JP2015162286A - Fuel battery cell stack device and fuel cell device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel battery cell stack device and a fuel cell battery which are improved in reliability.SOLUTION: A fuel battery cell stack device includes: a first manifold 4 in which a fuel battery cell stack 3 formed by arranging a plurality of fuel battery cells 2 each having a gas passage 16 in the inside thereof and one ends of the fuel battery cells 2 are fixed by a seal material 20 and which is used for supplying gas to the fuel battery cells 2; a second manifold 7 in which the other ends of the fuel battery cells 2 are fixed by the seal material 20 and which is used for recovering gas exhausted by the fuel battery cells 2; and conductive members 5 which are arranged at both ends in the arrangement direction of the fuel battery cells 2 so as to hold the fuel battery cell stack 3 therebetween. In at least one conductive member 5, at least one of one end and the other end is arranged so as to be separated from the manifold.

Description

  The present invention relates to a fuel cell stack device and a fuel cell device.

  In recent years, as a next-generation energy, a fuel cell stack device in which a plurality of fuel cells that can obtain electric power using a fuel gas (hydrogen-containing gas) and an oxygen-containing gas (air) are arranged in a storage container Various fuel cell modules that are housed and fuel cell devices in which the fuel cell module is housed in an exterior case have been proposed (see, for example, Patent Document 1).

  Further, an off-gas recycle type fuel cell device that collects and reuses fuel gas that has not been used for power generation has also been proposed.

JP 2007-59377 A

  By the way, in such an off-gas recycling type cell stack device, the fuel cells are sealed in a manifold for supplying the fuel gas to each fuel cell or a manifold for collecting the unused fuel gas. Although it is conceivable to fix through a material, there is a problem that a crack or the like is generated in the sealing material, thereby causing a gas leak.

  Therefore, it is an object of the present invention to provide a fuel cell stack device that can suppress the occurrence of cracks in the sealing material and has improved long-term reliability, and a fuel cell device including the same.

  The fuel cell stack device of the present invention has a fuel cell stack formed by arranging a plurality of fuel cells having gas flow paths therein, and one end of the fuel cell is fixed with a sealing material, A first manifold for supplying gas to the fuel battery cell and a second manifold for recovering the gas discharged from the fuel battery cell while the other end of the fuel battery cell is fixed by a sealant 2 manifolds, and conductive members arranged so as to sandwich the fuel cell stack at both ends in the arrangement direction of the fuel cells, and at least one of the conductive members has one end and the other end At least one of them is arranged to be separated from the manifold.

  The fuel cell device of the present invention is characterized in that the fuel cell stack device described above is accommodated in a storage container.

  The fuel cell stack device of the present invention can suppress the occurrence of cracks in the sealing material and can be a fuel cell stack device with improved long-term reliability.

The fuel cell device of the present invention can be a fuel cell device with improved long-term reliability.

It is an external appearance perspective view which shows an example of the fuel cell stack apparatus of this embodiment. (A) is sectional drawing of the fuel cell stack apparatus shown in FIG. 1, (b) is a top view which extracts and shows the broken-line part shown by (a). It is sectional drawing which shows another example of the fuel cell stack apparatus of this embodiment.

  FIG. 1 shows a configuration in which fuel cells 2 having gas flow paths (not shown) through which gas flows from one end to the other are arranged in a row, and between adjacent fuel cells 2 are cells. A fuel cell stack device 1 (hereinafter simply abbreviated as cell stack 3 or cell stack device 1) comprising fuel cell stacks 3 electrically connected in series via an inter-conductive member (not shown in FIG. 1). In some cases.) Each fuel cell 2 has a lower end fixed to the first manifold 4 with an insulating sealing material (not shown) such as glass, and an upper end similarly fixed to the second manifold 7 with a sealing material. Yes. A gas supply pipe 8 for supplying fuel gas is connected to the first manifold 4, and a gas recovery pipe 9 for recovering fuel gas that has not been used for power generation is connected to the second manifold 7. Yes. Further, in the cell stack device 1 shown in FIG. 1, conductive members 5 for deriving current generated by each fuel cell 2 are provided at both ends of the cell stack 3 in the arrangement direction of the fuel cells 2. Yes. The conductive member 5 is also connected via the inter-cell conductive member. Further, in the conductive member 5 shown in FIG. 1, a current deriving portion 6 that protrudes outside the cell stack 3 is provided on the lower end side of the conductive member 5. In addition, the conductive member 5 and the cell stack 3 are protected from contact with a heat insulating material disposed around the cell stack 3 as a part of the conductive member 5 and external impacts. Thus, a protective cover may be provided.

  Although FIG. 1 shows an example in which one cell stack 3 is fixed to each manifold, the number can be changed as appropriate. For example, a plurality of cell stacks 3 are fixed to each manifold. Also good.

  In the cell stack apparatus 1 described above, power can be generated by flowing a hydrogen-containing gas (fuel gas) through the gas flow path, and the first manifold 4 serves as a supply unit for supplying fuel gas, The manifold 7 serves as a recovery unit for recovering exhaust gas that is not used for power generation discharged from the fuel cells. That is, it can be used as a fuel cell of a type that recycles off-gas.

  Incidentally, the first manifold 4 and the second manifold 7 described above may be reversed.

  Each manifold stores a gas supplied to the fuel cell 2 or recovered from the fuel cell 2, a gas case 18 having an opening on the upper surface, the fuel cell 2 on the inside, and a gas case And a frame 19 fixed to the frame.

  2A is a cross-sectional view of the cell stack device 1 shown in FIG. 1, and FIG. 2B is a plan view showing an excerpt of a broken line portion shown in FIG. First, the fuel battery cell 2 will be described with reference to FIG. In addition, (a) is sectional drawing of the side surface side, and a part of hatching is abbreviate | omitted and the electrically-conductive member 5 is painted with the point in order to clarify.

The fuel battery cell 2 shown in FIG. 2 is a hollow flat plate type having a plurality of gas flow paths through which gas flows in the longitudinal direction, and has an inner electrode layer, a solid electrolyte layer, and an outer surface on the surface of a support substrate having the gas flow paths. The fuel cell 2 which laminates | stacks an electrode layer in order is illustrated. Hereinafter, although it demonstrates using the example of a hollow plate type, it can also be set as the fuel cell 2 of a flat plate type or a cylindrical type.

  The fuel cell 2 shown in FIG. 2 includes an inner electrode layer 11 and a solid body on one flat surface of a columnar conductive support substrate 15 (hereinafter, may be abbreviated as a support substrate 15) having a pair of opposed flat surfaces. It has a columnar shape (hollow flat plate shape or the like) formed by sequentially laminating the electrolyte layer 12 and the outer electrode layer 13. This conductive support substrate 15 is provided with gas flow paths 16 through which gas flows, and FIG. 2 shows an example in which six gas flow paths are provided. An interconnector 14 is provided on the other flat surface of the fuel battery cell 2, and a P-type semiconductor layer 17 is provided on the outer surface (upper surface) of the interconnector 14. By connecting the inter-cell conductive member 10 to the interconnector 14 via the P-type semiconductor layer 17, the contact between the two becomes an ohmic contact, and it is possible to reduce the potential drop and effectively avoid the deterioration of the conductive performance. Become. The support substrate also serves as an inner electrode layer, and a fuel cell can be configured by sequentially laminating a solid fuel cell layer and an outer electrode layer on the surface thereof. In the following description, the inner electrode layer is described as a fuel electrode layer, and the outer electrode layer is described as an air electrode layer.

For the inner electrode layer 11, generally known ones can be used, and porous conductive ceramics such as ZrO ₂ in which a rare earth element is dissolved (referred to as stabilized zirconia, including partial stabilization). ) And Ni and / or NiO.

The solid electrolyte layer 12 functions as an electrolyte that bridges electrons between the inner electrode layer 11 and the outer electrode layer 13, and at the same time, in order to prevent leakage between the fuel gas and the oxygen-containing gas. And is formed from ZrO ₂ in which 3 to 15 mol% of a rare earth element is dissolved. In addition, as long as it has the said characteristic, you may form using another material etc.

The outer electrode layer 13 is not particularly limited as long as it is generally used. For example, the outer electrode layer 13 can be formed of a conductive ceramic made of a so-called ABO ₃ type perovskite complex oxide. The outer electrode layer 13 needs to have gas permeability, and the open porosity is preferably 20% or more, particularly preferably in the range of 30 to 50%.

  The support substrate 15 is required to be gas permeable in order to transmit gas to the inner electrode layer 11 and further to be conductive in order to collect current via the interconnector 14. Therefore, as the support substrate 15, conductive ceramics, cermet, or the like can be used. When the fuel cell 2 is manufactured, when the support substrate 15 is manufactured by simultaneous firing with the inner electrode layer 11 or the solid electrolyte layer 12, the support substrate 15 is formed from the iron group metal component and the specific rare earth oxide. It is preferable. Further, the support substrate 15 preferably has an open porosity of 30% or more, particularly 35 to 50% in order to have gas permeability, and its conductivity is 300 S / cm or more, particularly 440S. / Cm or more is preferable.

An example of the P-type semiconductor layer 17 is a layer made of a transition metal perovskite oxide. Specifically, a material having higher electron conductivity than the material constituting the interconnector 14, for example, LaMnO ₃ composite oxide, LaFeO ₃ composite oxide, LaCoO in which Mn, Fe, Co, etc. are present at the B site the P-type semiconductor ceramics made of at least one such _3-based composite oxide can be used. In general, the thickness of the P-type semiconductor layer 17 is preferably in the range of 30 to 100 μm.

As described above, the interconnector 14 is preferably a lanthanum chromite perovskite complex oxide (LaCrO ₃ complex oxide) or a lanthanum strontium titanium perovskite complex oxide (LaSrTiO ₃ complex oxide). used. These materials have conductivity and are not reduced or oxidized even when they come into contact with a hydrogen-containing gas or an oxygen-containing gas (air or the like). Further, the interconnector 14 must be dense in order to prevent leakage of the gas flowing through the gas flow path 16 formed on the support substrate 15 and the gas flowing outside the support substrate 15, and is 93% or more. In particular, it is preferable to have a relative density of 95% or more.

  The inter-cell conductive member 10 and the conductive member 5 interposed for electrically connecting the fuel cells 2 are required for a member made of a metal or alloy having elasticity or a felt made of metal fiber or alloy fiber. It can comprise from the member which surface-treated.

  By the way, one end (lower end) and the other end (upper end) of such a fuel battery cell 2 are surrounded by a frame body 19 of each manifold, and the fuel battery cell is sealed with a sealing material 20 filled inside the frame body 19. The outer periphery of the lower end of 2 is fixed. That is, the cell stack 3 arranges a plurality of fuel cells 2 inside the frame body 19, and each fuel cell 2 is connected and accommodated via the inter-cell conductive member 10. It is glued to. In addition, the inner side of this frame 19 becomes a fixing part. Moreover, it is preferable to use the material which has heat resistance and insulation for the sealing material 20, For example, glass etc. can be used.

  On the other hand, the gas case 18 constituting the first manifold 4 and the second manifold 7 has an opening for supplying gas to the gas flow path 16 of the fuel cell 2, and one end of the annular frame 19. The portion is inserted into a groove formed in an annular shape so as to surround the opening of the gas case 18, and is fixed by the sealing material 20. Thereby, parts other than the gas flow path 16 of the fuel battery cell 2 are airtightly sealed.

  In this configuration, before connecting the fuel cell stack 3 to the gas case 18, one end of the fuel cell 2 is separately bonded to the frame body 19 with the sealing material 20, and then the frame body 19 is attached to the gas case 20. It can be adhered and sealed.

  By the way, in the cell stack apparatus 1, a crack etc. may arise in the sealing material 20 which consists of glass etc. at the time of a driving | operation or manufacture. This is because when the fuel cell 2, the inter-cell conductive member 10, the conductive member 5, etc. are fixed to the sealing material 20, stress is generated in the sealing material 20 due to expansion of each member due to heat during operation or manufacturing. However, it is considered that it occurs with the stress. In particular, this crack is likely to occur at the interface with the frame 19 and the interface with the fuel cell 2.

  Therefore, in the cell stack apparatus 1 shown in FIG. 2, the other end (upper end) of the conductive member 5 is used for the purpose of reducing the stress generated in the sealing material 20 in suppressing the occurrence of cracks in the sealing material 20. The second manifold 7 is spaced from the second manifold 7. In other words, the upper end of the conductive member 5 is not fixed to the sealing material 20. In addition, in FIG. 2, this part is shown with the dashed-dotted line.

  Since it can suppress that the stress which arises in the electrically-conductive member 5 propagates to the sealing material 20, it can suppress that a crack arises in the sealing material 20. FIG. Therefore, the cell stack device 1 with improved reliability can be obtained.

FIG. 2 shows an example in which the other end (upper end) of the conductive member 5 and the second manifold 7 are separated from each other, but one end (lower end) of the conductive member 5 and the first manifold are shown. 4, and the upper and lower ends of the conductive member 5 may be separated from the first manifold 4 and the second manifold 7. Further, in the cell stack apparatus 1 shown in FIG. 2, an example is shown in which the other end (upper end) of the conductive member 5 located at both ends and the second manifold 7 are separated from each other. Only the member 5 may be separated.

  Here, when separating the conductive member 5 from each manifold, it is preferable to separate the side where the stress generated in the conductive member is large from each manifold. For example, when the temperature is compared between the first manifold 4 side and the second manifold 7 side, the stress generated in the conductive member 5 and the stress generated in the sealing material tend to increase when the temperature is higher. Therefore, in the cell stack device 1 having such a configuration, it is possible to obtain more effects by separating the higher temperature side of the manifold from the end of the corresponding conductive member 5. Accordingly, when the conductive member 5 and each manifold are separated from each other, the temperature may be set as appropriate based on the temperature of the fluid flowing through the first manifold 4 and the temperature flowing through the second manifold 7.

  For example, in a configuration in which high-temperature fuel gas is introduced into the first manifold 4 of the cell stack device 1 and fuel gas that has not been used for power generation is recovered by the second manifold 7, the temperature of the introduced fuel gas Therefore, the one end (lower end) of the conductive member 5 and the first manifold 4 can be separated from each other.

  Incidentally, when the conductive member 5 is separated from each manifold, the conductive member 5 can be appropriately set in consideration of the balance with the power generation efficiency, but can be set to 1 to 10 mm, for example. In this case, the distance between the conductive member 5 and each manifold means the distance between the surface of the sealing material 20 and one end of the conductive member 5.

  FIG. 3 is a cross-sectional view showing another example of the fuel cell stack device of the present embodiment.

  In contrast to the cell stack apparatus 1 shown in FIG. 2, the other end of the conductive member 5 is fixed to the second manifold 7, while one end of the conductive member 5 is fixed to the first manifold 4. It is different. In FIG. 3, this separated portion is indicated by a one-dot broken line.

  In the cell stack device 21 shown in FIG. 3, a current deriving unit 6 for drawing current to the outside is provided on the lower end portion side of the conductive member 5. Here, in the conductive member 5, it is assumed that Joule heat is generated in the portion where the current deriving portion 6 is connected, and the temperature of the conductive member 5 itself increases. In this case, when the conductive member 5 itself is viewed, it is assumed that the temperature on the end portion side where the current deriving portion 6 is provided becomes high.

  Therefore, when the end of the conductive member 5 is separated from each manifold, the end of the conductive member 5 on the side where the current deriving portion 6 is provided can be separated from the manifold.

  Therefore, in the cell stack device 21 shown in FIG. 3, since the current deriving unit 6 is provided on the lower end side of the conductive member 5, the lower end of the conductive member 5 and the first manifold 4 are separated from each other. Yes.

  Thereby, since it can suppress that the stress which arises in the electrically-conductive member 5 propagates to the sealing material 20, it can suppress that a crack arises in the sealing material 20. FIG. Therefore, the cell stack device 21 with improved reliability can be obtained.

  When the conductive member 5 and each manifold are separated from each other as described above, the conductive member 5 and the inter-cell conductive member 10 may be separated.

Therefore, for the purpose of suppressing such peeling, a holding member for holding one end of the conductive member 5 is formed between the conductive member 5 and the seal member 20 and is made of a material different from the seal member 20. It can also be provided. The holding member needs to be elastic and deformable, for example, a cotton-like heat insulating material, a spiral wire made of glass or the like, a leaf spring, or the like is used. it can. Thereby, the stress generated in the conductive member 5 can be absorbed by the holding member, and the conductive member 5 can be prevented from peeling off.

  When the holding member is provided, if the frame body 19 of each manifold is conductive, there is a possibility that the holding member and the frame body 19 come into contact with each other, so that the holding member is insulative. Preferably there is. Therefore, in this case, the holding member is preferably made of a material such as aluminum oxide, silicon oxide, zirconium oxide, or a composite oxide containing these. In addition, with conductivity and insulation, in the operating environment of the cell stack device, what shows the property of conducting electricity is conductive and what shows the property of not conducting electricity is insulation.

  Further, as described above, in the sealing material 20, cracks are likely to occur at the interface portion with the fuel cell 2. Therefore, for the purpose of relieving stress between the fuel cell 2 and the sealing material 20, an oxide is a main component on the surface of the sealing material 20, and one end of the fuel cell 2 and the sealing material 20 are fixed. A fixing material can be provided. Thereby, the stress produced by expansion or deformation of the fuel cell 2 can be relaxed by the fixing material, and the occurrence of cracks or the like at the interface with the fuel cell 2 can be suppressed.

  As such a fixing material, for example, a heat insulating material mainly composed of aluminum oxide or silicon oxide can be used.

  And it can be set as the fuel cell apparatus which improved long-term reliability by accommodating the fuel cell stack apparatus 1 and 21 mentioned above in a storage container (not shown). The storage container preferably includes a heat source device such as a heater for raising the temperature of the fuel battery cell 2 and maintaining the temperature at a high temperature.

  Although the present invention has been described in detail above, the present invention is not limited to the above-described embodiments, and various modifications and improvements can be made without departing from the scope of the present invention.

  In the above example, the fuel cell 2 called a so-called vertical stripe type has been described, but a horizontal stripe type fuel cell stack in which a plurality of power generation element portions generally called a horizontal stripe type are provided on a support can also be used. .

DESCRIPTION OF SYMBOLS 1, 2: Fuel cell stack apparatus 2: Fuel cell 4: First manifold 5: Conductive member 6: Current derivation part 7: Second manifold

Claims (4)

A fuel cell stack formed by arranging a plurality of fuel cells having gas flow paths therein, one end of the fuel cell being fixed by a sealing material, and supplying gas to the fuel cell A first manifold of
A second manifold for recovering the gas discharged from the fuel battery cell, the other end of the fuel battery cell being fixed by a sealing material;
A conductive member arranged to sandwich the fuel cell stack at both ends in the arrangement direction of the fuel cells,
In at least one of the conductive members, at least one of one end and the other end is disposed so as to be separated from the manifold.   The conductive member is separated from one manifold through which a gas having a high temperature flows among the gas flowing through the first manifold and the gas flowing through the second manifold. A fuel cell stack device according to claim 1.   2. The conductive member according to claim 1, wherein the conductive member includes a current deriving portion for drawing an electric current to the outside, and an end on the current deriving portion side is disposed so as to be separated from the manifold. Fuel cell stack device.   A fuel cell device comprising the fuel cell stack device according to any one of claims 1 to 3 stored in a storage container.

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