JP6125941B2 - Fuel cell and fuel cell stack - Google Patents

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 to the three-phase interface (the interface between the reaction gas, the electrode, and the solid electrolyte layer) through the current collector and the electrode increases (hereinafter referred to as current collection resistance), and the contacted portion As a result, current concentration causes a problem that the cell voltage is greatly reduced.

  In addition, as in Patent Document 1, when a grid-like conductive layer (conductive strip) is provided on the entire electrode, there is a problem that resistance increases due to a decrease in gas diffusivity and voltage loss increases. There is a case.

  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 capable of avoiding deterioration of 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 It has a pad part and a connection part provided so as to connect between the contact pad parts of the adjacent current collector contact parts, and the width of the connection part is narrower than the width of the contact pad part The fuel cell characterized by the above-mentioned.

  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, the contact pad portions are respectively provided in the inner regions of the plurality of current collector contact portions on the surface of the electrode, and the contact pad portions of the adjacent current collector contact portions are connected to each other. Is provided with 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. Moreover, since the connection part in a conductive layer is narrower than the contact pad part provided in the internal area | region of a collector contact site | part, it can suppress the fall of the cell characteristic by a gas diffusibility fall. 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 is formed so as to connect the contact pad portion of the current collector contact portion located at a specific portion of the electrode and the contact pad portion of the current collector contact portion adjacent thereto. .

  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 the corner portion of the electrode and the contact pad portion of the current collector contact portion adjacent thereto. It may be formed. 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 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 of the conductive layer. 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. Current can be collected from the electrical contact area. Therefore, deterioration of the power generation efficiency in the fuel battery cell can be avoided.

  In the fuel cell, the warping of the outer edge portion and the center portion of the electrode may increase. In this case, the connection portion is provided so as to connect the contact pad portions of the plurality of current collector contact portions located on the outer edge portion of the electrode, and the plurality of current collector contact portions located on the diagonal line of the electrode It may be provided so as to connect the contact pad portions. When the contact pad part and the connection part are formed in this way, even when the current collector is separated from the current collector contact part of the outer edge part or the central part, the contact pad part and the connection of the adjacent current collector contact part The current can be reliably collected from the current collector contact portion at the outer edge or the central portion via the portion. Therefore, deterioration of the power generation efficiency in the fuel battery cell can be avoided.

  In some cases, the electrodes are circular in plan view. In this case, the connection part may be provided so that the contact pad part of the several electrical power collector contact location located on the same periphery may be connected. In this way, even when the current collector is separated from any current collector contact portion on the circumference, the current collector is separated via the contact pad portion and the connection portion of the adjacent current collector contact portion. Current can be collected from the current collector contact site. Therefore, deterioration of the power generation efficiency in the fuel battery cell can be avoided.

  The individual thicknesses (widths) of the connecting portions may be larger (wider) on the outflow side of the reaction gas than on the inflow side of the reaction gas supplied along the planar direction of the electrode. If the thickness of the connection part is uniformly formed in the plane of the electrode, the amount of power generated on the inflow side and the outflow side of the reaction gas according to the flow of the reaction gas (fuel gas and oxidant gas) supplied to the electrode May be non-uniform (that is, variations in power generation amount may occur). On the other hand, according to the flow of the reaction gas, by forming a thicker connection portion on the outflow side than on the inflow side, it becomes possible to make the in-plane current density uniform, and in the plane of the electrode It is possible to suppress variations in power generation amount between the gas inflow side and the gas outflow side.

  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 connection part becoming large too much, and cell characteristics will fall. Therefore, in the fuel cell, by setting the area ratio of the portion excluding the contact pad portion to be 1% or more and 10% or less, it is possible to secure a sufficient current collecting capability while avoiding deterioration of the cell characteristics. , Can generate electricity efficiently. 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, since the surface area of the connection portion is reduced, voltage loss due to a decrease in gas diffusibility due to the installation of the conductive layer can be suppressed.

  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.

  In the fuel cell stack, the tip end surface of the protrusion may be bonded to the surface of the electrode via a contact pad portion provided in the inner region of the current collector contact portion. If it does in this way, the contact resistance between each processus | protrusion of an electrical power collector and an electrode can be restrained low, and current collection efficiency can be improved.

  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 conductive layer (a contact pad part and a connection part). 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 conductive layer of another embodiment which has a diagonal connection part. The top view which shows the electroconductive layer of another embodiment which has a circular connection part. The top view which shows the conductive layer of another embodiment from which the width | variety of a connection part differs in a surface. The top view which shows the conductive layer of another embodiment from which the width | variety of a connection part and a pad expansion part differs in a surface.

  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 300 of the present embodiment is a solid oxide fuel cell (SOFC). As shown in FIG. 1, the fuel cell 300 includes a fuel cell stack 312 formed by stacking a plurality of fuel cells 311 that are the minimum unit of power generation.

  The fuel cell stack 312 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 311 constituting the fuel cell stack 312 is about 20. Further, in the fuel cell stack 312, end plates 14 and 15 are arranged at both ends (upper end and lower end in FIG. 1) in the stacking direction of the fuel cells 311. Furthermore, a plurality of through-holes that penetrate the stack 312 in the thickness direction are formed in the peripheral portion of the cell stack 312. Then, the fastening bolts 18 are inserted into the respective through holes, and nuts 19 are screwed onto the lower end portions of the bolts 18 protruding from the lower surface of the cell stack 312. Thus, the plurality of fuel cells 311 are fixed by fastening the end plates 14 and 15 in the stacking direction of the fuel cells 311 using the fastening bolts 18 and the nuts 19. Further, the end plates 14 and 15 disposed at both ends of the cell stack 312 serve as output terminals for current output from the cell stack 312.

  As shown in FIG. 2, the fuel cell 311 constituting the cell stack 312 is configured as a flat plate member having the air electrode 21, the fuel electrode 22, and the solid electrolyte layer 23, and generates electric power by a power generation reaction. In addition to the fuel cell 311, the cell stack 312 is provided with a connector plate 24, a separator 25, an air electrode current collector 27, a fuel electrode current collector 28, and the like, and a plurality of these are stacked. ing.

  More specifically, the connector plates 24 are formed of a conductive material such as stainless steel, and a pair of connector plates 24 are arranged on both sides of the fuel cell 311 in the thickness direction. Each connector plate 24 ensures conduction between the fuel cells 311 in the thickness direction. The connector plate 24 disposed between the adjacent fuel cells 311 serves as an interconnector, and separates the adjacent fuel cells 311.

  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 311.

  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 312 is attached to the upper surface of the solid electrolyte layer 23, and the fuel gas supplied to the cell stack 312 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 311 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 311 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 311, 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 311 so that the collector contact site | part 37 set in the shape of a 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 311 of the present embodiment is provided with a conductive layer 338 on the surface of the air electrode 21. The conductive layer 338 is provided in each inner region of the current collector contact portion 37, and a contact pad portion 339 with which the protrusion 35 of the air electrode side current collector 27 abuts and an adjacent current collector contact portion 37 abuts. And a connection portion 340 formed so as to connect the pad portions 339. Specifically, the air electrode 21 has a quadrangular shape in plan view. The conductive layer 338 includes a contact pad portion 339 of the current collector contact portion 37 located at the corner portion 41 as a specific portion in the air electrode 21, and a contact pad portion 339 of two current collector contact portions 37 adjacent thereto. Are formed in an L-shape in plan view. The conductive layer 338 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 340 which connects these inner area | regions is not provided between the contact pad parts 339 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 311, a contact pad portion 339 is formed in an 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 portion 339 (see FIG. 2). In the fuel battery cell 311 of the present embodiment, the width of the connection portion 340 is narrower than the width of the contact pad portion 339 provided in the inner region of each current collector contact portion 37. Further, in the fuel cell 311, the area ratio of the portion of the conductive layer 338 excluding the contact pad portion 339 of the current collector contact portion 37 (connection portion 340 protruding from the inner region of the current collector contact portion 37) is: The surface area of the air electrode 21 excluding the area of the current collector contact portion 37 is about 5%. In the present embodiment, the connection portion 340 of the conductive layer 338 is a developed pattern extending from the inner region (contact pad portion 339) of the current collector contact portion 37 to the outer region, and adjacent current collector contact It is formed between the parts 37. That is, the connection part 340 is a part that functions as a conductor that connects the contact pad parts 339 of the current collector contact portions 37.

  During power generation of the fuel cell 300, a power generation reaction occurs between the air electrode 21 and the air electrode side current collector 27 via the conductive layer 338 (the contact pad portion 339 and the connection portion 340) formed as described above. Accompanied by electronic transfer.

  In the fuel cell stack 312 of the present embodiment, a fuel supply path (not shown) for supplying fuel gas to the fuel chamber 31 of each fuel battery cell 311, and a fuel discharge path for discharging fuel gas from the fuel chamber 31 ( (Not shown). The cell stack 312 is provided with an air supply path (not shown) for supplying air to the air chamber 32 of each fuel battery cell 311 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 312.

  Next, a method for manufacturing the fuel cell stack 312 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, a flat plate fuel cell 311 having the air electrode 21, the fuel electrode 22, and the solid electrolyte layer 23 is manufactured.

  Thereafter, the fuel cell 311 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 339 corresponding to each current collector contact portion 37 and the pattern of the connection portion 340 that connects the current collector contact portion 37 of the corner portion 41 are formed by a conductive paste.

  The connector plate 24, the fuel battery cell 311 with the separator 25 brazed thereto, 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 311 are assembled. The fuel cell stack 312 is configured by stacking a plurality of layers. At this time, in the fuel cell stack 312, the fastening bolt 18 is fitted into the through hole and the nut 19 is screwed to the tip. As a result, the fuel battery cell stack 312 is assembled by integrating the fuel battery cells 311 while being pressed in the stacking direction.

  The conductive paste described above becomes the conductive layer 338 (silver palladium alloy) by removing ethyl cellulose and the like at the operating temperature of the fuel cell 300 (for example, 700 ° C.). In addition, the silver palladium alloy of the conductive layer 338 is softened to the operating temperature of the fuel cell 300 so that 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 339 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 311 in the fuel cell 300 of the present embodiment will be described.

  In the fuel cell 300, for example, while the fuel cell 300 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 300, the temperature rises due to the power generation reaction in each fuel cell 311 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 311 may deform | transform based on the thermal expansion difference of these 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 311 of the present embodiment, the conductive layer 338 (the contact pad portion 339 and the connection portion 340) is provided on the surface of the air electrode 21, and the current collector located at the corner portion 41 by the connection portion 340. The contact pad portion 339 of the body contact portion 37 and the contact pad portion 339 of the current collector contact portion 37 adjacent thereto are electrically connected. For this reason, 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 339 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 340.

  In the cell stack 312 of the present embodiment, a plurality of fuel cells 311 are stacked and connected in series. Therefore, in the fuel cell 300, 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 cell 311 of the present embodiment, on the surface of the air electrode 21, the current collector contact portion 37 positioned at each corner portion 41 and the two current collector contact portions 37 adjacent thereto are respectively provided. A conductive layer 338 (abutting pad portion 339 and connecting portion 340) having an L shape in plan view is formed so as to be connected. In this way, 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 300, the current collector adjacent to the corner portion 41 is disposed. Current can be collected from the contact pad portion 339 of the current collector contact portion 37 of the corner portion 41 through the contact pad portion 339 and the connection portion 340 of the contact portion 37. Moreover, since the connection part 340 in the conductive layer 338 is narrower than the contact pad part 339 provided in the internal region of the current collector contact portion, it is possible to suppress the deterioration in cell characteristics due to the decrease in gas diffusivity. . Therefore, deterioration of the power generation efficiency in the fuel battery cell 311 can be avoided, and power can be generated efficiently without voltage loss.

  (2) In the fuel battery cell 311 of the present embodiment, the area ratio of the connection part 340 (excluding the contact pad part 339) of the conductive layer 338 is the air electrode 21 excluding the area of the current collector contact part 37. The surface area is about 5%. Here, when the area ratio of the connection part 340 is less than 1%, the width of the connection part 340 connecting the adjacent current collector contact sites 37 is narrowed, so that the current collection resistance of the connection part 340 is increased. Cell characteristics will deteriorate. Moreover, when the area ratio of the connection part 340 exceeds 10%, the gas diffusibility in the air electrode 21 deteriorates and the cell characteristic deteriorates because the area of the conductive layer 338 becomes too large. Therefore, as in the fuel battery cell 311 of the present embodiment, by setting the area ratio of the connection portion 340 in the conductive layer 338 to 5%, sufficient current collection capability is ensured while avoiding deterioration of cell characteristics. Can be generated efficiently.

  (3) In the fuel cell 311 of the present embodiment, the contact pad portion 339 is provided in the inner region of the plurality of current collector contact portions 37, and the air electrode 21 and the air are interposed via the contact pad portion 339. The pole side current collector 27 is joined. 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 cell 311 of the present embodiment, the connection portion 340 linearly connects the contact pad portions 339 of the current collector contact portion 37 with the shortest distance. In this case, the surface area of the connection part 340 becomes small, and the fall of gas diffusivity by installing the connection part 340 can be suppressed.

  (5) In the fuel battery cell 311 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 311, the air electrode side current collector 27 ensures that the flow path of the oxidant gas is secured between the protrusion 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 311 of the present embodiment, the conductive layer 338 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 338 is formed using such a conductive material, charge transfer is facilitated through the conductive layer 338, and the current collection efficiency of the fuel cell 311 can be further increased.

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

  In the above embodiment, the L-shaped conductive layer 338 (the contact pad portion 339 and the connection portion 340) is formed at the corner portion 41 in the electrode plane of the air electrode 21, and the current collector contact located at the corner portion 41 is formed. Although the part 37 and the current collector contact part 37 adjacent thereto are connected, the present invention is not limited to this. For example, 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 electrode central portion 21a or the electrode outer edge portion 21b, it is shown in FIG. Such a conductive layer 343 (the contact pad portion 344 and the connection portion 345) may be formed. In FIG. 6, the plurality of current collector contact portions 37 disposed between the contact pad portions 344 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 345 is formed so as to connect the contact pad portions 344 of each other. When the conductive layer 343 is formed in this way, even when the protrusion 35 of the air electrode side current collector 27 is separated from the current collector contact portion 37 in the electrode central portion 21a or the electrode outer edge portion 21b, the adjacent current collector contact Current can be collected from the contact pad portion 344 of the separated current collector contact portion 37 via the contact pad portion 344 and the connection portion 345 of the portion 37. Also, in the conductive layer 343, since the width of the connection portion 345 is narrower than the width of the contact pad portion 344 provided in the inner region of each current collector contact portion 37, the deterioration of cell characteristics due to the decrease in gas diffusibility is suppressed. can do. Therefore, even when the conductive layer 343 is formed, it is possible to avoid deterioration in power generation efficiency in the fuel cell 311.

  In the above embodiment, the conductive layers 338 and 343 are formed on the rectangular air electrode 21 (electrode). However, the electrode shape is not limited to the rectangular shape, and other than the circular shape or the rectangular shape. A conductive layer may be formed on a polygonal air electrode. FIG. 7 shows a specific example in which the conductive layer 352 (the contact pad portion 353 and the connection portions 354 and 355) is formed on the electrode surface of the circular air electrode 351. Also in the air electrode 351 of FIG. 7, a plurality of current collector contact portions 356 that are in contact with the air electrode side current collector are provided in the form of dots. In the air electrode 351, a plurality of current collector contact portions 356 are disposed at positions on two circumferences having different diameters. And in the air electrode 351, the connection part 354 is provided so that it may connect between the contact pad parts 353 of the adjacent collector contact part 356 about each collector contact part 356 located on the same periphery, respectively. . Further, in the air electrode 351, the contact pad portion 353 of the current collector contact portion 356 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 356 are inward. Connection portions 355 are formed so as to connect the contact pad portions 353 of the adjacent current collector contact portions 356 respectively. When the conductive layer 352 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 356 of the specific portion, the contact pad portion 353 of the current collector contact portion 356 adjacent thereto and Current can be collected via the connection portions 354 and 355. Also, in the conductive layer 352, since the widths of the connection portions 354 and 355 are narrower than the width of the contact pad portion 353 provided in the inner region of each current collector contact portion 356, the cell characteristics are deteriorated due to the decrease in gas diffusivity. Can be suppressed. Therefore, even when the conductive layer 352 is formed on the electrode surface of the circular air electrode 351, it is possible to avoid the deterioration of the power generation efficiency in the fuel cell 311.

  In the fuel cell 311 of the above embodiment, on the surface of the air electrode 21, the contact pad portion 339 of the current collector contact portion 37 located at each corner portion 41 and two current collector contact portions adjacent thereto Although the connection part 340 was formed so that it might each connect with the 37 contact pad part 339, it is not limited to this. For example, the connection portion 340 may be formed so as to connect all the contact pad portions 339 of the current collector contact portion 37 on the surface of the air electrode 21. Further, the thickness of the connecting portion 340 may be different as long as it is formed narrower than the width of the contact pad portion 339 in the inner region of the current collector contact portion 37. FIG. 8 shows a specific example of the conductive layer 360 (the contact pad portion 361 and the connection portion 362). More specifically, in the conductive layer 360 of FIG. 8, the individual thicknesses (widths) of the connection portions 362 connecting the contact pad portions 361 of the adjacent current collector contact portions 37 are supplied along the planar direction of the electrodes. The reaction gas F1, A1 outflow side is thicker (wider) than the reaction gas (fuel gas F1 and oxidant gas A1) inflow side. Note that the oxidant gas A1 is supplied to the air electrode 21 from the right side to the left side in FIG. Further, a fuel gas F1 is supplied from the upper side to the lower side in FIG. 8 to the fuel electrode 22 provided on the back side of the air electrode 21. Therefore, in the conductive layer 360, the connection portion 362 on the upper right is formed to be the thinnest, and the connection portion 362 on the lower left is formed to be the thickest. As described above, when the conductive layer 360 is formed by changing the thickness of the connection portion 362 in accordance with the flow of the reaction gases F1 and A1 supplied along the planar direction of the electrode, the variation in the power generation amount in the electrode plane is suppressed. Power generation can be performed efficiently.

  Further, the conductive layer 360 shown in FIG. 8 is formed so as to have a coarse and dense connection portion 362 in the surface of the air electrode 21 in accordance with the flow of the reaction gases F1 and A1 supplied to the electrodes. A conductive layer 365 as shown in FIG. 9 may be formed. As shown in FIG. 9, the conductive layer 365 has contact pad portions 366 provided in the inner region of the current collector contact portion 37, and two current collector contact portions 37 adjacent in each corner portion 41. The contact pads 366 are connected to each other so as to connect the contact pads 366. Furthermore, the conductive layer 365 has a pad extension portion 368 provided so as to protrude from the contact pad portion 366 to the outside of the current collector contact portion 37.

  An oxidant gas A1 is supplied to the air electrode 21 from the right side to the left side in FIG. Further, the fuel gas F <b> 1 is supplied from the upper side to the lower side to the fuel electrode 22 provided on the back side of the air electrode 21. The conductive layer 365 is formed so that the area of the connection portion 367 and the pad expansion portion 368 is larger on the outflow side than on the inflow side in accordance with the flow of the oxidant gas A1 and the fuel gas F1. Specifically, the thickness (width) of the connecting portion 367 connecting the contact pad portions 366 of the current collector contact portions 37 adjacent to each other at the corner portion 41 is larger (wider) on the outflow side than on the inflow side. It has become. Further, the area (width) of the pad extension 368 protruding from the current collector contact portion 37 is larger (wider) on the outflow side than on the inflow side. Here, when a conductive layer (connection portion or pad extension portion) is uniformly formed in the surface of the air electrode 21, the reaction gas F1 is formed according to the directions of the reaction gases F1 and A1 supplied along the planar direction of the electrode. , The amount of power generation may be uneven on the inflow side and the outflow side of A1. On the other hand, as shown in FIG. 9, the density of the connection part 367 and the pad extension part 368 is not uniform according to the flow of the reaction gases F1, A1 supplied along the planar direction of the electrodes. When the conductive layer 365 is formed, the power generation amount can be made uniform in the electrode plane. In the conductive layer 365 of FIG. 9 as well, the area ratio of the portion excluding the contact pad portion 366 (connection portion 367 and pad extension portion 368) is the surface area of the air electrode 21 excluding the area of the current collector contact portion 37. On the other hand, it is 1% or more and 10% or less. 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 338, 343, 352, 360, and 365 are formed on the surfaces of the air electrodes 21 and 351, but a conductive layer may be formed on the surface of the fuel electrode 22. 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 On the surface of the fuel electrode 22, a conductive layer (contact pad portion and connection portion) is connected to the current collector contact portion where the fuel electrode-side current collector 28 is easily peeled off and the current collector contact portion adjacent thereto. ). Even if the fuel cell 311 is configured in this manner, it is possible to avoid the deterioration of the power generation efficiency, and thus it is possible to generate power efficiently 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 338, 343, 352, 360, 365 according to the operating temperature of the solid oxide fuel cell 300, but the conductive layers 338, 343, 343 The fuel cell stack 312 may be manufactured by separately performing a firing process for forming 352, 360, and 365. In addition, the conductive layers 338, 343, 352, 360, and 365 may be formed simultaneously with the firing process of the air electrode 21, the fuel electrode 22, and the solid electrolyte layer 23 in the fuel cell 311.

  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 connection part includes the contact pad part of the current collector contact part located at a specific part of the electrode, and the contact pad part of the current collector contact part adjacent thereto. It is formed so that may be connected. The fuel cell characterized by the above-mentioned.

  (2) 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.

  (3) 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. .

  (4) 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.

  (5) 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.

  (6) 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 21,351 ... Air electrode 22 ... Fuel electrode 23 ... Solid electrolyte layer 27 ... Air electrode side current collector 35 ... Protrusion 37, 356 ... Current collector contact part 41 ... Corner part 300 ... Fuel cell 311 ... Fuel cell 312 ... Fuel cell stack 338, 343, 352, 360, 365 ... Conductive layer 339, 344, 353, 361, 366 ... Contact pad part 340, 345, 354, 355, 362, 367 ... Connection part A1 ... oxidant gas as reaction gas F1 ... fuel gas as reaction gas

Claims (8)

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 current collector contact portions, and a contact pad portion with which a protrusion of the current collector contacts, and the contact pad portion of the adjacent current collector contact portion A connection portion provided so as to connect each other,
The fuel cell according to claim 1, wherein a width of the connection portion is narrower than a width of 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 a corner portion of the electrode and the contact of 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 electrode has a quadrangular shape in plan view, and the connection portion is provided so as to connect the contact pad portions of the plurality of current collector contact portions located on the outer edge portion of the electrode, and the diagonal line of the electrode 2. The fuel cell according to claim 1, wherein the fuel battery cell is provided so as to connect the contact pad portions of the plurality of current collector contact portions located on the upper side.   The electrode has a circular shape in a plan view, and the connection portion is provided so as to connect the contact pad portions of a plurality of the current collector contact portions located on the same circumference. The fuel battery cell according to claim 1.   The individual thicknesses of the connection portions are larger on the outflow side of the reaction gas than on the inflow side of the reaction gas supplied along the planar direction of the electrode. Fuel cell.   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 claim 1, wherein the fuel cell is provided. The fuel battery cell according to any one of claims 1 to 6,
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.   8. The fuel cell according to claim 7, wherein a tip end surface of the protrusion is joined to a surface of the electrode through the contact pad portion provided in an inner region of the current collector contact portion. Cell stack.

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