JP6797150B2 - Method for manufacturing electrochemical reaction unit, electrochemical reaction cell stack, and electrochemical reaction unit - Google Patents

Description

The techniques disclosed herein relate to electrochemical reaction units.

A solid oxide fuel cell (hereinafter referred to as "SOFC") is known as one of the fuel cells that generate electricity by utilizing an electrochemical reaction between hydrogen and oxygen. The fuel cell power generation unit (hereinafter referred to as "power generation unit"), which is a constituent unit of SOFC, includes a fuel cell single cell (hereinafter referred to as "single cell"), an interconnector, a conductive current collector, and a mica. With spacers. The single cell includes an electrolyte layer and an air electrode and a fuel electrode that face each other in a predetermined direction (hereinafter, referred to as “first direction”) with the electrolyte layer in between. The interconnector is arranged on the specific electrode side, which is at least one of the air electrode and the fuel electrode of the single cell. The current collector is arranged between the specific electrode and the interconnector. Further, the current collector includes a cell contact portion that contacts the surface of the specific electrode. At least a part of the spacer is arranged between the cell contact portion and the interconnector.

Japanese Patent No. 5346402

Since the spacer made of mica contains Si (silicon), in the above-mentioned conventional configuration, Si may be scattered from the spacer, and the performance of the single cell may be deteriorated due to poisoning by the scattered Si. .. Here, if the Si content of the entire surface of the spacer is uniformly lowered in order to suppress the amount of Si scattered from the spacer, the elastic force of the entire spacer is reduced, and as a result, the cell contact portion and the cell contact portion are formed. There is a risk that the contact pressure between the specific electrodes cannot be secured.

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

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

(1) The electrochemical reaction unit disclosed in the present specification includes an electrochemical reaction single cell including an electrolyte layer and an air electrode and a fuel electrode facing each other in a first direction across the electrolyte layer, and the electricity. An interconnector arranged on the specific electrode side of at least one of the air electrode and the fuel electrode of the chemical reaction single cell, and a conductive current collector arranged between the specific electrode and the interconnector. Electrochemistry comprising a current collector including a cell contact portion that contacts the surface of the specific electrode, and a mica spacer that is at least partially disposed between the cell contact portion and the interconnector. In the reaction unit, the spacer is an overlapping portion arranged at a position overlapping the cell contact portion in the first directional view, and the first surface on the cell contact portion side contacts the cell contact portion. The overlapping portion and the non-overlapping portion arranged at a position different from the cell contact portion in the first direction view, and at least in the gas chamber where the second surface on the specific electrode side faces the specific electrode. The content of Si on the first surface of the overlapping portion including the exposed non-overlapping portion is 18 wt% or more, and the content of Si on the second surface of the non-overlapping portion is included. The amount is less than the content of Si on the first surface of the overlapping portion.

In this electrochemical reaction unit, the spacer is arranged at a position different from the cell contact portion in the first direction view and the overlapping portion arranged at a position overlapping the cell contact portion of the current collector in the first direction view. It contains non-overlapping parts. The first surface of the overlapping portion on the cell contact portion side is in contact with the cell contact portion and is not exposed to the gas chamber facing the specific electrode. On the other hand, the second surface on the specific electrode side in the non-overlapping portion is exposed to the gas chamber. Therefore, Si (silicon) contained in the spacer is more likely to scatter from the second surface of the non-overlapping portion than the first surface of the overlapping portion. Therefore, in the present electrochemical reaction unit, the content of Si on the second surface of the non-overlapping portion is smaller than the content of Si on the first surface of the overlapping portion. As a result, the amount of Si scattered from the spacer can be suppressed as compared with the configuration in which the Si content on the second surface is the same as the Si content on the first surface. The content of Si on the first surface of the overlapping portion is 18 wt% or more. As a result, it is possible to suppress a shortage of contact pressure between the cell contact portion and the specific electrode due to a decrease in the elastic force of the spacer, as compared with the configuration in which the Si content on the first surface is less than 18 wt%. That is, according to the present electrochemical reaction unit, it is possible to suppress both the amount of Si scattered from the spacer and the decrease in the elastic force of the spacer.

(2) In the electrochemical reaction unit, the content of Si on the surface of the specific electrode may be 0.04 wt% or less. According to this electrochemical reaction unit, even if Si scattered from the spacer adheres to the surface of the specific electrode, the content of Si on the surface of the specific electrode is higher than 0.04 wt% from the beginning, as compared with the configuration of the specific electrode. Poisoning by Si in the reaction field of the above can be suppressed.

(3) In the electrochemical reaction cell stack, a plurality of electrochemical reaction units arranged side by side in the first direction are provided, and at least one of the plurality of electrochemical reaction units is the above (1) or (2). ) May be the electrochemical reaction unit. According to the present electrochemical reaction cell stack, it is possible to suppress both the amount of Si scattered from the spacer and the decrease in the elastic force of the spacer.

(4) The method for producing an electrochemical reaction unit disclosed in the present specification includes an electrochemical reaction single cell including an electrolyte layer and an air electrode and a fuel electrode facing each other in a first direction with the electrolyte layer interposed therebetween. , An interconnector arranged on the specific electrode side of at least one of the air electrode and the fuel electrode of the electrochemical reaction single cell, and a collection of conductivity arranged between the specific electrode and the interconnector. An electric body, a current collector including a cell contact portion that contacts the surface of the specific electrode, and a spacer made of mica, which is at least partially arranged between the cell contact portion and the interconnector. In the method for producing an electrochemical reaction unit, the spacer is an overlapping portion arranged at a position overlapping the cell contact portion in the first directional view, and the first surface on the cell contact portion side is said. The overlapping portion in contact with the cell contact portion and the non-overlapping portion arranged at a position different from the cell contact portion in the first direction view, and at least the second surface on the specific electrode side is the specific electrode. The content of Si on the first surface of the overlapping portion is 18 wt% or more, and the second portion of the non-overlapping portion includes a non-overlapping portion exposed to a gas chamber facing the surface. The step of forming the spacer in which the content of Si on the surface of the overlapped portion is smaller than the content of Si on the first surface of the overlapping portion, the electrochemical reaction single cell, the interconnector, and the above. The step of assembling the electrochemical reaction unit by using the current collector and the spacer satisfying the above conditions is included. According to the method for producing the present electrochemical reaction unit, it is possible to produce an electrochemical reaction unit in which both the suppression of the amount of Si scattered from the spacer and the suppression of the decrease in the elastic force of the spacer are achieved.

(5) In the method for producing an electrochemical reaction unit, the heat treatment is further arranged so that the cell contact portion of the current collector comes into contact with the surface of a part of the spacer before the heat treatment that does not satisfy the above conditions. The spacer may be formed by including a step of preparing a composite of the previous spacer and the current collector and subjecting the composite to a heat treatment to satisfy the above conditions. According to the method for producing the present electrochemical reaction unit, an electrochemical reaction unit in which the amount of Si scattered from the spacer and the decrease in the elastic force of the spacer are both suppressed is produced by a relatively simple method. be able to.

The technique disclosed in the present specification can be realized in various forms, for example, an electrochemical reaction unit (fuel cell power generation unit or electrolytic cell unit), and electricity having a plurality of electrochemical reaction units. It can be realized in the form of a chemical reaction cell stack (fuel cell stack or electrolytic cell stack), 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 this embodiment. It is explanatory drawing which shows the XZ cross-sectional structure of the fuel cell stack 100 at the position of II-II of FIG. It is explanatory drawing which shows the YZ cross-sectional structure of the fuel cell stack 100 at the position of III-III of FIG. It is explanatory drawing which shows the XZ cross section configuration of two power generation units 102 adjacent to each other at the same position as the cross section shown in FIG. It is explanatory drawing which shows the YZ cross section configuration of two power generation units 102 adjacent to each other at the same position as the cross section shown in FIG. It is explanatory drawing which shows the XY cross-sectional structure of the power generation unit 102 at the position of VI-VI of FIG. 4 and FIG. It is explanatory drawing which shows the XY cross-sectional structure of the power generation unit 102 at the position of VII-VII of FIG. 4 and FIG. It is a flowchart which shows the manufacturing method of the fuel cell stack 100. It is explanatory drawing which shows the performance evaluation result.

A. Embodiment:
A-1. Device configuration:
(Structure of fuel cell stack 100)
FIG. 1 is a perspective view showing an external configuration of the fuel cell stack 100 in the present embodiment, and FIG. 2 is an explanatory view showing an XZ cross-sectional configuration of the fuel cell stack 100 at the position II-II of FIG. FIG. 3 is an explanatory view showing a YZ cross-sectional configuration of the fuel cell stack 100 at the position III-III of FIG. Each figure shows XYZ axes that are orthogonal to each other to identify 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 in a direction different from such an orientation. It may be installed. The same applies to FIGS. 4 and later.

The fuel cell stack 100 includes a plurality of (seven in this embodiment) fuel cell power generation units (hereinafter, simply referred to as “power generation units”) 102, 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. As shown in FIGS. 2 and 3, between the nut 24 fitted on one side (upper side) of the bolt 22 and the upper surface of the end plate 104 forming the upper end of the fuel cell stack 100, and the bolt. An insulating sheet 26 is interposed between the nut 24 fitted on the other side (lower side) of the 22 and the lower surface of the end plate 106 forming the lower end of the fuel cell stack 100. However, in the place where the gas passage member 27 described later is provided, the insulating sheets arranged on the upper side and the lower side of the gas passage member 27 and the gas passage member 27 between the nut 24 and the surface of the end plate 106, respectively. 26 is intervening. The insulating sheet 26 is made of, for example, a mica sheet, a ceramic fiber sheet, a ceramic dust sheet, a glass sheet, a glass-ceramic composite agent, or the like.

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. As shown in FIGS. 1 and 2, the position is near the midpoint of one side (the side on the positive side of the X axis among the two sides parallel to the Y axis) on the outer circumference of the fuel cell stack 100 around the Z direction. In the space formed by the bolt 22 (bolt 22A) and the communication hole 108 through which the bolt 22A is inserted, the oxidant gas OG is introduced from the outside of the fuel cell stack 100, and the oxidant gas OG is generated for each power generation. It functions as an oxidizer gas introduction manifold 161 that is a gas flow path supplied to the unit 102, and is the midpoint of the side opposite to the side (the side on the negative direction of the X axis of the two sides parallel to the Y axis). The space formed by the bolt 22 (bolt 22B) located in the vicinity and the communication hole 108 through which the bolt 22B is inserted provides the oxidizer off-gas OOG, which is the gas discharged from the air chamber 166 of each power generation unit 102. It functions as an oxidant gas discharge manifold 162 that discharges to the outside of the fuel cell stack 100. In this embodiment, for example, air is used as the oxidant gas OG.

Further, as shown in FIGS. 1 and 3, the vicinity of the midpoint of one side (the side on the positive 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. A fuel gas FG is introduced from the outside of the fuel cell stack 100 into the space formed by the bolt 22 (bolt 22D) located in the above and the communication hole 108 through which the bolt 22D is inserted, and the fuel gas FG is generated by each power generation. A bolt 22 that functions as a fuel gas introduction manifold 171 to be supplied to the unit 102 and is 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). The space formed by (bolt 22E) and the communication hole 108 through which the bolt 22E is inserted sends 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. It functions as a fuel gas discharge manifold 172 to be discharged. In the present embodiment, for example, a hydrogen-rich gas obtained by reforming city gas is used as the fuel gas FG.

The fuel cell stack 100 is provided with four gas passage members 27. Each gas passage member 27 has a hollow tubular main body 28 and a hollow tubular branch 29 branched from the side surface of the main body 28. The hole of the branch portion 29 communicates with the hole of the main body portion 28. A gas pipe (not shown) is connected to the branch portion 29 of each gas passage member 27. Further, as shown in FIG. 2, the hole of the main body 28 of the gas passage member 27 arranged at the position of the bolt 22A forming the oxidant gas introduction manifold 161 communicates with the oxidant gas introduction manifold 161. The hole of the main body 28 of the gas passage member 27 arranged at the position of the bolt 22B forming the oxidant gas discharge manifold 162 communicates with the oxidant gas discharge manifold 162. Further, as shown in FIG. 3, the hole of the main body 28 of the gas passage member 27 arranged at the position of the bolt 22D forming the fuel gas introduction manifold 171 communicates with the fuel gas introduction manifold 171 and fuel gas. The hole of the main body 28 of the gas passage member 27 arranged at the position of the bolt 22E forming the discharge manifold 172 communicates with the fuel gas discharge manifold 172.

(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)
FIG. 4 is an explanatory view showing an XZ cross-sectional configuration of two power generation units 102 adjacent to each other at the same position as the cross section shown in FIG. 2, and FIG. 5 is an explanatory view showing an XZ cross-sectional configuration at the same position as the cross section shown in FIG. It is explanatory drawing which shows the YZ cross-sectional structure of two power generation units 102. Further, FIG. 6 is an explanatory view showing an XY cross-sectional configuration of the power generation unit 102 at the position of VI-VI of FIGS. 4 and 5, and FIG. 7 is a power generation unit at the position of VII-VII of FIGS. 4 and 5. It is explanatory drawing which shows the XY cross-sectional structure of 102.

As shown in FIGS. 4 and 5, the power generation unit 102 includes a single cell 110, a separator 120, an air pole side frame 130, an air pole side current collector 134, a fuel pole side frame 140, and a fuel pole side. It includes a 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 through which the above-mentioned bolts 22 are inserted are formed on 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 (see FIGS. 2 and 3).

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 electrolyte layer 112 is a flat plate-shaped member that is substantially rectangular in the Z direction, and is a dense layer (with a low porosity). The electrolyte layer 112 is formed of, for example, a solid oxide such as YSZ (yttria-stabilized zirconia), ScSZ (scandia-stabilized zirconia), SDC (samarium-doped ceria), GDC (gadolinium-doped ceria), and perovskite-type oxide. There is. The air electrode 114 is a substantially rectangular flat plate-shaped member smaller than the electrolyte layer 112 in the Z direction, and is a porous layer (having a higher porosity than the electrolyte layer 112). The air electrode 114 is formed of, for example, a perovskite-type oxide (for example, LSCF (lanternstrontium cobalt iron oxide), LSM (lanternstrontium manganese oxide), LNF (lantern nickel iron)). The fuel electrode 116 is a substantially rectangular flat plate-shaped member having substantially the same size as the electrolyte layer 112 in the Z direction, and is a porous layer (having a higher porosity than the electrolyte layer 112). The fuel electrode 116 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.

As shown in FIG. 6, 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. .. 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 introduction 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 FIG. 7, 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. 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 introduction 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.

The air pole 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. In this embodiment, the air electrode side current collector 134 and the interconnector 150 are formed as an integral member. That is, the flat plate-shaped portion of the integral member that is orthogonal to the vertical direction (Z-axis direction) functions as the interconnector 150, and is formed so as to project from the flat plate-shaped portion toward the air electrode 114. The current collector element 135, which is a plurality of convex portions, functions as the air electrode side current collector 134. Further, the integral member of the air electrode side current collector 134 and the interconnector 150 may be covered with a conductive coat, and both are placed between the air electrode 114 and the air electrode side current collector 134. A conductive bonding layer to be bonded may be interposed.

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. 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 is arranged 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 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. Good electrical connection with is maintained. The material for forming the spacer 149 and the like will be described later.

A-2. Operation of fuel cell stack 100:
As shown in FIGS. 2, 4 and 6, the oxidant gas is passed through a gas pipe (not shown) connected to a branch portion 29 of the gas passage member 27 provided at the position of the oxidant gas introduction manifold 161. When the OG is supplied, the oxidant gas OG is supplied to the oxidant gas introduction manifold 161 through the holes of the branch portion 29 and the main body portion 28 of the gas passage member 27, and each power generation unit is supplied from the oxidizer gas introduction manifold 161. It is supplied to the air chamber 166 through the oxidizer gas supply communication hole 132 of 102. Further, as shown in FIGS. 3, 5 and 7, the fuel gas is passed through a gas pipe (not shown) connected to the branch portion 29 of the gas passage member 27 provided at the position of the fuel gas introduction manifold 171. When the FG is supplied, the fuel gas FG is supplied to the fuel gas introduction manifold 171 through the holes of the branch portion 29 and the main body portion 28 of the gas passage member 27, and the fuel of each power generation unit 102 is supplied from the fuel gas introduction manifold 171. It is supplied to the fuel chamber 176 via the gas supply communication hole 142.

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, oxygen contained in the oxidant gas OG and hydrogen contained in the fuel gas FG in the single cell 110 are supplied. Power is generated by the electrochemical reaction with. This power generation reaction is an exothermic reaction. 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 electrically 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 ° C. to 1000 ° C.), the fuel cell stack 100 is a heater (for example, until the high temperature can be maintained by the heat generated by the power generation after the start-up. (Not shown) may be heated.

The oxidant off-gas OOG discharged from the air chamber 166 of each power generation unit 102 is discharged to the oxidant gas discharge manifold 162 through the oxidant gas discharge communication hole 133 as shown in FIGS. 2, 4 and 6. Further, the fuel is passed through the holes of the main body 28 and the branch 29 of the gas passage member 27 provided at the position of the oxidant gas discharge manifold 162, and through the gas pipe (not shown) connected to the branch 29. It is discharged to the outside of the battery stack 100. Further, the fuel off-gas FOG discharged from the fuel chamber 176 of each power generation unit 102 is discharged to the fuel gas discharge manifold 172 through the fuel gas discharge communication hole 143 as shown in FIGS. 3, 5 and 7. Further, the fuel cell stack 100 is passed through the holes of the main body 28 and the branch 29 of the gas passage member 27 provided at the position of the fuel gas discharge manifold 172, and through a gas pipe (not shown) connected to the branch 29. It is discharged to the outside of.

A-3. Materials for forming the spacer 149, etc., and the arrangement relationship between the spacer 149 and the air electrode side current collector 134:
As described above, the fuel electrode side current collector 144 is arranged in the fuel chamber 176. Specifically, as shown in FIGS. 4 and 5, the fuel pole side current collector 144 is arranged between the fuel pole 116 and the interconnector 150. Further, the fuel electrode side current collector 144 includes an electrode facing portion 145 that contacts the surface (upper surface) of the fuel electrode 116. At least a part of the spacer 149 is arranged between the electrode facing portion 145 and the interconnector 150 constituting the fuel chamber 176 in which the electrode facing portion 145 is arranged. Specifically, as shown in FIGS. 5 and 7, the spacer 149 includes an overlapping portion 210 and a non-overlapping portion 220. The overlapping portion 210 is a portion of the spacer 149 arranged at a position overlapping the electrode facing portion 145 in the vertical direction (Z-axis direction). The surface of the overlapping portion 210 on the electrode facing portion 145 side (hereinafter referred to as “first surface 212” below the upper surface) is in contact with the lower surface of the electrode facing portion 145. In other words, the first surface 212 of the overlapping portion 210 is covered by the electrode facing portion 145 and is not exposed to the fuel chamber 176. The non-overlapping portion 220 is a portion of the spacer 149 arranged at a position different from that of the electrode facing portion 145 in the vertical view. The surface of the non-overlapping portion 220 on the fuel electrode 116 side (hereinafter referred to as “second surface 222” below the upper surface) is not covered with other members and is exposed to the fuel chamber 176. In the present embodiment, the spacer 149 has a shape along the arrangement direction of the plurality of electrode facing portions 145 (in the present embodiment, the Y-axis direction) as a whole, and the overlapping portion 210 and the non-overlapping portion 220 are the same. They are arranged so as to be arranged alternately along the arrangement direction. The fuel pole 116 corresponds to a specific electrode in the claims, the fuel pole side current collector 144 corresponds to the current collector in the claims, and the electrode facing portion 145 corresponds to the cell contact in the claims. Corresponds to the department. Further, the fuel chamber 176 corresponds to a gas chamber within the scope of the claims.

Further, each power generation unit 102 satisfies the following first condition with respect to the Si content in the spacer 149.
<First condition>
"The content of Si on the first surface 212 of the overlapping portion 210 of the spacer 149 is 18 wt% or more.
Moreover, the content of Si on the second surface 222 of the non-overlapping portion 220 is smaller than the content of Si on the first surface 212 of the overlapping portion 210. "
The difference between the Si content on the second surface 222 of the non-overlapping portion 220 and the Si content on the first surface 212 of the overlapping portion 210 is preferably 5 wt% or more.
The first surface 212 of the overlapping portion 210 corresponds to the first surface in the claims, and the second surface 222 of the non-overlapping portion 220 corresponds to the second surface in the claims.

Further, it is preferable that each power generation unit 102 satisfies the following second condition with respect to the Si content in the fuel electrode 116.
<Second condition>
"In the fuel electrode 116, the Si content on the surface (lower surface) opposite to the electrolyte layer 112 is 0.04 wt% or less."

A-4. Manufacturing method of fuel cell stack 100:
Next, a method of manufacturing the fuel cell stack 100 will be described. FIG. 8 is a flowchart showing a method of manufacturing the fuel cell stack 100. First, spacers 149 satisfying the first condition are formed (S110 to S130). Specifically, a spacer precursor that does not satisfy the first condition is prepared (S110). The spacer precursor is a spacer 149 that is formed by heat treatment, and is, for example, soft mica before the debinder treatment. The Si content on the entire surface of this spacer precursor is 18 wt% or more. In order to secure the elastic force of the entire spacer 149, the Si content inside the spacer precursor is preferably 18 wt% or more.

Next, a composite of the spacer precursor and the fuel electrode side current collector 144 is formed (S120). Specifically, the spacer precursor is arranged on the fuel electrode side current collector 144 in the same manner as the spacer 149 described above. That is, the spacer precursor is a fuel electrode side current collector so that a portion that overlaps the electrode facing portion 145 and a portion that does not overlap the electrode facing portion 145 are formed on the spacer precursor in the vertical direction (Z-axis direction). They are arranged at 144 and integrated to form a complex. In the composite, it is preferable that the electrode facing portion 145 of the fuel electrode side current collector 144 is pressure-welded to the portion of the spacer precursor that overlaps with the electrode facing portion 145. The spacer precursor corresponds to the spacer before heat treatment in the claims.

Next, before assembling the power generation unit 102 and the fuel cell stack 100, the composite of the spacer precursor and the fuel electrode side current collector 144 is heat-treated (S130). The temperature of the heat treatment can be 700 ° C. or higher. The heat treatment time can be 100 hours or more. Further, the heat treatment can be performed in a reducing atmosphere in order to prevent oxidation of the fuel electrode side current collector 144. Further, the composite may be heat-treated with the pressing force applied to the fuel electrode side current collector 144 so that the pressing force from the electrode facing portion 145 to the spacer precursor is, for example, 0.1 MPa or more. it can. By heat treatment, the spacer precursor is debindered. At this time, since the portion of the spacer precursor that overlaps with the electrode facing portion 145 is covered with the electrode facing portion 145, Si contained in the spacer precursor is unlikely to scatter, and after the heat treatment, the overlapping portion 210 of the spacer 149 It becomes. On the other hand, of the spacer precursor, the portion that does not overlap with the electrode facing portion 145 is not covered by the electrode facing portion 145 and is open, so Si contained in the spacer precursor is likely to scatter, and after the heat treatment, the spacer is used. It becomes the non-overlapping portion 220 of 149. As a result, the spacer 149 satisfying the first condition is formed.

Next, the power generation unit 102 is produced by a known method (S140). At this time, as described above, the fuel electrode side current collector 144 on which the heat-treated spacer 149 formed in S130 is arranged is arranged between the fuel electrode 116 and the interconnector 150 in the single cell 110. Finally, a plurality of the produced power generation units 102 are arranged side by side in a predetermined arrangement direction (vertical direction), and each member is assembled to produce a fuel cell stack 100 (S150). Through the above steps, the production of the fuel cell stack 100 having the above-described configuration is completed.

A-5. Effect of this embodiment:
As described above, the spacer 149 has an overlapping portion 210 arranged at a position overlapping the electrode facing portion 145 of the fuel electrode side current collector 144 and the electrode facing portion 145 in the vertical direction (Z-axis direction). Includes non-overlapping portions 220, which are located at different positions. The first surface 212 on the electrode facing portion 145 side of the overlapping portion 210 is in contact with the electrode facing portion 145 and is not exposed to the fuel chamber 176 facing the fuel pole 116. On the other hand, the second surface 222 on the fuel pole 116 side of the non-overlapping portion 220 is exposed to the fuel chamber 176. Therefore, Si (silicon) contained in the spacer is more likely to scatter from the second surface 222 of the non-overlapping portion 220 than the first surface 212 of the overlapping portion 210. Therefore, in the power generation unit 102 of the present embodiment, the content of Si on the second surface 222 of the non-overlapping portion 220 is smaller than the content of Si on the first surface 212 of the overlapping portion 210 (the first condition above). Part of). As a result, the Si content on the second surface 222 of the non-overlapping portion 220 is the same as the Si content on the first surface 212 of the overlapping portion 210, as compared with the configuration in which the Si content is scattered from the spacer 149. The amount can be suppressed. Further, the content of Si on the first surface 212 of the overlapping portion 210 is 18 wt% or more (a part of the above first condition). As a result, compared to the configuration in which the Si content on the first surface 212 of the overlapping portion 210 is less than 18 wt%, the space between the electrode facing portion 145 and the fuel electrode 116 due to the decrease in the elastic force of the spacer 149 Insufficient contact pressure can be suppressed. That is, according to the power generation unit 102 of the present embodiment, it is possible to suppress both the amount of Si scattered from the spacer 149 and the decrease in the elastic force of the spacer 149.

Further, in the present embodiment, the Si content on the surface (lower surface) of the fuel electrode 116 opposite to the electrolyte layer 112 is preferably 0.04 wt% or less (second condition). If the second condition is satisfied, even if the Si scattered from the spacer 149 adheres to the surface of the fuel electrode 116, the Si content on the surface of the fuel electrode 116 is higher than 0.04 wt% from the beginning, as compared with the configuration. Poisoning by Si in the reaction field of the fuel electrode 116 can be suppressed.

Further, according to the method for manufacturing the fuel cell stack 100 in the present embodiment, the first condition is satisfied by performing heat treatment by integrating the spacer precursor that does not satisfy the first condition with the fuel electrode side current collector 144. The filling spacer 149 is formed (S110 to S130 in FIG. 8). Thereby, by a relatively simple method, it is possible to manufacture the power generation unit 102 (fuel cell stack 100) in which both the suppression of the amount of Si scattered from the spacer 149 and the suppression of the decrease in the elastic force of the spacer are achieved. ..

A-6. Performance evaluation:
The performance evaluation performed on the spacer (spacer 149) arranged on the fuel electrode side current collector 144 described above will be described below. FIG. 9 is an explanatory diagram showing the performance evaluation result. The Si content (wt%) of each surface in each sample can be measured by XRF analysis (X-Ray Fluorescence Analysis Analysis).

(For each sample)
As shown in FIG. 9, in this performance evaluation, seven samples 1 to 7 were used for the spacer. In the seven samples 1 to 7, at least one of the Si content on the first surface 212 of the overlapping portion 210 and the Si content on the second surface 222 of the non-overlapping portion 220 is different from each other. Samples 1 to 3 were prepared by performing a heat treatment by integrating the spacer precursor with the fuel electrode side current collector 144 in the same manner as in the above-mentioned production method. In each of the manufacturing processes of Samples 1 to 3, the heat treatment temperature of the composite of the spacer precursor and the fuel electrode side current collector 144 was about 850 ° C., and 40% water vapor and 60% hydrogen. The heat treatment was performed in the reducing atmosphere of. However, in the manufacturing processes of Samples 1 to 3, the heat treatment times are different from each other. Specifically, in sample 1, the heat treatment time was 1000 hours, in sample 2, the heat treatment time was 700 hours, and in sample 3, the heat treatment time was 300 hours. As a result, in Samples 1 to 3, the Si content on the first surface 212 of the overlapping portion 210 was the same (18 wt%) as each other, but the Si content on the second surface 222 of the non-overlapping portion 220. The amounts are different from each other. Specifically, the longer the heat treatment time, the lower the Si content of the non-overlapping portion 220 on the second surface 222.

Samples 4 to 6 were prepared by independently heat-treating the spacer precursor, which was different from the above-mentioned production method, before being integrated with the fuel electrode side current collector 144. In each of the manufacturing steps of Samples 4 to 6, the spacer precursor alone was heat-treated at 850 ° C. in a reducing atmosphere of 40% water vapor and 60% hydrogen. However, in the manufacturing steps of Samples 4 to 6, the heat treatment times are different from each other. Specifically, in sample 4, the heat treatment time was 1000 hours, in sample 5, the heat treatment time was 700 hours, and in sample 6, the heat treatment time was 300 hours. As a result, in Samples 4 to 6, both the Si content on the first surface 212 of the overlapping portion 210 and the Si content on the second surface 222 of the non-overlapping portion 220 decreased (less than 18 wt%). And the same amount. Further, in Samples 4 to 6, the longer the heat treatment time was, the smaller the Si content on the first surface 212 of the overlapping portion 210 and the Si content on the second surface 222 of the non-overlapping portion 220. .. Similar to Samples 4 to 6, Sample 7 was prepared by independently heat-treating the spacer precursor before integrating it with the fuel electrode side current collector 144. However, in the manufacturing process of sample 7, the spacer precursor alone was heat-treated at a heat treatment temperature of about 700 ° C. and in a reducing atmosphere of 100% hydrogen. Further, in sample 7, the heat treatment time was 3 hours. As a result, in Sample 7, since the heat treatment time is relatively short, the Si content on the first surface 212 of the overlapping portion 210 and the Si content on the second surface 222 of the non-overlapping portion 220 are different. There was almost no decrease in either case.

(About evaluation items and evaluation methods)
In this performance evaluation, two items, a spacer elastic modulus test and a Si scattering test, were evaluated. In the elastic modulus test of the spacer, the elastic modulus (GPa) of each sample was measured using a known measuring machine (for example, ultra-micro hardness tester HM2000 manufactured by Fisher Instruments Co., Ltd.). When the power generation unit 102 is manufactured using each sample, it is judged as acceptable (○) when the elastic modulus is higher than 1.9 GPa in order to secure the contact point between the fuel electrode side current collector 144 and the fuel electrode 116. When it was 1.9 GPa or less, it was judged as a failure (x).

Further, in the Si scattering test, each sample was arranged in the fuel electrode side current collector 144 in the power generation unit 102, the air chamber 166 was made into an air atmosphere, and the fuel chamber 176 was made into a reducing atmosphere of 40% water vapor and 60% hydrogen, and 850. The power generation unit 102 was generated at ° C. for 1000 hours. In addition, according to D-SIMS analysis (Dynamic-Specterry Ion Mass Spectrometry Analysis), the amount of Si poisoning (ppm) in the portion of the fuel electrode 116 on the side of the electrolyte layer 112 was increased before and after the test (hereinafter, "Si scattering increase amount"). ") Was asked. When the amount of increase in Si scattering was less than 900 ppm, it was determined to be acceptable (◯), and when the amount of increase in Si scattering was 900 ppm or more, it was determined to be rejected (x). In this Si scattering test, the amount of Si poisoning in the portion of the fuel electrode 116 on the side of the electrolyte layer 112 was measured in ppm by D-SIMS analysis.

(Evaluation results)
In the elastic modulus test of the spacer, samples 1 to 3 and 7 were judged to be acceptable (◯) because the elastic modulus was higher than 1.9 GPa. In Samples 1 to 3 and 7, since the Si content on the first surface 212 of the spacer overlapping portion 210 is 18 wt% or more, it is considered that the elastic modulus of the spacer overlapping portion 210 is relatively high. On the other hand, in Samples 4 to 6, since the elastic modulus was 1.9 GPa or less, it was determined to be rejected (x). In Samples 4 to 6, it is considered that the elastic modulus of the overlapping portion 210 of the spacer was relatively low because the content of Si on the first surface 212 of the overlapping portion 210 of the spacer was less than 18 wt%. That is, if the Si content on the first surface 212 of the overlapping portion 210 of the spacer is 18 wt% or more, the contact pressure between the electrode facing portion 145 and the fuel electrode 116 due to the decrease in the elastic force of the spacer is insufficient. It was confirmed that it can suppress.

Further, in the Si scattering test, in Samples 1 to 6, the amount of increase in Si scattering was less than 900 ppm, so that it was judged to be acceptable (◯). In Samples 1 to 6, since the content of Si on the second surface 222 of the non-overlapping portion 220 of the spacer is smaller than the content of Si on the first surface 212 of the overlapping portion 210, the amount of increase in Si scattering from the spacer It is probable that it was possible to suppress. On the other hand, in sample 7, since the amount of increase in Si scattering was 900 ppm or more, it was determined to be unacceptable (x). In sample 7, the Si content on the second surface 222 of the non-overlapping portion 220 of the spacer is the same as the Si content on the first surface 212 of the overlapping portion 210, so that the amount of increase in Si scattering from the spacer It is probable that it could not be suppressed. That is, if the Si content on the second surface 222 of the non-overlapping portion 220 of the spacer is smaller than the Si content on the first surface 212 of the overlapping portion 210, the amount of Si scattered from the spacer can be suppressed. confirmed. Further, from the evaluation results of Samples 1 to 6, the larger the difference between the Si content on the second surface 222 of the non-overlapping portion 220 of the spacer and the Si content on the first surface 212 of the overlapping portion 210, the greater the difference. It can be seen that the amount of increase in Si scattering can be reduced. The amount of increase in Si scattering is more preferably 700 ppm or less.

From the results of the performance evaluation described above, if the spacer satisfies the first condition, it was determined to pass (◯) in both the elastic modulus test and the Si scattering test of the spacer. This means that if the spacer satisfies the first condition, it is possible to suppress both the amount of Si scattered from the spacer and the decrease in the elastic force of the spacer.

B. 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.

The configuration of the fuel cell stack 100 in the above embodiment is merely an example and can be variously modified. For example, in the above embodiment, at least one of the plurality of power generation units 102 may not have the fuel pole 116 satisfying the second condition. Further, in the above embodiment, the Si content on the surface other than the first surface 212 of the spacer 149 (for example, the side surface along the vertical direction of the spacer 149) is the content of Si on the first surface 212 of the overlapping portion 210. It may be the same as the amount, but it is preferably less than the Si content in the first surface 212 of the overlapping portion 210.

Further, in the above embodiment, the spacer 149 is sandwiched between the electrode facing portion 145 of the air electrode 114 and the interconnector facing portion 146, but the spacer 149 is sandwiched between the electrode facing portion 145 and the interconnector 150. For example, there may be a space between the spacer 149 and the interconnector 150. Further, in the above embodiment, the current collector such as the fuel electrode side current collector 144 may be, for example, a mesh or the like.

Further, in the above embodiment, the present invention is applied to the fuel pole side current collector 144 and the spacer 149 arranged between the fuel pole 116 and the interconnector 150, but the air pole 114 and the air pole 114 face each other. The present invention may be applied to the spacer as long as the current collector including the cell contact portion and the spacer are arranged between the interconnector 150 constituting the air chamber 166. This is because even on the air chamber 166 side, the performance of the single cell 110 may deteriorate due to poisoning by Si. In this case, the air electrode 114 corresponds to the specific electrode in the claims, the air electrode side current collector corresponds to the current collector in the claims, and the air chamber 166 corresponds to the gas in the claims. Corresponds to a room.

The method for manufacturing the fuel cell stack 100 in the above embodiment is merely an example and can be variously modified. For example, in the step of forming the spacer 149 satisfying the first condition, the spacer precursor is heat-treated by masking, for example, the overlapping portion 210 before being integrated with the fuel electrode side current collector 144. As a result, the spacer 149 satisfying the first condition may be formed, and then the spacer 149 may be arranged on the fuel electrode side current collector 144 and integrated.

Further, in the present specification, the fact that the member B and the member C face each other with the member (or a portion having the member, the same applies hereinafter) A sandwiched is limited to the form in which the member A and the member B or the member C are adjacent to each other. However, it includes a form in which another component is interposed between the member A and the member B or the member C. For example, another layer may be provided between the electrolyte layer 112 and the air electrode 114. Even with such a configuration, it can be said that the air electrode 114 and the fuel electrode 116 face each other with the electrolyte layer 112 interposed therebetween.

Further, in the above embodiment, the fuel cell stack 100 has a configuration in which a plurality of flat plate-shaped power generation units 102 are stacked, but the present invention is described in another configuration, for example, International Publication No. 2012/1655409. As described above, the same applies to a configuration in which a plurality of substantially cylindrical fuel cell single cells are connected in series.

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 a constituent 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, the power generation unit 102 may be read as an electrolytic cell unit, and the single cell 110 may be read as an electrolytic single cell. 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. Even in the electrolytic cell unit having such a configuration, if the spacer 149 having the above configuration is adopted, it is possible to achieve both suppression of the amount of Si scattered from the spacer 149 and suppression of a decrease in the elastic force of the spacer 149. it can.

Further, in the above embodiment, the solid oxide fuel cell (SOFC) has been described as an example, but the present invention also applies to other types of fuel cells (or electrolytic cells) such as the molten carbonate fuel cell (MCFC). Applicable.

22: Bolt 24: Nut 26: Insulation sheet 27: Gas passage member 28: Main body 29: Branch 100: Fuel cell stack 102: Power generation unit 104, 106: End plate 108: Communication hole 110: Single cell 112: Electrolyte layer 114: Air pole 116: 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 collection Body 135: Collector 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 146: Interconnector facing part 147 : Connecting part 149: Spacer 150: Interconnector 161: Oxidizing agent gas introduction manifold 162: Oxidizing agent gas discharge manifold 166: Air chamber 171: Fuel gas introduction manifold 172: Fuel gas discharge manifold 176: Fuel chamber 210: Overlapping part 212: First surface 220: Non-overlapping part 222: Second surface FG: Fuel gas FOG: Fuel off gas OG: Oxidating agent gas OOG: Oxidating agent off gas

Claims (5)

An electrochemical reaction single cell including an electrolyte layer and an air electrode and a fuel electrode facing each other in a first direction across the electrolyte layer, and at least one of the air electrode and the fuel electrode of the electrochemical reaction single cell. An interconnector arranged on the specific electrode side, and a conductive current collector arranged between the specific electrode and the interconnector, including a cell contact portion that contacts the surface of the specific electrode. In an electrochemical reaction unit comprising a current collector and a spacer made of mica, which is at least partially disposed between the cell contact and the interconnector.
The spacer is
An overlapping portion arranged at a position overlapping the cell contact portion in the first directional view, and an overlapping portion in which the first surface on the cell contact portion side contacts the cell contact portion.
A non-overlapping portion arranged at a position different from the cell contact portion in the first directional view, and at least the second surface on the specific electrode side is exposed to the gas chamber facing the specific electrode. Including non-overlapping parts,
The content of Si on the first surface of the overlapping portion is 18 wt% or more.
Moreover, the content of Si on the second surface of the non-overlapping portion is smaller than the content of Si on the first surface of the overlapping portion.
An electrochemical reaction unit characterized by that. In the electrochemical reaction unit according to claim 1, further
The content of Si on the surface of the specific electrode is 0.04 wt% or less.
An electrochemical reaction unit characterized by that. In an electrochemical reaction cell stack having a plurality of electrochemical reaction units arranged side by side in the first direction.
An electrochemical reaction cell stack, wherein at least one of the plurality of electrochemical reaction units is the electrochemical reaction unit according to claim 1 or 2. An electrochemical reaction single cell including an electrolyte layer and an air electrode and a fuel electrode facing each other in a first direction across the electrolyte layer, and at least one of the air electrode and the fuel electrode of the electrochemical reaction single cell. An interconnector arranged on the specific electrode side, and a conductive current collector arranged between the specific electrode and the interconnector, including a cell contact portion that contacts the surface of the specific electrode. In a method for producing an electrochemical reaction unit comprising a current collector and a spacer made of mica, which is at least partially arranged between the cell contact portion and the interconnector.
The spacer is
An overlapping portion arranged at a position overlapping the cell contact portion in the first directional view, and an overlapping portion in which the first surface on the cell contact portion side contacts the cell contact portion.
A non-overlapping portion arranged at a position different from the cell contact portion in the first directional view, and at least the second surface on the specific electrode side is exposed to the gas chamber facing the specific electrode. Including non-overlapping parts,
The Si content of the overlapping portion on the first surface is 18 wt% or more, and the Si content of the non-overlapping portion on the second surface is the first surface of the overlapping portion. The step of forming the spacer satisfying the condition of less than the Si content in
A step of assembling the electrochemical reaction unit using the electrochemical reaction single cell, the interconnector, the current collector, and the spacer satisfying the above conditions.
including,
A method for producing an electrochemical reaction unit. In the method for producing an electrochemical reaction unit according to claim 4, further
A composite of the spacer before heat treatment and the current collector is prepared so that the cell contact portion of the current collector comes into contact with a part of the surface of the spacer before heat treatment that does not satisfy the above conditions. Including the process
By heat-treating the composite, the spacer satisfying the above conditions is formed.
A method for producing an electrochemical reaction unit.

Images