JP2015191693A - Cell stack, electrolysis module and electrolysis device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cell stack, an electrolysis module and an electrolysis device in which the electrical conductivity between an electrically conductive member and an electrolytic cell is kept high.SOLUTION: In a cell stack 2, fuel battery cells 3 and collector members 4 are alternately arranged, the fuel battery cells 3 and the first principal surfaces 4g of collector pieces 4a, 4b of the collector members 4 are joined to one another by conductive joint material 13 so that the plural fuel battery cells 3 are electrically connected to one another, voids 15 exist in the conductive joint material 13 to be in contact with the first principal surfaces 4g of the collector pieces 4a, 4b, and the rate (S2/S1×100) of the area S2 of the void 15 to the area S1 of the joint portion 13a between the first principal surface 4g of the collector piece 4a, 4b which is determined from a photograph after the collector member 4 is exfoliated from the conductive joint material 13 is equal to 20% or less.

Description

  The present invention relates to a cell stack, an electrolysis module, and an electrolysis apparatus in which an electrolysis cell and a conductive member are electrically connected using a conductive bonding material.

  In recent years, solid oxide fuel cells (a type of electrolytic cell) that generate power at a high temperature of 600 to 1000 ° C. using fuel gas (hydrogen-containing gas) and oxygen-containing gas (air, etc.) as next-generation energy It has been known. A plurality of fuel cells are electrically connected in series via a current collecting member (a kind of conductive member) to form a cell stack (see, for example, Patent Document 1). The current collecting member is bonded to the fuel cell using a conductive bonding material.

  Conventionally, Patent Document 1 discloses that a flat gap (equivalent circular diameter of 10 mm) larger than pores existing in the conductive bonding material in the conductive bonding material between the current collecting member and the fuel cell. It is described that the presence of ˜200 μm) can suppress the occurrence of cracks in the oxygen electrode after the end of the thermal cycle test.

JP 2005-339904 A

  However, in Patent Document 1, there is no control over the area ratio of the gap to the bonding area between the current collecting member and the conductive bonding material, and the conductivity between the current collecting member and the fuel cell may be reduced. there were.

  An object of the present invention is to provide a cell stack, an electrolytic module, and an electrolytic apparatus that can maintain high electrical conductivity between a conductive member and an electrolytic cell.

  In the cell stack of the present invention, the electrolytic cells and the conductive members are alternately arranged, the electrolytic cells and the main surfaces of the conductive pieces of the conductive members are bonded with a conductive bonding material, and a plurality of the electrolytic cells are electrically connected. In the cell stack formed by connecting to the conductive bonding material, a gap exists in contact with the main surface of the conductive piece, and the conductive member is peeled off from the conductive bonding material. The ratio of the area of the gap to the area of the joint between the main surface of the conductive piece and the conductive bonding material, which is obtained from a photograph, is 20% or less.

  The electrolytic module of the present invention is characterized in that the cell stack is stored in a storage container.

  Furthermore, the electrolysis apparatus of the present invention is characterized in that the electrolysis module and an auxiliary machine for operating the electrolysis module are housed in an outer case.

  According to the cell stack of the present invention, the conductivity between the conductive member and the electrolysis cell can be maintained high, and the electrolysis performance of the electrolysis module and the electrolysis apparatus using such a cell stack can be maintained high.

The cell stack apparatus is shown, (a) is a side view, (b) is an enlarged cross-sectional view showing a part of (a). It is a perspective view which extracts and shows the current collection member of FIG. (A) is the side view seen from the AA line of the current collection member shown in FIG. 2, (b) is the BB sectional drawing of the current collection member shown in FIG. It is a longitudinal cross-sectional view which shows the joining state of a fuel cell and a current collection member. 4A is an enlarged view of a part of FIG. 4 (along the line DD in FIG. 6A), and FIG. 6B is an enlarged view of the gap in FIG. FIG. 4A is a cross-sectional view taken along the line C-C of FIG. 4, FIG. 4B is a plan view of the conductive bonding material after the current collecting member is peeled from the conductive bonding material, and FIG. It is sectional drawing along the EE line | wire of (). It is an external appearance perspective view which decomposes | disassembles and shows the fuel cell module formed by accommodating the cell stack of FIG. 1 in a storage container. It is a perspective view which shows the fuel cell apparatus which accommodates a fuel cell module in an exterior case. It is a graph which shows the relationship between a space | gap and resistance including a fuel cell, an electroconductive joining material, and a current collection member.

  FIG. 1 shows a cell stack device. The cell stack device 1 has a solid oxide fuel cell 3 which is a kind of electrolytic cell. This fuel cell 3 has a gas flow path 12 therein, and has a pair of opposed main surfaces as a whole, a columnar conductive support 7 and one main surface of the conductive support 7. There is provided a power generation unit in which a fuel electrode layer 8 that is an inner electrode layer, a solid electrolyte layer 9, and an oxygen electrode layer 10 that is an outer electrode layer are arranged in this order. An interconnector 11 is arranged on the other main surface of the conductive support 7 to constitute a columnar (hollow flat plate) fuel cell 3.

  A plurality of fuel cells 3 are arranged in a row, and current collecting members 4 that are a kind of conductive members are arranged between adjacent fuel cells 3. As will be described in detail later, the fuel cell 3 and the current collecting member 4 are joined via a conductive bonding material 13, whereby a plurality of fuel cells 3 are joined via the current collecting member 4. The cell stack 2 is configured by electrical and mechanical joining.

  Further, a P-type semiconductor layer (not shown) can be provided on the outer surface of the interconnector 11. By connecting the current collecting member 4 to the interconnector 11 via the P-type semiconductor layer, the contact between them becomes an ohmic contact, and the potential drop can be reduced.

  The lower end portion of each fuel cell 3 constituting the cell stack 2 is fixed to the gas tank 6 by a sealing material 14 such as glass, so that the fuel gas in the gas tank 6 is provided inside the fuel cell 3. The gas can be supplied to the fuel electrode layer 8 of the fuel cell 3 through the gas flow path 12.

  The gas flow path 12 is provided penetrating in the longitudinal direction L of the conductive support 7, and the oxygen electrode layer 10 is disposed on the solid electrolyte layer 9 on one main surface of the conductive support 7 in the longitudinal direction L. The interconnector layer 11 is formed on the other main surface of the conductive support 7 in the entire longitudinal direction y.

In the cell stack apparatus 1 shown in FIG. 1, a hydrogen-containing gas flows as a fuel gas inside the gas flow path 12 of the fuel cell 3, and the outside of the fuel cell 3, particularly between a pair of fuel cells 3. The oxygen-containing gas (air) flows through the internal space S of the arranged current collecting member 4. As a result, the fuel gas is supplied from the gas tank 6 to the fuel electrode layer 8 and the oxygen-containing gas is supplied to the oxygen electrode layer 10, thereby generating power in the fuel cell 3.

  The cell stack device 1 is configured by arranging an elastically deformable conductive holding member 5 so as to hold the cell stack 2 from both ends in the arrangement direction x of the fuel cells 3, and a lower end of the holding member 5. The part is fixed to the gas tank 6. The sandwiching member 5 has a flat plate portion 5a provided so as to be positioned at both ends of the cell stack 2, and a shape extending outward along the arrangement direction x of the fuel cells 3, and the cell stack 2 (fuel cell) And a current extraction part 5b for extracting a current generated by the power generation of 3).

  Below, each member which comprises the fuel cell 3 of FIG. 1 is demonstrated.

As the fuel electrode layer 8, generally known ones can be used, and porous conductive ceramics such as ZrO ₂ (referred to as stabilized zirconia) in which a rare earth element oxide is dissolved, Ni and / or Or it can comprise with NiO.

The solid electrolyte layer 9 has a function as an electrolyte that bridges electrons between the electrodes, and at the same time, has to have a gas barrier property in order to prevent leakage between the fuel gas and the oxygen-containing gas. 3 to 15 mol% of a rare earth element oxide is formed of ZrO ₂ as a solid solution. In addition, as long as it has the said characteristic, you may comprise using another material etc.

The oxygen electrode layer 10 is not particularly limited as long as it is generally used. For example, the oxygen electrode layer 10 can be made of a conductive ceramic made of a so-called ABO ₃ type perovskite complex oxide. The oxygen electrode layer 10 needs to have gas permeability, and can have an open porosity of 20% or more, particularly 30 to 50%. As the oxygen electrode layer 10, for example, at least one of lanthanum manganite (LaSrMnO ₃ ), lanthanum ferrite (LaSrFeO ₃ ), lanthanum cobaltite (LaSrCoO ₃ ) and the like in which Mn, Fe, Co, etc. exist at the B site is used. Can do.

Although the interconnector 11 can be made of conductive ceramics, it needs to have reduction resistance and oxidation resistance because it comes in contact with a fuel gas (hydrogen-containing gas) and an oxygen-containing gas (air, etc.). For example, lanthanum chromite (LaCrO ₃ ) can be used. The interconnector 11 must be dense in order to prevent leakage of fuel gas flowing through the plurality of gas flow paths 12 existing in the conductive support 7 and oxygen-containing gas flowing outside the conductive support 7. The relative density is preferably 93% or more, particularly 95% or more.

  The conductive support 7 is required to be gas permeable in order to permeate the fuel gas up to the fuel electrode layer 8 and to be conductive in order to collect current through the interconnector 11. The Therefore, as the conductive support 7, it is necessary to use a material that satisfies this requirement. For example, conductive ceramics or cermet can be used.

  When the fuel cell 3 is manufactured, when the conductive support 7 is manufactured by co-firing with the fuel electrode layer 8 or the solid electrolyte layer 9, the conductive battery 7 is electrically conductive from the iron group metal component and the specific rare earth element oxide. The support 7 can be configured. Further, the conductive support 7 preferably has an open porosity of 30% or more, particularly 35 to 50% in order to have gas permeability, and the conductivity is 50 S / cm or more, Furthermore, it may be 300 S / cm or more and 440 S / cm or more.

Furthermore, as a P-type semiconductor layer (not shown), a layer made of a transition metal perovskite oxide can be exemplified. Specifically, those having higher electron conductivity than lanthanum chromite constituting the interconnector 11, for example, lanthanum manganite (LaSrMnO ₃ ), lanthanum ferrite (LaSrFeO ₃ ) in which Mn, Fe, Co, etc. exist at the B site. P-type semiconductor ceramics made of at least one of lanthanum cobaltite (LaSrCoO ₃ ) and the like can be used. In general, the thickness of such a P-type semiconductor layer is preferably in the range of 30 to 100 μm.

  The conductive joining material 13 joins the fuel cell 3 and the current collecting member 4 and can be configured using conductive ceramics or the like. As the conductive ceramic, one similar to that constituting the oxygen electrode layer 10 can be used. When the conductive ceramic is composed of the same components as the oxygen electrode layer 10, the bonding strength between the oxygen electrode layer 10 and the conductive bonding material 13 is high. Since it becomes high, it is preferable.

Specifically, LaSrCoFeO ₃ , LaSrMnO ₃ , LaSrCoO ₃ or the like can be used as the conductive bonding material 13. These materials may be produced using a single material, or the conductive bonding material 13 may be produced by combining two or more kinds.

  Further, the conductive bonding material 13 may be made of different materials having different particle diameters, or may be made of different materials having the same particle diameter. Furthermore, it may be composed of the same material having different particle diameters, or may be composed of the same material having the same particle diameter. When different particle diameters are used, it is preferable that the fine particle diameter is 0.1 to 0.5 μm and the coarse particle diameter is 1.0 to 3.0 μm. Moreover, when comprising the electroconductive joining material 13 with the same particle size, it is preferable that a particle size shall be 0.5-3 micrometers.

  Thus, by producing the conductive bonding material 13 using materials having different particle sizes, coarse particles having a large particle size improve the strength of the conductive bonding material 13, and fine particles having a small particle size are made conductive. The sinterability of the bonding material 13 can be improved.

  Next, the current collecting member 4 will be described with reference to FIGS. A current collecting member 4 shown in FIG. 2 includes a plurality of first current collecting pieces 4 a joined to one adjacent fuel cell 3 and a plurality of second current collecting joined to the other adjacent fuel cell 3. A piece 4b, a first connecting portion 4c for connecting ends of the plurality of first current collecting pieces 4a and a plurality of second current collecting pieces 4b, a plurality of first current collecting pieces 4a and a plurality of second current collecting pieces The second connecting portion 4d that connects the other ends of 4b is a set of units. A plurality of sets of these units are connected in the longitudinal direction of the fuel battery cell 3 by the conductive connecting piece 4e. The first current collecting piece 4 a and the second current collecting piece 4 b are portions joined to the fuel cell 3. Further, a space S through which the oxygen-containing gas passes is defined between the first current collecting piece 4a and the second current collecting piece 4b.

  In the fuel cell 3, as described above, the portion where the fuel electrode layer 8 and the oxygen electrode layer 10 face each other through the solid electrolyte layer 9 is a portion that generates power. Therefore, in order to efficiently collect the current generated by the power generation unit of the fuel cell 3, the length of the current collecting member 4 along the longitudinal direction y of the fuel cell 3 is the oxygen electrode in the fuel cell 3. The length of the layer 10 is preferably equal to or greater than the length in the longitudinal direction y. The structure of the current collecting member 4 is not limited to this.

  Since the current collecting member 4 is exposed to a high-temperature oxidizing atmosphere when the cell stack apparatus 1 is operated, a covering layer (not shown) is formed on the entire surface of the current collecting substrate (not shown). Thus, deterioration of the current collecting member 4 can be reduced. The thickness of the coating layer is desirably 1 to 20 μm, particularly 1.5 to 5 μm.

Since the current collecting member 4 needs to have conductivity in a heat resistant and high temperature oxidizing atmosphere, the current collecting substrate is made of an alloy containing Cr. In particular, since the current collecting member 4 is exposed to a high-temperature oxidizing atmosphere, the current collecting substrate is made of an alloy containing Cr at a rate of 4 to 30% by mass. The current collector substrate can be made of, for example, an Fe—Cr alloy or a Ni—Cr alloy. The current collecting substrate is a conductive substrate for high temperature (600 to 1000 ° C.).

  Further, in order to reduce the diffusion of Cr on the current collecting substrate into the fuel cell 3, particularly the oxygen electrode layer 10, a Zn oxide or a perovskite complex oxide containing La and Sr is used as a coating layer. Can be used. The coating layer only needs to reduce the diffusion of Cr and may be other than the above materials.

  As shown in FIG. 3, the first current collecting piece 4 a and the second current collecting piece 4 b include a first main surface 4 g that is perpendicular to the arrangement direction x of the fuel cells 3, and the arrangement direction of the fuel cells 3. The first side surface 4h and the second side surface 4i are parallel to x, and the second main surface 4j is a surface opposite to the first main surface 4g. In other words, the first main surface 4g facing the fuel cell 3, the first side surface 4h and the second side surface 4i adjacent to both sides of the first main surface 4g, and the second main surface facing the first main surface 4g. 4j. The first side surface 4 h and the second side surface 4 i are side surfaces parallel to the thickness direction (arrangement direction x) of the current collecting member 4. The areas of the first main surface 4g and the second main surface 4j are sufficiently larger than the areas of the first side surface 4h and the second side surface 4i. The first main surface 4g, the first side surface 4h, and the second side surface 4i of the first current collecting piece 4a and the second current collecting piece 4b are composed of the conductive bonding material 13 and the oxygen electrode layer 10 of the fuel cell 3 and the interconnector layer. 11 is joined.

  Next, the joining state of the current collecting member 4 and the fuel cell 3 by the conductive joining material 13 will be described with reference to FIG.

  As shown in FIG. 4, the fuel cells 3 and the current collecting members 4 are alternately arranged, and the fuel cells 3 and the first main surfaces 4 g of the current collecting pieces 4 a and 4 b of the current collecting member 4 are electrically conductively joined. A plurality of fuel cells 3 are joined together by a material 13 and electrically connected in series. That is, the current collecting member 4 and the fuel cell 3 are electrically and mechanically connected by the conductive bonding material 13. The conductive bonding material 13 is provided so as to cover the first main surface 4g, the first side surface 4h and the second side surface 4i of the current collecting pieces 4a and 4b, and is located on the first side surface 4h and the second side surface 4i. The conductive bonding material 13 is provided so as to increase toward the fuel cell 3 to be bonded (to form a meniscus). Alternatively, the conductive bonding material 13 may be provided so as to completely cover the current collecting pieces 4 a and 4 b by covering the entire circumference of the current collecting member 4.

  That is, in FIG. 4, the conductive bonding material 13 is arranged to bond the fuel cell 3 and the current collecting member 4, and the oxygen electrode layer 10 is disposed on the oxygen electrode layer 10 side of the fuel cell 3. It is provided over the entire surface. On the interconnector 11 side of the fuel cell 3, a conductive bonding material 13 is provided over the entire surface of the interconnector 11. Alternatively, the current collector 4 and the fuel cell 3 may be joined by providing the conductive joining material 13 only on part of the oxygen electrode layer 10 or the interconnector 11.

  In this embodiment, as shown in FIGS. 4 and 5, in the conductive bonding material 13, in other words, at the interface between the first main surface 4 g of the current collecting pieces 4 a and 4 b and the conductive bonding material 13. A gap 15 exists in contact with the first main surface 4g of the electric pieces 4a, 4b.

As shown in FIGS. 6B and 6C, the occupancy ratio of the gap 15 is the current collecting pieces 4a and 4b obtained from the metal micrograph after the current collecting member 4 is peeled off from the conductive bonding material 13. The ratio (S2 / S1 × 100) of the area S2 of the gap 15 to the area S1 of the joint portion 13a between the conductive bonding material 13 and the conductive bonding material 13 is 20% or less. The area ratio (S2 / S1 × 100) is preferably 18% or less, more preferably 15% or less, and is preferably 1% or more, and more preferably 5% or more.
The area S1 of the joint portion 13a is an area including the area S2 of the gap 15.

  The void 15 is sufficiently larger than the pores (pores composed of ceramic particles or the like) existing in the conductive bonding material 13.

  The metallurgical micrograph is a planar photograph of the portion where the current collecting member 4 is peeled off from the conductive bonding material 13 of the fuel cell 3 from above, and the area of the bonding portion 13a is, for example, one fuel cell. The first main surface 4 g of all the current collecting pieces 4 a or the current collecting pieces 4 b connected to the cell 3 is the total area to be joined to the conductive joining material 13. The joint portion 13a between the first main surface 4g and the conductive bonding material 1 after the current collecting pieces 4a and 4b of the current collecting member 4 are peeled off from the conductive bonding material 13 can be easily confirmed from the above planar photograph. . This area ratio (S2 / S1 × 100) can be obtained by an image analysis apparatus.

  FIG. 6C is a cross-sectional view after the current collecting pieces 4 a and 4 b of the current collecting member 4 are peeled off from the conductive bonding material 13. The total area of the bottom surface of the recess formed in the conductive bonding material 13 is the area S1 of the bonding portion 13a.

  As shown in FIG. 5, the gap 15 has an arbitrary cross section in the thickness direction of the current collecting member 4 (a cross section in the arrangement direction x of the fuel cells 3 and along the longitudinal direction y). It is desirable that the width B2 (B2 / B1 × 100) of the gap 15 with respect to the width B1 is 10% or less. In particular, the width B2 of the gap 15 with respect to the width B1 of the current collecting pieces 4a and 4b is preferably 2 to 5%. 5A is a cross-sectional view taken along the line DD in FIG. 6A.

  Whether or not the air gap 15 exists in contact with the first main surface 4g of the current collecting pieces 4a and 4b can be confirmed from a scanning electron microscope (SEM) photograph of a cross section of the current collecting member 4 in the thickness direction. In addition, as described above, the current collecting pieces 4a and 4b are peeled off from the conductive bonding material 13, so that the current collecting pieces 4a, It can be confirmed whether or not there is a recess that forms a gap 15 extending in the length direction of 4b (joint portion 13a). The length of the gap 15 is controlled to be shorter than the length of the joint portion 13a of the strip-shaped current collecting pieces 4a and 4b, and the gap 15 is elongated in the length direction of the current collecting pieces 4a and 4b. The gap 15 is formed on the bottom surface (joint portion 13a) of the concave portion of the conductive joining material 13 in which the current collecting pieces 4a and 4b are embedded.

  FIG. 6B shows a state in which the gap 15 is formed on the bottom surface of the concave portion of all the conductive bonding materials 13 in which the current collecting pieces 4 a and 4 b are buried. Among the plurality of current collecting pieces 4a or current collecting pieces 4b, the gaps 15 may not be formed in the joint portions 13a in which some of the current collecting pieces 4a or some of the current collecting pieces 4b are embedded. is there. In addition, in FIG. 6B, the case where a single gap 15 exists in the joint portion 13a has been described. However, a plurality of gaps 15 exist in the longitudinal direction y of the current collection pieces 4a and 4b. In some cases, it is divided into two.

  In FIG. 3B, FIG. 4, and FIG. 6, only a part of the many current collecting pieces 4a and 4b is shown.

  Further, the gap 15 has a flat shape in which the thickness of the current collecting member 4 in the thickness direction is smaller than the width, and the gap 15 has a convex shape on the fuel cell 3 side.

In such a form, the current collectors 4a and 4b are in contact with the main surfaces of the gaps 15 and the current collectors obtained from the metal micrograph after the current collectors 4 are peeled off from the conductive bonding materials 13 are obtained. Since the ratio (S2 / S1 × 100) of the area S2 of the gap 15 to the area S1 of the joint portion 13a between the pieces 4a, 4b and the conductive joint material 13 is 20% or less, the current collecting member 4 and the fuel cell High conductivity between the cells 3 can be maintained. Therefore, high power generation performance can be maintained by using such a cell stack for a fuel cell module and a fuel cell device.

  Next, the manufacturing method of a cell stack apparatus is demonstrated.

  A fuel cell 3, a current collecting member 4, and a conductive bonding material 13 are prepared, and a paste that becomes the conductive bonding material 13 is applied to the surfaces of the oxygen electrode layer 10 and the interconnector layer 11 of the fuel cell 3. The current collecting member 4 and the fuel battery cell 3 are alternately laminated and heat-treated at 1000 to 1100 ° C., whereby the current collecting member 4 and the fuel battery cell 3 can be joined by the conductive bonding material 13.

  The paste that becomes the conductive bonding material 13 can be made of conductive ceramic particles, a solvent (alcohol), an organic binder, and a pore former (organic resin). An ester solvent can be used as the solvent. The solvent is for adjusting the viscosity of the paste.

  The inventors of the present invention have a difference in the scattering state of the solvent in the paste between the portion of the paste where the current collecting piece is arranged and the portion of the paste where the current collecting piece is not arranged and exposed, and the current collecting piece is The solvent in the disposed paste is the part where the current collecting piece is disposed, the current collecting piece blocks the scattering of the solvent in the paste and is less likely to be scattered than the other part. It has been found that voids 15 are formed. And, the solvent in the paste exposed to the outside is quickly scattered and the paste is solidified from the surface. However, in the paste below the current collecting piece, the solvent tends to be scattered from the paste exposed to the outside. However, when solidification of the paste surface progressed, it was investigated that the scattering of the solvent from the solidified paste surface was blocked and a gap 15 was formed below the current collecting piece.

  Furthermore, by adjusting the scattering of the solvent, in order to promote the scattering of the solvent in the paste below the current collecting piece, the amount of the solvent is reduced and the solvent is easily scattered at a low temperature, thereby collecting the current collecting piece 4a. The gap 15 is present in contact with the first main surface 4g of 4b, and is obtained from a metal micrograph after the current collecting member 4 is peeled off from the fuel cell 3 as shown in FIG. The ratio (S2 / S1 × 100) of the area S2 of the air gap 15 to the area S1 of the joint portion 13a between the first main surface 4g of the current collecting pieces 4a and 4b and the conductive joint material 13 can be found to be 20% or less. It was.

  Specifically, the minimum amount of solvent that can be applied with the paste, for example, 20% by weight in the past is 16% by weight, and the solvent type is changed from terpineol alone to a mixed liquid of terpineol and ethyl alcohol. Thus, there is a gap 15 in contact with the first main surface 4g of the current collecting pieces 4a and 4b, and the area S1 of the joint portion 13a between the first main surface 4g of the current collecting pieces 4a and 4b and the conductive bonding material 13 is present. The ratio (S2 / S1 × 100) of the area S2 of the air gap 15 to 20% or less can be reduced.

  Next, the fuel cell module 20 in which the cell stack device 1 is stored in the storage container 21 will be described with reference to FIG.

  The fuel cell module 20 shown in FIG. 7 includes a reformer 22 for reforming raw fuel such as natural gas or kerosene to generate fuel gas in order to obtain fuel gas used in the fuel cell 3. It is arranged above the cell stack 2. The fuel gas generated by the reformer 22 is supplied to the gas tank 6 through the gas flow pipe 23 and supplied to the gas flow path 12 provided inside the fuel battery cell 3 through the gas tank 6. .

FIG. 7 shows a state where a part (front and rear surfaces) of the storage container 21 is removed and the cell stack device 1 and the reformer 22 housed inside are taken out rearward. Here, in the fuel cell module 20 shown in FIG.
1 can be slid and stored.

  Further, in FIG. 7, the oxygen-containing gas introduction member 24 provided inside the storage container 21 is disposed between a pair of cell stacks 2 juxtaposed in the gas tank 6 and the oxygen-containing gas flows into the fuel gas. Accordingly, the oxygen-containing gas is supplied to the lower end side of the fuel cell 3 so that the fuel cell 3 flows laterally from the lower end side toward the upper end side. The surplus fuel gas (fuel offgas) that has been discharged from the gas flow path 12 of the fuel cell 3 and was not used for power generation is burned above the upper end of the fuel cell 3, so that the temperature of the cell stack 2 is increased. Can be effectively increased, and the activation of the cell stack device 1 can be accelerated. In addition, the fuel gas that has not been used for power generation discharged from the gas flow path 12 of the fuel battery cell 3 is burned above the upper end of the fuel battery cell 3 to be disposed above the cell stack 2. The reformer 22 can be warmed. Thereby, the reforming reaction can be efficiently performed in the reformer 22.

  Next, a fuel cell device 25 in which the fuel cell module 20 and an auxiliary machine (not shown) for operating the fuel cell module 20 are housed in an outer case will be described with reference to FIG.

  The fuel cell device 25 shown in FIG. 8 has a module housing chamber 29 in which the inside of an outer case made up of a support column 26 and an outer plate 27 is vertically divided by a partition plate 28 and the upper side thereof houses the fuel cell module 20 described above. The lower side is configured as an auxiliary equipment storage chamber 30 for storing auxiliary equipment for operating the fuel cell module 20. In addition, the auxiliary machine stored in the auxiliary machine storage chamber 30 is omitted.

  Further, the partition plate 28 is provided with an air circulation port 31 for flowing the air in the auxiliary machine storage chamber 30 to the module storage chamber 29 side, and a part of the exterior plate 27 constituting the module storage chamber 29 An exhaust port 32 for exhausting air in the module storage chamber 29 is provided.

  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.

For example, in the above embodiment, a cell stack, a fuel cell module, and a fuel cell device using fuel cells have been described. However, the present invention is not limited to this, and water vapor and voltage are applied to an electrolytic cell to provide water vapor. It can also be applied to an electrolysis cell (SOEC) that generates hydrogen and oxygen (O ₂ ) by electrolyzing (water), a cell stack including the electrolysis cell, an electrolysis module, and an electrolysis apparatus.

  Moreover, in the said form, although what was called the vertical stripe type which provided one electric power generation element part in the electroconductive porous substrate 1 was demonstrated, this invention is not limited to this, An insulating porous substrate is used. Of course, a so-called horizontal stripe type having a plurality of power generation element portions may be used.

  Furthermore, the shape of the current collecting member is not limited to FIG.

First, on one side of the supporting substrate made of Ni and _Y 2 _{O 3,} Ni and _Y 2 _{O 3} fuel consists of _ZrO 2 (YSZ) was dissolved electrode layer, a solid electrolyte layer made of _{YSZ, La} 0.6 Sr _The fuel cell shown in FIG. 1 was produced in which an oxygen electrode layer made of _0.4 Co _0.2 Fe _0.8 O ₃ and an interconnector layer made of lanthanum chromite were formed on the other side.

  Thereafter, a coating layer made of ZnO was formed on the surface of the current collecting substrate by sputtering.

The paste constituting the conductive bonding material is 16% by mass of a mixed liquid of terpineol and ethyl alcohol as a solvent, 4% by mass of ethyl cellulose as an organic binder, 3% by mass of crystalline cellulose as a pore former, and the balance is La _0. It was prepared by adding ₆ Sr _0.4 Co _0.2 Fe _0.8 O ₃ powder.

  And the paste which comprises an electroconductive joining material is apply | coated to the oxygen electrode layer surface and interconnector layer surface of six fuel cells, and a fuel cell and a current collection member are laminated | stacked alternately, and it is 5 at 120 degreeC. By drying for a period of time and heat-treating at 1000 ° C. for 2 hours, the fuel cell and the current collecting member were joined as shown in FIG. 4 using a conductive joining material to produce a cell stack.

  Thereafter, as shown in FIG. 1, the lower end portion of the cell stack electrically connected via the current collecting member was inserted into the opening of the gas tank, and was joined and fixed with the sealing material 14.

  Thereafter, the resistance of the cell stack at 800 ° C. (resistance including one fuel cell, a conductive bonding material joined to the fuel cell, and a current collecting member) is obtained, and the relationship with the occupation ratio of the gap is obtained. Obtained and described in FIG.

  The space occupation ratio is determined by peeling the current collecting pieces and peeling the current collecting pieces from the area S1 of the joint portions 13a of the first main surfaces 4g of all the first current collecting pieces 4a joined to one fuel cell. The area ratio (S2 / S1 × 100) of the voids, which is the ratio of the recesses (voids) that can be observed later, to the area S2, was obtained with a metal micrograph and an image analysis device, and was defined as the void occupation rate.

  From FIG. 11, it can be seen that when the area ratio of the gap to the bonding area between the current collecting piece and the conductive bonding material is 20% or less, the conductivity between the fuel cell and the current collecting member can be maintained high.

  In addition, the thing with 30% or more of space | gap occupancy is a comparative example, and is a case where 20 mass% of terpineol is used as a solvent of the paste which comprises an electroconductive joining material.

1: cell stack device 2: cell stack 3: fuel cell 4: current collecting member 4a, 4b: current collecting piece 4g: first main surface 13: conductive bonding material 13a: bonding portion 15: gap 20: fuel cell module 21: Storage container 25: Fuel cell device B1: Current collecting strip width B2: Cavity width S1: Joint area S2: Cavity area

Claims (5)

  A cell stack formed by alternately arranging electrolytic cells and conductive members, joining the electrolytic cells and main surfaces of conductive pieces of the conductive members with a conductive bonding material, and electrically connecting a plurality of the electrolytic cells. In the conductive bonding material, there is a gap in contact with the main surface of the conductive piece, and the conductivity obtained from the photograph after peeling the conductive member from the conductive bonding material. A cell stack, wherein a ratio of an area of the gap to an area of a joint portion between a main surface of the piece and the conductive bonding material is 20% or less.   2. The cell stack according to claim 1, wherein the current collecting piece has a strip shape, and the gap extends elongated in a length direction of the current collecting piece.   The cell stack according to claim 1, wherein the gap has a convex shape on the electrolysis cell side.   An electrolytic module comprising the cell stack according to claim 1 stored in a storage container.   5. An electrolysis apparatus comprising the electrolysis module according to claim 4 and an auxiliary machine for operating the electrolysis module housed in an outer case.

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