JP6166418B2 - Cell stack and fuel cell module - Google Patents

Description

  The present invention relates to a cell stack and a fuel cell module in which a plurality of fuel cells are electrically connected using a current collecting member.

  In recent years, as a next-generation energy, a solid oxide fuel cell that generates power at a high temperature of 600 ° C. to 1000 ° C. using a fuel gas (hydrogen-containing gas) and an oxygen-containing gas (air, etc.) is known. . A plurality of fuel cells are electrically connected in series via a current collecting 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.

JP 2005-339904 A

  Conventionally, the current collecting member has been bonded to the fuel cell using a conductive bonding material. However, in some cases, air bubbles may be caught in the conductive bonding material between the current collecting member and the fuel cell. However, when power is generated for a long time, the power generation performance may deteriorate over time.

  An object of this invention is to provide the cell stack and fuel cell module which can maintain high electric power generation performance.

The cell stack of the present invention comprises a plurality of stacked fuel cells and current collecting members respectively disposed between the plurality of fuel cells, and a portion of the current collecting member facing the fuel cells Is bonded to the fuel cell with a conductive bonding material containing conductive ceramics, and is opposed to the current collecting member of the fuel cell at the junction between the current collecting member and the fuel cell. The portion is convex toward the current collecting member, and the portion of the current collecting member facing the fuel cell is convex toward the fuel cell. And

  The fuel cell module of the present invention is obtained by storing the cell stack in a storage container.

According to the cell stack of the present invention, a conductive bonding material between the current collecting member and the fuel cell, the bubbles can escape to a position other than between the current collecting member and the fuel cell, and further, Bubbles can be discharged to the outside of the conductive bonding material, and even when power is generated for a long period of time, a decrease in power generation performance over time can be suppressed and high power generation performance can be maintained for a long period of time.

The fuel cell stack apparatus is shown, (a) is an explanatory view schematically showing the fuel cell stack apparatus, and (b) is an enlarged cross-sectional view showing a part of (a). FIGS. 1A and 1B show the fuel cell shown in FIG. 1, in which FIG. 1A is a cross-sectional view, and FIG. 1B is a side view of the state where the interconnector of FIG. 1A and 1B show a current collecting member shown in FIG. 1, in which FIG. 1A is a perspective view, and FIG. 1B is a cross-sectional view taken along line BB in FIG. It is a cross-sectional view which shows the state which electrically connected a pair of fuel cell by the current collection member, (b) is sectional drawing along CC line of (a). It is explanatory drawing which expands and shows the junction part of the cell facing part of a current collection member, and a fuel cell. It is a perspective view which shows the fuel cell module of the state which took out the fuel cell stack apparatus from the storage container. It is a perspective view which shows the fuel cell apparatus formed by accommodating the fuel cell module shown in FIG. 6 in an exterior case.

  A fuel cell cell stack device 11 (hereinafter also referred to as a cell stack device 11) having a cell stack 12 will be described with reference to FIG. In addition, in FIGS. 1-7, in order to understand easily, the thickness, length, width | variety, etc. of a member may be expanded and shown.

  The cell stack device 11 has a pair of opposing main surfaces. On one main surface of a long plate-like conductive support 17 as a whole, a fuel electrode 18 that is an inner electrode layer, and a solid The fuel cell unit 13 includes a solid oxide fuel cell 13 including a power generation unit in which an electrolyte 19 and an oxygen electrode 20 as an outer electrode layer are stacked in this order. Inside the conductive support 17, a plurality of gas flow paths 22 are formed penetrating in the length direction. The flow of gas flowing through the gas flow path 22 is indicated by arrows in FIG.

  The fuel cell 13 (hollow flat plate type) has a long columnar shape in which an interconnector 21 is laminated on the other main surface of the conductive support 17, and a plurality of these fuel cells 13 are arranged in a row. (Stacking), a current collecting member 14 is disposed between adjacent fuel cells 13, and the fuel cells 13 are electrically connected in series to form a cell stack 12.

  The fuel cell 13 and the current collecting member 14 are joined via the conductive bonding material 23, whereby the plurality of fuel cells 13 are joined electrically and mechanically via the current collecting member 14. Thus, the cell stack 12 is configured.

  As understood from the shape shown in FIG. 2, the conductive support 17 includes a pair of flat surfaces n that are parallel to each other and arcuate surfaces (side surfaces) m that connect the pair of flat surfaces n. Has been. Both surfaces of the flat surface n are formed substantially parallel to each other, and a porous fuel electrode 18 is provided so as to cover one flat surface n (lower surface) and the arcuate surfaces m on both sides. A dense solid electrolyte 19 is laminated so as to cover 18. A porous oxygen electrode 20 is laminated on the solid electrolyte 19 so as to face the fuel electrode 18.

  In other words, the fuel electrode 18 and the solid electrolyte 19 are formed up to the other flat surface n (upper surface) via the arcuate surfaces m at both ends of the conductive support 17, and interconnectors are formed at both ends of the solid electrolyte 19. The both ends of 21 are joined, the electroconductive support body 17 is surrounded by the solid electrolyte 19 and the interconnector 21, and it is comprised so that the fuel gas which distribute | circulates the inside may not leak outside.

  And the lower end part of each fuel cell 13 which comprises the cell stack 12 is fixed to the gas tank 16 with sealing materials (not shown), such as glass, the cell stack apparatus 11 is comprised, and fuel gas is It is supplied to the fuel electrode 18 through a gas flow path 22 provided inside the fuel battery cell 13.

  In the cell stack device 11 shown in FIG. 1, a hydrogen-containing gas flows as a fuel gas in the gas flow path 22 of the fuel battery cell 13, and the inside of the current collecting member 14 disposed between the fuel battery cells 13 An oxygen-containing gas (air) flows. As a result, the fuel gas is supplied from the gas tank 16 to the fuel electrode 18, and the oxygen-containing gas is supplied to the oxygen electrode 20 through the inside of the current collecting member 14, thereby generating power in the fuel cell 13.

  The cell stack device 11 includes an elastically deformable conductive member 15 having a lower end fixed to a gas tank 16 so as to sandwich the cell stack 12 from both ends in the arrangement direction x of the fuel cells 13. Here, the conductive member 15 shown in FIG. 1 has a shape extending outward along the flat plate portion 15a and the arrangement direction x of the fuel cells 13 and is generated by power generation of the cell stack 12 (fuel cells 13). And a current extraction portion 15b for extracting an electric current.

Below, each member which comprises the fuel cell 13 is demonstrated. As the fuel electrode 18, a generally known one can be used, and porous conductive ceramics such as ZrO ₂ (referred to as stabilized zirconia) in which a rare earth element is dissolved, Ni and / or NiO, Can be formed from

The solid electrolyte 19 has a function as an electrolyte that bridges electrons between the electrodes, and at the same time, is required to have a gas barrier property in order to prevent leakage between the fuel gas and the oxygen-containing gas. It 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 other materials, such as a lanthanum gallate.

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

Although the interconnector 21 can be formed from conductive ceramics, it is required to have reduction resistance and oxidation resistance because it is in contact with a fuel gas (hydrogen-containing gas) and an oxygen-containing gas (air, etc.). Therefore, lanthanum chromite (LaCrO ₃ ) can be used. The interconnector 21 is dense in order to prevent leakage of the fuel gas flowing through the plurality of gas flow paths 22 formed in the conductive support 17 and the oxygen-containing gas flowing outside the conductive support 17. The relative density is preferably 93% or more, particularly 95% or more.

  The conductive support 17 is required to be gas permeable in order to allow the fuel gas to permeate to the fuel electrode 18 and to be conductive in order to collect current via the interconnector 21. . Therefore, it is necessary to use a material that satisfies this requirement as the conductive support member 17, and for example, conductive ceramics, cermets, and the like can be used.

In the production of the fuel cell 13, in the case of producing the conductive support 17 by co-firing with the fuel electrode 18 or the solid electrolyte 19, the conductive support is composed of an iron group metal component and a specific rare earth oxide. 17 can be formed. The conductive support 17 preferably has an open porosity of 30% or more, particularly 35 to 50% in order to provide the required gas permeability, and the conductivity is 50 S / cm or more. Further, it may be 300 S / cm or more and 440 S / cm or more. The fuel battery cell 13 can also have the function of the fuel electrode 18 as a support without using the conductive support 17.

Furthermore, a P-type semiconductor layer can be formed on the oxygen electrode 20. Examples of the P-type semiconductor layer (not shown) include a layer made of a transition metal perovskite oxide. Specifically, those having higher electronic conductivity than lanthanum chromite constituting the interconnector 21, 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 bonding material 23 is provided for bonding the fuel cell 13 and the current collecting member 14 and can be formed using conductive ceramics or the like. As the conductive ceramic, the same ceramics that form the oxygen electrode 20 can be used.

Specifically, LaSrCoFeO ₃ , LaSrMnO ₃ , LaSrCoO ₃ or the like can be used. These materials may be manufactured using a single material, or the conductive bonding material 23 may be manufactured by combining two or more kinds.

  Next, the current collecting member 14 will be described with reference to FIG. The current collecting member 14 includes a plurality of plate-shaped (strip-shaped) first cell facing portions 14a1 joined to one adjacent fuel cell 13 and both sides of the first cell facing portion 14a1 so as to be separated from the fuel cells. The extended plate-shaped (strip-shaped) first separation portion 14a2, the plurality of plate-shaped (strip-shaped) second cell facing portions 14b1 joined to the other adjacent fuel cell 13 and the fuel cells away from each other And a plate-like (band-like) second spacing portion 14b2 extending from both sides of the second cell facing portion 14b1.

  Further, the first connection portion 14c that connects one ends of the plurality of first separation portions 14a2 and the plurality of second separation portions 14b2, and the other ends of the plurality of first separation portions 14a2 and the plurality of second separation portions 14b2 The second connecting portion 14d to be connected is a set of units, and a plurality of sets of these units are connected in the length direction of the fuel cell 13 by conductive connecting pieces 14e. As shown in FIG. 4, the first cell facing portion 14 a 1 and the second cell facing portion 14 b 1 are portions that are joined to the fuel battery cell 13, and these portions are portions where the generated power of the fuel battery cell 13 enters and exits. It has become.

  That is, the fuel battery cell 13 and the cell facing portions 14 a 1 and 14 b 1 of the current collecting member 14 are joined by the conductive joining material 23. In other words, the plurality of fuel cells 13 have a flat portion, the flat portion has a flat interconnector 21, and the interconnector 21 faces the first cell facing portion 14a1. The second cell facing portion 14 b 1 faces the flat oxygen electrode 20, and these are joined by the conductive joining material 23. FIG. 4B is a longitudinal sectional view taken along line CC in FIG. The cell facing portions 14 a 1 and 14 b 1 extend in the width direction of the fuel cell 13 and are joined to the oxygen electrode 20 and the interconnector 21 at a predetermined interval in the length direction of the fuel cell 13.

  In the fuel battery cell 13, as described above, a portion where the fuel electrode 18 and the oxygen electrode 20 face each other through the solid electrolyte 19 is a portion that generates power. Therefore, in order to efficiently collect the current generated by the power generation unit of the fuel cell 13, the length of the current collecting member 14 along the longitudinal direction of the fuel cell 13 is the length direction of the fuel cell 13. It is preferable that the length is equal to or greater than the length of the oxygen electrode layer 20.

The current collecting member 14 needs to have heat resistance and conductivity, and can be made of a metal or an alloy. In particular, the current collecting member 14 can be made from an alloy containing Cr at a rate of 4 to 30% because it is exposed to a high-temperature oxidizing atmosphere, and can be made of an Fe—Cr alloy or Ni—Cr alloy. It can be made of an alloy or the like.

  Further, since the current collecting member 14 is exposed to a high-temperature oxidizing atmosphere, the surface of the current collecting member 14 may be provided with an oxidation resistant coating. Thereby, deterioration of the current collecting member 14 can be reduced. It is preferable to apply the oxidation resistant coating to the entire surface of the current collecting member 14. Thereby, it can suppress that the surface of the current collection member 14 is exposed to high temperature oxidation atmosphere.

  Here, the manufacturing method of the current collection member 14 is demonstrated. A single rectangular plate member is pressed to form a plurality of slits extending in the width direction of the plate member at predetermined intervals in the longitudinal direction of the plate member. And the current collection member shown in FIG. 3 is made to project alternately by the site | part between the slit used as the 1st cell facing part 14a1, the 1st cell spacing part 14a2, the 2nd cell facing part 14b1, and the 2nd cell spacing part 14b2. 14 can be produced.

  In this embodiment, as shown in FIGS. 3B, 4B, and 5, the current collecting member 14 has the first cell facing portion 14a1 in the length direction of the first cell facing portion 14a1. The cross-section of Fig. 4 is flat (see Fig. 4), but when viewed in the cross-section in the width direction of the first cell facing portion 14a1, the junction of the current collecting member 14 with the fuel cell faces toward the interconnector 21 side. It has a convex shape and a half pipe shape. In other words, when the first cell facing portion 14a1 is seen in a cross section in the width direction, the first cell facing portion 14a1 has an arc shape protruding toward the interconnector 21 side, and the radius of curvature forms the conductive bonding material 23. It is appropriately set depending on the paste viscosity and the like. The second cell facing portion 14b1 is flat in both the lengthwise cross section and the width direction cross section of the second cell facing portion 14b1.

  The lengths of the cell facing portions 14a1 and 14b1 are joined to the interconnector 21 positioned on the conductive support 17 where the fuel electrode 18 and the solid electrolyte 19 are not formed. The end of the interconnector 21 and the fuel electrode 18, The length is such that the solid electrolyte 19 is not joined to the stepped portion where the end portions of the solid electrolyte 19 overlap.

  Accordingly, even when the air bubbles A are bitten when the first cell facing portion 14a1 and the interconnector 21 of the fuel cell 13 are joined by the conductive joining material 23, the air bubbles A From the conductive joint material 23 between the first cell facing portion 14a1 of the current collecting member 14 and the interconnector 21 of the fuel cell 13 at the convex portion of the first cell facing portion 14a1, the first cell facing portion 14a1 and the interface The bubble A can be released to a position other than the position between the connector 21 and further, the bubble A can be discharged to the outside of the conductive bonding material 23. Even when power is generated for a long time, the power generation performance deteriorates over time. Can be suppressed and high power generation performance can be maintained.

  That is, when the first cell facing portion 14a1 is flat when the paste for forming the conductive bonding material 23 is applied to the interconnector 21 and the first cell facing portion 14a1 is pressed, FIG. As shown in FIG. 5 (a), the entrained bubble A remains as it is, but as shown in FIG. 5 (b), the first cell facing portion 14a1 has an arcuate shape so that the bubble A faces the first cell facing. The first cell facing portion 14a1 and the interconnector 21 move along the surface of the portion 14a1 from the conductive bonding material 23 between the first cell facing portion 14a1 of the current collecting member 14 and the interconnector 21 of the fuel cell 13. It can be moved to a position other than between. In particular, when the first cell facing portion 14a1 is viewed in a cross-section in the width direction, since the moving distance of the bubbles A can be shortened by forming the convex shape on the interconnector 21 side, the bubbles A can be easily removed.

3B, 4 </ b> B, and 5, when the first cell facing portion 14 a 1 is viewed in a cross section in the width direction of the first cell facing portion 14 a 1, the interconnector 21 side at the joint portion However, when the second cell facing portion 14b1 is seen in the cross section in the width direction of the second cell facing portion 14b1, the joint portion is convex toward the oxygen electrode 20 side. In addition, even when the bubble A is caught when the conductive bonding material 23 is bonded, the bubble A is formed between the second cell facing portion 14b1 of the current collecting member 14 and the oxygen electrode 20 of the fuel cell 13. It is possible to escape from the conductive bonding material 23 to a position other than between the second cell facing portion 14b1 and the oxygen electrode 20.

  3B, FIG. 4B, and FIG. 5, when the first cell facing portion 14a1 is viewed in a cross section in the width direction of the first cell facing portion 14a1, the interconnector 21 side at the joint portion However, when the first cell facing portion 14a1 is viewed in a cross section in the length direction of the first cell facing portion 14a1, even if it is convex toward the interconnector 21 side, a certain degree of effect is obtained. Can be obtained.

  In FIG. 1, the fuel battery cell 13 is provided on the tank 16 so that the length direction is vertical. However, the fuel cell 13 is a cell stack provided with the length direction of the fuel battery cell 13 sideways. Also good.

  Next, the fuel cell module 30 in which the cell stack 12 is stored in the storage container 31 will be described with reference to FIG.

  A fuel cell module 30 shown in FIG. 6 includes a reformer 32 for reforming raw fuel such as natural gas or kerosene to generate fuel gas for use in the fuel cell 13. It is arranged above the cell stack 12. The fuel gas generated by the reformer 32 is supplied to the gas tank 16 via the gas flow pipe 33 and supplied to the gas flow path 22 provided inside the fuel battery cell 13 via the gas tank 16. .

  FIG. 6 shows a state where a part (front and rear surfaces) of the storage container 31 is removed and the cell stack device 11 and the reformer 32 housed inside are taken out rearward. Here, in the fuel cell module 30 shown in FIG. 6, the cell stack device 11 can be slid and stored in the storage container 31.

  Further, in FIG. 6, the oxygen-containing gas introduction member 34 provided inside the storage container 31 is disposed between the cell stacks 12 juxtaposed to the gas tank 16, and the oxygen-containing gas is adapted to the flow of the fuel gas. Thus, the oxygen-containing gas is supplied to the lower end side of the fuel cell 13 so that the fuel cell 13 flows laterally from the lower end side toward the upper end side. The surplus fuel gas (fuel offgas) that has not been used for power generation discharged from the gas flow path 22 of the fuel battery cell 13 is burned above the fuel battery cell 13, so that the temperature of the cell stack 12 is effectively increased. The cell stack device 11 can be started quickly. Further, the reformer 32 disposed above the cell stack 12 is burned above the fuel cell 13 by burning the fuel gas discharged from the gas flow path 12 of the fuel cell 13 and not used for power generation. Can be warmed. Thereby, the reforming reaction can be efficiently performed in the reformer 32.

  Next, a fuel cell device 35 in which a fuel cell module 30 and an auxiliary machine (not shown) for operating the fuel cell module 30 are housed in an outer case will be described with reference to FIG.

A fuel cell device 35 shown in FIG. 7 has a module housing chamber in which an outer case made up of struts 36 and an outer plate 37 is divided into upper and lower portions by a partition plate 38 and the upper side of the fuel cell module 30 is housed. 39, the lower side is configured as an auxiliary equipment storage chamber 40 for storing auxiliary equipment for operating the fuel cell module 30. In addition, the description of the auxiliary machine accommodated in the auxiliary machine storage chamber 40 and the description of a part of the exterior plate 37 are omitted.

  In addition, the partition plate 38 is provided with an air circulation port 41 for allowing the air in the auxiliary machine storage chamber 40 to flow toward the module storage chamber 39, and a part of the exterior plate 37 constituting the module storage chamber 39, An exhaust port 42 for exhausting air in the module storage chamber 39 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, the hollow flat plate fuel cell 13 is used, but a cylindrical fuel cell and a flat plate fuel cell can also be used.

  Moreover, in the said form, although the fuel cell 13 which has the interconnector 21 was used, the fuel cell which does not have an interconnector can also be used.

  Furthermore, in the said form, although the current collection member 14 as shown in FIG. 3 was used, it is not limited to this.

  Moreover, in the said form, although the part facing the fuel battery cell 13 of the current collection member 14 was made into convex shape, the part facing the collector 14 of the fuel battery cell 13, for example, the interconnector 21, is convex. It is also possible. In this case, it becomes easier to remove the bubbles A. Further, instead of making the portion of the current collecting member 14 facing the fuel cell 13 convex, the portion of the fuel cell 13 facing the current collector 14, for example, the interconnector 21 can be convex. is there.

11: Fuel cell stack device 12: Cell stack 13: Fuel cell 14: Current collecting member 14a1: First cell facing portion 14b1: Second cell facing portion 30: Fuel cell module 31: Storage container 35: Fuel cell device

Claims (2)

A plurality of stacked fuel cells, and current collecting members disposed between the plurality of fuel cells,
A portion of the current collecting member facing the fuel cell is joined to the fuel cell with a conductive bonding material containing conductive ceramics ,
In the junction between the current collecting member and the fuel cell,
The portion of the fuel cell that faces the current collecting member has a convex shape toward the current collecting member .
The cell stack , wherein a portion of the current collecting member facing the fuel battery cell is convex toward the fuel battery cell side . A fuel cell module comprising the cell stack according to claim 1 stored in a storage container.