JP2007073359A - Fuel cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide pressing structure of a flat plate lamination type fuel cell capable of adding stable and optimum pressure at all time even under an atmosphere of high temperature at power generation. <P>SOLUTION: The flat plate lamination type fuel cell 1 is formed by alternately laminating a plurality of separators 8 having power generating cells 5 and reaction gas flow passages with the power generating cells 5 located at central part of the separators 8, and adding pressure on the laminate in lamination direction by a pressing means. A weight 22 is mounted on a part where the power generating cell 5 at upper end of the laminate is located (separator body 8a), and the pressure of the weight 22 is utilized as a laminate pressing means. Further, an edge part of the separator is held by a flexible separator arm 8b, and the other end part of the separator arm 8b is fixed to a position shifted from supporting position of the separator in lamination direction. In the above case, elasticity of the separator arm 8a is utilized as the laminate pressing means. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a flat plate type fuel cell in which a large number of power generation cells and separators are alternately stacked, and more particularly to a weighted structure for a stacked body.

  Conventionally, a large number of power generation cells with a structure in which a solid electrolyte layer made of an oxide ion conductor is sandwiched between the air electrode layer (cathode) and the fuel electrode layer (anode) from both sides are stacked with a separator in between. There are known fuel cells.

This flat plate type fuel cell has a structure in which a large number of power generation cells configured by laminating the above-described plurality of power generation elements are further stacked via a conductive member such as a separator, thereby ensuring stable battery performance. Therefore, excellent adhesion (electrical contact) between components is required.
For this reason, in order to ensure the cell surface pressure necessary for power generation in the flat plate type fuel cell, a structure is adopted in which each component is pressed against each other by applying a load in the stacking direction from both ends after stack assembly. Patent Document 1 discloses a structure in which end plates arranged on the upper and lower ends of a stack are tightened with bolts and nuts (tightening with tie rods), and in Patent Document 2, a spring interposed between the stack and the end plates is disclosed. A structure that is elastically loaded is disclosed.
JP 2004-288539 A JP 2004-288618 A

However, the tightening structure using the above-described tie rod may cause the power generation cell to be damaged because the power generation cell is overloaded. On the other hand, in the weighted structure by the spring, the spring material applicable to the operating temperature atmosphere (for example, 800 to 1000 ° C. in the case of a solid oxide fuel cell) is poor, and therefore the spring is heated by high heat in the high temperature atmosphere as described above. Since the elasticity of the resin is cured, there is a problem that it is difficult to always apply an optimum load corresponding to the thermal expansion of the stack constituent members such as the power generation cell, the current collector, and the separator.
When the optimum load is not applied to each power generation cell, the cell voltage varies, and stable battery performance cannot be obtained.

  The present invention has been made in view of such problems, and provides a weighted structure of a flat plate type fuel cell that can always provide a stable optimum load even in a high-temperature atmosphere during power generation. The purpose is that.

  That is, the present invention according to claim 1 is a flat plate laminate type in which a large number of separators having power generation cells and reaction gas passages are alternately stacked, and a load in the stacking direction is applied to the stack by a load means. In the fuel cell, a weight is placed on a portion of the upper end portion of the stacked body where the power generation cell is located, and a pressing force by the weight is used as a weighting unit for the stacked body.

  According to a second aspect of the present invention, in the flat plate type fuel cell according to the first aspect, the edge of the separator is supported by a flexible separator arm having the other end fixed. It is a feature.

  According to a third aspect of the present invention, in the flat plate type fuel cell according to the first aspect, the edge of the separator is supported by a flexible separator arm and the other end of the separator arm is provided. Is fixed at a position shifted in the stacking direction from the support position of the separator, and the elasticity of the separator arm at that time is used as a weighting means for the stack.

  According to a fourth aspect of the present invention, there is provided a flat plate laminate type in which a large number of separators having power generation cells and reaction gas passages are alternately stacked, and a load in the stacking direction is applied to the stack by a load means. In the fuel cell, the edge of the separator is supported by a flexible separator arm, and the other end of the separator arm is fixed at a position shifted in the stacking direction from the support position of the separator. It is characterized in that the elasticity of the separator arm is used as a weighting means for the laminate.

  According to a fifth aspect of the present invention, in the flat plate type fuel cell according to any one of the second to fourth aspects, the other end of the separator arm is fixed to a reaction gas introducing manifold. In addition, the reaction gas passage of the separator and the manifold communicate with each other through a gas hole of the separator arm.

  According to the present invention, since the load due to the weight is used as a weighting means to the laminate (power generation cell), it is not affected by thermal expansion or contraction of the stack constituent member (power generation cell, current collector, separator) in the thermal cycle, Since a constant surface pressure can always be applied to the power generation cell, stable battery performance (output power) that does not cause variations in the cell voltages can be ensured.

  Further, according to the present invention, since the elasticity exerted by the flexible separator arm is used as a weighting means for the power generation cell, it is possible to change the magnitude of the load depending on the length of the separator arm and the thickness of the stack constituent members. Moreover, an appropriate surface pressure can be applied to the power generation cell by pressing the thermal expansion of the current collector with a gentle elastic restoring force of the separator arm. Thereby, favorable electrical contact property can be obtained between the respective power generating elements, and stable battery performance (output power) that does not cause variations in each cell voltage can be ensured.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows the structure of a flat plate fuel cell stack according to the first embodiment of the present invention, FIG. 2 shows a partially enlarged view of FIG. 1, FIG. 3 shows the structure of the separator of FIG. 3 shows a configuration of a flat plate fuel cell stack according to a second embodiment of the present invention.

  As shown in FIG. 2, the single cell 10 includes a circular power generation cell 5 in which a fuel electrode layer 3 and an air electrode layer 4 are disposed on both sides of a solid electrolyte layer 2, and a fuel electrode assembly disposed outside the fuel electrode layer 3. The electric current collector 6, an air electrode current collector 7 disposed outside the air electrode layer 4, and a separator 8 disposed outside each current collector 6, 7 are configured.

Among these power generation elements, the solid electrolyte layer 2 is composed of stabilized zirconia (YSZ) or the like to which yttria is added, and the fuel electrode layer 3 is composed of a metal such as Ni or a cermet such as Ni—YSZ. Is composed of LaMnO ₃ , LaCoO ₃ or the like, the fuel electrode current collector 6 is composed of a sponge-like porous sintered metal plate such as Ni, and the air electrode current collector 7 is composed of a sponge-like porous ceramic such as Ag. It consists of a metal plate.

  As shown in FIG. 3, the separator 8 is formed of a substantially rectangular stainless steel plate having a thickness of several millimeters, and a central separator body 8a in which the power generation cell 5 and the current collectors 6 and 7 described above are stacked. And a pair of separator arms 8b and 8b that extend in the surface direction from the separator body 8a and support the opposite edge of the separator body 8a at two locations.

  The separator body 8a in the center portion has a function of electrically connecting the power generation cells 5 via the current collectors 6 and 7 and supplying a reaction gas to the power generation cells 5, and has a fuel therein. A fuel gas passage 11 that introduces gas from the edge of the separator 8 and discharges it from a substantially central portion 11 a of the surface of the separator 8 that faces the anode current collector 6, and an oxidant gas (air) at the edge of the separator 8 And an oxidant gas passage 12 that is discharged from substantially the center 12 a of the surface of the separator 8 that faces the air electrode current collector 7.

Each separator arm 8b, 8b has a structure in which it is flexible in the laminating direction as an elongated band extending at the opposite corner with a slight gap along the outer periphery of the separator body 8a. In addition, a pair of gas holes 13 and 14 penetrating in the thickness direction are provided at the end portions of the separator arms 8b.
One gas hole 13 communicates with the fuel gas passage 11 of the separator 8, and the other gas hole 14 communicates with the oxidant gas passage 12 of the separator 8, and the gas passages 11, 12 are connected to the gas holes 13, 14. The fuel gas and the oxidant gas are supplied to each electrode surface of each power generation cell 5 through.

The single cells 10 having the above-described configuration are sequentially stacked with insulating manifold rings 15 and 16 interposed therebetween, and a rectangular upper fastening plate 20a and a lower fastening larger than the separator 8 are formed on the upper and lower ends of the laminated body. By providing the attached plate 20b, the flat plate stack type fuel cell stack 1 according to the first embodiment shown in FIG. 1 is configured.
A round hole 23 larger than the outer diameter of the power generation cell 5 is provided in the central portion of the upper fastening plate 20a, and the separator body 8a, that is, the portion where the power generation cell 5 is located is exposed from the hole 23. It has become. The lower fastening plate 20b supports the bottom of the laminate.

In the fuel cell stack 1, as shown in FIG. 1, an upper fastening plate 20a and a lower fastening plate 20b are fastened with bolts 21 and nuts 26 (tie rods) at several places (for example, four corners) of the peripheral portion. Due to the tightening load, the gas holes 13 and 14 of the separator arm 8b and the manifold rings 15 and 16 (the wide portions around this are referred to as manifold portions 8c) are mechanically adhered and joined.
With this tightening load by the tie rods, the manifold rings 15 and 16 are connected in the stacking direction via the gas holes 13 and 14 of the separator 8, respectively. A gas manifold 16 and an oxidant gas manifold 17 are formed.

In the present embodiment, the weight 22 is placed through the insulating member 24 at the center portion (portion of the hole 23) of the upper fastening plate 20a, and the separator main body 8a is moved in the stacking direction by the load from the weight 22. The plurality of power generation elements constituting the single cell 10 are pressed against each other and fixed integrally.
Since the fuel electrode current collector 6 and the air electrode current collector 7 interposed between the separators 8 are sponge-like porous sintered metals, these sponge-like members are elastically deformed by the load of the weight 22, The upper and lower separators 8 are pressed and clamped with a certain degree of elasticity.

Further, in the fuel cell stack 1 of the present embodiment, the separator arm 8b is made flexible so that the manifold portion 8c of the separator 8 and the separator main body 8a where the power generation cells 5 are located are not affected each other. The structure is such that an optimum load can be applied. Even if the load on the power generation cell 5 by the weight 22 is extremely small compared to the strong tightening load of the manifold portion 8c by the bolt 21 and nut 26 described above, it is good between the power generation elements. Electrical contact can be obtained.
As a result, a constant surface pressure can be always applied to the power generation cell 5 even under the temperature of the stack or module member capable of generating power (600 to 800 ° C.), so that the cell voltage does not vary. Stable battery performance (output power) can be ensured.

Note that the load in the stacking direction applied to the fuel cell stack 1 is the minimum necessary to ensure the electrical contact of each power generating element with respect to the separator main body 8a at the center of the stack in consideration of damage to the stack constituent members. In this embodiment, the load is set to about several kgf.
On the other hand, a load of about several hundred kgf is set for the manifold portion 8c at the separator edge in order to ensure the sealing performance with the manifold rings 15 and 16.

Next, a second embodiment of the present invention will be described with reference to FIG.
The fuel cell stack 1 of the second embodiment has substantially the same stack configuration as that of the first embodiment shown in FIG. 1, and the separator 8 uses the separator having the structure shown in FIG. The weighting structure to the power generation cell 5 is different.

  That is, in the second embodiment, the flexibility of the separator arm 8b is used as an elastic restoring force, and the separator main body 8a is pressed downward with a gentle load instead of the load by the weight 22 in FIG.

  Therefore, in the present embodiment, as shown in FIG. 4, an insulating member 25 having substantially the same width as that of the separator body 8a is interposed between the separator 8 located at the lowermost stage and the lower fastening plate 20b. The support position of the main body 8a is lifted upward by the thickness of the insulating member 25 from the fixing position of the end portions (manifold rings 15 and 16) of the separator arm 8b. As a result, the separator arm 8b is fixed in a state of being obliquely distorted downward, and a downward pressing force with the fixed portion of the separator arm 8b as a fulcrum is generated by the elastic restoring force at that time.

  In such a weighted structure, it is possible to change the load on the power generation cell 5 depending on the length of the separator arm 8b or the thickness of the power generation cell 5 and the current collectors 6 and 7 outside thereof, and the fuel during power generation By suppressing the thermal expansion of the electrode current collector 7 and the air electrode current collector 7 with a gentle elastic restoring force of the separator arm 8b, an appropriate surface pressure is always applied to the power generation cell 5 (several kgff as in FIG. 1). Degree). Thereby, favorable electrical contact property can be obtained between the respective power generating elements, and stable battery performance (output power) that does not cause variations in each cell voltage can be ensured.

  As in FIG. 1, the weight of the edge portion on the manifold portion 8c is determined by bolts 21 and nuts 26 (tie rods) at several places on the periphery of the upper fastening plate 20a and the lower fastening plate 20b at the lower end of the stack. By tightening, it is set to about several hundred kgf. Also in this case, due to the flexibility of the separator arm 8b, the weight of the manifold portion 8c by the tie rod does not affect the weight of the separator body 8a where the power generation cell 5 is located.

As described above, in the present embodiment, the case where the other end of the separator arm 8b is fixed to the internal manifold has been described, but the present invention is an external manifold type fuel cell stack in which each manifold is disposed outside the fuel cell stack 1. Of course, the other end of the separator arm 8b is fixed to each external manifold in the same manner as described above.
In the present embodiment, the rectangular separator 8 is used, but the shape is not limited to this and may be a disk shape. Furthermore, the separator arm 8b can also be formed into a flexible tube shape instead of the above-described elongated strip shape.

  Further, in the present invention, it is of course possible to adopt a weighting structure having both the weighting structure of the first embodiment by the weight 22 shown in FIG. 1 and the weighting structure of the second embodiment by the elastic return force of the separator arm shown in FIG. Is possible.

1 is a diagram showing a configuration of a flat plate fuel cell stack according to a first embodiment of the present invention. FIG. The partially expanded view of FIG. The figure which shows the structure of the separator of FIG. The figure which shows the structure of the flat laminated fuel cell stack by 2nd Embodiment of this invention.

Explanation of symbols

1 Fuel cell (fuel cell stack)
5 Power generation cell 8 Separator 8b Separator arm 11, 12 Reaction gas passage (fuel gas passage, oxidant gas passage)
13, 14 Gas hole 16, 17 Manifold 22 Weight

Claims (5)

In a flat plate type fuel cell in which a large number of separators having power generation cells and reaction gas passages are alternately stacked, and a load in the stacking direction is applied to the stack by a load means.
A flat plate stack type fuel cell, wherein a weight is placed on a portion of the upper end portion of the laminated body where the power generation cell is located, and a pressing force by the weight is used as a weighting means to the laminated body. 2. The flat plate type fuel cell according to claim 1, wherein an edge portion of the separator is supported by a flexible separator arm having the other end fixed. The edge of the separator is supported by a flexible separator arm, and the other end of the separator arm is fixed at a position shifted from the support position of the separator in the stacking direction, and the elasticity of the separator arm at that time 2. The flat plate type fuel cell according to claim 1, wherein a weighting means is applied to the laminated body. In a flat plate type fuel cell in which a large number of separators having power generation cells and reaction gas passages are alternately stacked, and a load in the stacking direction is applied to the stack by a load means.
The edge of the separator is supported by a flexible separator arm, and the other end of the separator arm is fixed at a position shifted from the support position of the separator in the stacking direction, and the elasticity of the separator arm at that time A flat plate type fuel cell characterized in that is used as a weighting means for the laminated body. The other end of the separator arm is fixed to a reaction gas introduction manifold, and the reaction gas passage of the separator and the manifold communicate with each other through a gas hole of the separator arm. The flat plate type fuel cell according to any one of claims 2 to 4.

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