JP5097360B2 - Fuel cell stack - Google Patents

Description

  The present invention relates to a fuel cell stack formed by arranging a plurality of fuel cells, and more particularly to a fuel cell stack of a solid oxide fuel cell.

  In recent years, various types of fuel cells in which a cell stack formed by connecting a plurality of fuel cells is accommodated in a storage container have been proposed as next-generation energy. As such a fuel cell, various types such as a polymer electrolyte fuel cell, a phosphoric acid fuel cell, a molten carbonate fuel cell, and a solid electrolyte fuel cell are known. In particular, solid electrolyte fuel cells have advantages such as high power generation efficiency and high operating temperatures of 700 ° C to 1000 ° C, so that the exhaust heat can be used, and research and development are being promoted. ing.

The solid electrolyte fuel cell is configured by, for example, sequentially forming a solid electrolyte layer and an air electrode layer on the surface of the fuel electrode layer, and flowing fuel (hydrogen) to the fuel electrode layer side, Electric power is generated at about 600 to 1000 ° C. by flowing air (oxygen).
As described above, since the solid oxide fuel cell uses two kinds of gas and is exposed to high temperature, various improvements have been made to the sealing performance in the gas supply pipe and the cell so that the gas does not leak even at high temperature. Has been made. For example, conventionally, a cell stack apparatus in which an alloy gas supply pipe is joined to the side surface of an alloy gas manifold, and a support plate of the cell stack is joined to the opening of a rectangular parallelepiped gas manifold body having an upper surface opened. It is known (see, for example, Patent Document 1).
In this fuel cell, the cell stack is configured such that a fuel cell is inserted into the cell insertion hole of an alloy support plate in which a number of cell insertion holes are formed, a glass material is filled in the gap, and the support plate is gastight. It was joined to the gas manifold in a sealed state.
In such a fuel cell, for example, a fuel gas such as hydrogen is supplied into a gas manifold via a gas supply pipe, and this fuel gas is supplied to a gas passage formed inside the fuel cell constituting the cell stack. On the other hand, air is supplied to the outside of the fuel cell, and power can be generated in the power generation unit in which the solid electrolyte layer is sandwiched between the fuel electrode layer and the air electrode layer.
Also, without using the alloy manifold, a hole for supplying gas is formed at the end of the fuel cell, the holes are connected to each other through a ring-shaped spacer, and bonded and sealed with a sealing member such as glass. A stopped fuel cell stack has been proposed (see Patent Document 2). In such a fuel cell stack, for example, a fuel gas such as hydrogen is supplied into the spacer, and this fuel gas is supplied to a gas passage formed inside the fuel cell constituting the cell stack, Air is supplied to the outside of the battery cell, and power can be generated in a power generation unit in which the solid electrolyte layer is sandwiched between the fuel electrode layer and the air electrode layer.

JP 2005-216620 A JP 2006-79974 A

However, in the fuel cell disclosed in Patent Document 1 described above, the fuel cell is inserted into the cell insertion hole of the alloy support plate, the glass material is filled in the gap, and the fuel cell is supported by the glass material with the alloy. Because it was airtightly bonded to the plate, there is a risk that the glass material may crack or peel off during manufacturing or power generation due to the difference in thermal expansion coefficient between the alloy support plate and the glass material, and the gas manifold still has a sealing property There was a problem of being low.
For this reason, one end in the axial length direction of a plurality of fuel cells is integrated with a glass material, and a plurality of fuel cells are erected on a rectangular cell support plate made of a glass material to form a cell stack. It is conceivable that the stack is joined to the opening of the alloy manifold with the upper surface opened by a glass material. In this case, however, the fuel expansion is caused by the difference in the thermal expansion coefficient between the cell support plate made of the glass material and the alloy manifold. There is a risk that cracks or peeling will occur on the cell support plate made of a glass material during battery production or power generation, and there is a problem in the sealing performance and strength of the gas manifold.

On the other hand, in the fuel cell stack disclosed in Patent Document 2 described above, a gap or the like is likely to be formed at the joint between the ring-shaped spacer and the fuel cell, and therefore, gas leaks are generated and the joint strength is weakened and easily damaged. There was a problem.
An object of the present invention is to provide a fuel cell stack that is excellent in gas leakage resistance and excellent in strength without using a spacer such as a metal member or a connecting ring.

  As a result of intensive research to solve the above-mentioned problems, the present inventors have integrated a sealing member to cover and supply the gas supply portion of the fuel cell constituting the fuel cell stack. The present invention has been completed by finding that a fuel cell stack having excellent properties and strength can be provided.

That is, the fuel cell stack in the present invention has the following configuration.
(1) A long substrate-like fuel cell unit has a through hole penetrating from one surface of the fuel cell to the other surface at one end in the longitudinal direction, and the plurality of the through holes are arranged in one direction. In the fuel cell stack in which the fuel cells are bundled, the plurality of fuel cells each have a gas flow path in the longitudinal direction, and one end portion having the through holes of the plurality of fuel cells is a sealing member And a gas supply path in which the through holes communicate with each other is formed inside the seal member , and the gas flow path communicates with the gas supply path. And fuel cell stack.
(2) The fuel cell stack according to (1), wherein the fuel cell is covered and sealed with the seal member up to a bottom surface of one end portion of the fuel cell.
( 3 ) The fuel cell stack according to ( 1 ) or (2) , wherein a gas introduction pipe is joined to the seal member so as to communicate with the gas supply path.
( 4 ) The fuel cell stack according to any one of (1) to ( 3 ), wherein the plurality of fuel cells are arranged with their longitudinal directions alternately changed.
( 5 ) The fuel cell stack according to any one of (1) to ( 4 ), wherein the seal member is made of an inorganic material.
(6) from a substantially circular said through-hole, so that the distance of the gas flow path to the other longitudinal tip through the area of the power generation is substantially the same, respectively, the shape of the other tip portion is bulged The fuel cell stack according to any one of (1) to ( 5 ), comprising:

According to (1) to ( 2 ), the fuel cell stack according to the present invention has a structure in which a portion for gas supply is integrated and sealed by a sealing member, so that leakage at the sealing portion can be prevented. It is possible to provide a fuel cell stack that is excellent in strength, excellent in reliability and power generation performance.
According to the above ( 3 ), since the pipe for introducing the gas from the outside is covered and joined by the seal member, the seal portion is excellent in leak resistance.
According to the above ( 4 ), when the plurality of fuel cells are bundled so that the through holes are aligned in one direction, the fuel cell stack with improved power generation performance is arranged by alternately changing the direction in the longitudinal direction. Can be efficiently accommodated in a compact volume, and the output per unit volume can be improved.
According to the above ( 5 ), since the sealing member is made of an inorganic material, the sealing part is excellent in leak resistance, excellent in strength, and high reliability can be obtained.
According to the above ( 6 ), in the gas flow path in the fuel cell, by making the distance of the gas flow path from the boundary portion of the through hole to the other tip through the power generation region the same distance, Since the pressure loss of each gas flow path can be made equal, a uniform flow rate can be maintained and power generation performance can be improved.

An embodiment of the fuel cell stack of the present invention will be described with reference to FIGS. 1 and 2. FIG. 1 shows an embodiment of a fuel cell stack according to the present invention. A fuel cell stack 10 includes a plurality of plate-shaped solid electrolyte fuel cell cells 40 each having a gas flow path 41a in the longitudinal direction. One end of the fuel cell 40 is covered with a seal member 11 and is fixed upright. In FIG. 1, a part of the fuel cell 40 is omitted and simplified.
The fuel battery cell 40 has, for example, a flat cross section, an elliptical columnar shape (hollow flat plate type) as a whole, and an elongated substrate shape, and a plurality of gas flow paths 41a are long in the inside thereof. It is formed to penetrate in the direction. The fuel battery cell 40 will be described later.
In the fuel cell stack 10, the fuel cells 40 are arranged in the cell thickness direction so that the side surfaces thereof face each other, and the fuel cells 40 are electrically connected in series between the fuel cells 40. A current collecting member 14 is disposed.
On the other hand, the sealing member 11 is made of an insulating inorganic material, for example, crystallized glass. As shown in FIG. 1B, the through holes 12 at one end of the fuel cell 40 are formed inside the sealing member 11. A gas supply path 13 is formed which communicates in a cylindrical space. The gas flow path 41 a communicates with the gas supply path 13. A gas introduction pipe 15 for supplying gas to the gas supply path 13 is joined to one side surface of the seal member 11, and the gas introduction pipe 15 is formed at a pipe portion 15 b and a tip of the pipe portion 15 b. The flange portion 15 a is joined to the seal member 11. It is desirable that the flange portion 15a be integrally covered and sealed with the same material as the seal member 11 or a material having a thermal expansion coefficient intermediate between the constituent member of the gas introduction pipe 15 and the seal member 11.
The flange portion 15a is not necessarily covered. The gas introduction pipe 15 is preferably formed of a heat resistant alloy, but the flange portion 15a can be formed of an inorganic material such as ceramic or glass. In this case, the flange portion 15a is abutted against the seal member 11. Can be joined in contact.

  As described above, in the fuel cell stack 10 of the present invention, the gas introduced from the gas introduction pipe 15 passes through the gas flow path 41a of each cell via the gas supply path 13, and is generated by surplus gas and power generation. Gas is discharged from the top. Since the gas supply part is integrally covered and sealed by the seal member 11 to form a manifold, the gas leakage resistance is high and the strength is excellent, and the highly reliable fuel cell stack 10 is provided. can get. Further, the fuel cell stack 10 can be manufactured at a low cost without using a metal member or a connection ring.

(Production method)
The fuel cell stack 10 configured as described above can be manufactured as shown in FIG. In FIG. 2, a part of the fuel cell 40 is omitted, and the current collecting member 14 is also omitted.
First, as shown to Fig.2 (a), the shaping | molding die 31 of the bottomed rectangular parallelepiped shaped sealing member 11 with which the upper surface opened is prepared. A paste made of an inorganic material, such as glass paste, is poured into the mold 31 and allowed to stand naturally or dried at a temperature of about 100 ° C. with a dryer to form a bonding layer 11a having a predetermined thickness. The poured glass paste may be calcined. Moreover, you may arrange | position plate-shaped glass instead of pouring glass paste.

  Next, a plurality of fuel cells 40 each having a through hole 12 having a predetermined diameter formed at a predetermined position at the lower end of the fuel cell 40 are arranged so that the through holes 12 are aligned in one direction and the fuel cell 40 The current collecting member 14 is arranged and bundled between them, and they are put into the mold 31 with the lower end portion having the through hole 12 facing down. A through hole 29 having substantially the same size as that of the through hole 12 is formed on the side wall of the mold 31, and the through hole 12 extends from the outside of the mold 31 to the through hole 29 and the through hole 12 of the fuel cell 40. 29, a core 30 having substantially the same size and shape as that of 29 is inserted. At this time, one end of the core 30 is inserted so as to be located at a position 1 to 10 mm away from the inner surface of the side wall of the mold 31. By doing so, a closed portion is formed at one end and an opening is formed at the other end in the space formed when the core 30 is later pulled out of the mold 31.

  The mold 31 is formed of a material that absorbs the solvent of the slurry and has poor wettability, such as a ceramic fiber molded body, and the core 30 is also formed of the same material. Yes. The core 30 forms a space of the gas supply path 13 in which the through holes 12 communicate with each other. The shape of the internal space of the gas supply path 13 is the same as that of the through hole 12. It is determined by the shape. For example, if the core 30 is cylindrical, the inner space of the gas supply path 13 is also cylindrical by inserting the core 30 into the through hole 12 of the fuel cell 40 and pouring slurry.

  Thereafter, as shown in FIG. 2B, the sealing member 11 made of an insulating inorganic material is formed between the mold 31 and the core 30. For example, a slurry containing crystallized glass or ceramic powder and an organic component such as an organic binder and a solvent is poured until at least the upper surface of the core 30 is covered, and is allowed to stand naturally, or about 100 ° C. in a dryer. After drying at a temperature to volatilize the solvent, baking is performed. In the case of a ceramic powder, the firing temperature is fired at a temperature equal to or higher than the sintering temperature of the ceramic. In the case of a glass powder, the fire is performed at a temperature equal to or higher than the glass softening point.

Thereafter, as shown in FIG. 2C, after the core 30 is pulled out from the gas supply path 13, the molding die 31 is removed leaving the bonding layer 11a, and the flange portion 15a is attached to the side surface where the gas supply path 13 is opened. Join. The flange portion 15a can be integrally covered and sealed with an inorganic material of the same material as the seal member 11 with a thickness of 0.5 to 5 mm. Then, it is dried and fired.
In addition, after calcining to such an extent that the molded body can be handled, the core 30 may be pulled out, the molding die 31 may be removed, and then the firing may be performed.

That is, the gas introduction pipe 15 having the flange portion 15a having a shape matching the side surface where the gas supply path 13 is opened is prepared. The gas introduction pipe 15 may be configured by inserting a pipe portion 15b made of a heat-resistant metal into a through hole provided in a flange portion 15a made of ceramic or glass. The pipe portion 15b can be formed of a material having a thermal expansion coefficient close to that of the fuel battery cell 40 or the seal member 11 and a high-strength inorganic material.
Then, as shown in FIG. 1C, the flange portion 15 a is brought into contact with the side surface where the gas supply path 13 is opened, and the flange portion 15 a is covered and sealed with the same material slurry as the seal member 11. And it can be made to dry and bake and the fuel cell stack 40 of this invention can be produced.

In addition, as a material of the sealing member 11, an insulating inorganic material is preferable, and crystallized glass is preferable from the viewpoint of sealing performance and high temperature deformation resistance. In this case, the firing is performed by heating at a temperature equal to or higher than the softening point temperature of the crystallized glass to provide integral molding and a sealing function in accordance with the mold 31 and then crystallizing at a temperature equal to or higher than the crystallization temperature and removing the cooling. The crystallized glass to be used is not particularly limited as long as it has a thermal expansion coefficient close to that of the fuel cell stack 10, but silica-based crystallized glass can be suitably used in terms of high temperature resistance. .
The thermal expansion coefficient of the sealing member 11 is preferably within ± 1 ppm with respect to the thermal expansion coefficient of the porous support substrate 41 that occupies a large proportion in the fuel cell. Thus, in terms of bringing the coefficient of thermal expansion closer to the fuel cell, it is desirable to add 10 to 30 mass% of the material constituting the porous support substrate 41 as the crystallized glass constituting the seal member 11.

  Further, as described above, the material of the mold 31 and the core 30 is preferably made of a material that can easily absorb the solvent of the slurry of the seal member 11 and has poor wettability with the slurry. This is because if the solvent is easily absorbed, the raw material powder in the slurry is well filled, cracking during drying and firing hardly occurs, the strength is high, and the sealing member 11 having excellent gas sealing properties can be obtained. In addition, when the wettability is poor, the restraining force accompanying the shrinkage during drying and firing becomes weak, so that it is difficult to break. A ceramic heat insulating material is preferable as such a material. This ceramic heat insulating material is also excellent in high temperature resistance, can be fired together with the slurry, and can be easily removed after firing, thus facilitating the process. As the ceramic heat insulating material, a heat insulating material made of alumina fiber or alumina-silica fiber is preferable from the viewpoint of ease of processing and cost.

(Other embodiments)
Another embodiment of the fuel cell stack of the present invention will be described with reference to the drawings. FIG. 3 shows another embodiment of the fuel cell stack according to the present invention. The fuel cell stack 10 includes a plurality of plate-shaped solid electrolyte fuel cells 40 having gas flow paths 41a in the longitudinal direction, and the plurality of fuel cells 40 so that the through holes 12 are aligned in one direction. As shown in FIG. 3, the longitudinal direction is alternately changed, and one end portion having a plurality of the through holes 12 is integrated and sealed with a seal member 11 as shown in FIG. ing. In FIG. 3, some of the fuel cells 40 are omitted and simplified.

That is, with the gas supply path 13 in the seal member 11 as the center, the adjacent cells 40 extend and protrude toward the opposite side. As described above, by arranging the fuel cells 40 with the longitudinal directions alternately changed, the fuel cell stack with improved power generation performance can be efficiently accommodated in a compact volume. The angle formed by one direction of the longitudinal direction and the other direction is not particularly limited, but is preferably 180 degrees.
The fuel cell stack 10 can be manufactured by the same method as in the above-described embodiment.
For example, in order to prevent the sealing member 11 from entering one end of the gas flow path 41a of the fuel battery cell 40, an organic substance such as paraffin wax that disappears by firing is filled in advance. The core 30 is inserted into the through hole 12 of the fuel cell 40 in advance. Then, they are inserted into a bottomed mold 31 formed by making a cut corresponding to the thickness of the fuel battery cell 40 in accordance with the insertion position of the fuel battery cell 40 until the bottom of the cut comes into contact with the cell side surface R portion. Then, the slurry of the seal member 11 is poured until the other one upper surface of the R portion of the side surface of the fuel cell 40 is covered.

(Fuel battery cell)
The fuel cell 40 used in the present invention will be described with reference to the drawings. As shown in FIG. 5, the fuel battery cell 40 has a hollow flat plate shape, has a flat cross section, and includes a porous support substrate (support) 41 having a rod shape and an elongated substrate shape as a whole. Inside the support substrate 41, four fuel gas passages 41a (forming gas passages) are formed penetrating in the length direction (axial direction) at appropriate intervals. Has a structure in which various members are provided on the support substrate 41. A plurality of such fuel cells 40 can be arranged in a line as shown in FIG. 1 to form the fuel cell stack 10.

The support substrate 41 includes a flat portion A and arc-shaped portions B at both ends of the flat portion A, and the flat portion A constitutes a main surface. Both main surfaces of the flat portion A are formed substantially parallel to each other, and a fuel electrode layer 42 is provided so as to cover one main surface of the flat portion A and the arc-shaped portions B on both sides, and further covers the fuel electrode layer 42. Thus, a dense solid electrolyte layer 43 is laminated, and an air electrode layer 44 is formed on the main surface on one side of the flat portion A so as to face the fuel electrode layer 42 on the solid electrolyte layer 43. Are stacked. The fuel electrode layer 42 and the solid electrolyte layer 43 are continuously formed on the main surface on one side of the flat portion A in the gas flow path forming direction G.
Further, the other side of the major surface of the flat portion A of the fuel electrode layer 42 and the solid conductive Kaishitsu layer 43 is not laminated, the interconnector 45 is formed. As is clear from FIG. 5, the fuel electrode layer 42 and the solid electrolyte layer 43 extend to both sides of the interconnector 45 and are configured so that the surface of the support substrate 41 is not exposed to the outside.

In the fuel cell 40 having the above-described structure, the portion of the fuel electrode layer 42 facing the air electrode layer 44 operates as a fuel electrode to generate electric power. That is, an oxygen-containing gas such as air is allowed to flow outside the air electrode layer 44, and a fuel gas (hydrogen) is allowed to flow through the gas passage 41a in the support substrate 41 and heated to a predetermined operating temperature. Then, an electrode reaction of the following formula (1) is generated, and power is generated by generating an electrode reaction of the following formula (2), for example, in the portion that becomes the fuel electrode of the fuel electrode layer.
Air electrode layer 44: 1 / 2O ₂ + 2e ⁻ → O ²⁻ (1)
Fuel electrode layer 42: O ²⁻ + H ₂ → H ₂ O + 2e ⁻ (2)
The current generated by such power generation is collected via an interconnector 45 attached to the support substrate 41.

The fuel cell 40, as shown in FIG. 4, from substantially circular the through hole 12, the distance of the gas flow path 41a to the other longitudinal tip through the area of power generation, each substantially the same Thus, it is preferable that the other tip end has a bulging shape. As described above, in the plurality of gas flow paths 41a in the fuel cell 40, the distances of the gas flow paths 41a from the boundary portion of the through hole 12 to the other tip end portion through the power generation region are the same distance. Thus, the pressure loss of each gas flow path 41a can be made equal, so that the gas flowing through each gas flow path 41a has a uniform flow rate, and the power generation performance can be improved.

In addition, this invention is not limited to the said form, A various change is possible in the range which does not change the summary of invention. For example, in the above embodiment, as shown in FIG. 5, the so-called vertical stripe fuel cell 40 in which the power generation element portion is disposed on one main surface of the support substrate 41 and the interconnector 45 is disposed on the other main surface. Although shown, a horizontal stripe fuel cell may be used. That is, the power generation element portion having a multilayer structure in which the fuel electrode layer 42 as the inner electrode, the solid electrolyte 43 and the air electrode layer 44 as the outer electrode are sequentially laminated on the surface of the support substrate 41 is used as the axial length of the support substrate 41. It is configured by forming a plurality at predetermined intervals in the direction. The power generating element portions adjacent to each other are electrically connected in series by respective interconnectors .

A through hole 12 having a diameter of 20 mm was formed by cutting a lower end portion of the vertical stripe fuel cell 40 having a width of 26 mm, a thickness of 3 mm, and a length of 150 mm. Next, the current collecting member 14 was sandwiched between the 10 fuel cells 40 having the through holes 12 and the portions of the through holes 12 were aligned, and the fuel cell stack 10 was formed. At this time, a cylindrical core 30 having the same size as the through hole 12 was inserted into the through hole 12 in advance. For the core 30, a heat insulating material made of alumina fiber was used.
On the other hand, a box-shaped mold 31 having a thickness of 100 mm × width 40 mm × height 50 mm and having a thickness of 5 mm was formed using a heat insulating material made of alumina fiber. And the glass paste which consists of borosilicate glass was poured into the bottom face of the shaping | molding die 31 so that it might become thickness 5mm, and it was made to dry.
Next, the fuel cell stack 10 in which the fuel cells 40 were stacked was placed on the mold 31 with the through-hole 12 part facing down. And after pouring glass paste to the height of 2 mm above the core 30, it was baked at 900 degreeC after making it dry. After firing, the mold 31 and the core 30 were removed.

  Then, the flange portion 15a joined with the pipe portion 15b made of a heat-resistant alloy is joined with a glass seal in accordance with one end face with the opening of the fuel cell stack 10 after the mold 31 and the core 30 are removed. Then, the flange portion 15a was covered with borosilicate glass and fired at 900 ° C. to produce the fuel cell stack 10 of the present invention.

(Leakage resistance)
The other gas flow path 41a embedded in the sealing material 11 of the fuel battery cell 40 of the obtained fuel battery cell stack 10 was closed with tape or the like, and air pressurized to 20 kPa was introduced from the gas introduction pipe 15. . And soap water was apply | coated to the seal | sticker part and the gas introduction pipe 15 junction part, and the presence or absence of generation | occurrence | production of a bubble was measured visually and it confirmed that there was no gas leak.

1 is a fuel cell stack according to an embodiment of the present invention, in which (a) is a partially exploded perspective view, (b) is a sectional view, and (c) is a sectional view taken along line XX of (b). It is a longitudinal cross-sectional view which shows the manufacturing process of the fuel cell stack based on this invention. It is a longitudinal cross-sectional view of the fuel cell stack which concerns on other embodiment of this invention. It is a top view which shows an example of the fuel cell concerning this invention. It is (a) horizontal cross-sectional view and (b) longitudinal cross-sectional view which show one Example of the fuel cell used by this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Fuel cell stack 11 Seal member 11a Joining layer 12 Through-hole 13 Gas supply path 14 Current collection member 15 Gas introduction pipe 15a Flange part 15b Pipe part 30 Core 31 Molding die 40 Fuel cell 41a Gas flow path

Claims (6)

A plurality of the fuels having a through hole penetrating from one surface of the fuel cell to the other surface at one end in the longitudinal direction of the elongated substrate-like fuel cell, and the through hole being aligned in one direction In the fuel cell stack in which the battery cells are bundled, each of the plurality of fuel cells has a gas flow path in the longitudinal direction, and one end portion having the through holes of the plurality of fuel cells is integrated with a seal member A gas supply path in which the through holes communicate with each other inside the seal member , and the gas flow path communicates with the gas supply path. Battery stack.   2. The fuel cell stack according to claim 1, wherein the fuel cell is covered and sealed with the sealing member up to a bottom surface of one end portion of the fuel cell. Gas introduction pipe, according to claim 1 or 2 fuel cell stack according to characterized in that it is joined to the sealing member so as to communicate with the gas supply passage. The fuel cell stack according to any one of claims 1 to 3 , wherein the plurality of fuel cells are arranged by alternately changing the direction of the longitudinal direction. The sealing member, the fuel cell stack according to any one of claims 1 to 4, characterized in that it consists of an inorganic material. A substantially circular said through-hole, so that the distance of the gas flow path to the other longitudinal tip through the area of the power generation is substantially the same, respectively, having a shape that the other tip portion is bulged the fuel cell stack according to any one of claims 1 to 5, wherein.

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