JP2019083180A - Electrochemical reaction unit and electrochemical reaction cell stack - Google Patents

Abstract

To improve supply efficiency of a gas to an electrode, and reduce electric resistance of a contact position of a projection part and a junction part.SOLUTION: An electrochemical reaction unit comprises: a unit cell including an electrolyte layer, and an air electrode and a fuel electrode facing each other in a first direction while sandwiching the electrolyte layer between the air electrode and the fuel electrode; a collector member that is arranged on one electrode side of the air electrode and the fuel electrode of the unit cell, and includes a projection part projecting to the one electrode; and a conductive junction part joining the projection part to the one electrode. In at least one cross section in parallel with a first direction including the projection part, the junction part and the one electrode, at least one end of both ends of an electrode side contact wire in contact with the one electrode in the junction part is included within a projection range where the projection part is projected onto the one electrode. A projection part side contact wire in contact with the projection part in the junction part is extended to a corner part of the projection part, and the length of the projection part side contact wire is longer than that of the electrode side contact wire.SELECTED DRAWING: Figure 6

Description

  The technology disclosed by the present specification relates to an electrochemical reaction unit.

  A solid oxide fuel cell (hereinafter also referred to as “SOFC”) provided with an electrolyte layer containing solid oxide is one of the types of fuel cells that generate electricity using the electrochemical reaction of hydrogen and oxygen. Are known. The fuel cell power generation unit (hereinafter, also simply referred to as “power generation unit”), which is the minimum unit of SOFC power generation, is a single unit including an electrolyte layer and an air electrode and a fuel electrode facing each other in the first direction across the electrolyte layer. A cell and conductive current collectors disposed on the air electrode side and the fuel electrode side of the unit cell to collect power generated in the unit cell. In general, the current collecting member disposed on the air electrode side of the unit cell has a protrusion projecting toward the air electrode. The air electrode and the current collecting member are electrically connected by joining the air electrode and the protruding portion of the current collecting member by the conductive joint.

  Conventionally, a configuration is known in which the width in the second direction orthogonal to the first direction of the joint is relatively narrow over the entire length in the first direction of the joint (see, for example, Patent Document 1). Specifically, in the configuration in which the width of the joint is narrow, the width in the second direction of the joint in the cross section parallel to the first direction including the projection, the joint, and the air electrode is The width of the joint in the second direction is smaller than the width in the second direction, and both ends of the joint in the second direction are substantially parallel to the first direction. Also, conventionally, a configuration is known in which the width in the second direction of the bonding portion is relatively wide over the entire length in the first direction of the bonding portion (see, for example, Patent Document 2). Specifically, in the configuration in which the width of the joint is wide, in the cross section parallel to the first direction including the projection, the joint and the air electrode, the width in the second direction of the joint is The width of the junction in the second direction is wider as the width is wider than the width in the second direction and toward the air electrode.

WO 2016/152924 JP, 2016-24996, A

  In the configuration in which the width of the joint is narrow, the contact area between the projection and the joint is relatively small, and current flows intensively at a specific part of the contact point between the projection and the joint. May be damaged. Further, in the configuration in which the width of the joint is wide, the contact area between the projection and the joint is relatively large, and therefore damage to the projection due to current concentration can be suppressed. Among the above, since the surface area of the exposed portion to the air chamber is narrow, the supply efficiency of the gas supplied to the air chamber to the air electrode may be reduced.

  Such a problem is also common to the configuration in which the protruding portion of the current collecting member disposed on the fuel electrode side of the unit cell and the fuel electrode are joined by the conductive joint portion. Such a problem is also common to the electrolytic cell unit, which is the smallest unit of the solid oxide electrolytic cell (hereinafter also referred to as "SOEC") that generates hydrogen by utilizing the electrolysis reaction of water. It is a task. In the present specification, the power generation unit and the electrolysis cell unit are collectively referred to as an electrochemical reaction unit.

  The present specification discloses a technology that can solve at least one of the above-described problems.

  The technology disclosed in the present specification can be realized, for example, as the following form.

(1) A single cell comprising an electrolyte layer containing a solid oxide, and an air electrode and a fuel electrode facing each other in a first direction across the electrolyte layer, the electrochemical reaction unit disclosed in the present specification. A current collecting member disposed on the side of one of the air electrode and the fuel electrode of the unit cell and having a protruding portion protruding toward the one electrode; and the protruding portion and the one electrode And at least one cross section parallel to the first direction including the protrusion, the joint, and the one electrode, in an electrochemical reaction unit including a conductive joint to be joined. Among them, at least one end of the both ends of the electrode-side contact line in contact with the one electrode is included in a projection range obtained by projecting the protrusion onto the one electrode, , The side of the protrusion contacting the protrusion Sawasen extends to the corner portion of the projecting portion, and the length of the protrusion side contact line is longer than the length of the electrode side contact line. In the electrochemical reaction unit, in at least one cross section parallel to the first direction including the protrusion, the junction, and one of the electrodes, one of the junctions at both ends of the electrode-side contact line in contact with the one electrode. At least one end of the one is included in a projection range in which the projection is projected onto one of the electrodes. Therefore, the surface area of the exposed portion of the electrode facing the gas chamber is wider than that of the configuration in which both ends of the electrode-side contact line protrude outside the projection range, so the gas supplied to the gas chamber It is possible to improve the supply efficiency of the Further, in the present electrochemical reaction unit, the protrusion-side contact line in contact with the protrusion in the joint extends to the corner of the protrusion, and the length of the protrusion-side contact line is the electrode-side contact Longer than the length of the line. For this reason, the electrical resistance of the contact portion between the protrusion and the joint is higher than in the configuration in which the protrusion-side contact wire does not extend to the corner of the protrusion or the configuration in which the protrusion-side contact wire is shorter than the electrode-side contact wire. Therefore, for example, it is possible to suppress damage to the protrusion due to the current flowing intensively to the specific portion of the contact point between the protrusion and the joint. That is, according to the present electrochemical reaction unit, it is possible to improve the supply efficiency of the gas supplied to the gas chamber to the electrode, and to reduce the electrical resistance at the contact portion between the protrusion and the joint.

(2) In the electrochemical reaction unit, in the at least one cross section, the joint portion extends from the end of the protrusion-side contact line toward the center of the protrusion-side contact line, It is good also as composition which includes an inclined portion which inclines so that distance with a joined part may become short at least in part. In the electrochemical reaction unit, the junction includes an inclined portion which is inclined so that the distance between the electrode and the junction becomes shorter from the end of the protrusion-side contact line toward the center of the protrusion-side contact line. It is. As a result, the gas can be more easily supplied to the electrode along the sloped portion as compared with a configuration in which the bonding portion does not include the sloped portion, thereby improving the supply efficiency of the gas supplied to the gas chamber to the electrode side. Can.

(3) In the electrochemical reaction unit, in the at least one cross section, the thickness of the bonding portion increases from the end of the protrusion-side contact line toward the center of the protrusion-side contact line It is good also as composition. In the electrochemical reaction unit, the thickness of the joint in the inclined portion increases from the end of the protrusion-side contact line toward the center of the protrusion-side contact line. That is, the width in a direction (hereinafter, referred to as “lateral direction”) orthogonal to the first direction of the portion on the electrode side in the bonding portion is narrower than the width in the lateral direction of the portion on the protruding portion side. Thereby, the surface area of the exposed portion of the electrode facing the gas chamber is wider than in the configuration in which the thickness of the bonding portion in the inclined portion is substantially uniform from the end of the protrusion-side contact line, The supply efficiency of the gas supplied to the gas chamber to the electrode can be further improved.

(4) In the electrochemical reaction unit, in the at least one cross section, the bonding portion includes the at least one end of the electrode-side contact line included in the projection range and the protrusion-side contact line A first inclination angle with respect to the one electrode of the first tangent at a first position on the outer peripheral line, the first position on the outer peripheral line, and the electrode side. A second tilt angle with respect to the one electrode of the second tangent at a second position between the contact line and a third position between the first position and the second position on the outer peripheral line The magnitude relation between the third tangent angle at the position and the third inclination angle with respect to the one electrode is such that the third inclination angle <the first inclination angle, and the third inclination angle <the second It may be configured to satisfy both of the inclination angle,In the electrochemical reaction unit, the third inclination angle with respect to the third tangential electrode at the third position on the outer peripheral line is greater than the first inclination angle with respect to the first tangential electrode at the first position of the outer peripheral line small. Thereby, the gas is more easily supplied to the electrode along the outer peripheral line as compared to the configuration in which the third inclination angle is equal to or more than the first inclination angle, so the supply of the gas supplied to the gas chamber to the electrode side Efficiency can be improved. Also, the third inclination angle is smaller than the second inclination angle with respect to the second tangential electrode at the second position of the outer peripheral line. As a result, the electrode-side contact line becomes shorter as compared to the configuration in which the third inclination angle is equal to or greater than the second inclination angle, and therefore, the area of the exposed portion of the electrode can be secured widely.

  The technology disclosed in the present specification can be realized in various forms, for example, a fuel cell power generation unit, a fuel cell stack including a plurality of fuel cell power generation units, and a power generation module including a fuel cell stack. A fuel cell system including a power generation module, an electrolysis cell unit, an electrolysis cell stack including a plurality of electrolysis cell units, a hydrogen generation module including an electrolysis cell stack, and a hydrogen generation system including a hydrogen generation module It is.

It is a perspective view showing the appearance composition of fuel cell stack 100 in an embodiment. It is explanatory drawing (XZ sectional drawing) which shows the structure of the electric power generation unit 102 roughly. It is explanatory drawing (YZ sectional drawing) which shows the structure of the electric power generation unit 102 roughly. FIG. 3 is an explanatory view (XY cross-sectional view) schematically showing a configuration of a power generation unit 102. FIG. 3 is an explanatory view (XY cross-sectional view) schematically showing a configuration of a power generation unit 102. FIG. 4 is an explanatory view showing the configuration of a portion X1 (current collector element 135, bonding layer 138 and air electrode 114) in FIG. 3 in an enlarged manner. It is explanatory drawing which shows a performance evaluation result. FIG. 16 is an explanatory view showing the configurations of a current collector element 135X, a bonding layer 138X and an air electrode 114 in Example 3 in an enlarged manner. FIG. 16 is an explanatory view showing the configurations of a current collector element 135Y, a bonding layer 138Y and an air electrode 114 in Example 4 in an enlarged manner.

A. Embodiment:
A-1. Constitution:
(Configuration of fuel cell stack 100)
FIG. 1 is an external perspective view schematically showing a configuration of a fuel cell stack 100 in the present embodiment. FIG. 1 shows mutually orthogonal XYZ axes for specifying the direction. In this specification, for convenience, the Z-axis positive direction is referred to as the upward direction, and the Z-axis negative direction is referred to as the downward direction. However, the fuel cell stack 100 is installed in a direction different from such an orientation. It is also good. The same applies to FIG.

  The fuel cell stack 100 is disposed so as to sandwich a plurality (seven in this embodiment) of power generation units 102 and seven power generation units 102 arranged in a predetermined arrangement direction (vertical direction in the present embodiment) from above and below. And a pair of end plates 104 and 106. The number of power generation units 102 included in the fuel cell stack 100 shown in FIG. 1 is merely an example, and the number of power generation units 102 is appropriately determined according to the output voltage and the like required for the fuel cell stack 100. The arrangement direction (vertical direction) corresponds to the first direction in the claims.

  A plurality of (eight in the present embodiment) through holes 108 extending in the vertical direction from the upper end plate 104 to the lower end plate 106 are formed in the peripheral portion around the Z direction of the fuel cell stack 100. The layers constituting the fuel cell stack 100 are tightened and fixed by bolts 22 inserted into the respective through holes 108 and nuts 24 fitted to the bolts 22.

  The outer diameter of the shaft portion of each bolt 22 is smaller than the inner diameter of each through hole 108. Therefore, a space is secured between the outer peripheral surface of the shaft portion of each bolt 22 and the inner peripheral surface of each through hole 108. A bolt 22 (bolt 22A) and a through hole located near the middle point of one side (a side on the X-axis positive direction side of two sides parallel to the Y-axis) in the outer periphery around the Z direction of the fuel cell stack 100 In the space formed by 108, an oxidant gas OG is introduced from the outside of the fuel cell stack 100, and functions as an oxidant gas introduction manifold 161 which is a gas flow path for supplying the oxidant gas OG to each power generation unit 102. , And is formed by a bolt 22 (bolt 22B) located in the vicinity of the middle point of the side opposite to the side (the side on the X-axis negative direction side of the two sides parallel to the Y axis) and the through hole 108. The space functions as an oxidant gas discharge manifold 162 for discharging the oxidant off gas OOG which is a gas exhausted from the air chamber 166 of each power generation unit 102 to the outside of the fuel cell stack 100 (see FIG. Reference). In addition, a bolt 22 (bolt 22D) located in the vicinity of the middle point of the other side (the side on the Y-axis positive direction side of the two sides parallel to the X-axis) in the outer periphery around the Z direction of the fuel cell stack 100 The space formed by the through holes 108 functions as a fuel gas introduction manifold 171 which receives the fuel gas FG from the outside of the fuel cell stack 100 and supplies the fuel gas FG to each power generation unit 102, and The space formed by the bolt 22 (bolt 22E) located near the middle point of the side of the side (the side on the Y-axis negative direction side of the two sides parallel to the X axis) and the through hole 108 It functions as a fuel gas discharge manifold 172 for discharging the fuel off gas FOG which is the gas discharged from the fuel chamber 176 of the unit 102 to the outside of the fuel cell stack 100 (see FIG. 3). In the present embodiment, for example, air is used as the oxidant gas OG, and a hydrogen rich gas obtained by reforming city gas is used as the fuel gas FG.

(Configuration of end plates 104 and 106)
The pair of end plates 104 and 106 is a substantially rectangular flat conductive member and is made of, for example, stainless steel. One end plate 104 is disposed on the upper side of the uppermost power generation unit 102, and the other end plate 106 is disposed on the lower side of the lowermost power generation unit 102. The plurality of power generation units 102 are held in a pressed state by the pair of end plates 104 and 106. The upper end plate 104 functions as a positive output terminal of the fuel cell stack 100, and the lower end plate 106 functions as a negative output terminal of the fuel cell stack 100.

(Configuration of power generation unit 102)
2 to 5 are explanatory diagrams schematically showing the configuration of the power generation unit 102. FIG. 2 shows the cross-sectional configuration of the power generation unit 102 at the positions II-II in FIGS. 1, 4 and 5, and the position III-III in FIGS. 1, 4 and 5 in FIG. 4 shows the cross-sectional configuration of the power generation unit 102, and FIG. 4 shows the cross-sectional configuration of the power generation unit 102 at the position of IV-IV in FIG. 2, and FIG. 5 shows the position of V-V in FIG. The cross-sectional configuration of the power generation unit 102 in FIG.

  As shown in FIGS. 2 and 3, the power generation unit 102, which is the minimum unit of power generation, includes the unit cell 110, the separator 120, the air electrode side frame 130, the air electrode side current collector 134, and the fuel electrode side frame. 140, a fuel electrode side current collector 144, and a pair of interconnectors 150 constituting the top layer and the bottom layer of the power generation unit 102. Holes corresponding to the through holes 108 into which the above-described bolts 22 are inserted are formed at peripheral portions around the Z direction of the separator 120, the air electrode side frame 130, the fuel electrode side frame 140, and the interconnector 150.

  The interconnector 150 is a substantially rectangular flat conductive member and is made of, for example, ferritic stainless steel. The interconnector 150 ensures electrical continuity between the power generation units 102 and prevents the mixing of reaction gases between the power generation units 102. In the present embodiment, when two power generation units 102 are arranged adjacent to each other, one interconnector 150 is shared by the two adjacent power generation units 102. That is, the upper interconnector 150 in a certain power generation unit 102 is the same member as the lower interconnector 150 in another power generation unit 102 adjacent to the upper side of the power generation unit 102. Further, since fuel cell stack 100 is provided with a pair of end plates 104 and 106, power generation unit 102 located at the top of fuel cell stack 100 does not have upper interconnector 150 and is located at the bottom. The power generation unit 102 does not have the lower interconnector 150.

  The unit cell 110 includes an electrolyte layer 112 and an air electrode (cathode) 114 and a fuel electrode (anode) 116 which face each other in the vertical direction (arrangement direction in which the power generation units 102 are arranged) sandwiching the electrolyte layer 112. The unit cell 110 of this embodiment is a unit cell of the fuel electrode support type in which the electrolyte layer 112 and the air electrode 114 are supported by the fuel electrode 116.

  The electrolyte layer 112 is a substantially rectangular flat plate-shaped member and contains at least Zr. For example, solid oxidation such as YSZ (yttria stabilized zirconia), ScSZ (scandia stabilized zirconia), CaSZ (calcia stabilized zirconia), etc. It is formed by a thing. The air electrode 114 is a substantially rectangular flat plate-shaped member, and is formed of, for example, a perovskite type oxide (for example, LSCF (lanthanum strontium cobalt iron oxide), LSM (lanthanum strontium manganese oxide), LNF (lanthanum nickel iron)). It is done. The fuel electrode 116 is a substantially rectangular flat plate-shaped member, and is made of, for example, Ni (nickel), a cermet composed of Ni and ceramic particles, a Ni-based alloy or the like. Thus, the unit cell 110 (power generation unit 102) of the present embodiment is a solid oxide fuel cell (SOFC) using a solid oxide as an electrolyte.

  The separator 120 is a frame-shaped member in which a substantially rectangular hole 121 penetrating in the vertical direction is formed in the vicinity of the center, and is formed of, for example, metal. The peripheral portion of the hole 121 in the separator 120 faces the peripheral portion of the surface of the electrolyte layer 112 on the air electrode 114 side. The separator 120 is bonded to the electrolyte layer 112 (unit cell 110) by a bonding portion 124 formed of a brazing material (for example, Ag wax) disposed in the facing portion. The air chamber 166 facing the air electrode 114 and the fuel chamber 176 facing the fuel electrode 116 are separated by the separator 120, and the gas leaks from the one electrode side to the other electrode side in the peripheral portion of the unit cell 110. Be suppressed. The unit cell 110 to which the separator 120 is joined is also referred to as a unit cell with a separator.

  As shown in FIGS. 2 to 4, the air electrode side frame 130 is a frame-like member in which a substantially rectangular hole 131 penetrating in the vertical direction is formed near the center, and is formed of an insulator such as mica, for example. It is done. The hole 131 of the air electrode side frame 130 constitutes an air chamber 166 facing the air electrode 114. The air electrode side frame 130 is in contact with the peripheral portion of the surface of the separator 120 opposite to the side facing the electrolyte layer 112 and the peripheral portion of the surface of the interconnector 150 facing the air electrode 114. . Further, the air electrode side frame 130 electrically insulates between the pair of interconnectors 150 included in the power generation unit 102. Further, an oxidant gas supply passage 132 communicating the oxidant gas introduction manifold 161 with the air chamber 166, and an oxidant gas communicating the air chamber 166 with the oxidant gas discharge manifold 162 in the air electrode side frame 130. A discharge communication hole 133 is formed.

  As shown in FIG. 2, FIG. 3 and FIG. 5, the fuel electrode side frame 140 is a frame-like member in which a substantially rectangular hole 141 penetrating in the vertical direction is formed in the vicinity of the center. ing. The hole 141 of the fuel electrode side frame 140 constitutes a fuel chamber 176 facing the fuel electrode 116. The fuel electrode side frame 140 is in contact with the peripheral portion of the surface of the separator 120 facing the electrolyte layer 112 and the peripheral portion of the surface of the interconnector 150 facing the fuel electrode 116. Further, in the fuel electrode side frame 140, a fuel gas supply passage 142 communicating the fuel gas introduction manifold 171 with the fuel chamber 176, and a fuel gas discharge passage 143 communicating the fuel chamber 176 with the fuel gas discharge manifold 172. And are formed.

  As shown in FIGS. 2, 3 and 5, the fuel electrode side current collector 144 is disposed in the fuel chamber 176. The fuel electrode side current collector 144 includes an interconnector facing portion 146, a plurality of electrode facing portions 145, and a connecting portion 147 for connecting each electrode facing portion 145 and the interconnector facing portion 146, for example, nickel Or nickel alloy, stainless steel or the like. Specifically, the fuel electrode side current collector 144 is manufactured by cutting a rectangular flat member and processing a plurality of rectangular portions so as to bend up. The square portion bent and raised becomes the electrode facing portion 145, and the flat plate portion in a hole state other than the bent and raised portion becomes the interconnector facing portion 146, and the portion connecting the electrode facing portion 145 and the interconnector facing portion 146 is connected It becomes the part 147. In addition, in the partial enlarged view in FIG. 5, in order to show the manufacturing method of the fuel electrode side collector 144, the state before the bending and raising process of one part of several square parts is completed is shown. The electrode facing portion 145 is in contact with the surface of the fuel electrode 116 opposite to the surface facing the electrolyte layer 112, and the interconnector facing portion 146 is on the surface of the interconnector 150 facing the fuel electrode 116. It is in contact. However, as described above, since the lowermost power generation unit 102 in the fuel cell stack 100 does not have the lower interconnector 150, the interconnector facing portion 146 in the power generation unit 102 is the lower end plate Contact 106. The fuel electrode side current collector 144 electrically connects the fuel electrode 116 and the interconnector 150 (or the end plate 106) because of such a configuration. A spacer 149 made of mica, for example, is disposed between the electrode facing portion 145 and the interconnector facing portion 146. Therefore, the fuel electrode side current collector 144 follows the deformation of the power generation unit 102 due to the temperature cycle and reaction gas pressure fluctuation, and the fuel electrode 116 and the interconnector 150 (or end plate 106) via the fuel electrode side current collector 144 The electrical connection with is well maintained.

  As shown in FIGS. 2 to 4, the air electrode side current collector 134 is disposed in the air chamber 166. The air electrode side current collector 134 is composed of a plurality of substantially square prism-like current collector elements 135, and is made of, for example, a metal containing Cr (chromium) such as ferritic stainless steel. The air electrode side current collector 134 is in contact with the surface of the air electrode 114 opposite to the side facing the electrolyte layer 112 and the surface of the interconnector 150 opposite to the air electrode 114. However, as described above, since the power generation unit 102 positioned at the top in the fuel cell stack 100 does not have the upper interconnector 150, the air electrode side current collector 134 in the power generation unit 102 is the upper end plate It is in contact with 104. Because of such a configuration, the air electrode side current collector 134 electrically connects the air electrode 114 and the interconnector 150 (or the end plate 104). The air electrode side current collector 134 and the interconnector 150 may be formed as an integral member. In the present embodiment, the air electrode 114 corresponds to one electrode in the claims, the air electrode side current collector 134 corresponds to the current collecting member in the claims, and the current collector element 135 is It corresponds to the protrusion in the claims.

As shown in FIGS. 2 and 3, the surface of the cathode side current collector 134 is covered by a conductive coat 136. The coat 136 is a spinel type oxide containing at least one of Zn (zinc), Mn (manganese), Co (cobalt) and Cu (copper) (for example, Mn _1.5 Co _1.5 O ₄ or MnCo ₂ It is formed of O ₄ , ZnCo ₂ O ₄ , ZnMnCoO ₄ , CuMn ₂ O ₄ ). The formation of the coat 136 on the surface of the air electrode side current collector 134 is performed by a known method such as, for example, spray coating, ink jet printing, spin coating, dip coating, plating, sputtering, thermal spraying and the like. As described above, in the present embodiment, the air electrode side current collector 134 and the interconnector 150 are formed as an integral member. Therefore, in practice, the interface with the interconnector 150 among the surfaces of the air electrode side current collector 134 is not covered by the coat 136 while the flow path of at least the oxidant gas in the surface of the interconnector 150 (The surface facing the air electrode 114 in the interconnector 150, the surface facing the through holes 108 constituting the oxidant gas introduction manifold 161 and the oxidant gas discharge manifold 162, etc.) is covered by the coat 136 There is. Also, a chromium oxide film may be formed by heat treatment of the air electrode side current collector 134, in which case the coat 136 is not the film but the air electrode side current collector 134 on which the film is formed. It is a layer formed to cover. In the following description, the air electrode side current collector 134 (or the current collector element 135) means "the air electrode side current collector 134 (or the current collector element 135 covered by the coat 136)" unless otherwise stated. Do.

The air electrode 114 and the air electrode side current collector 134 are bonded by a conductive bonding layer 138. The bonding layer 138 is a spinel-type oxide containing at least one of Zn, Mn, Co and Cu (eg, Mn _1.5 Co _1.5 O ₄ , MnCo ₂ O ₄ , ZnCo ₂ , etc.) like the coat 136. It is formed of O ₄ , ZnMnCoO ₄ , CuMn ₂ O ₄ ). In the present embodiment, the coat 136 and the bonding layer 138 are formed of spinel-type oxides in which the main component elements are the same. The main component referred to herein is a metal element constituting a spinel-type oxide. In addition, identification of the spinel type oxide can be realized by performing X-ray diffraction and elemental analysis. In the bonding layer 138, for example, the paste for the bonding layer is printed on a portion of the surface of the air electrode 114 facing the tip of each of the current collector elements 135 constituting the air electrode side current collector 134, It is formed by firing under a predetermined condition in a state where the tip of the current collector element 135 is pressed against the paste. The bonding layer 138 electrically connects the air electrode 114 and the air electrode side current collector 134. It was stated earlier that the air electrode side current collector 134 was in contact with the surface of the air electrode 114, but more precisely, the air electrode side current collector 134 (covered by the coat 136) and the air electrode 114 A bonding layer 138 intervenes between the two. The porosity of the bonding layer 138 is preferably 20% or more and 35% or less, and the bonding layer 138 preferably has a pore size of 0.1 μm or more and 4 μm or less. The bonding layer 138 corresponds to the bonding portion in the claims. Detailed configurations of the current collector element 135 (air electrode side current collector 134) and the bonding layer 138 will be described later.

A-2. Power generation operation in fuel cell stack 100:
As shown in FIG. 2, when the oxidant gas OG is supplied to the oxidant gas introduction manifold 161, the oxidant gas OG passes through the oxidant gas supply communication holes 132 of the respective power generation units 102 from the oxidant gas introduction manifold 161. Then, the air is supplied to the air chamber 166. Further, as shown in FIG. 3, when the fuel gas FG is supplied to the fuel gas introduction manifold 171, the fuel gas FG passes from the fuel gas introduction manifold 171 through the fuel gas supply communication holes 142 of each power generation unit 102, It is supplied to the chamber 176.

  When the oxidant gas OG is supplied to the air chamber 166 of each power generation unit 102 and the fuel gas FG is supplied to the fuel chamber 176, the single cell 110 performs power generation by the electrochemical reaction of the oxidant gas OG and the fuel gas FG. It will be. In each power generation unit 102, the air electrode 114 of the unit cell 110 is electrically connected to one interconnector 150 via the air electrode side current collector 134 (and the coat 136, the bonding layer 138), and the fuel electrode 116 is a fuel It is electrically connected to the other interconnector 150 via the pole side current collector 144. Also, the plurality of power generation units 102 included in the fuel cell stack 100 are connected in series. Therefore, the electrical energy generated in each power generation unit 102 is taken out from the end plates 104 and 106 functioning as the output terminals of the fuel cell stack 100. Since the SOFC generates power at a relatively high temperature (for example, 700 to 1000 degrees C.), the fuel cell stack 100 is heated until it can be maintained at a high temperature by the heat generated by the power generation after startup. It may be heated by

  As shown in FIG. 2, the oxidant off gas OOG (oxidant gas not used for the power generation reaction in each power generation unit 102) passes from the air chamber 166 through the oxidant gas discharge communication hole 133 and the oxidant gas discharge manifold 162. , And is discharged to the outside of the fuel cell stack 100. Further, as shown in FIG. 3, the fuel off gas FOG (fuel gas not used for the power generation reaction in each power generation unit 102) passes from the fuel chamber 176 to the fuel gas discharge communication hole 143 and the fuel gas discharge manifold 172, The battery stack 100 is discharged to the outside.

A-3. Detailed configuration of current collector element 135 and bonding layer 138:
6 is an explanatory view showing the configuration of the X1 portion (the current collector element 135, the bonding layer 138 and the air electrode 114) in FIG. 3 in an enlarged manner. As shown in FIG. 6, in a cross section (YZ cross section) parallel to the vertical direction of each current collector element 135 constituting the air electrode side current collector 134, the pair of corner portions 135A of the current collector element 135 As the center of the lateral direction (Y-axis direction) orthogonal to the vertical direction of the collector element 135 is approached, it is an inclined surface which inclines so as to approach the air electrode 114.

In addition, in a cross section (YZ cross section) parallel to the vertical direction of each current collector element 135 constituting the air electrode side current collector 134, the bonding layer 138 has both of the following first and second requirements. Fulfill.
First requirement: "At least one end of both ends of the electrode-side contact line L1 is included in the projection range H."
The electrode-side contact line L1 is an outer peripheral line segment of the air electrode 114 at the contact portion between the bonding layer 138 and the air electrode 114. In addition, when the space | gap exists between the joining layer 138 and the air pole 114, two or more contact parts with the joining layer 138 and the air pole 114 may exist. In this case, the electrode-side contact line L1 is an outer peripheral line segment of the air pole 114 connecting both ends in the lateral direction (Y-axis direction) of the plurality of whole contact portions. In this case, the ratio of the total length of the plurality of contact portions to the entire length of the electrode-side contact line L1 is preferably 80% or more.
The projection range H is an outer peripheral line segment of the air pole 114 located in a range in which the current collector element 135 is projected onto the air pole 114 in the vertical direction (Z-axis direction). Specifically, the outer peripheral line of the air electrode 114 connecting the intersections of the air electrode 114 with each of two perpendicular lines which respectively pass through both lateral ends of the current collector element 135 and are parallel to the vertical direction It is a minute. Here, the position of “each of both ends in the lateral direction of current collector element 135” is a portion closest to air electrode 114 in current collector element 135 (the bottom of current collector element 135 in FIG. From the region) to the side opposite to the air electrode 114 (Z-axis positive direction), parallel to the lateral direction located within a predetermined range separated by 25% to 55% of the total length in the vertical direction of the current collector element 135 Preferred is an intersection point between an arbitrary imaginary straight line and the outer peripheral line of the current collector element 135, and the inclination angle of the tangent of the current collector element 135 at the intersection point to the lateral direction is 80 degrees or more. . In the configuration in which the angle portion of the current collector element 135 is inclined as shown in FIG. 6, the inclination angle is preferably 90 degrees or less. In addition, the predetermined range is a range opposite to the air electrode 114 and separated from the lowermost portion of the current collector element 135 by 30% to 55% of the total length of the current collector element 135 in the vertical direction. Is preferred.

Second requirement: “The protrusion-side contact line L2 extends to the corner 135A of the current collector element 135, and the length of the protrusion-side contact line L2 is longer than the length of the electrode-side contact line L1. "
The protrusion-side contact line L2 is an outer peripheral line of the current-collector element 135 at the contact portion between the bonding layer 138 and the current-collector element 135. Note that, due to the presence of an air gap between the bonding layer 138 and the current collector element 135, there may be a plurality of contact portions between the bonding layer 138 and the current collector element 135. In this case, the electrode-side contact line L1 is an outer peripheral line segment of the current-collector element 135 connecting both ends in the lateral direction in the entire plurality of contact portions.

Furthermore, in a cross section (YZ cross section) parallel to the vertical direction of each current collector element 135, the bonding layer 138 satisfies the following third requirement.
The third requirement: "Includes at least a portion of the inclined portion 138A."
The inclined portion 138A is a portion which is inclined such that the distance between the air electrode 114 and the bonding layer 138 is shortened from the end of the protrusion-side contact line L2 toward the center of the protrusion-side contact line L2.

Furthermore, in a cross section (YZ cross section) parallel to the vertical direction of each current collector element 135, the bonding layer 138 satisfies the following fourth requirement.
Fourth requirement: "The thickness of the bonding layer 138 in the inclined portion 138A is thicker from the end of the protrusion side contact line L2 toward the center of the protrusion side contact line L2."
The thickness of the bonding layer 138 is the width of the bonding layer 138 in a direction substantially orthogonal to the direction in which the bonding layer 138 extends.

Furthermore, in a cross section (YZ cross section) parallel to the vertical direction of each current collector element 135, the bonding layer 138 satisfies the following fifth requirement.
Fifth requirement: “a first inclination angle at each of the first position, the third position, and the second position, which are arranged in order from the current collector element 135 side on the lateral outer peripheral line segment of the bonding layer 138 The magnitude relationship between θ1, the third inclination angle θ3 and the second inclination angle θ2 is
The third inclination angle θ3 <the first inclination angle θ1 and the third inclination angle θ3 <the second inclination angle θ2. "
The first inclination angle θ1 is an inclination angle of the first tangent line SL1 at the first position with respect to the surface of the air pole 114, and the third inclination angle θ3 is the air of the third tangent line SL3 at the third position. The second tilt angle θ2 is a tilt angle of the second tangent line SL2 to the surface of the air pole 114 in the second position. Note that each tangent line can be identified by a SEM image when a cross section (YZ cross section) parallel to the vertical direction of the current collector element 135 is photographed at 30 to 100 times with a scanning electron microscope (SEM). preferable.

  Also, a method of forming the bonding layer 138 satisfying the fifth requirement is as follows. When forming the bonding layer 138, the current-collector element 135 is masked and a bonding layer-forming material is applied so as to cover up to the corner 135A of the current-collector element 135. Here, when the corner portion 135A of the current collector element 135 has a slope, the bonding layer 138 can be formed along the shape of the current collector element 135 according to the viscosity of the bonding layer forming material. Also, the junction layer 138 having a slope from the current collector element 135 toward the air electrode 114 is formed by applying the junction layer forming material to the current collector element 135 multiple times using masks of different sizes. Can.

A-4. Effects of the present embodiment:
As described above, in the unit cell 110 according to the present embodiment, the bonding layer 138 has the first requirement “at least one end of both ends of the electrode-side contact line L1 within the projection range in the YZ cross section. It is included in H. Therefore, the surface area of the exposed portion of the air electrode 114 to the air chamber 166 is wider than in a configuration in which both ends of the electrode-side contact line L1 protrude outside the projection range H (for example, Comparative Example 2 described later) The supply efficiency of the oxidant gas OG supplied to the air chamber 166 to the air electrode 114 can be improved. Moreover, in the unit cell 110 of the present embodiment, both ends of the electrode-side contact line L1 are included in the projection range H. Therefore, the surface area of the exposed portion of the air electrode 114 to the air chamber 166 is larger than that of the configuration in which only one of the ends of the electrode-side contact line L1 is included in the projection range H. The supply efficiency of the supplied oxidant gas OG to the air electrode 114 can be more effectively improved.

  Further, in the unit cell 110 according to the present embodiment, in the YZ cross section, the bonding layer 138 has the second requirement “protruding part side contact line L2 extends to the corner 135A of the current collector element 135, Also, the length of the protrusion-side contact line L2 is longer than the length of the electrode-side contact line L1. Therefore, a configuration in which the protrusion-side contact line L2 does not extend to the corner 135A of the current collector element 135 or a configuration in which the protrusion-side contact line L2 is shorter than the electrode-side contact line L1 (for example, Comparative Example 1 described later) Since the electric resistance at the contact point between the current-collector element 135 and the bonding layer 138 is lower than that of the current collector element 135, for example, current flows intensively at a specific site at the contact point between the current-collector element 135 and the bonding layer 138. Can prevent the current collector element 135 from being damaged. That is, according to the single cell 110 of the present embodiment, the supply efficiency of the oxidant gas OG supplied to the air chamber 166 to the air electrode 114 is improved, and the contact between the current collector element 135 and the bonding layer 138 It is possible to reduce the electrical resistance at the location.

  Further, in the unit cell 110 of the present embodiment, the bonding layer 138 satisfies the third requirement “includes the inclined portion 138A at least in part” in the YZ cross section. Therefore, the oxidant gas OG is easily supplied to the air electrode 114 along the inclined portion 138A as compared with the configuration (for example, Comparative Examples 1 and 2 described later) in which the bonding layer 138 does not include the inclined portion 138A. The supply efficiency of the oxidant gas OG supplied to the air chamber 166 to the air electrode 114 side can be improved.

  In the unit cell 110 according to the present embodiment, in the YZ cross section, the bonding layer 138 has the fourth requirement “the thickness of the bonding layer 138 in the inclined portion 138A is from the end of the protrusion-side contact line L2 It becomes thicker as it goes to the center of projection side contact line L2. For this reason, the surface area of the exposed portion of the air electrode 114 is smaller than that in the configuration in which the thickness of the bonding layer 138 in the inclined portion 138A is substantially uniform from the end of the protrusion side contact line L2 (for example, Example 4 described later). Since the width is wide, the supply efficiency of the oxidant gas OG supplied to the air chamber 166 to the air electrode 114 side can be further improved.

  Further, in the unit cell 110 of the present embodiment, in the YZ cross section described above, the bonding layer 138 is arranged in order from the current collector element 135 side on the lateral outer peripheral line segment of the bonding layer 138 described above. The magnitude relationship between the first inclination angle θ1, the third inclination angle θ3 and the second inclination angle θ2 at the first position, the third position and the second position is the third inclination angle θ3 < The first inclination angle θ1 and the third inclination angle θ3 <second inclination angle θ2 are satisfied. For this reason, compared with the configuration in which the third inclination angle θ3 is equal to or more than the first inclination angle θ1 (for example, Examples 1 and 4 described later), the oxidant gas along the lateral outer peripheral line segment of the bonding layer 138 Since OG is easily supplied to the air electrode 114, the supply efficiency of the oxidant gas OG supplied to the air chamber 166 to the air electrode 114 side can be improved. It is possible to secure a large area of the exposed portion of the air electrode 114 and secure a long protrusion side contact line L2 to reduce the electrical resistance at the contact portion between the current collector element 135 and the bonding layer 138. In addition, the electrode-side contact line L1 is shorter than in a configuration in which the third inclination angle θ3 is equal to or more than the second inclination angle θ2 (for example, Examples 1 and 4 described later). A large area can be secured.

A-5. Performance evaluation:
A plurality of single cell samples were produced, and performance evaluation was performed using the produced plurality of single cell samples. FIG. 7 is an explanatory view showing the result of performance evaluation. Hereinafter, this performance evaluation will be described. In addition, "(circle)" of each requirement column in FIG. 7 means satisfy | filling each requirement, and "x" means not satisfy | filling the requirement. Further, “pressure loss” in FIG. 7 means a pressure loss that occurs when the supply amount of the oxidant gas OG to the air electrode 114 is a predetermined amount, and an electrode between the bonding layer 138 and the air electrode 114 The shorter the side contact line, the smaller the pressure loss. “◎” in the “pressure loss” column means that the surface area (hereinafter referred to as “exposed area”) of the air electrode 114 exposed to the fuel electrode 116 side is equivalent to that of the comparative example 1, “o” It means that the exposed area of the air electrode 114 is smaller than that of Comparative Example 1, and "x" means that the exposed area of the air electrode 114 is significantly smaller than that of Comparative Example 1. Also, “electrical resistance” in FIG. 7 means the electrical resistance between the current collector element 135 and the bonding layer 138, and the protrusion side contact line between the current collector element 135 and the bonding layer 138 The longer the length, the smaller the electrical resistance. "○" in the "Electrical resistance" column means that the length of the protrusion-side contact line is equal to that of Comparative Example 2, and "×" indicates that the length of the protrusion-side contact line is Comparative Example 2. It means being short compared with.

  Further, “power generation characteristics” in FIG. 7 means the comprehensive evaluation of the pressure loss and the electrical resistance, “「 ”in the“ power generation characteristics ”column indicates that the evaluation of pressure loss is“ ◎ ”and the electrical resistance is The evaluation means "o", "o" means that both the evaluation of pressure loss and the evaluation of electric resistance are "o", and "x" means the evaluation of pressure loss and electric resistance It means that at least one with the evaluation of is "x". Further, “contact pressure” in FIG. 7 means the pressure at the contact portion between the bonding layer 138 and the air electrode 114, and the longer the length of the protrusion side contact line, the smaller the contact pressure. It was evaluated that peeling was likely to occur between the layer 138 and the air electrode 114. "○" in the "contact pressure" column means that the contact pressure is equal to that of Comparative Example 1, and "×" means that the contact pressure is smaller than that of Comparative Example 1.

A-5-1. For each sample:
As shown in FIG. 7, the performance evaluation of a single cell was performed for Comparative Examples 1 and 2 and Examples 1 to 4. The comparative example 1 corresponds to the conventional configuration in which the width of the above-mentioned joint is narrow, and satisfies the first requirement but does not satisfy any of the second requirement to the fifth requirement. Comparative Example 2 corresponds to the configuration in which the width of the above-described joint is wide, and satisfies the second requirement, but does not satisfy any of the first requirement and the third to fifth requirements.

  The first to fourth examples satisfy both the first and second requirements. Example 2 corresponds to the configuration of FIG. 6 and satisfies all of the first to fifth requirements. In the first embodiment, the third and fourth requirements are satisfied in the second embodiment, but the fifth requirement is not satisfied. Specifically, in Example 1, the entire lateral outer periphery of the bonding layer 138 is inclined so as to approach the air electrode 114 toward the center in the lateral direction of the bonding layer 138, and The first inclination angle, the third inclination angle, and the second inclination angle at each of the three positions are substantially the same.

  FIG. 8 is an explanatory view showing the configurations of the current collector element 135X, the bonding layer 138X and the air electrode 114 in Example 3 in an enlarged manner. As shown in FIG. 8, in the cross section (YZ cross section) parallel to the vertical direction of the current collector element 135X, the width in the lateral direction (Y axis direction) of the current collector element 135X is the vertical direction of the current collector element 135X. The entire length in the (Z-axis direction) is substantially the same. That is, unlike the current collector element 135 shown in FIG. 6, the current collector element 135X does not have an inclined surface. The surface of the current collector element 135X is covered with a conductive coat 136X. Unlike the bonding layer 138 shown in FIG. 6, the bonding layer 138X does not satisfy the third requirement because it does not have a sloped portion. Specifically, the lateral outer peripheral line segment of the bonding layer 138X has a stepped shape in which the air electrode 114 side is positioned closer to the center of the bonding layer 138X in the lateral direction than the current collector element 135X. . In other words, the lateral width of the portion on the air electrode 114 side in the bonding layer 138X is narrower than the lateral width of the portion on the current collector element 135X side, which satisfies the fourth requirement. Further, both ends of the electrode-side contact line L1X are included in the projection range HX, and the length of the protrusion-side contact line L2X is longer than the length of the electrode-side contact line L1X.

  FIG. 9 is an explanatory view showing the configurations of the current collector element 135Y, the bonding layer 138Y and the air electrode 114 in Example 4 in an enlarged manner. As shown in FIG. 9, in the cross section (YZ cross section) parallel to the vertical direction of current collector element 135Y, the shape of current collector element 135Y is substantially the same as the shape of current collector element 135 shown in FIG. ing. Bonding layer 138Y has inclined portion 138AY. However, since the thickness of the bonding layer 138Y in the inclined portion 138AY is substantially uniform, the fourth requirement described above is not satisfied. The thickness of the inclined portion 138AY is substantially uniform over the entire length of the inclined portion 138AY.

A-5-2. Evaluation results:
As shown in FIG. 7, in Comparative Examples 1 and 2, both were determined to be defective (×) in the evaluation of the power generation characteristics. On the other hand, in Examples 1 to 4, it was determined that all were evaluated as good (o) or more in the evaluation of the power generation characteristics. Also from this evaluation result, by satisfying both the first and second requirements, the efficiency of supplying the oxidant gas OG to the air electrode 114 can be improved, and the current collector element 135 and the bonding layer 138 can be separated. It turns out that coexistence with reduction of the electrical resistance of a contact location can be aimed at. Moreover, it was determined that only Comparative Example 2 was defective (x) in the evaluation of the contact pressure. This is because only the comparative example 2 does not satisfy the first requirement, and the exposed area of the air electrode 114 is particularly small as compared with the other samples.

  Moreover, in Example 2, it was determined to be the best (() in the evaluation of the power generation characteristics. In the second embodiment, by further satisfying the third and fifth requirements, the oxidant gas OG can be smoothly led to the air electrode 114 along the sloped portion of the bonding layer, and This is because a large exposed area of 114 can be secured, and as a result, it is considered that the evaluation of “pressure loss” is high. In the third embodiment, the bonding layer 138X does not have a sloped portion, but by satisfying the fourth and fifth requirements, the oxidant gas OG can be smoothly transferred to the air electrode 114 along the bonding layer 138X. While being able to be led, the exposed area of the air electrode 114 can be secured large, and as a result, it is considered that the evaluation of the "pressure loss" has become high.

B. Modification:
The technology disclosed in the present specification is not limited to the above-described embodiments, and can be modified into various forms without departing from the scope of the present invention. For example, the following modifications are also possible.

  In the unit cell 110 of the above embodiment, both ends of the electrode-side contact line L1 are included in the projection range H, but only one of the ends of the electrode-side contact line L1 may be included in the projection range H .

  In the above embodiment, although the first to fifth requirements are satisfied for all the current collector elements 135 constituting the air electrode side current collector 134, the present invention is not limited thereto, and at least one current collector For the element 135, the first and second requirements may be satisfied. In the above embodiment, although the first and second requirements are satisfied in all cross sections (YZ cross sections) parallel to the vertical direction of the current collector element 135, the present invention is not limited thereto. The first and second requirements may be satisfied in at least one cross section (YZ cross section or XZ cross section) parallel to the vertical direction of the element 135. Further, among the plurality of cross sections (YZ cross section or XZ cross section) parallel to the vertical direction of current collector element 135, the first to fifth requirements may be satisfied for the common cross section, or in different cross sections. You may fill each one.

  Further, in the above embodiment, although the protrusion-side contact line L2 extends to each of the pair of corner portions 135A of the current collector element 135, it extends to one of the pair of corner portions 135A of the current collector element 135. It may extend and may not extend to the other. In the above embodiment, the protrusion-side contact line L2 extends so as to cover the entire corner portion 135A of the current-collector element 135. However, the protrusion-side contact line L2 corresponds to the current-collector element 135 It may extend so as to cover at least a part of the corner 135A.

  Further, in the above embodiment, an example in which the present invention is applied to a configuration in which the protruding portion of the current collecting member disposed on the air electrode side of the single cell and the air electrode are joined by the conductive bonding portion has been described. The present invention may be applied to a configuration in which the protruding portion of the current collecting member disposed on the fuel electrode side of the single cell and the fuel electrode are joined by the conductive joint.

  Further, in each of the above embodiments, the coat 136 and the bonding layer 138 are formed of spinel oxides having the same main component element, but are formed of spinel oxides having different main component elements. It is also good. In each of the above-described embodiments, the coat 136 and the bonding layer 138 are formed of spinel-type oxides including at least one of Zn, Mn, Co, and Cu, but spinel-type oxidation not including these elements It may be formed of an object. Moreover, in each said embodiment, although the coat 136 and the joining layer 138 are formed by spinel type oxide, you may be formed by other materials, such as a perovskite type oxide. Also, in the above embodiment, the current collector element 135 may not be covered by the coat 136.

  In each of the above embodiments, the electrolyte layer 112 is formed of a solid oxide, but the electrolyte layer 112 may contain another substance in addition to the solid oxide. Moreover, the material which forms each member in said each embodiment is an illustration to the last, and each member may be formed with another material. For example, in each of the above embodiments, the air electrode side current collector 134 is formed of a metal containing Cr, but the air electrode side current collector 134 is formed of another material if it is covered by the coat 136. It may be done. Further, the shape of each current collector element 135 constituting the air electrode side current collector 134 is not limited to a square pole but may be another shape as long as it protrudes from the interconnector 150 side to the air electrode 114 side. It may be.

  In each of the above embodiments, a reaction prevention layer containing ceria, for example, is provided between the electrolyte layer 112 and the air electrode 114, and the zirconium in the electrolyte layer 112 and the strontium in the air electrode 114 react with each other. An increase in the electrical resistance between the electrolyte layer 112 and the air electrode 114 may be suppressed. In each of the above embodiments, the air electrode side current collector 134 and the adjacent interconnector 150 may be separate members. Further, the fuel electrode side current collector 144 may have the same configuration as the air electrode side current collector 134, and even if the fuel electrode side current collector 144 and the adjacent interconnector 150 are an integral member. Good. Further, the fuel electrode side frame 140 instead of the air electrode side frame 130 may be an insulator. Further, the air electrode side frame 130 and the fuel electrode side frame 140 may have a multilayer structure.

  In the above embodiment, the current collector element 135 satisfies the first and second requirements for all the power generation units 102 included in the fuel cell stack 100, but at least at least the fuel cell stack 100 is included in the fuel cell stack 100. With such a configuration for one power generation unit 102, the efficiency of supply of the oxidant gas OG supplied to the air chamber 166 to the air electrode 114 is improved, and the current collector element 135 and the bonding layer are provided. The electric resistance at the contact point with 138 can be reduced.

  Further, in the above embodiment, the fuel cell stack 100 has a configuration in which a plurality of flat single cells 110 are stacked, but the present invention is described in other configurations, for example, in WO 2012/165409. Thus, the present invention is similarly applicable to a configuration in which a plurality of substantially cylindrical fuel cell single cells are connected in series.

  Further, in the above embodiment, SOFCs that generate electric power using electrochemical reaction between hydrogen contained in fuel gas and oxygen contained in oxidant gas are targeted, but the present invention relates to the electrolysis reaction of water The present invention is similarly applicable to an electrolysis cell unit which is a minimum unit of a solid oxide electrolytic cell (SOEC) that generates hydrogen by using hydrogen, and an electrolysis cell stack including a plurality of electrolysis cell units. The configuration of the electrolytic cell stack is not described in detail here because it is known as described in, for example, JP-A-2016-81813, but it is roughly the same as the fuel cell stack 100 in the embodiment described above. Configuration. That is, the fuel cell stack 100 in the embodiment described above may be read as an electrolysis cell stack, and the power generation unit 102 may be read as an electrolysis cell unit. However, during operation of the electrolytic cell stack, a voltage is applied between the two electrodes so that the air electrode 114 is positive (anode) and the fuel electrode 116 is negative (cathode), and through the through hole 108 Water vapor as a source gas is supplied. As a result, an electrolysis reaction of water occurs in each electrolysis cell unit, hydrogen gas is generated in the fuel chamber 176, and hydrogen is taken out of the electrolysis cell stack through the through holes 108. Also in the electrolytic cell unit and the electrolytic cell stack of such a configuration, as in the above embodiment, if the current collector element 135 adopts a configuration that satisfies the first and second requirements, the air chamber 166 is used. The supply efficiency of the supplied oxidant gas OG to the air electrode 114 can be improved, and the electrical resistance at the contact portion between the current collector element 135 and the bonding layer 138 can be reduced.

22: Bolt 24: Nut 100: Fuel cell stack 102: Power generation unit 104, 106: End plate 108: Through hole 110: Single cell 112: Electrolyte layer 114: Air pole 116: Fuel pole 120: Separator 121: Hole 124: Junction 124 Part 130: Air electrode side frame 131: Hole 132: Oxidant gas supply communication hole 133: Oxidant gas discharge communication hole 134: Air electrode side current collector 135, 135X, 135Y: Current collector element 135A: Corner part 136, 136X: coat 138A, 138AY: inclined portion 138, 138X, 138Y: bonding layer 140: fuel electrode side frame 141: hole 142: fuel gas supply communication hole 143: fuel gas discharge communication hole 144: fuel electrode side current collector 145: Electrode facing portion 146: Interconnector facing portion 147: ream Part 149: Spacer 150: Interconnector 161: Oxidant gas introduction manifold 162: Oxidant gas discharge manifold 166: Air chamber 171: Fuel gas introduction manifold 172: Fuel gas discharge manifold 176: Fuel chamber FG: Fuel gas FOG: Fuel off gas H, HX: Projection range L1, L1X: Electrode side contact line L2, L2X: Projection side contact line OG: oxidant gas OOG: oxidant off gas SL1: first tangent SL2: second tangent SL3: third Tangent line θ1: first inclination angle θ2: second inclination angle θ3: third inclination angle

Claims (5)

A single cell including an electrolyte layer containing a solid oxide, and an air electrode and a fuel electrode facing each other in a first direction across the electrolyte layer;
A current collecting member disposed on one of the electrode sides of the air electrode and the fuel electrode of the unit cell and having a protrusion projecting toward the one electrode;
In an electrochemical reaction unit, comprising: a conductive joint that joins the protrusion and the one electrode.
At least one cross section parallel to the first direction including the protrusion, the joint, and the one electrode;
At least one end of both ends of the electrode-side contact line in contact with the one electrode in the bonding portion is included in a projection range obtained by projecting the protrusion on the one electrode;
Among the junctions, a protrusion-side contact line in contact with the protrusion extends to a corner of the protrusion,
And the length of the said protrusion part side contact wire is longer than the length of the said electrode side contact wire, The electrochemical reaction unit characterized by the above-mentioned. In the electrochemical reaction unit according to claim 1,
In said at least one cross section,
The joint includes at least an inclined portion inclined such that a distance between the one electrode and the joint becomes shorter from the end of the projection-side contact line toward the center of the projection-side contact line. An electrochemical reaction unit characterized in that it contains in part. In the electrochemical reaction unit according to claim 1 or 2,
In said at least one cross section,
The thickness of the said junction part is characterized by becoming thick toward the center of the said protrusion part side contact line from the end of the said protrusion part side contact line, The electrochemical reaction unit characterized by the above-mentioned. The electrochemical reaction unit according to any one of claims 1 to 3
In said at least one cross section,
The junction includes an outer peripheral line located between the at least one end of the electrode-side contact line included in the projection range and the protrusion-side contact line.
A first inclination angle with respect to the one electrode of the first tangent at a first position on the outer peripheral line, and a second position between the first position on the outer peripheral line and the electrode-side contact line A second tilt angle of the second tangent with respect to the one electrode, and the one electrode of a third tangent at a third position between the first position and the second position on the outer peripheral line The magnitude relationship with the third inclination angle with respect to
An electrochemical reaction unit characterized by satisfying both the third tilt angle <the first tilt angle and the third tilt angle <the second tilt angle. In an electrochemical reaction cell stack comprising a plurality of electrochemical reaction units,
An electrochemical reaction cell stack, wherein at least one of the plurality of electrochemical reaction units is the electrochemical reaction unit according to any one of claims 1 to 4.

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