JP6773526B2 - Interconnector-electrochemical reaction single cell complex and electrochemical reaction cell stack - Google Patents

Description

The techniques disclosed herein relate to interconnector-electrochemical reaction single cell complexes.

As one of the types of fuel cells, solid oxide fuel cells (hereinafter referred to as "SOFC") are known. The interconnector-fuel cell single cell composite (hereinafter, simply referred to as “composite”) constituting the SOFC is, for example, in a predetermined direction (hereinafter, referred to as “first direction”) with the electrolyte layer and the electrolyte layer interposed therebetween. It includes a fuel cell single cell (hereinafter, simply referred to as “single cell”) including an air electrode and a fuel electrode facing each other, and an interconnector arranged in the first direction of the single cell. The complex further comprises a current collector and a spacer. The current collector is arranged between the single cell and the interconnector, and includes a cell contact portion that contacts the single cell and an interconnector contact portion that contacts the interconnector. The spacer is arranged at least one of the space between the cell contact portion and the interconnector and the space between the interconnector contact portion and the single cell.

If the surface roughness of the surface of the current collector on the spacer side is small, the spacer is likely to be misaligned with respect to the current collector, and the interconnector or electrochemical reaction single cell is caused by the misalignment of the spacer with respect to the current collector. There is a risk that the electrical connection between the current collector and the current collector cannot be maintained well. On the other hand, conventionally, in order to suppress the displacement of the spacer with respect to the current collector, there is known a technique of increasing the surface roughness of the surface of the current collector on the spacer side to a predetermined value or more (for example, Patent Document 1). reference).

International Publication No. 2014/17097

If the surface roughness of the surface of the current collector on the spacer side is large as in the conventional technique, the surface pressure between the spacer and the current collector becomes non-uniform, and as a result, a single cell or an interconnector If the surface pressure between the single cell or the like and the current collector becomes non-uniform, the electrical connection between the single cell or the like and the current collector may not be maintained well.

It should be noted that such a problem is common not only to SOFC but also to other types of fuel cells. Further, such a problem is not limited to the interconnector-fuel cell single cell composite, but the electrolytic cell, which is the minimum constituent unit of the electrolytic cell that generates hydrogen by utilizing the electrolysis reaction of water, and the interconnector. It is also a common issue for interconnector-electrolytic cell complexes with. In the present specification, the fuel cell single cell and the electrolytic cell are collectively referred to as an electrochemical reaction single cell, and the interconnector-fuel cell single cell composite and the interconnector-electrolytic cell composite are collectively referred to as an interconnector-. It is called an electrochemical reaction single cell complex.

This specification discloses a technique capable of solving the above-mentioned problems.

The technique disclosed in the present specification can be realized, for example, in the following forms.

(1) The interconnector-electrochemical reaction single cell composite disclosed in the present specification includes an electrolyte layer and electricity including an air electrode and a fuel electrode facing each other in a first direction across the electrolyte layer. With a chemical reaction single cell, an interconnector arranged in the first direction of the electrochemical reaction single cell, and a conductive current collector arranged between the electrochemical reaction single cell and the interconnector. A current collector including a cell contact portion in contact with the electrochemical reaction single cell and an interconnector contact portion in contact with the interconnector, and between the cell contact portion and the interconnector, and the inter. In an interconnector-electrochemical reaction single cell composite comprising a spacer arranged at at least one between the connector contact portion and the electrochemical reaction single cell, the surface of the current collector on the spacer side is: The maximum height, which is the maximum value of the height difference between the peaks and valleys adjacent to each other in the surface shape, including the edge side region including the edge portion of the surface and the center side region located on the center side of the surface from the edge side region. The difference is that the edge side region is larger than the central side region, and the 10-point average roughness in the central side region is each of a plurality of locations arranged in the second direction along the edge portion of the edge side region. It is smaller than the average value of the maximum height difference in the second direction view in. According to this interconnector-electrochemical reaction single cell composite, the maximum height difference (Zm), which is the maximum value of the height difference between adjacent peaks and valleys in the surface shape, is larger in the veranda region than in the central region. large. This means that the edge side region has a convex portion having a larger height difference than the central side region. Further, the 10-point average roughness (Rzjis) in the central region is smaller than the average value of the maximum height difference in the second direction at each of the plurality of locations arranged in the second direction along the edge of the veranda region. This means that the central region, which mainly functions as a conduction path, has a smoother surface than the veranda region. As a result, it is possible to prevent the electrical connection between the interconnector or the electrochemical reaction single cell and the current collector from becoming poor due to the surface roughness (concavo-convex shape) of the central region. Further, it is possible to prevent the electrical connection between the interconnector or the electrochemical reaction single cell and the current collector from becoming poor due to the displacement of the spacer with respect to the current collector due to the unevenness of the edge side region.

(2) In the interconnector-electrochemical reaction single cell composite, the difference between the maximum height difference and the 10-point average roughness in the central region may be 1 (μm) or less. According to this interconnector-electrochemical reaction single cell composite, the surface roughness of the central region is larger than that of the difference between the maximum height difference and the 10-point average roughness of 1 (μm) in the central region. It is possible to more reliably suppress the failure of the electrical connection between the interconnector or the electrochemical reaction single cell and the current collector due to the above.

(3) In the interconnector-electrochemical reaction single cell composite, the maximum height difference in the veranda region may be larger than 10 (μm). According to this interconnector-electrochemical reaction single cell composite, the interconnector and the interconnector are caused by the displacement of the spacer with respect to the current collector as compared with the case where the maximum height difference in the veranda region is 10 (μm) or less. It is possible to more reliably suppress the failure of the electrical connection between the electrochemical reaction single cell and the current collector.

(4) In the interconnector-electrochemical reaction single cell composite, the 10-point average roughness in the central region may be less than 4 (μm). According to this interconnector-electrochemical reaction single cell composite, the interconnector is caused by the surface roughness of the central region as compared with the case where the 10-point average roughness in the central region is 4 (μm) or more. And electrochemical reaction It is possible to more reliably suppress the failure of the electrical connection between the single cell and the current collector.

(5) In the interconnector-electrochemical reaction single cell composite, the spacer may include a portion of the current collector that protrudes from the surface of the current collector on the spacer side in the first directional view. According to this interconnector-electrochemical reaction single cell composite, the spacer sandwiches the spacer as compared with the case where the spacer does not include a portion protruding from the surface of the current collector on the spacer side in the first directional view. It is possible to prevent the members from coming into contact with each other (for example, the cell contact portion of the current collector and the interconnector contact portion). Furthermore, since the edge region of the current collector can be reliably contacted with the spacer, the electrical connection between the interconnector or the electrochemical reaction single cell and the current collector due to the displacement of the spacer with respect to the current collector can be established. It is possible to more reliably suppress the deterioration.

(6) In the electrochemical reaction cell stack, in the electrochemical reaction cell stack including a plurality of interconnectors-electrochemical reaction single cell composites arranged side by side in the first direction, the plurality of interconnectors-electrochemistry At least one of the reaction single-cell complexes may be configured to be the interconnector-electrochemical reaction single-cell complex according to any one of claims 1 to 5.

The techniques disclosed herein can be realized in various forms, for example, an interconnector-electrochemical reaction single cell complex (interconnector-fuel cell single cell complex or interconnector-. Electrolytic single cell complex), interconnector-electrochemical reaction electrochemical reaction unit (fuel cell power generation unit or electrolytic cell unit) having an electrochemical reaction single cell complex, multiple interconnectors-electrochemical reaction single cell or electrochemical reaction unit It can be realized in the form of an electrochemical reaction cell stack (fuel cell stack or electrolytic cell stack) provided, a method for producing them, and the like.

It is a perspective view which shows the appearance structure of the fuel cell stack 100 in 1st Embodiment. It is explanatory drawing (XZ sectional view) which shows schematic structure of the power generation unit 102. It is explanatory drawing (YZ sectional view) which shows schematic structure of the power generation unit 102. It is explanatory drawing (XY sectional view) which shows the structure of the power generation unit 102 schematicly. It is explanatory drawing (XY sectional view) which shows the structure of the power generation unit 102 schematicly. It is explanatory drawing which shows the spacer side surface 145A of the electrode facing portion 145 before being bent. It is explanatory drawing (XZ cross section) which shows the cross-sectional structure of the fuel electrode side current collector 144 at the position of VII-VII of FIG. It is explanatory drawing which shows schematic structure of the fuel cell stack 100a in the modification.

A. First Embodiment:
A-1. Constitution:
(Structure of fuel cell stack 100)
FIG. 1 is a perspective view showing an external configuration schematically showing the configuration of the fuel cell stack 100. FIG. 1 shows XYZ axes that are orthogonal to each other to specify the direction. In the present specification, for convenience, the Z-axis positive direction is referred to as an upward direction, and the Z-axis negative direction is referred to as a downward direction, but the fuel cell stack 100 is actually installed in a direction different from such an orientation. May be done. The same applies to FIGS. 2 and later. The fuel cell stack 100 corresponds to an electrochemical reaction cell stack within the claims.

The fuel cell stack 100 includes a plurality of power generation units 102 (seven in this embodiment) and a pair of end plates 104 and 106. The seven power generation units 102 are arranged side by side in a predetermined arrangement direction (vertical direction in the present embodiment). The pair of end plates 104 and 106 are arranged so as to sandwich an aggregate composed of seven power generation units 102 from above and below. The arrangement direction (vertical direction) corresponds to the first direction in the claims.

A plurality of holes (eight in this embodiment) penetrating in the vertical direction are formed on the peripheral edge of each layer (power generation unit 102, end plates 104, 106) constituting the fuel cell stack 100 in the vertical direction. , The holes formed in each layer and corresponding to each other communicate with each other in the vertical direction to form a communication hole 108 extending in the vertical direction from one end plate 104 to the other end plate 106. In the following description, the holes formed in each layer of the fuel cell stack 100 to form the communication holes 108 may also be referred to as communication holes 108. A bolt 22 extending in the vertical direction is inserted into each communication hole 108, and the fuel cell stack 100 is fastened by the bolt 22 and the nuts 24 fitted on both sides of the bolt 22.

The outer diameter of the shaft portion of each bolt 22 is smaller than the inner diameter of each communication 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 communication hole 108. Bolts 22 (bolts 22A) located near the midpoint of one side (the side on the positive side of the X-axis of the two sides parallel to the Y-axis) on the outer circumference of the fuel cell stack 100 in the Z-direction, and their The space formed by the communication hole 108 into which the bolt 22A is inserted is a gas flow path in which the oxidant gas OG is introduced from the outside of the fuel cell stack 100 and the oxidant gas OG is supplied to each power generation unit 102. Bolt 22 (bolt 22B) that functions as an oxidizer gas supply manifold 161 and is located near the midpoint of the opposite side (the side on the negative side of the X axis of the two sides parallel to the Y axis). And the space formed by the communication hole 108 into which the bolt 22B is inserted discharges the oxidant off-gas OOG, which is the gas discharged from the air chamber 166 of each power generation unit 102, to the outside of the fuel cell stack 100. It functions as an oxidant gas discharge manifold 162 (see FIG. 2). In this embodiment, for example, air is used as the oxidant gas OG.

Further, with the bolt 22 (bolt 22D) located near the midpoint of one side (the side on the positive direction side of the Y axis among the two sides parallel to the X axis) on the outer circumference of the fuel cell stack 100 around the Z direction. In the space formed by the communication hole 108 into which the bolt 22D is inserted, the fuel gas FG is introduced from the outside of the fuel cell stack 100, and the fuel gas FG is supplied to each power generation unit 102. The bolt 22 (bolt 22E) located near the midpoint of the side opposite to the side (the side on the negative side of the Y axis of the two sides parallel to the X axis) and the bolt 22E The space formed by the inserted communication holes 108 functions as a fuel gas discharge manifold 172 that discharges the fuel off-gas FOG, which is the gas discharged from the fuel chamber 176 of each power generation unit 102, to the outside of the fuel cell stack 100. To do. In the present embodiment, for example, a hydrogen-rich gas obtained by reforming city gas is used as the fuel gas FG.

(Structure of end plates 104 and 106)
The pair of end plates 104 and 106 are substantially rectangular flat plate-shaped conductive members, and are made of, for example, stainless steel. One end plate 104 is arranged above the power generation unit 102 located at the top, and the other end plate 106 is arranged below the power generation unit 102 located at the bottom. A plurality of power generation units 102 are held in a pressed state by a 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.

(Structure of power generation unit 102)
2 to 5 are explanatory views 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 position of II-II in FIGS. 1, 4 and 5, and FIG. 3 shows the position of III-III in FIGS. 1, 4 and 5. The cross-sectional configuration of the power generation unit 102 in FIG. 4 is shown, 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 VV in FIG. The cross-sectional structure of the power generation unit 102 in the above is shown. In addition, in FIG. 2 and FIG. 3, a part of the cross section is enlarged and shown.

As shown in FIGS. 2 and 3, the power generation unit 102, which is the minimum unit of power generation, includes a single cell 110, a separator 120, an air pole side frame 130, an air pole side current collector 134, and a fuel pole side frame. It includes 140, a fuel electrode side current collector 144, and a pair of interconnectors 150 that form the uppermost layer and the lowermost layer of the power generation unit 102. Holes corresponding to the communication holes 108 into which the bolts 22 described above are inserted are formed in the peripheral edges of the separator 120, the air pole side frame 130, the fuel pole side frame 140, and the interconnector 150 in the Z direction.

The interconnector 150 is a substantially rectangular flat plate-shaped 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 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 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 the fuel cell stack 100 includes a pair of end plates 104 and 106, the power generation unit 102 located at the top of the fuel cell stack 100 does not have the upper interconnector 150 and is located at the bottom. The power generation unit 102 does not include the lower interconnector 150.

The single cell 110 includes an electrolyte layer 112, an air electrode (cathode) 114 and a fuel electrode (anode) 116 facing each other in the vertical direction (arrangement direction in which the power generation units 102 are arranged) with the electrolyte layer 112 in between. The single cell 110 of the present embodiment is a fuel pole support type single cell in which the fuel pole 116 supports the electrolyte layer 112 and the air pole 114. The single cell 110 corresponds to an electrochemical reaction single cell in the claims.

The electrolyte layer 112 is a substantially rectangular flat plate-shaped member and contains at least Zr, and solid oxides such as YSZ (yttria-stabilized zirconia), ScSZ (scandia-stabilized zirconia), and CaSZ (calcia-stabilized zirconia). It is formed of objects. 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 (lanternstrontium cobalt iron oxide), LSM (lanternstrontium manganese oxide), LNF (lantern nickel iron)). Has been done. The fuel electrode 116 is a substantially rectangular flat plate-shaped member, and is formed of, for example, Ni (nickel), a cermet composed of Ni and ceramic particles, a Ni-based alloy, or the like. As described above, the single cell 110 (power generation unit 102) of the present embodiment is a solid oxide fuel cell (SOFC) that uses 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 near the center, and is made of metal, for example. The peripheral portion of the hole 121 in the separator 120 faces the peripheral edge of the surface of the electrolyte layer 112 on the side of the air electrode 114. The separator 120 is bonded to the electrolyte layer 112 (single cell 110) by a bonding portion 124 formed of a brazing material (for example, Ag wax) arranged at the opposite portion thereof. The separator 120 partitions the air chamber 166 facing the air electrode 114 and the fuel chamber 176 facing the fuel electrode 116, and a gas leak from one electrode side to the other electrode side at the peripheral edge of the single cell 110. It is suppressed. The single cell 110 to which the separator 120 is joined is also referred to as a single cell with a separator.

As shown in FIGS. 2 to 4, the air electrode side frame 130 is a frame-shaped member in which a substantially rectangular hole 131 penetrating in the vertical direction is formed near the center, and is formed of, for example, an insulator such as mica. Has been 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 edge of the surface of the separator 120 opposite to the side facing the electrolyte layer 112 and the peripheral edge 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, in the air electrode side frame 130, the oxidant gas supply communication hole 132 that communicates the oxidant gas supply manifold 161 and the air chamber 166, and the oxidant gas that communicates the air chamber 166 and the oxidant gas discharge manifold 162. A discharge communication hole 133 is formed.

As shown in FIGS. 2, 3 and 5, the fuel electrode side frame 140 is a frame-shaped member in which a substantially rectangular hole 141 penetrating in the vertical direction is formed near the center, and is formed of, for example, metal. ing. 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 edge of the surface of the separator 120 facing the electrolyte layer 112 and the peripheral edge of the surface of the interconnector 150 facing the fuel electrode 116. Further, in the fuel electrode side frame 140, a fuel gas supply communication hole 142 that communicates the fuel gas supply manifold 171 and the fuel chamber 176, and a fuel gas discharge communication hole 143 that communicates the fuel chamber 176 and 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 arranged in the fuel chamber 176. The fuel electrode side current collector 144 includes an interconnector facing portion 146, an electrode facing portion 145, and a connecting portion 147 connecting the electrode facing portion 145 and the interconnector facing portion 146. For example, nickel or nickel alloy. , Stainless steel, etc. Specifically, the fuel electrode side current collector 144 is manufactured by making a notch in a substantially rectangular flat plate-shaped member and processing the plurality of substantially rectangular portions so as to bend them up. The bent substantially rectangular portion becomes the electrode facing portion 145, the flat plate portion in a perforated state other than the bent portion becomes the interconnector facing portion 146, and the portion connecting the electrode facing portion 145 and the interconnector facing portion 146 becomes. It becomes the connecting portion 147. In addition, in the partially enlarged view in FIG. 5, in order to show the manufacturing method of the fuel electrode side current collector 144, the state before the bending raising process of a part of a plurality of square portions is completed is shown. The electrode facing portion 145 is in contact with the surface of the fuel pole 116 opposite to the side facing the electrolyte layer 112, and the interconnector facing portion 146 is on the surface of the interconnector 150 facing the fuel pole 116. Are in contact. However, as described above, since the power generation unit 102 located at the bottom of 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. It is in contact with 106. Since the fuel pole side current collector 144 has such a configuration, the fuel pole 116 and the interconnector 150 (or the end plate 106) are electrically connected to each other. A spacer 149 formed of, for example, mica is arranged between the electrode facing portion 145 and the interconnector facing portion 146. As described above, the spacer 149 preferably has elasticity. As a result, the fuel electrode side current collector 144 follows the deformation of the power generation unit 102 due to the temperature cycle and the reaction gas pressure fluctuation, and the fuel electrode 116 and the interconnector 150 (or the end plate 106) via the fuel electrode side current collector 144 follow. ) Is well maintained. The spacer 149 may have an insulating property. The fuel electrode side current collector 144 corresponds to the current collector in the claims, the electrode facing portion 145 corresponds to the cell contact portion in the claims, and the interconnector facing portion 146 corresponds to the claims. Corresponds to the interconnector contact part in.

As shown in FIGS. 2 to 4, the air electrode side current collector 134 is arranged in the air chamber 166. The air electrode side current collector 134 is composed of a plurality of substantially square columnar current collector elements 135, and is formed of, for example, 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 on the side facing the air electrode 114. However, as described above, since the power generation unit 102 located at the top of 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 has an upper end plate. It is in contact with 104. Since the air electrode side current collector 134 has such a configuration, the air electrode 114 and the interconnector 150 (or the end plate 104) are electrically connected. The air electrode side current collector 134 and the interconnector 150 may be formed as an integral member. The configuration including the single cell 110, the fuel pole side frame 140, the fuel pole side current collector 144, and the interconnector 150 (interconnector 150 in contact with the fuel pole side current collector 144) is an interconnector-electrochemical reaction unit. It corresponds to a cell complex (so-called cassette).

A-2. Power generation operation in the fuel cell stack 100:
As shown in FIG. 2, when the oxidant gas OG is supplied to the oxidant gas supply manifold 161, the oxidant gas OG passes the oxidant gas supply communication hole 132 of each power generation unit 102 from the oxidant gas supply manifold 161. After that, it is supplied to the air chamber 166. Further, as shown in FIG. 3, when the fuel gas FG is supplied to the fuel gas supply manifold 171, the fuel gas FG passes through the fuel gas supply communication hole 142 of each power generation unit 102 from the fuel gas supply manifold 171 and fuels. It is supplied to room 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, power is generated by the electrochemical reaction of the oxidant gas OG and the fuel gas FG in the single cell 110. Will be. In each power generation unit 102, the air pole 114 of the single cell 110 is electrically connected to one of the interconnectors 150 via the air pole side current collector 134, and the fuel pole 116 is via the fuel pole side current collector 144. It is electrically connected to the other interconnector 150. Further, the plurality of power generation units 102 included in the fuel cell stack 100 are connected in series. Therefore, the electric energy generated in each power generation unit 102 is taken out from the end plates 104 and 106 that function as the output terminals of the fuel cell stack 100. Since the SOFC generates electricity at a relatively high temperature (for example, 700 to 1000 degrees Celsius), the fuel cell stack 100 is a heater until the high temperature can be maintained by the heat generated by the power generation after the start-up. May be heated by.

As shown in FIG. 2, the oxidant off-gas OOG discharged from the air chamber 166 of each power generation unit 102 passes through the oxidizer gas discharge communication hole 133 and the oxidizer gas discharge manifold 162 from the air chamber 166, and the fuel cell stack 100 It is discharged to the outside of. Further, as shown in FIG. 3, the fuel off-gas OFG discharged from the fuel chamber 176 of each power generation unit 102 is discharged to the outside of the fuel cell stack 100 through the fuel gas discharge communication hole 143 and the fuel gas discharge manifold 172. To.

A-3. Surface shape of current collector 144 on the fuel electrode side:
As described above, the fuel electrode side current collector 144 is manufactured by making a notch in a flat plate-shaped member and processing a plurality of substantially rectangular portions so as to bend them, and the bent substantially rectangular portions are electrodes. It becomes the facing portion 145 (see the partially enlarged view of FIG. 5). Among the electrode facing portions 145, the surface shape of the surface facing the spacer 149 (hereinafter referred to as “spacer side surface 145A”) is as follows. The spacer-side surface 145A corresponds to the spacer-side surface of the current collector within the scope of the claims.

FIG. 6 is an explanatory view showing the spacer side surface 145A of the electrode facing portion 145 (substantially rectangular portion) before being bent, and FIG. 7 is a fuel pole side current collector 144 at the position of VII-VII in FIG. It is explanatory drawing which shows the cross-sectional structure (XZ cross-section) of. Hereinafter, as shown in FIG. 6, of the spacer-side surface 145A of the electrode facing portion 145, the surface region extending along the three sides cut by the cut is referred to as “edge-side region E2”, and is referred to from the edge-side region E2. The rectangular surface region located on the center side of the spacer side surface 145A is referred to as "center side region E1". The width D of the veranda region E2 (dimensions in the direction orthogonal to each of the above sides) is preferably 0.2 (mm) or less, for example.

Regarding the surface shape (surface state) of the central region E1 and the edge region E2 on the spacer side surface 145A, both the following first condition and the second condition are satisfied.
<First condition>
Maximum height difference Zm (2) in the veranda region E2> Maximum height difference Zm (1) in the central region E1
The maximum height difference Zm is the maximum value of the height difference between peaks and valleys adjacent to each other in the surface shape. The definition of the height difference between adjacent peaks and valleys (element height Zt of the curve) shall be in accordance with JIS B 0601 2013. The maximum height difference Zm (2) of the veranda region E2 is the maximum height difference Zm in the entire veranda region E2, and the maximum height difference Zm (1) of the central region E1 is the maximum height difference Zm in the entire central region E1. is there.

<Second condition>
10-point average roughness Rzjis in the central region E1 <Average value of the maximum height difference Zm in the edge region E2 The definition of the 10-point average roughness Rzjis shall be based on JIS B 0601 2013, for example, the reference length. Is the sum of the average from the maximum peak height to the fifth of the contour curve and the average from the deepest valley depth to the fifth.
The average value of the maximum height difference Zm in the veranda region E2 is the average value of the maximum height difference Zm in the longitudinal direction at each of the plurality of locations arranged in the longitudinal direction of the veranda region E2.

Specifically, in the present embodiment, as shown in FIG. 6, for example, in a linear region along one side (a side parallel to the Y-axis direction) in the edge side region E2, the one side The measurement points are 10 points k (k1 to k10) arranged at predetermined intervals in the direction along the Y-axis direction (hereinafter referred to as “measurement point arrangement direction”). The length of the linear region in the longitudinal direction is preferably the same as the reference length in the above-mentioned 10-point average roughness Rzjis. Then, at each measurement point k, the maximum height difference Zm in the measurement point arrangement direction view is specified. Here, the lower right partially enlarged view of FIG. 2 is an explanatory view showing a cross-sectional configuration of the fuel electrode side current collector 144 at the position II-II of FIG. 5, and is shown in the lower right partially enlarged view of FIG. Shows the surface shape of the spacer-side surface 145A in the measurement point alignment direction view for one measurement point k. To briefly explain using the partially enlarged view at the lower right of FIG. 2, the element height Zt of the contour curve having three peaks exists in the veranda region E2, and the element height Zt of the peak located in the center exists. However, the maximum height difference is Zm (Zm (2)). Then, the maximum height difference Zm of each of the 10 measurement points k is obtained, and the average value of the maximum height difference Zm of the obtained 10 measurement points k is calculated to obtain the maximum height difference Zm in the veranda region E2. The average value can be specified. The reference numeral Zm (1) in the partially enlarged view means the maximum height difference of the central region E1. Further, the measurement point arrangement direction corresponds to the second direction in the claims.

An example of a method for forming the spacer side surface 145A into a surface shape that satisfies both the first condition and the second condition is as follows. That is, a notch is made in the above-mentioned flat plate-shaped member by using laser processing or blade (pressing) processing. As a result, burrs are generated in the vicinity of the notch in the flat plate-shaped member (see FIGS. 2, 3 and 7), so that the spacer-side surface 145A satisfies both the first condition and the second condition. The surface shape meets the requirements. The maximum height difference Zm (1) and the 10-point average roughness Rzjis of the central region E1 can be adjusted by surface processing of the flat plate-shaped member described above. The maximum height difference Zm (2) and the average value of the maximum height difference Zm in the veranda region E2 are the laser output in laser machining, the width and irradiation time of the laser beam, and the angle (escape) of the blade with respect to the flat plate-shaped member in blade machining. It can be adjusted by changing the angle).

An example of each value under the first condition and the second condition is as follows.
Maximum height difference Zm (1): 7.9 (μm) of the central region E1
10-point average roughness Rzjis in the central region E1: 8.4 (μm)
Maximum height difference Zm (2) of veranda region E2: 20.6 (μm)
Mean value of maximum height difference Zm in veranda region E2: 23.44 (μm)
(Maximum height difference Zm at each measurement point: 20.6 (μm), 16.52 (μm), 25.61 (μm), 32.72 (μm), 26.25 (μm), 18.82 (μm) ), 32.09 (μm), 21.1 (μm), 25.39 (μm), 15.28 (μm))
As described above, the difference between the maximum height difference Zm (1) in the central region E1 and the 10-point average roughness Rzjis in the central region E1 is preferably 1 (μm) or less. Further, the maximum height difference Zm (2) of the veranda region E2 is preferably larger than 10 (μm). The surface shape of the entire surface of the electrode facing portion 145 facing the fuel electrode 116 (hereinafter referred to as "electrode side surface 145B") is about the same as the central region E1 of the spacer side surface 145A, and is on the spacer side. It is assumed that both the first condition and the second condition are satisfied with the edge region E2 of the surface 145A.

Further, as shown in FIGS. 2, 5 and 7, in the present embodiment, the spacer 149 is the spacer side surface of the electrode facing portion 145 of the fuel electrode side current collector 144 in the vertical direction (Z-axis direction). The portion 149A protruding from 145A is included. In the present embodiment, the spacer 149 constitutes the electrode facing portion 145 and protrudes from the three sides having the edge side region E2.

A-4. Effect of this embodiment:
When the spacer 149 is displaced with respect to the fuel pole side current collector 144, the followability of the fuel pole side current collector 144 to the deformation of the power generation unit 102 due to the temperature cycle or the like described above is lowered, so that the fuel pole side current collector is collected. The electrical connection between the fuel pole 116 and the interconnector 150 (or end plate 106) via the body 144 may not be well maintained. On the other hand, if there is a convex portion having a relatively large height difference on the spacer side surface 145A of the electrode facing portion 145, the convex portion is caught by the spacer 149, so that the spacer 149 with respect to the fuel electrode side current collector 144 is present. Positional deviation can be suppressed.

However, due to the presence of this convex portion, on the contrary, the electrical connection between the fuel pole 116 and the interconnector 150 (or the end plate 106) via the fuel pole side current collector 144 may not be maintained well. That is, the electrode side surface 145B of the electrode facing portion 145 is in contact with the fuel electrode 116, and the central region of the electrode side surface 145B is mainly used as a conductive path between the fuel electrode 116 and the interconnector 150. Function. Therefore, when the surface pressure between the central region of the electrode side surface 145B and the fuel electrode 116 is non-uniform, the electrical connection between the fuel electrode 116 and the interconnector 150 becomes unstable. On the other hand, the central region E1 of the spacer-side surface 145A in the electrode facing portion 145 is located on the opposite side (directly behind) to the central region of the electrode-side surface 145B. Therefore, if a convex portion exists in the central side region E1 of the spacer side surface 145A, the electrode side surface 145B of the electrode facing portion 145 tilts with respect to the lower surface of the fuel electrode 116, so that the electrode side surface 145B becomes the central side region. The surface pressure with the fuel electrode 116 becomes non-uniform. As a result, the electrical connection between the fuel pole 116 and the interconnector 150 (or the end plate 106) via the fuel pole side current collector 144 may not be maintained well.

On the other hand, according to the present embodiment, the maximum height difference Zm (2) of the edge side region E2 is the maximum of the central side region E1 with respect to the spacer side surface 145A of the electrode facing portion 145 in the fuel electrode side current collector 144. The height difference is larger than Zm (1). This means that the veranda region E2 has a convex portion having a larger height difference than the central region E1. As a result, as shown in FIGS. 2, 3 and 7, the convex portion having a large height difference existing in the veranda region E2 is caught on the end face of the spacer 149 or bites into the surface of the spacer 149, thereby causing the spacer 149. The displacement of the fuel electrode side with respect to the current collector 144 is suppressed.

Further, the 10-point average roughness Rzjis in the central region E1 is smaller than the average value of the maximum height difference Zm in the veranda region E2. This means that the surface of the central region E1 that mainly functions as a conduction path is smoother than that of the edge region E2. As a result, the electrical connection between the interconnector 150 or the single cell 110 and the fuel electrode side current collector 144 becomes poor due to the surface roughness (concavo-convex shape) of the central region E1, and the fuel electrode side collection. It is possible to suppress both the poor electrical connection between the interconnector 150 or the single cell 110 and the fuel electrode side current collector 144 due to the misalignment of the spacer 149 with respect to the electric body 144.

Further, the difference between the maximum height difference Zm (1) in the central region E1 and the 10-point average roughness Rzjis in the central region E1 is 1 (μm) or less. As a result, in the central region E1, the degree of unevenness of the central region E1 is smaller than that in the case where the difference between the maximum height difference Zm and the 10-point average roughness Rzjis is larger than 1 (μm). It is possible to more reliably suppress the electrical connection between the interconnector 150 or the single cell 110 and the fuel electrode side current collector 144 due to the surface roughness of the region E1.

Further, the maximum height difference Zm (2) of the veranda region E2 is larger than 10 (μm). As a result, the force for locking the spacer 149 by the convex portion existing in the veranda region E2 becomes larger than that in the case where the maximum height difference Zm (2) of the veranda region E2 is 10 (μm) or less. Therefore, it is more certain that the electrical connection between the interconnector 150 or the single cell 110 and the fuel electrode side current collector 144 becomes poor due to the misalignment of the spacer 149 with respect to the fuel electrode side current collector 144. Can be suppressed.

Further, the spacer 149 includes a portion 149A protruding from the spacer side surface 145A of the electrode facing portion 145 of the fuel electrode side current collector 144 in the vertical direction (Z-axis direction). As a result, it is possible to prevent the electrode facing portion 145 sandwiching the spacer 149 from coming into contact with the interconnector facing portion 146, as compared with the case where the spacer 149 does not include the protruding portion 149A. Further, since the convex portion existing in the edge side region E2 bites into the surface of the spacer 149, the misalignment of the spacer 149 with respect to the fuel electrode side current collector 144 can be more reliably suppressed.

B. Second embodiment:
The central region E1 of the spacer-side surface 145A in the second embodiment is flatter than the central region E1 of the spacer-side surface 145A in the first embodiment. Since the other points have the same configuration as the first embodiment described above, the description thereof will be omitted.

Specifically, it is as follows.
Maximum height difference Zm (1) of central region E1: 2.88 (μm)
10-point average roughness Rzjis in the central region E1: 2.80 (μm)
As described above, the 10-point average roughness Rzjis in the central region E1 is less than 4 (μm). As a result, compared to the case where the 10-point average roughness Rzjis in the central region E1 is 4 (μm) or more, the interconnector 150 or the single cell 110 and the fuel electrode side are due to the surface roughness of the central region E1. It is possible to more reliably suppress the failure of the electrical connection with the current collector 144.

C. Modification example:
The technique disclosed in the present specification is not limited to the above-described embodiment, and can be transformed into various forms without departing from the gist thereof. For example, the following modifications are also possible.

In the above embodiment, an example in which the present invention is applied to the spacer side surface 145A of the fuel electrode side current collector 144 has been described, but the present invention is not limited thereto. For example, the present invention may be applied to the surface of the current collector 144 on the fuel electrode side on the spacer 149 side of the interconnector facing portion 146. Further, the air electrode side current collector 134 includes a cell contact portion in contact with the power generation unit 102 and an interconnector contact portion in contact with the interconnector 150, and an interconnector between the cell contact portion and the interconnector. When the spacer is provided on at least one of the connector contact portion and the electrochemical reaction single cell, the present invention may be applied to the spacer-side surface of the air electrode side current collector 134.

In the above embodiment, the spacer 149 arranged between the electrode facing portion 145 and the interconnector facing portion 146 has been illustrated, but the spacer is not limited thereto. For example, as described in Japanese Patent Application Laid-Open No. 2014-26843, a spacer arranged between the cell contact portion and the interconnector, or a spacer arranged between the interconnector contact portion and the single cell may be used. In short, the spacer may be arranged at least one of the cell contact portion and the interconnector and the interconnector contact portion and the electrochemical reaction single cell. In other words, the spacer is placed either between the cell contact part and the interconnector contact part, between the cell contact part and the interconnector, or between the interconnector contact part and the electrochemical reaction single cell. It should be.

In the above embodiment, the difference between the maximum height difference Zm (1) in the central region E1 and the 10-point average roughness Rzjis in the central region E1 may be larger than 1 (μm). Further, the maximum height difference Zm (2) of the veranda region E2 may be 10 (μm) or less. Further, the 10-point average roughness Rzjis in the central region E1 may be 4 (μm) or more.

In the above embodiment, the protruding portion 149A of the spacer 149 protrudes from the spacer side surface 145A over the entire three sides constituting the electrode facing portion 145 of the fuel electrode side current collector 144 in the vertical direction, but only a part thereof. It may be a configuration that protrudes. Further, the spacer 149 does not have to include the protruding portion 149A.

Further, in the above embodiment, the configuration of the fuel cell stack 100 includes a plurality of flat plate-shaped single cells 110, but the present invention is described in another configuration, for example, International Publication No. 2012/1655409. As described above, the same applies to a fuel cell stack 100a including a plurality of substantially cylindrical single cells 110a. FIG. 8 is an explanatory diagram schematically showing the configuration of the fuel cell stack 100a in the modified example. The fuel cell stack 100a in the modified example shown in FIG. 8 includes a plurality of power generation units 102a arranged side by side at predetermined intervals in the Z direction. The plurality of power generation units 102a are electrically connected in series via a current collector 870 arranged between adjacent power generation units 102a. Each power generation unit 102a has a flat column-shaped appearance, and includes an electrode support 830, a single cell 110a, and an interconnector 810. The single cell 110a includes a fuel electrode 840, an electrolyte layer 850, an air electrode 860, and a reaction prevention layer 900. The Z direction in the modified example shown in FIG. 8 corresponds to the first direction in the claims.

The electrode support 830 is a columnar body having a substantially elliptical cross section, and is made of a porous material. Inside the electrode support 830, a plurality of fuel gas flow paths 820 extending in the extending direction of the columnar body are formed. The fuel electrode 840 is provided so as to cover one of a pair of flat surfaces parallel to each other and two curved surfaces connecting the ends of the flat surfaces on the side surface of the electrode support 830. The electrolyte layer 850 is provided so as to cover the side surface of the fuel electrode 840. The air electrode 860 is provided so as to cover a portion of the side surface of the electrolyte layer 850 that is located on the flat surface of the electrode support 830. However, the reaction prevention layer 900 is arranged between the electrolyte layer 850 and the air electrode 860. The interconnector 810 is provided on the flat surface of the electrode support 830 on the side where the fuel electrode 840 and the electrolyte layer 850 are not provided. The current collector 870 electrically connects the air electrode 860 of the power generation unit 102a and the interconnector 810 of the power generation unit 102a adjacent to the power generation unit 102a. When the oxidant gas is supplied to the outside of the air electrode 860, the fuel gas is supplied to the fuel gas flow path 820 formed in the electrode support 830, and the fuel gas is heated to a predetermined operating temperature, power is generated in the fuel cell stack 100a. Will be done.

Further, in the fuel cell stack 100a, a spacer 910 is arranged between a portion of the current collector 870 that contacts the air electrode 860 and a portion that contacts the interconnector 810. In the fuel cell stack 100a having such a configuration, the surface roughness of the central region and the current collector are obtained by applying the present invention to the surface of the current collector 870 on the spacer 910 side as in the above embodiment. It is possible to prevent the electrical connection between the interconnector 810 and the like and the current collector 870 from becoming poor due to the displacement of the spacer with respect to the above.

Further, in the above embodiment, the SOFC that generates power by utilizing the electrochemical reaction between hydrogen contained in the fuel gas and oxygen contained in the oxidizing agent gas is targeted, but the present invention comprises an electrolysis reaction of water. It is also applicable to an electrolytic cell unit, which is the smallest unit of a solid oxide fuel cell (SOEC) that uses it to generate hydrogen, and an electrolytic cell stack having a plurality of electrolytic cell units. The configuration of the electrolytic cell stack is not described in detail here because it is known, for example, as described in Japanese Patent Application Laid-Open No. 2016-81813, but is generally the same as the fuel cell stack 100 in the above-described embodiment. It is the composition of. That is, the fuel cell stack 100 in the above-described embodiment may be read as an electrolytic cell stack, and the power generation unit 102 may be read as an electrolytic cell unit. However, during the operation of the electrolytic cell stack, a voltage is applied between both electrodes so that the air electrode 114 is positive (anode) and the fuel electrode 116 is negative (cathode), and the voltage is applied through the communication hole 108. Water vapor as a raw material gas is supplied. As a result, an electrolysis reaction of water occurs in each electrolytic cell unit, hydrogen gas is generated in the fuel chamber 176, and hydrogen is taken out to the outside of the electrolytic cell stack through the communication hole 108. In the electrolytic cell unit and the electrolytic cell stack having such a configuration, the surface roughness of the central region is roughened by applying the present invention to the air pole side current collector or the fuel pole side current collector as in the above embodiment. It is possible to prevent the electrical connection between the electrochemical reaction single cell or the like and the current collector from becoming poor due to the displacement of the spacer with respect to the current collector.

Further, in the above embodiment, the electrolyte layer 112 is said to be formed of a solid oxide, but the electrolyte layer 112 may contain other substances in addition to the solid oxide. Further, the material forming each member in the above embodiment is merely an example, and each member may be formed of another material. Further, the shape of each current collector element 135 constituting the air pole side current collector 134 is not limited to a square columnar shape, and any other shape may be used as long as it protrudes from the interconnector 150 side to the air pole 114 side. There may be.

Further, in the above embodiment, a reaction prevention layer containing, for example, ceria is provided between the electrolyte layer 112 and the air electrode 114, and zirconium or the like in the electrolyte layer 112 reacts with strontium or the like in the air electrode 114. The increase in electrical resistance between the electrolyte layer 112 and the air electrode 114 may be suppressed. Further, in the above embodiment, the air electrode side current collector 134 and the adjacent interconnector 150 may be separate members. Further, the fuel pole side current collector 144 may have the same configuration as the air pole side current collector 134, and even if the fuel pole side current collector 144 and the adjacent interconnector 150 are integrated members. Good. Further, the fuel pole side frame 140 may be an insulator instead of the air pole side frame 130. Further, the air pole side frame 130 and the fuel pole side frame 140 may have a multi-layer structure.

Further, in the above embodiment, the end plates 104 and 106 function as output terminals, but instead of the end plates 104 and 106, the conductors arranged between each of the end plates 104 and 106 and the power generation unit 102. The board may function as an output terminal. Further, in the above embodiment, the space between the outer peripheral surface of the shaft portion of each bolt 22 and the inner peripheral surface of each communication hole 108 is used as each manifold, but instead of this, the shaft is used for each bolt 22. A hole in the direction may be provided and the hole may be used as each manifold, or each manifold may be provided separately from each communication hole 108 through which each bolt 22 is inserted.

22: Bolt 24: Nut 100,100a: Fuel cell stack 102,102a: Power generation unit 104,106: End plate 108: Communication hole 110,110a: Single cell 112,850: Electrolyte layer 114,860: Air electrode 116,840 : Fuel pole 120: Separator 121: Hole 124: Joint 130: Air pole side frame 131: Hole 132: Oxidizing agent gas supply communication hole 133: Oxidizing agent gas discharge communication hole 134: Air pole side current collector 135: Current collector Body element 140: Fuel pole side frame 141: Hole 142: Fuel gas supply communication hole 143: Fuel gas discharge communication hole 144: Fuel pole side current collector 145: Electrode facing part 145A: Spacer side surface 145B: Electrode side surface 146: Interconnector facing part 147: Connecting part 149,910: Spacer 149A: Overhanging part 150,810: Interconnector 161: Oxidizing agent gas supply manifold 162: Oxidizing agent gas discharge manifold 166: Air chamber 171: Fuel gas supply manifold 172: Fuel Gas discharge manifold 176: Fuel chamber 820: Fuel gas flow path 830: Electrode support 870: Current collector 900: Reaction prevention layer D: Width E1: Central area E2: Edge area FG: Fuel gas FOG: Fuel off gas OFG: Fuel off gas OG: Oxidating agent gas OOG: Oxidating agent off gas

Claims (7)

An electrochemical reaction single cell containing an electrolyte layer and an air electrode and a fuel electrode facing each other in a first direction across the electrolyte layer.
With the interconnector arranged in the first direction of the electrochemical reaction single cell,
A conductive current collector arranged between the electrochemical reaction single cell and the interconnector, the cell contact portion in contact with the electrochemical reaction single cell and the interconnector contact in contact with the interconnector. A current collector including a portion, a connecting portion connecting the cell contact portion and the interconnector contact portion, and the like.
Spacers arranged between the cell contact portion and the interconnector contact portion, between the cell contact portion and the interconnector, or between the interconnector contact portion and the electrochemical reaction single cell. in the electrochemical reaction unit cells complexes, - wherein the first interconnector that have been space formed to permit the displacement of the spacer in the direction perpendicular to the direction
Among the current collector, the surface in contact in the said spacer first direction, includes a edge region including an edge of the surface, and a center-side region located closer to the center than the edge region and the surface ,
The maximum height difference, which is the maximum value of the height difference between the peaks and valleys adjacent to each other in the surface shape, is larger in the veranda region than in the central region.
And,
The 10-point average roughness in the central region is smaller than the average value of the maximum height difference in the second direction at each of a plurality of locations arranged in the second direction along the edge of the veranda region. An interconnector-electrochemical reaction single cell complex characterized by. In the interconnector-electrochemical reaction single cell composite according to claim 1.
The connecting portion has a shape that connects one ends of the cell contact portion and the interconnector contact portion.
An interconnector-electrochemical reaction single cell composite, characterized in that the spacer is arranged between the cell contact portion and the interconnector contact portion. In the interconnector-electrochemical reaction single cell complex according to claim 1 or 2 .
An interconnector-electrochemical reaction single cell composite, characterized in that the difference between the maximum height difference and the 10-point average roughness in the central region is 1 (μm) or less. In the interconnector-electrochemical reaction single cell composite according to any one of claims 1 to 3 .
An interconnector-electrochemical reaction single cell complex, characterized in that the maximum height difference in the veranda region is greater than 10 (μm). In the interconnector-electrochemical reaction single cell composite according to any one of claims 1 to 4 .
An interconnector-electrochemical reaction single cell complex characterized in that the 10-point average roughness in the central region is less than 4 (μm). In the interconnector-electrochemical reaction single cell composite according to any one of claims 1 to 5 .
The spacer is an interconnector-electrochemical reaction single cell composite, which comprises a portion of the current collector that protrudes from the surface of the current collector on the spacer side in the first direction. In an electrochemical reaction cell stack comprising a plurality of interconnector-electrochemical reaction single cell complexes arranged side by side in the first direction.
The interconnector-electrochemical reaction single cell complex according to any one of claims 1 to 6 , wherein at least one of the plurality of interconnector-electrochemical reaction single cell complexes is characterized. Electrochemical reaction cell stack.

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