed around the outer peripheral surface of the cell 100 along the direction r of the cell 100. The gap G may be constant over the entire circumference, but may not be constant. A bonding material 300 is disposed in the gap G.

<Bonding material>
The bonding material 300 is made of crystallized glass, for example. As the crystallized glass, for example, SiO ₂ —B ₂ O ₃ type, SiO ₂ —CaO type, MgO—B ₂ O ₃ type, or SiO ₂ —MgO type is used. As the crystallized _glass, it intended SiO 2 -MgO system is most preferred.

  The crystallized glass used here has a ratio (crystallinity) of “volume occupied by the crystalline phase” to the total volume of 60% or more, and a ratio of “volume occupied by the amorphous phase and impurities” to the total volume. Is less than 40% glass. Note that amorphous glass, brazing material, ceramics, or the like may be employed as the material of the bonding material 300.

  The bonding material 300 prevents the fuel gas in the internal space S1 of the manifold 200 from mixing with the air in the external space outside the manifold 200 and the plurality of cells 100. Specifically, as illustrated in FIGS. 4, 5, and 6, the bonding material 300 is disposed between the manifold 200 and each cell 100 and bonds the manifold 200 and each cell 100. Thus, the bonding material 300 partitions the internal space S1 (space exposed to the fuel gas) and the external space (space exposed to air). That is, the bonding material 300 functions as a sealing material.

  In FIGS. 4, 5, and 6, the shape of each member is exaggerated for easy explanation.

  As shown in FIGS. 4 and 6, the bonding material 300 fills the gap G so that the gap G between each cell support hole 221 and each cell 100 of the manifold 200 is closed from the outside of the manifold 200 and each cell 100. Is done.

  Specifically, as illustrated in FIG. 6, the bonding material 300 includes a filling portion 301 and a pool portion 302. The filling unit 301 is disposed in the gap G. The filling portion 301 is filled on the outer space side of the gap G (upper part of the gap G) in the x-axis direction. The filling portion 301 contacts the outer surface of the inflow side end portion 10a of each cell 100 and the inner surface of each cell support hole 221 of the manifold 200 to join and fix them.

  In this state, the lower surface of the filling portion 301 is formed at an obtuse angle D with respect to the outer surface of the inflow side end portion 10 a of each cell 100. The obtuse angle D may be established continuously in the entire circumference in the direction r (see FIG. 5) along the outer surface of the cell 100, but may be established intermittently in the direction r. In FIG. 6, the obtuse angle D in the cross section which cut | disconnected each cell 100 by xz plane is shown as an example. Thereby, stress concentration is unlikely to occur at the corner portion constituted by the lower surface of the filling portion 301 and the outer surface of the inflow side end portion 10a of the cell 100.

  The pool portion 302 contacts the outer surface of the inflow side end portion 10a of each cell 100 and the outer surface of the manifold 200 (the surface on the outer space side of the support plate 220) outside the gap G, and joins and fixes them. .

  An unfilled space S2 (an example of a space) in which the bonding material 300 is not filled is provided below the filling portion 301 in the x-axis direction of the gap G, that is, on the inner space side of the gap G (below the gap G). Yes. In other words, the unfilled space S <b> 2 is provided between the bonding material 300 in the gap G and the internal space S <b> 1 of the manifold 200.

  In the state where the bonding material 300 is arranged in the gap G as described above, as shown in FIG. 6, the filling portion 301 (the bonding material 300 in the gap G) contacts the cell 100 in the first region R1. Further, the reservoir 302 is in contact with the cell 100 in the second region R2.

  The first region R <b> 1 is a surface where the filling part 301 contacts the cell 100. The first region R1 contacts and adheres to the cell 100 in the direction r along the outer surface of the cell 100. The length of the first region R1 in the x-axis direction is defined by the first contact length C1.

  The second region R2 is a surface on which the pool portion 302 contacts and adheres to the cell 100. The second region R2 contacts and adheres to the cell 100 in the direction r along the outer surface of the cell 100. The length of the second region R2 in the x-axis direction is defined by the second contact length C2.

  The ratio (C2 / C1) of the second contact length C2 to the first contact length C1 is not less than 0.25 and not more than 29.80. As a result, the cell 100 and the manifold 200 can be firmly bonded with the bonding material 300, and cracks in the bonding material 300 can be suppressed to suppress gas leakage.

  The first contact length C1 is not particularly limited, but is preferably 5% or more of the length T0 of the cell support hole 221 in consideration of the gas sealability of the bonding material 300. The first contact length C1 can be set to, for example, 0.05 mm or more and 2.0 mm or less. The second contact length C2 is not particularly limited, but is preferably 5% or more of the length T0 of the cell support hole 221 in consideration of the gas sealing property of the bonding material 300. The second contact length C2 can be, for example, not less than 0.5 mm and not more than 1.5 mm.

  Here, the first contact length C1 is obtained as follows. First, at four measurement positions M1 to M4 shown in FIG. 5, a cross section perpendicular to the outer surface of the cell 100 is observed, and a region where the filling portion 301 of the bonding material 300 contacts the cell 100 is confirmed. The measurement positions M1 and M2 are located at both ends in the width direction of the cell 100 and face each other. The measurement positions M3 and M4 are located on both sides in the center in the width direction of the cell 100 and face each other. Next, at each of the four measurement positions M <b> 1 to M <b> 4, the contact length at which the filling unit 301 contacts the cell 100 is measured. The arithmetic average value of the contact lengths measured at the four measurement positions M1 to M4 is defined as a first contact length C1.

  Similar to the first contact length C1, the second contact length C2 is obtained as follows. First, at four measurement positions M1 to M4 shown in FIG. 5, a cross section perpendicular to the outer surface of the cell 100 is observed to confirm a region where the pool portion 302 of the bonding material 300 is in contact with the cell 100. Next, at each of the four measurement positions M <b> 1 to M <b> 4, the contact length at which the pool portion 302 contacts the cell 100 is measured. The arithmetic average value of the contact lengths measured at the four measurement positions M1 to M4 is defined as a second contact length C2.

  As shown in FIG. 6, the reservoir 302 is in contact with the manifold 200 in the third region R3. In the third region R <b> 3, the pool portion 302 contacts and adheres to the outer surface of the support plate 220 in the manifold 200. The third region R3 contacts and adheres to the manifold 200 in the direction r along the outer surface of the cell 100. The length of the third region R3 in the z-axis direction is defined by the third contact length C3.

  The ratio (C3 / C1) of the third contact length C3 to the first contact length C1 is preferably 0.05 or more and 29.60 or less. Thereby, since the strength of the bonding material can be further improved, gas leakage from the bonding material 300 can be further suppressed.

  The third contact length C3 is not particularly limited, but may be, for example, 0.1 mm or more and 1.5 mm or less. The third contact length C3 is an arithmetic average value of the contact lengths measured at each of the four measurement positions M1 to M4 illustrated in FIG. 5, similarly to the first contact length C1.

  As shown in FIG. 6, the filling part 301 contacts the cell support hole 221 in the fourth region R4. In the fourth region R4, the filling portion 301 contacts and adheres to the inner peripheral surface of the cell support hole 221 in the manifold 200. The fourth region R4 contacts and adheres to the manifold 200 in the direction r along the outer surface of the cell 100. The length of the fourth region R4 in the x-axis direction is defined by the fourth contact length C4.

  The fourth contact length C4 is different from the first contact length C1, and is shorter than the first contact length C1. The ratio (C1 / C4) of the first contact length C1 to the fourth contact length C4 is preferably 1.19 or more and 39.40 or less. Accordingly, the inner surface of the filling portion 301 can be inclined with respect to the outer surface of the cell 100 and the inner peripheral surface of the cell support hole 221. Therefore, compared with the case where the first contact length C1 and the fourth contact length C4 are the same, the vicinity of the boundary between the inner surface of the filling portion 301 and the outer surface of the cell 100, the inner surface of the filling portion 301, and the cell support hole 221 Stress concentration near the boundary with the inner peripheral surface can be suppressed. As a result, the occurrence of cracks in the filling portion 301 is suppressed.

  The fourth contact length C4 is not particularly limited, but may be, for example, 0.1 mm or more and 1.5 mm or less. The fourth contact length C4 is an arithmetic average value of the contact lengths measured at each of the four measurement positions M1 to M4 illustrated in FIG. 5, similarly to the first contact length C1.

  Further, the ratio (C1 / K) of the first contact length C1 to the gap K of the gap G is not particularly limited, but is preferably 0.05 or more. As a result, it is difficult to appropriately generate gas leak, and the bonding force between the cell 100 and the cell support hole 221 can be appropriately improved. The gap K of the gap G can be set within a range of, for example, 0.1 mm or more and 1.0 mm or less, but is not limited thereto.

  In consideration of shape accuracy such as variation in the shape of the cell support hole 221 of each sample, variation in warpage of each cell 100, variation in thickness of the main surface of each cell 100, the interval K of the gap G is set to 0. It is not easy to set it to less than 1 mm. Further, if the gap K of the gap G is set to be less than 0.1 mm, the manufacturing cost may increase. For this reason, it is preferable to set the gap K of the gap G to 0.1 mm or more.

  The interval K of the gap G is obtained as follows. First, the cross section perpendicular to the outer surface of the cell 100 is observed at the four measurement positions M1 to M4 shown in FIG. Next, the gap G is measured at each of the four measurement positions M1 to M4. The arithmetic average value of the gap G measured at the four measurement positions M1 to M4 is defined as a gap K.

<Other structures>
As shown in FIG. 4, the stack structure 1 further includes current collecting members 400 and 500. The current collecting member 400 is provided between the adjacent cells 100. Specifically, the current collecting member 400 is provided between adjacent cells 100 in order to electrically connect the fuel electrode of one cell 100 and the air electrode of the other cell 100 in series. The current collecting member 400 is made of, for example, a metal mesh. The current collecting member 500 is provided in each cell 100. Specifically, the current collecting member 500 is provided in each cell 100 in order to electrically connect the front side and the back side of each cell 100 in series.

<Operation of stack structure>
The stack structure 1 operates as follows, for example. In the stack structure 1, high-temperature (for example, 600 to 800 ° C.) fuel gas (hydrogen gas or the like) is introduced from the introduction pipe 230 into the internal space S <b> 1 of the manifold 200. Then, this fuel gas is introduced into the fuel gas channel 11 of each cell 100. When the fuel gas passes through the fuel gas passage 11, the fuel gas is discharged from the discharge port at the discharge side end of the fuel gas passage 11 to the outside. On the other hand, air (such as a gas containing oxygen) passes in the y-axis direction of the cell 100 in the space between the adjacent cells 100.

  By moving the fuel gas and air in this manner, in each power generating element portion A, an oxygen partial pressure difference, that is, a potential difference is generated between the front and back surfaces of the solid electrolyte membrane. In this state, when the cell 100 is electrically connected to an external load, chemical reactions represented by the following formulas (1) and (2) occur. Thereby, a current flows in the cell 100 and a power generation state is established. In this power generation state, power is extracted from the cell 100.

(1/2) · O ₂ + 2e− → O ₂ − (in the air electrode) (1)
H ₂ + O ₂ − → H ₂ O + 2e− (in the fuel electrode) (2)
<Assembly of stack structure>
The above-described stack structure 1 is assembled as follows, for example.

  First, a material having high affinity with the bonding material 300 (hereinafter referred to as “affinity material”) is applied to the surface of the inflow side end portion 10a of the cell 100, and heat treatment (crystallization treatment) is performed.

  At this time, as shown in FIG. 6, by adjusting the coating length T1 in the region facing the cell support hole 221 in the surface of the inflow side end 10a and the coating length T2 in the outer region, The ratio (C2 / C1) of the second contact length C2 to the first contact length C1 can be controlled to 0.25 or more and 29.80 or less. Further, by adjusting the coating length T1, the ratio (C1 / C4) of the first contact length C1 to the fourth contact length C4 can be controlled to 1.19 or more and 39.40 or less. Furthermore, the ratio (C3 / C1) of the third contact length C3 to the first contact length C1 can be controlled to 0.05 or more and 29.60 or less by adjusting the coating length T2.

  Next, the plurality of cells 100 are fixed using a predetermined jig or the like in a state of being arranged in a stack. Subsequently, the inflow side end portions 10a of the plurality of cells 100 are inserted into the plurality of cell support holes 221 in the manifold 200 separately with the plurality of cells 100 aligned and fixed in a stack.

  Subsequently, when the bonding material 300 is supplied from the outside of the manifold 200 and each cell 100 so as to close the gap G, the filling portion 301 and the pool portion 302 are formed. At this time, the wettability of the bonding material 300 with respect to the affinity material having the coating length T1 applied to the cell 100 is higher than the wettability of the bonding material 300 with respect to the inner surface of the cell support hole 221 of the manifold 200. As shown in FIG. 6, the first contact length C1 is longer than the fourth contact length C4. In addition, since the wettability of the bonding material 300 with respect to the affinity material having the coating length T2 applied to the cell 100 is different from the wettability of the bonding material 300 with respect to the outer surface of the manifold 200, as shown in FIG. The contact length C2 and the third contact length C3 are adjusted respectively.

  Finally, a heat treatment (crystallization process) is performed on the bonding material 300 (for example, an amorphous material paste). When the temperature of the amorphous material reaches the crystallization temperature by this heat treatment, a crystal phase is generated inside the amorphous material, and the bonding material 300 is crystallized. As a result, the amorphous material is solidified and ceramicized to become crystallized glass.

  Thereby, the inflow side end portion 10 a of each cell 100 is joined and fixed to each cell support hole 221 of the manifold 200 by the joining material 300 made of the crystallized glass. In other words, the inflow side end portion 10 a of each cell 100 is joined and supported to the support plate 220 of the manifold 200 by the joining material 300. Thereafter, the predetermined jig described above is removed from the plurality of cells 100, and the stack structure 1 is completed.

<Other embodiments>
In the above-described embodiment, the fourth contact length C4 at which the filling portion 301 contacts the cell support hole 221 is shorter than the first contact length C1 at which the filling portion 301 contacts the cell 100. It is not limited. For example, as shown in FIG. 7, the fourth contact length C4 may be longer than the first contact length C1. Although not shown, the fourth contact length C4 may be the same as the first contact length C1.

  Even in these cases, cracks in the bonding material 300 can be suppressed by setting the ratio (C2 / C1) of the second contact length C2 to the first contact length C1 to 0.25 or more and 29.80 or less. Gas leak can be suppressed.

  The ratio of the second contact length C2 to the first contact length C1 is applied in advance to the inner peripheral surface of the cell support hole 221 before filling the gap G with the bonding material 300, as shown in FIG. It can be adjusted by the application length T4 of the affinity material.

  Examples of the cell according to the present invention will be described below, but the present invention is not limited to the examples described below.

(Production of sample No. 1 to No. 14)
Sample no. 1-No. Fourteen fuel cell stack structures were produced. Sample No. 1-No. 14 has the configuration shown in FIG. 6. First, a cell having a length of 200 mm, a width of 50 mm, and a thickness of 2 mm was prepared. The outer surface of the cell is covered with a YSZ seal film. A fuel flow path is formed inside the cell.

  Next, after applying an amorphous material paste as an affinity material to the entire outer surface of one end of the cell, the affinity material was crystallized by heat treatment (850 ° C., 1 hour). At this time, as shown in Table 1, by adjusting the coating length T1 in the region facing the cell support hole and the coating length T2 in the outer region as shown in FIG. A first contact length C1 between the filling portion and the cell, a second contact length C2 between the joint material reservoir and the cell, and a third contact length C3 between the joint material reservoir and the manifold. Changed every time.

  Next, a stainless steel manifold having a cell support hole was prepared, and one end of the cell was inserted into the cell support hole.

  Next, after filling the gap between the cell and the cell support hole with a paste of an amorphous material as a bonding material, the bonding material was crystallized by heat treatment (850 ° C., 1 hour).

(Production of sample No. 15 to No. 28)
Sample no. 15-No. 28 fuel cell stack structures were prepared. Sample No. 15-No. 28 has the configuration shown in FIG. 7. First, a cell having a length of 200 mm, a width of 50 mm, and a thickness of 2 mm was prepared. The outer surface of the cell is covered with a YSZ seal film. A fuel flow path is formed inside the cell.

  Next, a stainless steel manifold having cell support holes was prepared.

  Next, after applying a paste of an amorphous material as an affinity material to the entire inner peripheral surface of the cell support hole, the affinity material was crystallized by heat treatment (850 ° C., 1 hour). At this time, as shown in Table 2, as shown in Table 2, by adjusting the coating length T2 on the outer surface of the cell and the coating length T4 on the inner peripheral surface of the cell support hole 221, as shown in FIG. A first contact length C1 between the filling portion and the cell, a second contact length C2 between the joint material reservoir and the cell, and a third contact length C3 between the joint material reservoir and the manifold. Changed every time.

  Next, one end of the cell was inserted into the cell support hole.

  Next, after filling the gap between the cell and the cell support hole with a paste of an amorphous material as a bonding material, the bonding material was crystallized by heat treatment (850 ° C., 1 hour).

(Observation of bonding material)
First, in each sample, a cross section perpendicular to the outer surface of the cell was exposed at two places on both ends in the width direction of the cell and two places on both sides in the center in the width direction of the cell.

  Next, the first to third contact lengths C1 to C3 were calculated by observing four cross sections of each sample with a scanning electron microscope (manufactured by JEOL Ltd., model JSM6610LV). The first to third contact lengths C1 to C3 are arithmetic average values of measured values in each of the four cross sections. The calculation results are summarized in Table 1 and Table 2.

(Gas leak test after bonding material formation)
After the outlet of the fuel flow path of each sample was sealed with a rubber cap, pressurized fuel gas was introduced into the manifold.

  Next, each sample was immersed in a liquid, and whether or not bubbles were generated from the bonding material was visually observed. In Tables 1 and 2, samples in which bubbles are generated are evaluated as “leak”, and samples in which bubbles are not generated are evaluated as “no leak”.

(Gas leak test after thermal cycle test)
The process of raising the ambient temperature from room temperature to 750 ° C. in 2 hours and reducing it to room temperature in 4 hours was repeated 10 cycles while reducing fuel gas was circulated through the fuel flow path of each sample.

  Next, after the outlet of the fuel flow path of each sample was sealed with a rubber cap, pressurized fuel gas was introduced into the manifold.

  Next, each sample was immersed in a liquid, and whether or not bubbles were generated from the bonding material was visually observed. In Tables 1 and 2, samples in which bubbles are generated are evaluated as “leak”, and samples in which bubbles are not generated are evaluated as “no leak”.

  As shown in Table 1 and Table 2, the sample No. 1 in which the ratio (C2 / C1) of the second contact length C2 to the first contact length C1 was 0.25 to 29.80. In 3-12, 17-26, the gas leak from the joining material after joining material formation was able to be suppressed. This is because, by controlling the ratio of the second contact length C2 to the first contact length C1 to an appropriate value, the cell and the manifold can be firmly bonded with the bonding material, and cracks in the bonding material can be suppressed. This is because.

  As shown in Tables 1 and 2, Sample No. 3 to 12 and 17 to 26, the sample No. 1 was set such that the ratio (C3 / C1) of the third contact length C3 to the first contact length C1 was 0.05 or more and 29.60 or less. In 4 to 11 and 18 to 25, gas leakage from the bonding material could be suppressed even after the thermal cycle test. This is because the strength of the bonding material could be further improved by controlling the ratio of the third contact length C3 to the first contact length C1 to an appropriate value.

  The present invention can be widely applied to fuel cell stack structures.

DESCRIPTION OF SYMBOLS 1 Stack structure 100 Cell 200 Manifold 221 Cell support hole 300,300a Joining material 10 Support substrate 11 Fuel gas flow path A Power generation element part C1 1st contact length C2 2nd contact length C3 3rd contact length C4 4th Contact length G Gap K Gap spacing S1 Internal space S2 Unfilled space

Claims (2)

A fuel cell;
A manifold having a cell support hole into which the fuel cell is inserted;
A bonding material for bonding the fuel cell and the manifold;
With
The bonding material includes a filling portion disposed in a gap between the fuel battery cell and the cell support hole, and a pool portion disposed outside the filling portion,
In a cross section perpendicular to the outer surface of the fuel cell, the ratio of the second contact length between the reservoir and the fuel cell to the first contact length between the filling portion and the fuel cell is 0. 25 or more and 29.80 or less,
Fuel cell stack structure. In the cross section perpendicular to the outer surface of the fuel cell, the ratio of the third contact length between the reservoir and the manifold to the first contact length is 0.05 to 29.60.
The fuel cell stack structure according to claim 1.