JP2015028887A - Fuel battery cell and fuel battery cell stack - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel battery cell capable of suppressing deterioration of cell characteristics even when a part of an electrode is separated from a part of a collector.SOLUTION: A fuel battery cell 11 has an air electrode 21, a fuel electrode 22 and a solid electrolyte layer 23, and is arranged adjacent to a collector 27 having a plurality of projections 35 for current collection. Collector contact parts 37 capable of being in contact with a plurality of projections 35 of the collector 27, are installed on a surface of the air electrode 21 in a dotted state. A conductive layer 38 is provided on the surface of the air electrode 21. A wire connection 40 is formed on the conductive layer 38 so that a contact pad part 39 of a collector contact part 37 positioned at a corner part 41 on the air electrode 21, is connected to a contact pad part 39 of the collector contact part 37 adjacent to the collector contact part 37 positioned at a corner part 41.

Description

  The present invention relates to a fuel battery cell configured as a flat plate member having a fuel electrode, an air electrode, and an electrolyte layer, and a fuel battery cell stack including the fuel battery cell.

  Conventionally, a solid oxide fuel cell (SOFC) including a solid electrolyte layer (solid oxide layer) is known as a fuel cell which is a kind of power generation device. Solid oxide fuel cells have a very high energy conversion efficiency of 50% or more and can be miniaturized, and therefore are being developed as a power source for household cogeneration systems and automobiles.

  Specifically, the solid oxide fuel cell includes a flat fuel cell in which a fuel electrode in contact with the fuel gas and an air electrode in contact with the oxidant gas are disposed on both sides of the solid electrolyte layer (for example, , See Patent Document 1). The fuel gas is for generating hydrogen, and the oxidant gas is for generating oxygen. Then, when hydrogen and oxygen react via a solid electrolyte layer (power generation reaction), DC power is generated with the air electrode as the positive electrode and the fuel electrode as the negative electrode.

  Further, in the solid oxide fuel cell disclosed in Patent Document 1, conductive strips are continuously provided on the surfaces of each electrode of the fuel electrode and the air electrode. In this fuel cell, electrons flow parallel to the electrodes through the conductive strips. That is, the conductive strip functions as a current collector and the resistance in the planar direction is reduced. For this reason, the electric current generated at each electrode flows in a direction parallel to the electrode without voltage loss.

JP-A-4-298963

  By the way, in order to extract good power generation characteristics in the above-described solid oxide fuel cell, it is necessary to operate at a high temperature. In this case, it is conceivable that a metal member or a ceramic member constituting the fuel battery cell expands due to heat generated during power generation, and the member warps due to a difference in thermal expansion between these members. Due to the warpage, for example, peeling may occur at a part between the electrode and the current collector, particularly at the corner of the electrode. As a result, the electrical resistance (hereinafter referred to as current collection resistance) up to the three-phase interface (the interface between the reaction gas, electrode, and solid electrolyte layer) through the current collector and the electrode increases, and the current flows at the contacted part. Due to the concentration, the cell voltage is greatly reduced.

  In addition, as in Patent Document 1, when a grid-like conductive layer (conductive strip) is installed on the entire electrode, the gas diffusibility decreases, so that the resistance increases and the voltage loss increases. May occur.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a fuel cell that can suppress deterioration in cell characteristics even when the electrode and the current collector are partially separated. There is. Another object is to provide a fuel cell stack that uses the fuel cell and can efficiently generate power without voltage loss.

  And as a means (means 1) for solving the above-mentioned problem, a flat plate member arranged adjacent to a current collector having a plurality of projections for current collection and having a fuel electrode, an air electrode and an electrolyte layer A fuel cell comprising a current collector contact portion configured to be in the form of scattered dots on the surface of at least one of the fuel electrode and the air electrode. And a conductive layer provided on the surface of the electrode, wherein the conductive layer is provided in an inner region of each of the plurality of current collector contact portions, and a contact with which a projection of the current collector contacts Connection formed so as to connect the pad portion, the contact pad portion of the current collector contact portion located in a specific portion of the electrode, and the contact pad portion of the current collector contact portion adjacent thereto A fuel cell comprising: That.

  According to the invention described in the means 1, the fuel cell is configured as the flat plate member by the fuel electrode, the air electrode, and the electrolyte layer. For this reason, at the time of power generation of the fuel cell, the fuel cell may be deformed based on the difference in thermal expansion of the constituent members, and the specific portion of the electrode may be warped due to the thermal deformation of the cell. Then, the protrusion of the current collector may be separated from the current collector contact site located at the specific site due to the warping of the electrode, and the contact may not be taken. In the fuel cell of the present invention, a conductive layer having a contact pad portion and a connection portion is provided on the surface of the electrode, and the contact pad portion of the current collector contact portion located at a specific portion and An abutting pad portion of an adjacent current collector contact portion is electrically connected by a connection portion. Therefore, even when the current collector contact portion at the specific portion and the protrusion of the current collector cannot be contacted due to the warpage of the electrode, sufficient current collection is achieved through the contact pad portion or the connection portion of the current collector contact portion adjacent thereto. Electric power can be secured. In other words, by providing a conductive layer on the electrode surface, the current collector contact part from which the current collector is peeled off and the current collector contact part from which the current collector has not been peeled off are connected through the contact pad part and the connection part. Therefore, they can be conducted and a reduction in the area of the power generation unit can be prevented. For this reason, when a fuel cell is constituted using the fuel cell of the present invention, it is possible to efficiently generate power without voltage loss.

  The connection portion constituting the conductive layer includes a contact pad portion of the current collector contact portion located on the outer edge portion of the electrode and a contact pad portion of the current collector contact portion adjacent to the electrode center portion side of the contact pad portion. You may form so that it may connect. In the fuel cell of the present invention, when the warpage of the outer edge of the electrode is increased, the current collector contact portion located at the outer edge of the electrode may not be able to contact the protrusion of the current collector. In this case, the contact pad portion of the current collector contact portion located on the outer edge of the electrode is connected to the contact pad portion of the current collector contact portion adjacent to the electrode central portion side through the connection portion. Thus, the current collector can collect current from the contact pad portion of the current collector contact portion of the electrode outer edge portion via the contact pad portion and the connection portion of the current collector contact portion on the electrode center side. it can. Therefore, a decrease in power generation efficiency in the fuel battery cell can be suppressed.

  In addition, the connection part constituting the conductive layer includes a contact pad part of the current collector contact part located in the center part of the electrode, and a contact pad part of the current collector contact part adjacent to the outer edge side of the electrode. It may be formed so as to connect. In the fuel cell of the present invention, when the warpage of the electrode central portion becomes large, the current collector contact portion located on the electrode central portion side may not be able to come into contact with the protrusion of the current collector. In this case, the contact pad portion of the current collector contact portion located at the center of the electrode is connected to the contact pad portion of the current collector contact portion adjacent to the electrode outer edge side through the connecting portion. Thus, the current collector can collect current from the contact pad portion of the current collector contact portion at the center of the electrode via the contact pad portion and the connection portion of the current collector contact portion on the electrode outer edge side. it can. Therefore, a decrease in power generation efficiency in the fuel battery cell can be suppressed.

  The electrode has a quadrangular shape in plan view, and the connection portion connects the contact pad portion of the current collector contact portion located at each corner portion of the electrode and the contact pad portion of the current collector contact portion adjacent thereto. It may be formed as follows. When the electrode of the fuel cell has a quadrangular shape, when the warpage of the corner portion of the electrode increases, the current collector contact portion located at the corner portion is easily separated from the protrusion of the current collector. In the fuel battery cell of the present invention, the current collector contact portion at the corner portion and the current collector contact portion adjacent thereto are connected via the contact pad portion and the connection portion. For this reason, even when the current collector is separated from the current collector contact portion of the corner portion, the current collector of the separated corner portion is collected via the contact pad portion and the connection portion of the current collector contact portion adjacent to the corner portion. The current can be collected from the contact pad portion of the electrical contact portion. Therefore, a decrease in power generation efficiency in the fuel battery cell can be suppressed.

  The conductive layer has an L-shape in plan view so as to connect the contact pad portion of the current collector contact portion located at each corner portion and the contact pad portions of the two current collector contact portions adjacent to each other. It may be formed. When the conductive layer is formed in this way, even when the current collector is separated from the current collector contact portion of the corner portion, the corner portion is interposed via the contact pad portion and the connection portion of the two adjacent current collector contact portions. The current can be reliably collected from the contact pad portion of the current collector contact portion. Therefore, a decrease in power generation efficiency in the fuel battery cell can be suppressed.

  The area ratio of the conductive layer excluding the contact pad part of the current collector contact part (part of the connection part protruding from the current collector contact part) is based on the electrode surface area excluding the area of the current collector contact part. 1% or more and 10% or less. Here, when the area ratio of the portion excluding the contact pad portion in the conductive layer is less than 1%, the width of the connection portion that connects between the contact pad portions of the adjacent current collector contact portions becomes narrow. The current collecting resistance of the part increases and the cell characteristics deteriorate. Moreover, when the area ratio of the part except a contact pad part in a conductive layer exceeds 10%, the gas diffusibility in an electrode will fall by the area of a conductive layer becoming too large, and cell characteristics will fall. Therefore, in the fuel cell, by setting the area ratio of the portion excluding the contact pad portion to 1% or more and 10% or less, it is possible to ensure the current collecting capacity while avoiding the deterioration of the cell characteristics, and thus the efficiency. It can generate electricity well. Incidentally, in the conventional fuel cell disclosed in Patent Document 1, the grid-like conductive strip functions as a current collector, and the electrode surface is in contact with the conductive strip (current collector). There is no conductive layer protruding from the part.

  The connection part may connect the contact pad parts of the current collector contact portion linearly at the shortest distance. In this case, the surface area of the connection portion is reduced, and a decrease in gas diffusibility due to the installation of the conductive layer can be suppressed.

  On the surface of the electrode, a connection portion is formed at a site where warpage occurs in a direction away from the current collector due to thermal deformation during power generation. Thus, on the surface of an electrode, by forming a connection part only in the part which generate | occur | produces curvature, the fall of gas diffusivity can be suppressed reliably.

  The plurality of current collector contact portions may have the same shape and area, and may be regularly set in a grid pattern vertically and horizontally on the surface of the electrode. If it does in this way, it will become possible to achieve this object, securing the flow path of the reactive gas between the projection of the current collector and the electrode surface in the fuel cell.

  The conductive layer is formed using a conductive material having a resistance value lower than that of the electrode forming material. Specifically, the conductive layer includes platinum (Pt), silver (Ag), palladium (Pd), lanthanum (La), strontium (Sr), manganese (Mn), cobalt (Co), iron (Fe), copper It is formed using a conductive material containing at least one of (Cu), nickel (Ni), gold (Au), iridium (Ir), ruthenium (Ru), and rhodium (Rh). When a conductive layer is formed using such a conductive material, charge transfer is facilitated through the conductive layer, and current collection efficiency can be increased.

  The fuel cell is used in a solid oxide fuel cell, and the electrode on which the conductive layer is formed may be a fuel electrode or an air electrode. Taking the case of the air electrode as an example, the exchange of electrons between the air electrode and the current collector is efficiently performed through the conductive layer, and the power generation efficiency can be sufficiently increased.

In the case where the electrolyte layer constituting the fuel cell is a solid oxide layer, examples of the forming material include ZrO ₂ ceramic and LaGaO ₃ ceramic.

The air electrode is in contact with an oxidant gas serving as an oxidant and functions as a positive electrode in the fuel cell. Here, examples of the material for forming the air electrode include a metal material, a metal oxide, and a metal composite oxide. Preferable examples of the metal material include Pt, Au, Ag, Pd, Ir, Ru, Rh, etc., and alloys thereof. Preferable examples of metal oxides include La, Sr, Ce, Co, Mn, Fe oxides (La ₂ O ₃ , SrO, CeO ₂ , Co ₂ O ₃ , MnO ₂ , FeO). . Preferable examples of metal composite oxides include, for example, composite oxides containing La, Pr, Sm, Sr, Ba, Co, Fe, and Mn (La _1-x Sr _x CoO ₃ -based composite oxide, La _{1 -x} Sr _x FeO _3-based composite _{oxide, La 1-x Sr x Co} 1-y Fe y O 3 composite _{oxide, La 1-x Sr x MnO} 3 composite _oxide, Pr _1-x Ba _x CoO ₃ type composite oxide, Sm _1-x Sr _x CoO ₃ type composite oxide) and the like.

The fuel electrode is in contact with a fuel gas serving as a reducing agent and functions as a negative electrode in the fuel battery cell. Here, examples of the material for forming the fuel electrode include ZrO ₂ ceramics stabilized by rare earth elements (Sc, Y, etc.), and CeO ₂ ceramics doped with rare earth elements (Sm, Gd, etc.). Among them, a metal ceramic material in which at least one ceramic material is mixed with at least one of metal materials such as Pt, Au, Ag, Pd, Ir, Ru, Rh, Ni, Fe and alloys of these metal materials. Mixtures (cermets) can be used.

  Further, as another means (means 2) for solving the above-mentioned problem, the fuel cell according to means 1 and a plurality of projections for collecting current are provided, and the front end surfaces of the plurality of projections are A current collector disposed on the surface of the electrode so as to contact the current collector contact portion, and a plurality of the fuel cells and the current collector are stacked. There is a fuel cell stack.

  According to the invention described in Means 2, the fuel cell stack is configured by laminating a plurality of fuel cells and current collectors of Means 1. In this fuel cell stack, even if the current collector contact portion of the specific portion of the electrode in the fuel cell and the protrusion of the current collector cannot be contacted due to thermal deformation during power generation, the adjacent current collector Sufficient current collection capability can be ensured through the contact pad portion and the connection portion of the body contact portion. Therefore, the fuel cell stack of the present invention can generate power efficiently without any voltage loss.

  Moreover, a solid oxide fuel cell (SOFC) is mentioned as a fuel cell comprised using said fuel cell stack. The fuel cell of the present invention includes a solid oxide electrochemical cell such as a solid oxide electrolytic cell (SOEC).

The schematic block diagram which shows the fuel cell of this Embodiment. The schematic sectional drawing which shows a fuel cell stack. The top view which shows arrangement | positioning of the processus | protrusion of a collector. The top view which shows a collector contact part and a conductive layer. The principal part sectional drawing which shows the state at the time of the curvature generation | occurrence | production in an electrode. The top view which shows the L-shaped electroconductive layer of another embodiment. The top view which shows the T-shaped electroconductive layer of another embodiment. The top view which shows the triangular-shaped electroconductive layer of another embodiment. The top view which shows the square-shaped electroconductive layer of another embodiment. The top view which shows the cross-shaped electroconductive layer of another embodiment. The top view which shows the X-shaped and square-shaped electroconductive layer of another embodiment. The top view which shows the conductive layer of another embodiment which has a circular-shaped air electrode.

  Hereinafter, an embodiment in which the present invention is embodied in a fuel cell will be described in detail with reference to the drawings.

  The fuel cell 10 of the present embodiment is a solid oxide fuel cell (SOFC). As shown in FIG. 1, the fuel cell 10 includes a fuel cell stack 12 formed by stacking a plurality of fuel cells 11 that are the minimum unit of power generation.

  The fuel cell stack 12 has, for example, a substantially rectangular parallelepiped shape with a length of 180 mm × width of 180 mm × height of 80 mm. In the present embodiment, the number of stacked fuel cells 11 constituting the fuel cell stack 12 is about 20. In the fuel cell stack 12, end plates 14 and 15 are disposed at both ends (upper and lower ends in FIG. 1) in the stacking direction of the fuel cells 11. Furthermore, a plurality of through-holes that penetrate the stack 12 in the thickness direction are formed in the peripheral portion of the cell stack 12. A fastening bolt 18 is inserted into each through hole, and a nut 19 is screwed to a lower end portion of the bolt 18 protruding from the lower surface of the cell stack 12. In this manner, the plurality of fuel cells 11 are fixed by tightening the end plates 14 and 15 in the stacking direction of the fuel cells 11 using the fastening bolts 18 and the nuts 19. Further, the end plates 14 and 15 arranged at both ends of the cell stack 12 serve as output terminals for current output from the cell stack 12.

  As shown in FIG. 2, the fuel cell 11 constituting the cell stack 12 is configured as a flat plate member having an air electrode 21, a fuel electrode 22, and a solid electrolyte layer 23, and generates electric power by a power generation reaction. In addition to the fuel cell 11, the cell stack 12 is provided with a connector plate 24, a separator 25, an air electrode side current collector 27, a fuel electrode side current collector 28, and the like, and a plurality of these are stacked. ing.

  More specifically, the connector plates 24 are made of a conductive material such as stainless steel, and a pair is arranged on both sides of the fuel cell 11 in the thickness direction. Each connector plate 24 ensures conduction between the fuel cells 11 in the thickness direction. The connector plate 24 disposed between the adjacent fuel cells 11 serves as an interconnector, and separates the adjacent fuel cells 11.

  The separator 25 is made of a conductive material such as stainless steel and has a substantially rectangular frame shape having a rectangular opening 29 at the center. The separator 25 functions as a partition plate between the fuel cells 11.

  The solid electrolyte layer 23 is formed in a rectangular plate shape by a ceramic material (oxide) such as yttria stabilized zirconia (YSZ). The solid electrolyte layer 23 is fixed to the lower surface of the separator 25 and is disposed so as to close the opening 29 of the separator 25. The solid electrolyte layer 23 functions as an oxygen ion conductive solid electrolyte body.

  An air electrode 21 in contact with the oxidant gas supplied to the cell stack 12 is attached to the upper surface of the solid electrolyte layer 23, and the fuel gas supplied to the cell stack 12 is also attached to the lower surface of the solid electrolyte layer 23. A fuel electrode 22 in contact therewith is affixed. That is, the air electrode 21 and the fuel electrode 22 are disposed on both sides of the solid electrolyte layer 23. The air electrode 21 is disposed in the opening 29 of the separator 25 so as not to contact the separator 25. In the fuel cell 11 of the present embodiment, the fuel chamber 31 is formed below the separator 25 and the air chamber 32 is formed above the separator 25.

In the fuel cell 11 of the present embodiment, the air electrode 21 is formed in a rectangular plate shape by LSCF (La _0.6 Sr _0.4 Co _0.2 Fe _0.8 O ₃ ) which is a metal complex oxide. Has been. The fuel electrode 22 is formed in a rectangular plate shape by a mixture of nickel and yttria-stabilized zirconia (Ni-YSZ). In the fuel cell 11, the air electrode 21 functions as a cathode layer, and the fuel electrode 22 functions as an anode layer.

  The air electrode 21 is electrically connected to the connector plate 24 by the air electrode side current collector 27, and the fuel electrode 22 is electrically connected to the connector plate 24 by the fuel electrode side current collector 28. The air electrode side current collector 27 is made of a dense metal plate such as a SUS430 ferrite alloy to which a small amount of La, Mn, Ti, Si, C, Ni, Al, Zr or the like is added. On the other hand, the fuel electrode side current collector 28 is made of, for example, a nickel porous body so that the fuel gas can pass therethrough.

  As shown in FIGS. 2 to 4, the air electrode side current collector 27 has a plurality of protrusions 35 for collecting current, and the tip surfaces of the protrusions 35 are on the surface of the air electrode 21. It arrange | positions adjacent to the fuel cell 11 so that the collector contact part 37 set in the shape of a scattered dot may be contacted. In the present embodiment, the plurality of current collector contact portions 37 are, for example, quadrangular regions, have the same shape and area, and are regularly set in a grid pattern vertically and horizontally on the surface of the air electrode 21. . The plurality of protrusions 35 in the air electrode side current collector 27 are quadrangular protrusions having the same shape and size, and are regularly arranged in a lattice shape vertically and horizontally.

  As shown in FIG. 4, the fuel cell 11 of the present embodiment is provided with a conductive layer 38 on the surface of the air electrode 21. The conductive layer 38 is provided in each inner region of the current collector contact portion 37, and connects between the contact pad portion 39 with which the protrusion 35 of the air electrode side current collector 27 contacts and the adjacent contact pad portion 39. The connection part 40 is formed as described above. Specifically, the air electrode 21 has a quadrangular shape in plan view. The conductive layer 38 includes a contact pad portion 39 of a current collector contact portion 37 located at a corner portion 41 as a specific portion in the air electrode 21 and a contact pad portion 39 of two current collector contact portions 37 adjacent thereto. Are formed in an L-shape in plan view. The conductive layer 38 is made of a silver-palladium alloy (alloy having a palladium content of 1 to 10 mol%), and has a thickness of, for example, about several tens of μm. In addition, the connection part 40 which connects them is not provided between the contact pad parts 39 of the electrical power collector contact site | part 37 located other than each corner part 41 of the air electrode 21. FIG. Here, the inner region of the current collector contact portion 37 is a region where the quadrangular protrusions 35 of the air electrode side current collector 27 are in contact, and is a region at the center of the current collector contact portion 37, that is, a square. A region located inside the shape.

  In the fuel cell 11, a contact pad portion 39 is formed in the inner region of the plurality of current collector contact portions 37 set in a scattered manner on the surface of the air electrode 21 so as to cover the entire region. The air electrode 21 and the air electrode side current collector 27 are joined via the contact pad part 39 (see FIG. 2). In the fuel cell 11 of the present embodiment, the area of the conductive layer 38 excluding the contact pad portion 39 of the current collector contact portion 37 (connection portion 40 protruding from the inner region of the current collector contact portion 37). The ratio is about 5% with respect to the surface area of the air electrode 21 excluding the area of the current collector contact portion 37. In the present embodiment, the connection portion 40 of the conductive layer 38 is a developed pattern extending from the inner region (contact pad portion 39) of the current collector contact portion 37 to the outer region, and adjacent current collector contacts. It is formed between the parts 37. That is, the connection part 40 is a part that functions as a conducting wire that connects the contact pad parts 39 of the current collector contact portions 37.

  During power generation of the fuel cell 10, a power generation reaction occurs between the air electrode 21 and the air electrode side current collector 27 via the conductive layer 38 (contact pad portion 39 and connection portion 40) formed as described above. Accompanied by electronic transfer.

  In the fuel cell stack 12 of the present embodiment, a fuel supply path (not shown) for supplying fuel gas to the fuel chamber 31 of each fuel cell 11, and a fuel discharge path for discharging fuel gas from the fuel chamber 31 (not shown) (Not shown). The cell stack 12 is provided with an air supply path (not shown) for supplying air to the air chamber 32 of each fuel cell 11 and an air discharge path (not shown) for discharging air from the air chamber 32. ing. Each supply path and each discharge path are connected to an external pipe (not shown) via a joint portion (not shown) provided on the side surface of the fuel cell stack 12.

  Next, a method for manufacturing the fuel cell stack 12 in the present embodiment will be described.

  First, for example, a plate material made of SUS430 is punched to manufacture the connector plate 24 and the separator 25. Further, the material of the solid electrolyte layer 23 is printed on the green sheet of the fuel electrode 22, and the material of the air electrode 21 is printed thereon, followed by firing. By this firing, the planar fuel cell 11 having the air electrode 21, the fuel electrode 22, and the solid electrolyte layer 23 is manufactured.

  Thereafter, the fuel cell 11 and the separator 25 are fixed by brazing. Further, the air electrode side current collector 27 and the fuel electrode side current collector 28 are fixed to the adjacent upper connector plate 24 and lower connector plate 24 by brazing, respectively.

  Moreover, an Ag-Pd conductive paste is produced by mixing three rolls of Ag-Pd powder (Pd: 1 mol%), ethyl cellulose, and an organic solvent. Next, the conductive paste is screen-printed on the surface of the air electrode 21 and then dried. Here, the pattern of the contact pad portion 39 corresponding to each current collector contact portion 37 and the pattern of the connection portion 40 that connects the current collector contact portion 37 of the corner portion 41 are formed by a conductive paste.

  Then, the above-described connector plate 24, the fuel battery cell 11 to which the separator 25 is brazed, the air electrode side current collector 27, the fuel electrode side current collector 28 and the like are assembled together, and those members including the fuel battery cell 11 are assembled. The fuel cell stack 12 is configured by stacking a plurality of layers. At this time, in the fuel cell stack 12, the fastening bolt 18 is fitted into the through hole and the nut 19 is screwed to the tip. As a result, the fuel cell stack 12 is assembled by integrating the fuel cells 11 while being pressed in the stacking direction.

  The conductive paste described above becomes the conductive layer 38 (silver palladium alloy) by removing ethyl cellulose and the like at the operating temperature of the fuel cell 10 (for example, 700 ° C.). Further, at the operating temperature of the fuel cell 10, the silver palladium alloy of the conductive layer 38 is softened, and the air electrode 21 and the air electrode side current collector 27 are in close contact with each other. When the operation is stopped, the contact pad portion 39 of the current collector contact portion 37 is formed by joining the air electrode 21 and the air electrode side current collector 27 together.

  Next, the operation of the fuel cell 11 in the fuel cell 10 of the present embodiment will be described.

  In the fuel cell 10, for example, while the fuel cell 10 is heated to the operating temperature, the fuel gas is supplied from the fuel supply path to the fuel chamber 31 and the oxidant gas is supplied from the air supply path to the air chamber 32. At this time, hydrogen in the fuel gas and oxygen in the oxidant gas react (power generation reaction) through the solid electrolyte layer 23, and DC power is generated with the air electrode 21 as the positive electrode and the fuel electrode 22 as the negative electrode. .

  During operation of the fuel cell 10, the temperature rises due to a power generation reaction in each fuel cell 11 and reaches a high temperature of 700 ° C. At this time, cell members of the air electrode 21, the fuel electrode 22, and the electrolyte layer 23, and metal members such as the connector plate 24 and the separator 25 are expanded by heat. And the fuel cell 11 may deform | transform based on the thermal expansion difference of those members, and the corner part 41 of the air electrode 21 may warp. As shown in FIG. 5, when the curvature of the corner portion 41 increases in the air electrode 21, the protrusions 35 of the air electrode side current collector 27 are separated from the current collector contact portion 37 located in the corner portion 41, and May not be able to be contacted. In the fuel cell 11 according to the present embodiment, the conductive layer 38 (the contact pad portion 39 and the connection portion 40) is provided on the surface of the air electrode 21, and the current collector located at the corner portion 41 by the connection portion 40. The contact pad portion 39 of the body contact portion 37 and the contact pad portion 39 of the current collector contact portion 37 adjacent thereto are electrically connected. Therefore, even when the air electrode side current collector 27 is separated from the current collector contact portion 37 of the corner portion 41, the contact pad portion 39 and the connection of the current collector contact portion 37 adjacent to the corner portion 41 are connected. Current is collected from the current collector contact portion 37 of the corner portion 41 via the portion 40.

  In the cell stack 12 of the present embodiment, a plurality of fuel cells 11 are stacked and connected in series. Therefore, in the fuel cell 10, direct current power is generated from the upper end plate 14 (positive electrode) electrically connected to the air electrode 21 and the lower end plate 15 (negative electrode) electrically connected to the fuel electrode 22. Is output.

  Therefore, according to the present embodiment, the following effects can be obtained.

  (1) In the fuel battery cell 11 of the present embodiment, on the surface of the air electrode 21, the current collector contact portion 37 located at each corner portion 41 and the two current collector contact portions 37 adjacent thereto are respectively provided. A conductive layer 38 (abutting pad portion 39 and connection portion 40) having an L shape in plan view is formed so as to be connected. Thus, even when the protrusion 35 of the air electrode side current collector 27 is separated from the current collector contact portion 37 located at the corner portion 41 during operation of the fuel cell 10, the current collector adjacent to the corner portion 41 is used. The current can be collected from the contact pad portion 39 of the current collector contact portion 37 of the corner portion 41 via the contact pad portion 39 and the connection portion 40 of the contact portion 37. That is, by providing the contact pad portion 39 and the connection portion 40 on the electrode surface, the contact pad portion 39 and the air electrode of the current collector contact portion 37 of the corner portion 41 where the air electrode side current collector 27 is peeled off. Since the contact pad portion 39 of the adjacent current collector contact portion 37 where the side current collector 27 is not peeled is connected through the connection portion 40, the current collector contact portion 37 can be conducted. . Then, electrons are also supplied to the current collector contact portion 37 of the peeled corner portion 41 to ionize oxygen molecules, thereby preventing a reduction in the area of the power generation portion. Accordingly, a decrease in power generation efficiency in the fuel battery cell 11 can be suppressed.

  (2) In the fuel cell 11 of the present embodiment, the area ratio of the connection part 40 of the conductive layer 38 (the part excluding the contact pad part 39 of the current collector contact part 37) is the same as that of the current collector contact part 37. It is about 5% with respect to the surface area of the air electrode 21 excluding the area. Here, when the area ratio of the connection part 40 is less than 1%, the width of the connection part 40 that connects the adjacent current collector contact sites 37 becomes narrow, so that the current collection resistance of the connection part 40 increases. Cell characteristics will deteriorate. Moreover, when the area ratio of the connection part 40 exceeds 10%, since the area of the conductive layer 38 becomes large too much, the gas diffusibility in the air electrode 21 will fall and a cell characteristic will fall. Therefore, as in the fuel battery cell 11 of the present embodiment, by setting the area ratio of the connection portion 40 protruding from the inner region of the current collector contact portion 37 in the conductive layer 38 to 5%, cell characteristics are deteriorated. As a result, sufficient current collection capability can be ensured and power can be generated efficiently.

  (3) In the fuel battery cell 11 of the present embodiment, the inner regions of the plurality of current collector contact sites 37 set in the form of dots on the surface of the air electrode 21 are covered with the entire region. A contact pad portion 39 is formed, and the air electrode 21 and the air electrode side current collector 27 are joined via the contact pad portion 39. If comprised in this way, the contact resistance between each processus | protrusion 35 of the air electrode side collector 27 and the air electrode 21 can be restrained low, and current collection efficiency can fully be improved.

  (4) In the fuel battery cell 11 of the present embodiment, the connection portion 40 linearly connects the contact pad portions 39 of the current collector contact portion 37 with the shortest distance. In this case, the surface area of the connection part 40 becomes small, and the fall of the gas diffusibility by installing the connection part 40 can be suppressed.

  (5) In the fuel battery cell 11 of the present embodiment, the plurality of current collector contact portions 37 have the same shape and area, and are regularly set in a grid pattern vertically and horizontally on the surface of the air electrode 21. . In this way, in the fuel cell 11, the air electrode side current collector 27 ensures that the flow path of the oxidant gas is secured between the projection 35 of the air electrode side current collector 27 and the surface of the air electrode 21. Can be collected.

  (6) In the fuel cell 11 of the present embodiment, the conductive layer 38 is formed using a conductive material (specifically, a silver-palladium alloy) having a lower resistance value than the material for forming the air electrode 21. When the conductive layer 38 is formed using such a conductive material, charge transfer is facilitated through the conductive layer 38, and the current collection efficiency of the fuel cell 11 can be further increased.

  In addition, you may change embodiment of this invention as follows.

  -In above-mentioned embodiment, in the air electrode 21, the contact pad part 39 was formed in the inner area | region of each collector contact part 37 so that those area | regions might be covered, but it is not limited to this. Absent. For example, as shown in FIG. 6, the pattern of the conductive layer 43 (contact pad portion 44) in the inner region of the current collector contact portion 37 may be formed thin. That is, the contact pad portion 44 formed in the inner region of the current collector contact portion 37 has the same width as the connection portion 45, and the conductive layer 43 is formed so as to have an L shape in plan view. Similarly to the conductive layer 38 of the above embodiment, the conductive layer 43 is also formed so as to connect the current collector contact portion 37 of each corner portion 41 and the two current collector contact portions 37 adjacent thereto. ing. Further, the conductive layer 43 (contact pad portion 44) is not provided in the inner region of each current collector contact portion 37 on the center side. In this case, even when the air electrode side current collector 27 is separated from the current collector contact portion 37 of the corner portion 41, the contact pads 44 and the connection portions 45 of the two adjacent current collector contact portions 37 are used. Current can be collected from the current collector contact portion 37 of the corner portion 41. Accordingly, a decrease in power generation efficiency in the fuel battery cell 11 can be suppressed.

  In the above embodiment, the conductive layers 38 and 43 connected to the current collector contact portion 37 of each corner portion 41 are L-shaped, but the conductive layers 47, 48, and 49 (see FIGS. 7 to 9) The shape of the contact pad portions 51, 52, 53 and the connection portions 54, 55, 56) may be changed as appropriate. The conductive layer 47 in FIG. 7 is formed in a T shape, and the conductive layer 48 in FIG. 8 is formed in a triangular shape. Further, the conductive layer 49 in FIG. 9 is formed in a square shape. These conductive layers 47 to 49 also connect the contact pad portions 51 to 53 of the current collector contact portion 37 of each corner portion 41 and the contact pad portions 51 to 53 of the current collector contact portion 37 adjacent thereto. Thus, connection parts 54 to 56 are formed. Even when the air electrode side current collector 27 is peeled off from the current collector contact portion 37 of the corner portion 41 by forming the respective conductive layers 47 to 49, the conductive layers 47 to 49 of the adjacent current collector contact portions 37 are separated. Current can be collected from the current collector contact portion 37 of the corner portion 41 through 49 (the contact pad portions 51 to 53 and the connection portions 54 to 56). Accordingly, a decrease in power generation efficiency in the fuel battery cell 11 can be suppressed.

  In the above embodiment, the conductive layers 38, 43, 47 to 49 are formed in the corner portion 41 on the electrode plane of the air electrode 21, and the current collector contact portion 37 located in the corner portion 41 and the current collector adjacent thereto Although the body contact part 37 is connected, the present invention is not limited to this. For example, the fuel cell 11 may be deformed such that the current collector contact portion 37 located at the center of the electrode is peeled off from the protrusion 35 of the air electrode side current collector 27. In this case, as shown in FIG. 10, the current collector contact portion 37 located at the electrode central portion 21a of the air electrode 21 is connected to the current collector contact portion 37 adjacent to the electrode outer edge portion 21b. Thus, the conductive layer 57 (the contact pad portion 58 and the connection portion 59) may be formed. The air electrode 21 in FIG. 10 is connected to the contact pad portions 58 of the four current collector contact portions 37 on the left and right and upper and lower sides with respect to the contact pad portion 58 of the current collector contact portion 37 of the electrode central portion 21a. Thus, a connection part 59 is formed. Even when the conductive layer 57 is formed in this way, it is possible to suppress a decrease in power generation efficiency in the fuel cell 11.

  Further, when there is a possibility of peeling from the protrusion 35 of the air electrode side current collector 27 from the current collector contact portion 37 located at either the corner portion 41 or the electrode central portion 21a, as shown in FIG. The conductive layer 60 (the contact pad portion 61 and the connection portion 62) may be formed. In the conductive layer 60 of FIG. 11, a plurality of current collectors disposed between the contact pad portions 61 of the plurality of current collector contact portions 37 disposed on the electrode outer edge portion 21 b and on the diagonal line of the air electrode 21. A connecting portion 62 is formed so as to connect the contact pad portions 61 of the body contact portion 37. Even when the conductive layer 60 is formed in this manner, it is possible to suppress a decrease in power generation efficiency in the fuel cell 11.

  In the above embodiment, the conductive layers 38, 43, 47 to 49, 57, 60 are formed on the rectangular air electrode 21 (electrode), but the electrode shape is not limited to the rectangular shape. Alternatively, the conductive layer may be formed on the air electrode 21 having a polygonal shape other than a circular shape or a square shape. FIG. 12 shows a specific example in which the conductive layer 65 (the contact pad portion 66 and the connection portions 67 and 68) is formed on the electrode surface of the circular air electrode 64. Also in the air electrode 64 of FIG. 12, a plurality of current collector contact portions 69 that are in contact with the air electrode side current collector are provided in a dotted pattern. In the air electrode 64, a plurality of current collector contact portions 69 are disposed at positions on two circumferences having different diameters. And in the air electrode 64, the connection part 67 is provided so that it may connect between the contact pad parts 66 of the adjacent collector contact part 69 about each collector contact part 69 located on the same periphery, respectively. . Further, in the air electrode 64, the contact pad portion 66 of the current collector contact portion 69 at the four positions of the right end, the left end, the upper end, and the lower end on the electrode outer edge side and the current collector contact portion 69 are located inside. Connection portions 68 are formed so as to connect the contact pad portions 66 of the adjacent current collector contact portions 69 respectively. When the conductive layer 65 is formed in this way, even when the protrusion of the air electrode side current collector is peeled off from the current collector contact portion 69 of the specific portion, the contact pad portion 66 of the current collector contact portion 69 adjacent thereto and It is possible to collect current via the connection portions 67 and 68. Accordingly, a decrease in power generation efficiency in the fuel battery cell 11 can be suppressed.

  In the above embodiment, the conductive layer 38 (contact pad portion 39) having a size substantially equal to that of the current collector contact portion 37 is formed. However, the present invention is not limited to this, and the current collector contact portion 37 is not limited thereto. A conductive layer having a larger size may be formed. However, when a conductive layer having a size larger than that of the current collector contact portion 37 is formed, a pad extension portion and a connection portion 40 that protrude from the contact pad portion 39 of the current collector contact portion 37 to the outside of the current collector contact portion 37. The area ratio of (the portion excluding the contact pad portion 39 in the conductive layer) is set to 1% to 10% with respect to the surface area of the air electrode 21 excluding the area of the current collector contact portion 37. If it does in this way, it can generate electric power efficiently, suppressing a fall of gas diffusivity.

  In the above embodiment, the conductive layers 38, 43, 47 to 49, 57, 60, 65 are formed on the surfaces of the air electrodes 21, 64, but a conductive layer is formed on the surface of the fuel electrode 22. May be. Even in this case, the fuel electrode-side current collector 28 has a plurality of protrusions, and the fuel electrode 22 has a current collector contact portion where the protrusions of the fuel electrode-side current collector 28 can come into contact with each other. The Then, a conductive layer is formed on the surface of the fuel electrode 22 so as to be connected to the current collector contact portion where the fuel electrode side current collector 28 is easily peeled and the current collector contact portion adjacent thereto. Even if the fuel battery cell 11 is configured in this manner, a sufficient current collecting capability can be ensured, so that power can be efficiently generated without voltage loss.

  In the above embodiment, the shape of the current collector contact portion 37 (each projection 35 of the air electrode side current collector 27) is a regular square shape, but the shape is changed to a rectangle, a circle, an ellipse, or the like. Also good.

  In the above embodiment, the conductive paste is baked to form the conductive layers 38, 43, 47 to 49, 57, 60, 65 depending on the operating temperature of the solid oxide fuel cell 10. The fuel cell stack 12 may be manufactured by separately performing a firing step for forming 38, 43, 47 to 49, 57, 60, 65. In addition, the conductive layers 38, 43, 47 to 49, 57, 60, 65 may be formed simultaneously with the firing step of the air electrode 21, the fuel electrode 22 and the solid electrolyte layer 23 in the fuel battery cell 11.

  Next, in addition to the technical ideas described in the claims, the technical ideas grasped by the embodiments described above are listed below.

  (1) In the means 1, the wire connecting portion includes the contact pad portion of the current collector contact portion located on the outer edge portion of the electrode and the current collector contact portion adjacent to the electrode central portion side of the contact pad portion. A fuel cell, wherein the fuel cell is formed so as to connect to the contact pad portion.

  (2) In the means 1, the wire connecting portion is formed between the contact pad portion of the current collector contact portion located in the center portion of the electrode and the current collector contact portion adjacent to the electrode outer edge side. A fuel cell, wherein the fuel cell is formed so as to connect to the contact pad portion.

  (3) The fuel cell according to (1), wherein the connection portion linearly connects the contact pad portions of the current collector contact portion with a shortest distance.

  (4) The means 1 is characterized in that the connection portion is formed on a surface of the electrode where warpage in a direction away from the current collector occurs due to thermal deformation during power generation. Fuel cell.

  (5) The fuel cell according to (1), wherein the plurality of current collector contact portions have the same shape and area, and are regularly set in a grid pattern vertically and horizontally on the surface of the electrode. .

  (6) The fuel cell according to means 1, wherein the conductive layer is formed using a conductive material having a resistance value lower than that of the electrode forming material.

  (7) In means 1, the conductive layer comprises platinum (Pt), silver (Ag), palladium (Pd), lanthanum (La), strontium (Sr), manganese (Mn), cobalt (Co), iron (Fe ), Copper (Cu), nickel (Ni), gold (Au), iridium (Ir), ruthenium (Ru), rhodium (Rh), and a conductive material. Fuel cell.

  (8) The fuel cell according to means 1, wherein the electrode is used for a solid oxide fuel cell, and the electrode on which the conductive layer is formed is the air electrode.

DESCRIPTION OF SYMBOLS 10 ... Fuel cell 11 ... Fuel cell 12 ... Fuel cell stack 21, 64 ... Air electrode 22 ... Fuel electrode 23 ... Solid electrolyte layer 27 ... Air electrode side current collector 35 ... Protrusion 37, 69 ... Current collector contact portions 38, 43, 47 to 49, 57, 60, 65 ... conductive layers 39, 44, 51 to 53, 58, 61, 66 ... contact pad portions 40, 45, 54 to 56, 59, 62 , 67, 68 ... Connection part 41 ... Corner part

Claims (5)

Adjacent to a current collector having a plurality of protrusions for current collection, and configured as a flat plate member having a fuel electrode, an air electrode and an electrolyte layer, and at least one of the fuel electrode and the air electrode On the surface of the electrode, a fuel battery cell in which a current collector contact portion capable of contacting a plurality of protrusions of the current collector is set in a scattered shape,
Comprising a conductive layer provided on the surface of the electrode;
The conductive layer is provided in an inner region of each of the plurality of current collector contact portions, and a contact pad portion with which a protrusion of the current collector contacts, and the current collector contact portion positioned at a specific portion of the electrode And a connection portion formed so as to connect the contact pad portion of the current collector contact portion adjacent to the contact pad portion.   The electrode has a quadrangular shape in plan view, and the connection portion includes the contact pad portion of the current collector contact portion located at each corner portion of the electrode and the current collector contact portion adjacent thereto. The fuel cell according to claim 1, wherein the fuel cell is formed so as to connect the contact pad portion.   The conductive layer connects the contact pad part of the current collector contact part located at each corner part and the contact pad part of the two current collector contact parts adjacent thereto, respectively. The fuel cell according to claim 2, wherein the fuel cell is formed in an L shape in a plan view.   In the conductive layer, an area ratio of a portion of the current collector contact portion excluding the contact pad portion is 1% or more and 10% or less with respect to a surface area of the electrode excluding an area of the current collector contact portion. The fuel cell according to any one of claims 1 to 3, wherein the fuel cell is provided. The fuel cell according to any one of claims 1 to 4,
A plurality of protrusions for current collection, and a current collector disposed such that tip surfaces of the plurality of protrusions are in contact with the current collector contact portion set on the surface of the electrode, A fuel cell stack, wherein a plurality of the fuel cells and the current collector are laminated.

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