JP2013178956A - Fuel cell stack - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel cell stack that reduces resistance between components and improves the ease of assembly.SOLUTION: A fuel cell stack includes a stack and interconnectors. The stack has a plurality of parallel modules laminated in a plurality of tiers. Each parallel module has a plurality of cylindrical cells arranged in a width direction thereof. Each cylindrical cell has a first electrode, a solid oxide electrolyte, and a second electrode, laminated on an outer circumference of a porous metal support. Each interconnector is a sheet conductive member, and is arranged between two adjacent tiers of the parallel modules. The interconnector connects respective metal supports of the parallel module in a first tier of the two adjacent tiers, and is in contact with respective second electrodes of the parallel module in a second tier, without contact with respective second electrodes of the parallel module in the first tier.

Description

  The present invention relates to a fuel cell stack.

  A fuel cell is a device that generally obtains electric energy using hydrogen and oxygen as fuel. Since this fuel cell is excellent in terms of the environment and can realize high energy efficiency, it has been widely developed as a future energy supply system.

  A solid oxide fuel cell (SOFC) has a structure in which a solid oxide electrolyte is sandwiched between an anode and a cathode. As a solid oxide fuel cell, a cylindrical cell supported by a metal support is disclosed (for example, see Patent Document 1). In Patent Document 1, the current collector is connected to the outer electrode layer at the center, and extends from the center toward both ends of the adjacent fuel cell unit and is electrically connected to the inner electrode. And a connecting portion.

International Publication No. 2010/114050

  However, in the technique of Patent Document 1, a current collector is provided for each cylindrical cell, so that the resistance between components at the time of current collection increases. Moreover, there exists a possibility that an assembly | attachment property may worsen.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a fuel cell stack capable of reducing resistance between components and improving assembly.

  A fuel cell stack according to the present invention includes a plurality of parallel modules in which a plurality of cylindrical cells in which a first electrode, a solid oxide electrolyte, and a second electrode are stacked on the outer periphery of a porous metal support are arranged in the width direction. A stack formed by stacking one layer and one conductive member, which is disposed between two parallel modules, connects each metal support of one parallel module, and each second electrode of the one parallel module And an interconnector that is in contact with each second electrode of the other parallel module without contacting the other. According to the fuel cell stack of the present invention, it is possible to reduce the resistance between components and improve the assembling property.

  The interconnector may have elasticity, and may be biased and in contact with each second electrode of the other parallel module. The interconnector may have a corrugated cross section, and the convex portion of the corrugated plate toward the other parallel module may be located between the cylindrical cells of the other parallel module. . The convex portion toward the one parallel module in the corrugated plate shape may be located between the cylindrical cells of the one parallel module. The first electrode may not be formed up to the end of the metal support, and the interconnector may be in contact with the end of the metal support. The metal support may include an enlarged diameter portion at the end, and the interconnector may be in contact with the end side of the enlarged diameter portion.

  According to the present invention, it is possible to provide a fuel cell stack with reduced resistance between components and improved assemblability.

(A) is the external view of a single cell, (b) is the sectional view on the AA line of (a), (c) is the sectional view on the BB line of (a). (A) And (b) is a figure for demonstrating the form which connected the several single cell in parallel in the width direction, (c) is a circuit diagram of (a). (A) is a block diagram of the fuel cell stack using the several single cell, (b) is a figure showing a fuel manifold. It is an AA line sectional view of Drawing 3 (a). FIG. 4 is a cross-sectional view taken along line BB in FIG.

  Hereinafter, modes for carrying out the present invention will be described.

(Single cell configuration)
FIG. 1A to FIG. 1C are diagrams for explaining the structure of a single cell 10 that functions as a unit of a fuel cell constituting the fuel cell stack 100 according to the present embodiment. FIG. 1A is an external view of the single cell 10. FIG.1 (b) is the sectional view on the AA line of Fig.1 (a). FIG.1 (c) is the BB sectional drawing of Fig.1 (a).

  The single cell 10 has a structure in which one electrode, an electrolyte membrane, and the other electrode are laminated in this order on the outer periphery of a cylindrical support. Referring to FIGS. 1A to 1C, in this embodiment, a unit cell 10 includes, as an example, an anode 12, an electrolyte membrane 13, and a cathode 14 on the outer surface of a cylindrical support 11. Have a structure laminated in this order. In the single cell 10, the anode 12, the electrolyte membrane 13 and the cathode 14 function as a power generation unit.

  As the support 11, a member having gas permeability and capable of supporting the electrolyte membrane 13 can be used. As the support 11, a porous metal support can be used. As an example, the porous metal support has a plurality of holes 11a communicating the inner wall and the outer wall. The porous metal support is not particularly limited as long as it is a material (such as stainless steel) having high heat resistance and higher conductivity than the anode 12 and the cathode 14. As the support 11, a seamless type steel pipe, a semi-seamless (flat plate press, drawing after welding) type steel pipe, or the like can be used. The holes 11a can be formed by machining such as pressing, etching, or the like.

The material of the anode 12 is not particularly limited as long as it has electrode activity as an anode. For example, an electrode constituent material containing a solid oxide such as NiO / ZrO ₂ , NiO / CeO ₂ , NiO / BaZrO ₃ Can be used. The material of the electrolyte membrane 13 is not particularly limited. For example, a ZrO ₂ -based, CeO ₂ -based, LaGaO ₃ -based or BaZrO ₃ -based oxygen ion conductive solid oxide electrolyte can be used. The material of the cathode 14 is not particularly limited as long as it has electrode activity as a cathode. For example, an electrode constituent material containing a solid oxide such as LaMnO ₃ , LaCoO ₃ , La ₂ NiO ₄ , or SmCoO ₃ Can be used.

  In the present embodiment, in the longitudinal direction of the support 11, the anode 12 is formed shorter than the support 11, the electrolyte membrane 13 is formed shorter than the anode 12, and the cathode 14 is formed shorter than the electrolyte membrane 13. Yes. Thereby, the edge part of the support body 11, the edge part of the anode 12, and the edge part of the electrolyte membrane 13 are exposed. In addition, the support body 11 is provided with an expanded portion 11b having a diameter larger than that of other portions at the end portion in the longitudinal direction. The pipe expansion part 11b can be formed by a barrel (expansion) process. Details of the expanded pipe portion 11b will be described later. Moreover, the hole 11a is not formed over the whole support body 11, but is formed in the area | region which the cathode 14 covers. As a result, the gas flowing inside the support 11 and the gas flowing outside the support 11 are isolated. An ink jet method, a dipping method, or the like can be used to form the anode 12, the electrolyte membrane 13, and the cathode. In addition, each film may be sintered, or all films may be sintered at once after film formation.

  The single cell 10 generates power by the following action. A fuel gas containing hydrogen is supplied inside the support 11, and an oxidant gas containing oxygen is supplied outside the support 11. In the cathode 14, oxygen supplied to the cathode 14 reacts with electrons supplied from the external electric circuit to become oxygen ions. The oxygen ions are transferred to the anode 12 side through the electrolyte membrane 13.

On the other hand, the hydrogen supplied to the inside of the support 11 passes through the holes 11 a of the support 11 and reaches the anode 12. The hydrogen that has reached the anode 12 emits electrons at the anode 12 and reacts with oxygen ions conducted through the electrolyte membrane 13 from the cathode 14 side to become water (H ₂ O). The emitted electrons are taken out by an external electric circuit. The electrons taken outside are supplied to the cathode 14 after performing electrical work. Power generation is performed by the above operation.

  Here, the cylindrical unit cell is excellent in reliability and heat resistance because it is strong against mechanical shock and thermal shock due to its own structure. Moreover, since it has a larger physique output density than that of a flat single cell, it is possible to quickly warm up and save energy by downsizing and low heat capacity. However, it is necessary to increase the number of cells with respect to the same output while the physique output density increases with the cell diameter reduction. Increasing the number of cells increases the number of current collection points and seal points, which complicates the manufacturing process, resulting in problems such as reduced productivity and increased process costs. Further, since the cylindrical inner diameter electrode (the anode 12 in the example of FIG. 1) collects current at the end in the longitudinal direction of the cylinder, the generated voltage drop due to the current lateral resistance of the electrode thin film with low conductivity becomes remarkable. Therefore, power generation conditions, cylindrical length, electrode film thickness (cross-sectional area), electrode material type, and cell body structure are greatly restricted.

  On the other hand, in the single cell 10, the resistance can be reduced by using the support 11 having higher conductivity than the anode 12 as the current collecting member. As an example, when 50 Ni / YSZ is used as the anode 12, the conductivity σ of the anode 12 is about 1000 S / m to about 1100 S / m at 650 ° C. As an example, when SUS430 is used as the support 11, the conductivity σ of the support 11 is about 8700 S / m (650 ° C.). That is, the support 11 has a conductivity about eight times that of the anode 12. In this case, even if the anode 12 is thinned to 5 μm to 200 μm and current is taken out from a part of the circumference of the support 11, the electrical resistance can be almost ignored.

The general-purpose material SUS430 series does not contain Ni (nickel) and is a material that is relatively inexpensive and excellent in heat resistance even with a SUS material. Therefore, it is preferable to use a SUS430 system as the support 11. Further, since the linear thermal expansion coefficient of the SUS430 system is about 11 × 10 ⁻⁶ , the difference in linear thermal expansion coefficient among the anode 12, the electrolyte membrane 13, and the cathode 14 can be reduced. As a result, peeling of the anode 12, the electrolyte membrane 13, and the cathode 14 can be suppressed. In addition, since the anode 12 can be thinned by using the support 11, the amount of Ni when Ni / YSZ is used as the anode 12 can be reduced.

(Configuration of parallel module)
FIG. 2A and FIG. 2B are diagrams for explaining a form in which a plurality of single cells 10 are connected in parallel in the width direction. FIG. 2 (c) is a circuit diagram of FIG. 2 (a) and FIG. 2 (b). Referring to FIG. 2A, if a plurality of single cells 10 are arranged and interconnector 5 a is arranged so as to be in contact with each cathode 14, each single cell 10 is connected in parallel. Further, referring to FIG. 2B, the circuit shown in FIG. 2C is obtained by connecting the support 11 of each single cell 10 with another interconnector 5b.

  When the parallel modules are stacked in a plurality of stages, the interconnector 5a for connecting the cathodes 14 of the lower parallel module and the interconnector 5b for connecting the supports 11 of the upper parallel module are combined into one interconnector. If it can be made to function by, the said interconnector can bear the parallelization of each single cell 10, and the serialization of each parallel module. In this case, resistance between components can be reduced by simplifying the components. Moreover, the assembling property of each single cell 10 is improved. Hereinafter, a specific example of the interconnector will be described.

(Configuration of fuel cell stack)
FIG. 3A is a configuration diagram of a fuel cell stack 100 using a plurality of single cells 10. Referring to FIG. 3A, the fuel cell stack 100 has a configuration in which the parallel modules described with reference to FIG. In the example of FIG. 3A, the staggered arrangement is performed so that the single cells 10 of other parallel modules are arranged on the two adjacent single cells 10.

  An interconnector 30 is disposed between the lower parallel module and the upper parallel module. The interconnector 30 is arranged on the upper side of each parallel module so as to contact the cathode 14 of each single cell 10. Thereby, each single cell 10 in the parallel module is connected in parallel via each cathode 14. The interconnector 30 has a corrugated shape. Each convex portion of the interconnector 30 on the lower side of the waveform is arranged so as to be positioned between the two adjacent single cells 10 at a position corresponding to the upper single cell 10. Each convex portion of the waveform of the interconnector 30 toward the upper stage is disposed so as to be positioned between the two adjacent single cells 10 at a position corresponding to the lower single cell 10. As a result, the fuel cell stack 100 is saved in space. The interconnector 30 is connected to the support 11 of each single cell 10 of the parallel module without contacting the cathode 14 of each single cell 10 of the upper parallel module. Thereby, a short circuit of each parallel module is prevented. The connection between the interconnector 30 and the support 11 will be described later.

  FIG. 3B is a diagram illustrating the fuel manifold 40. The fuel manifold 40 is a flow path for supplying fuel gas to each single cell 10 or a flow path for discharging fuel gas after passing through each single cell 10. Connected to the end. Thereby, fuel gas is supplied to each single cell 10 in parallel. The material of the fuel manifold 40 is not particularly limited, and may be a metal or a heat resistant material.

  FIG. 4 is a cross-sectional view taken along line AA in FIG. Referring to FIG. 4, a convex portion 21 that holds each single cell 10 is provided on the inner wall of case 20 at a position where the end of each single cell 10 is located. Thereby, each single cell 10 is positioned. The convex-shaped part 21 is formed shorter than the part from the pipe expansion part 11b of the support body 11 to an edge part. Further, the lower interconnector 30 of each single cell 10 is inserted between the convex portion 21 and the support 11. Thereby, the anode 12 of each single cell 10 is connected in parallel. In addition, the provision of the expanded pipe portion 11b positions the interconnector 30 in the longitudinal direction of the single cell 10, and prevents the interconnector 30 from falling off.

  The convex portion 21 is made of an insulating material such as ceramics. Moreover, it is preferable that the convex-shaped part 21 is comprised with the material of the same or the same linear thermal expansion coefficient as the fuel manifold 40 from a viewpoint of the reliability of a gas seal. The fuel manifold 40 and the convex portion 21 are gas-sealed with a sealant and fastened with bolts or the like.

  The convex portion 21 and the support 11 are bonded by an adhesive 50 such as a glass paste. Thereby, fuel gas and oxidant gas are isolated. For example, the convex portion 21 and the support 11 are bonded and fixed at one end of each single cell 10 with a melted glass paste, and then the melted glass system at the other end of each single cell 10. The support 11 and the convex portion 21 may be bonded and fixed with a paste. In this case, each single cell 10 can be fixed together.

  Referring to FIG. 4, interconnector 30 is in contact with each support body 11 of the upper parallel module, but is not in contact with cathode 14. Further, the interconnector 30 has elasticity and is curved so as to protrude toward the lower parallel module in an unbiased state (free shape). Thereby, the interconnector 30 is urged by the contact pressure when contacting the lower cathode 14. That is, the interconnector 30 functions as a spring. Thereby, the dimensional change by the thermal expansion of the single cell 10 can be absorbed.

  Referring to FIG. 3A again, the lowermost interconnector 30 is arranged under the lowermost parallel module. The interconnector 30 is connected to the support 11 of each single cell 10 of the parallel module without contacting the cathode 14 of each single cell 10 of the lowermost parallel module. Further, the interconnector 30 is in contact with the current collector terminal 60. A cathode current collector terminal (not shown) is in contact with the uppermost parallel module. Thereby, the generated power of each parallel module can be taken out.

  A heat insulating member 70 is disposed between the current collector plate terminal 60 and the inner wall of the case 20. In this case, the heat dissipation of the fuel cell stack 100 can be reduced, while the temperature rise of the case 20 can be suppressed. Thereby, the safety | security with respect to a human body and peripheral components can be aimed at. Moreover, the thermal expansion of each single cell 10 can be absorbed by using the material which has elasticity for the heat insulation member 70.

  FIG. 5 is a cross-sectional view taken along line BB in FIG. Referring to FIG. 5, a plurality of holes 31 are formed in the interconnector 30. Thereby, oxidant gas is supplied to each parallel module. 3A and 5, each convex portion 32 to the upper side of the waveform of the interconnector 30 functions as a spring when the single cell 10 is thermally expanded. It can absorb dimensional changes due to expansion.

  According to the present embodiment, the interconnector 30 has both a function of connecting each single cell 10 in parallel in a parallel module and a function of connecting each parallel module in series. Thereby, components are simplified and resistance between components can be reduced. Moreover, the assembling property of each single cell 10 is improved. In addition, a current value determined by parallel connection and a voltage value determined by series connection can be freely selected as necessary. Furthermore, the interconnector 30 has a function of absorbing thermal expansion of each single cell 10 by having corrugated irregularities. The interconnector 30 is preferably made of a material having the same or the same linear thermal expansion coefficient as the support 11. This is because a difference in thermal expansion between the support 11 and the interconnector 30 can be suppressed in the longitudinal direction of the support 11.

  The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited to such specific embodiments, and various modifications can be made within the scope of the gist of the present invention described in the claims.・ Change is possible. For example, in the above embodiment, the anode, the electrolyte membrane, and the cathode are sequentially stacked on the support, but the cathode, the electrolyte membrane, and the anode may be sequentially stacked on the support. Moreover, in the said embodiment, although the interconnector has a waveform cross section, it contacts each support body without contacting each cathode of one parallel module of an adjacent parallel module, and each support body of the other parallel module As long as it is in contact with each cathode without being in contact with each other, there is no particular limitation.

DESCRIPTION OF SYMBOLS 10 Single cell 11 Support body 11a Hole 11b Expanded pipe part 12 Anode 13 Electrolyte membrane 14 Cathode 20 Case 21 Convex-shaped part 30 Interconnector 40 Fuel manifold 50 Adhesive 60 Current collector terminal 70 Heat insulation member 70
100 Fuel cell stack

Claims (6)

A stack in which a plurality of parallel modules in which a plurality of cylindrical cells each having a first electrode, a solid oxide electrolyte, and a second electrode laminated on the outer periphery of a porous metal support are arranged in the width direction are laminated;
One conductive member, which is disposed between two parallel modules, connects each metal support of one parallel module, and does not contact each second electrode of the one parallel module and the other A fuel cell stack comprising: an interconnector that contacts each second electrode of the parallel module.   2. The fuel cell stack according to claim 1, wherein the interconnector has elasticity, and is biased and in contact with each second electrode of the other parallel module. The interconnector has a corrugated cross section,
3. The fuel cell stack according to claim 1, wherein the corrugated convex portion toward the other parallel module is located between the cylindrical cells of the other parallel module. 4.   4. The fuel cell stack according to claim 3, wherein the corrugated convex portion toward the one parallel module is located between the cylindrical cells of the one parallel module. 5. The first electrode is not formed up to the end of the metal support,
The fuel cell stack according to claim 1, wherein the interconnector is in contact with an end portion of the metal support. The metal support includes an enlarged diameter portion at the end,
6. The fuel cell stack according to claim 5, wherein the interconnector is in contact with an end side of the enlarged diameter portion.

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