JP6873944B2 - Electrochemical reaction cell stack - Google Patents

Description

The techniques disclosed herein relate to electrochemical reaction cell stacks.

A solid oxide fuel cell (hereinafter referred to as "SOFC") having an electrolyte layer containing a solid oxide is known as one of the types of fuel cells that generate electricity by utilizing an electrochemical reaction between hydrogen and oxygen. Has been done. A fuel cell single cell (hereinafter, simply referred to as “single cell”), which is a constituent unit of SOFC, has an electrolyte layer and air that faces each other in a predetermined direction (hereinafter, referred to as “first direction”) across the electrolyte layer. Includes poles and fuel poles.

SOFCs are generally used in the form of a fuel cell stack comprising a plurality of single cells arranged side by side in a first direction, a plurality of conductive members, and a fastening member. The plurality of conductive members are respectively arranged on both sides of the plurality of single cells in the first direction and between the single cells. Further, the plurality of conductive members are formed with through holes penetrating in the first direction. The fastening member extends in the first direction and is inserted into through holes formed in a plurality of conductive members, and the fuel cell stack is fastened by the fastening member.

Japanese Unexamined Patent Publication No. 2016-22508

In a conventional fuel cell stack in which a fastening member is inserted into a through hole of a conductive member, for example, when a high voltage is generated, the fastening member is originally electrically connected to the fastening member among a plurality of conductive members. A discharge occurs between the inner wall of the through hole formed in the non-connecting conductive member (for example, the conductive member arranged between single cells) and the fastening member, which should not be used, and the non-connecting conductive member and the fastening member. May be short-circuited. If the non-connecting conductive member and the fastening member are short-circuited, the performance of the fuel cell stack deteriorates (for example, the output decreases).

In addition, such a problem is electrolysis including a plurality of electrolytic single cells which are constituent units of solid oxide type electrolytic cells (hereinafter, also referred to as “SOEC”) that generate hydrogen by utilizing the electrolysis reaction of water. This is a common issue for cell stacks. In this specification, the fuel cell stack and the electrolytic cell stack are collectively referred to as an electrochemical reaction cell stack. Further, such a problem is common not only to SOFC and SOEC but also to other types of electrochemical reaction cell stacks.

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

The techniques disclosed herein can be realized in the following forms.

(1) The electrochemical reaction cell stack disclosed in the present specification includes a plurality of single cells each including an electrolyte layer, an air electrode, and a fuel electrode, arranged side by side in the first direction, and the first direction. A plurality of conductive members arranged on both sides of the plurality of single cells and between the single cells, wherein through holes are formed through the plurality of conductive members in the first direction. A conductive member of the above, and a fastening member extending in the first direction and inserted into the through holes formed in the plurality of conductive members, and an electrochemical reaction fastened by the fastening member. In the cell stack, among the plurality of conductive members, there is an insulating property between the through hole formed in the plurality of non-connecting conductive members that are not electrically connected to the fastening member and the fastening member. Is arranged, and the tubular member surrounds the outer periphery around the axis of the fastening member and is located at one end of the plurality of non-connecting conductive members in the first direction. It extends from the first non-connecting conductive member to the second non-connecting conductive member located at the other end of the first direction. According to the present electrochemical reaction cell stack, an insulating tubular member is arranged between the through hole formed in the plurality of non-connecting conductive members and the fastening member. This tubular member surrounds the outer circumference around the axis of the fastening member, and is in the first direction among the plurality of non-connecting conductive members that are not electrically connected to the fastening member among the plurality of conductive members. It extends from a first non-connecting conductive member located at one end to a second non-connecting conductive member located at the other end in the first direction. That is, a tubular member is interposed between the plurality of non-connecting conductive members and the fastening member. As a result, it is possible to prevent the non-connecting conductive member and the fastening member from being short-circuited, as compared with a configuration in which no member is interposed between the through hole formed in the non-connecting conductive member and the fastening member. ..

(2) In the electrochemical reaction cell stack, in the plane direction perpendicular to the first direction, between the inner wall of the through hole formed in the plurality of non-connecting conductive members and the tubular member. The configuration may be such that a gap of 1 is formed. According to the present electrochemical reaction cell stack, a first gap is formed between the inner wall of the through hole formed in the plurality of non-connecting conductive members and the tubular member in the plane direction perpendicular to the first direction. Has been done. As a result, thermal stress due to the difference in thermal expansion between the non-connecting conductive member and the tubular member is generated in the tubular member as compared with the configuration in which no gap is formed between the through hole and the tubular member. As a result, for example, cracking of the tubular member can be suppressed.

(3) In the electrochemical reaction cell stack, at least one of both ends of the tubular member in the first direction is separated from the members constituting the electrochemical reaction cell stack in the first direction. It may be configured as such. According to the present electrochemical reaction cell stack, at least one of both ends of the tubular member in the first direction is separated from the member constituting the electrochemical reaction cell stack in the first direction. That is, the tubular member can be displaced in the first direction in the through hole. As a result, the heat of the conductive member and the tubular member is higher than that of the tubular member in which both ends in the first direction are in contact with the members constituting the electrochemical reaction cell stack in the first direction. It is possible to suppress the occurrence of thermal stress due to the expansion difference in the tubular member, and as a result, for example, cracking of the tubular member can be suppressed.

(4) In the electrochemical reaction cell stack, a second gap may be formed between the fastening member and the tubular member in the plane direction perpendicular to the first direction. According to the present electrochemical reaction cell stack, a second gap is formed between the fastening member and the tubular member in the plane direction perpendicular to the first direction. As a result, it is possible to prevent the tubular member from being subjected to thermal stress due to the difference in thermal expansion between the fastening member and the tubular member, as compared with the configuration in which no gap is formed between the fastening member and the tubular member. As a result, for example, cracking of the tubular member can be suppressed.

The technique disclosed in the present specification can be realized in various forms, for example, an electrochemical reaction cell stack (fuel cell stack or electrolytic cell stack) including a plurality of electrochemical reaction single cells. It can be realized in the form of the manufacturing method or 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 structure for fastening the fuel cell stack 100. It is explanatory drawing which enlarges and shows the peripheral part of the flange part 228 of the bolt 22 in FIG.

A. Embodiment:
A-1. Constitution:
(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 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.

As shown in FIG. 1, holes penetrating in the vertical direction are formed at the four corners of the outer circumference of each power generation unit 102 in the Z direction, and holes formed in each layer and corresponding to each other are formed in the vertical direction. The bolt holes 109 that communicate with each other and extend in the vertical direction are formed. A conductive bolt 22 is inserted into each bolt hole 109, and the fuel cell stack 100 is fastened by each bolt 22. The configuration for fastening the fuel cell stack 100 will be described in detail later. The bolt 22 corresponds to a fastening member within the scope of claims.

Further, as shown in FIGS. 1 to 3, holes are formed in the vicinity of the midpoint of the outer periphery of each power generation unit 102 around the Z direction to penetrate each power generation unit 102 in the vertical direction. The holes formed in 102 and corresponding to each other communicate with each other in the vertical direction to form a communication hole 108 extending in the vertical direction over a plurality of power generation units 102. In the following description, the holes formed in each power generation unit 102 to form the communication holes 108 may also be referred to as communication holes 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. The communication hole 108 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 the air chamber 166 described later in each power generation unit 102. The communication hole 108, which functions as 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), is the air of each power generation unit 102. It functions as an oxidant gas discharge manifold 162, which is a gas flow path for discharging the oxidant off-gas OOG, which is the gas discharged from the chamber 166, 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. The communication hole 108 located in is a gas flow path for introducing the fuel gas FG from the outside of the fuel cell stack 100 and supplying the fuel gas FG to the fuel chamber 176 described later in each power generation unit 102. The communication hole 108 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) is the fuel cell of each power generation unit 102. It functions as a fuel gas discharge manifold 172, which is a gas flow path for discharging the fuel off-gas FOG, which is the gas discharged from the 176, to the outside of the fuel cell stack 100. 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 sandwiched by a pair of end plates 104 and 106 in a pressed state. 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. As shown in FIGS. 2 and 3, four flow path through holes 107 are formed in the lower end plate 106. The four flow path through holes 107 communicate with the oxidant gas introduction manifold 161, the oxidant gas discharge manifold 162, the fuel gas introduction manifold 171 and the fuel gas discharge manifold 172, respectively.

As shown in FIGS. 2 and 3, 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. As shown in FIG. 2, the hole of the main body 28 of the gas passage member 27 arranged at the position of the oxidant gas introduction manifold 161 is passed through the flow path through hole 107 formed in the lower end plate 106. , The hole of the main body 28 of the gas passage member 27, which communicates with the oxidant gas introduction manifold 161 and is arranged at the position of the oxidant gas discharge manifold 162, is for a flow path formed in the lower end plate 106. It communicates with the oxidant gas discharge manifold 162 through the through hole 107. 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 fuel gas introduction manifold 171 is passed through the flow path through hole 107 formed in the lower end plate 106. The hole of the main body 28 of the gas passage member 27, which communicates with the fuel gas introduction manifold 171 and is arranged at the position of the fuel gas discharge manifold 172, penetrates the flow path formed in the lower end plate 106. It communicates with the fuel gas discharge manifold 172 through the hole 107. An insulating sheet 26 is interposed between each gas passage member 27 and the surface of the end plate 106. 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.

(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 the XZ cross-sectional configuration of the 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-sectional structure of two power generation units 102. As shown in FIGS. 4 and 5, each 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. It includes a 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. On the peripheral edges of the separator 120, the air pole side frame 130, the fuel pole side frame 140, and the interconnector 150 around the Z direction, holes corresponding to the above-mentioned bolt holes 109 and each manifold 161, 162, 171 and 172 are provided. A hole corresponding to the constituent communication hole 108 is formed.

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.

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 interposed therebetween. 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 substantially rectangular flat plate-shaped member, for example, YSZ (yttria-stabilized zirconia), ScSZ (scandia-stabilized zirconia), SDC (samarium-doped ceria), GDC (gadolinium-doped ceria), perovskite-type oxide. It is formed of solid oxides such as. 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 formed of, for example, metal. 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 joined to the single cell 110 by a joining 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 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.

The fuel pole 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 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. Since the fuel pole side current collector 144 has such a configuration, the fuel pole 116 and the interconnector 150 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. Therefore, the fuel pole 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 electrical connection between the fuel pole 116 and the interconnector 150 via the fuel pole side current collector 144 is established. Well maintained.

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 pole side current collector 134 is in contact with the surface of the air pole 114 on the side opposite to the side facing the electrolyte layer 112 and the surface of the interconnector 150 on the side facing the air pole 114. Since the air electrode side current collector 134 has such a configuration, the air electrode 114 and the interconnector 150 are electrically connected to each other. 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 integrated 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.

A-2. Operation of fuel cell stack 100:
As shown in FIGS. 2 and 4, the oxidant gas OG is supplied via a gas pipe (not shown) connected to the branch portion 29 of the gas passage member 27 provided at the position of the oxidant gas introduction manifold 161. Then, 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 the oxidizer gas introduction manifold 161 oxidizes each power generation unit 102. It is supplied to the air chamber 166 through the agent gas supply communication hole 132. Further, as shown in FIGS. 3 and 5, the fuel gas FG is supplied via 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. Then, 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 gas supply communication of each power generation unit 102 is performed from the fuel gas introduction manifold 171. It is supplied to the fuel chamber 176 through the 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, power is generated by the electrochemical reaction of the oxidant gas OG and the fuel gas FG in the single cell 110. Will be. 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, after the start-up, until the high temperature can be maintained by the heat generated by the power generation. It may be heated by (not shown).

As shown in FIGS. 2 and 4, 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, and further oxidized. 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 agent gas discharge manifold 162, and the gas pipe (not shown) connected to the branch 29. It is discharged to the outside of. Further, as shown in FIGS. 3 and 5, 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, and further, the fuel gas. To the outside of the fuel cell stack 100 via the holes of the main body 28 and the branch 29 of the gas passage member 27 provided at the position of the discharge manifold 172, and via a gas pipe (not shown) connected to the branch 29. It is discharged.

A-3. Configuration for fastening the fuel cell stack 100:
FIG. 6 is an explanatory diagram showing a configuration for fastening the fuel cell stack 100. FIG. 6 shows the cross-sectional configuration of the fuel cell stack 100 at the position of VI-VI in FIG. As described above, the fuel cell stack 100 is fastened by a plurality of bolts 22. As shown in FIG. 6, the bolt 22 includes a shaft portion 226 and a flange portion 228 formed at one end (upper side in the present embodiment) of the shaft portion 226. The shaft portion 226 and the flange portion 228 are integral members. The flange portion 228 has a diameter (dimension in the direction orthogonal to the axial direction of the shaft portion 226) larger than that of the shaft portion 226 and has a seating surface 229. The seat surface 229 is a surface on the shaft portion 226 side of the surfaces of the flange portion 228 that are orthogonal to the axial direction of the shaft portion 226. A threaded portion 224 is formed at an end of the shaft portion 226 of the bolt 22 opposite to the flange portion 228. Male threads are formed on the outer peripheral surface of the threaded portion 224.

The bolt hole 109 is composed of a through hole formed in each power generation unit 102 and a through hole formed in the upper end plate 104. Further, the lower end plate 106 is formed with a screw hole 103 that communicates with the bolt hole 109. The screw hole 103 penetrates the lower end plate 106 in the vertical direction, and a female screw is formed on the inner peripheral surface thereof. Bolt holes 109 and screw holes 103 correspond to through holes in the claims.

The bolt 22 is inserted into the bolt hole 109, and the screw portion 224 formed in the shaft portion 226 of the bolt 22 is screwed into the screw hole 103 formed in the lower end plate 106. In this state, the shaft portion 226 of the bolt 22 is in a posture of extending in the vertical direction (Z-axis direction). Further, the flange portion 228 is located on the upper side (Z-axis positive direction side) with respect to the shaft portion 226, and the seat surface 229 of the flange portion 228 is in contact with the upper surface of the upper end plate 104.

Further, as shown in FIGS. 2 and 3, an insulating sheet 210 is interposed between the lower surface of the upper end plate 104 and the uppermost power generation unit 102 (upper surface of the interconnector 150). The insulating sheet 210 is formed with holes 212 forming the bolt holes 109. The diameter of the hole 212 formed in the insulating sheet 210 is substantially the same as the diameter of the through hole formed in each power generation unit 102. Further, an insulating sheet 220 is interposed between the upper surface of the lower end plate 106 and the lowermost power generation unit 102 (lower surface of the interconnector 150). The insulating sheet 220 is formed with a hole 222 that communicates with the bolt hole 109. The diameter of the hole 222 formed in the insulating sheet 220 is smaller than the diameter of the through hole formed in each power generation unit 102. The insulating sheets 210 and 220 are 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. Therefore, in the present embodiment, the pair of end plates 104 and 106 are electrically connected to the bolt 22, but the separator 120, the fuel electrode side frame 140, and the interconnector 150 in each power generation unit 102 are connected to the bolt 22. Not electrically connected to. The pair of end plates 104 and 106, the separator 120, the fuel electrode side frame 140, and the interconnector 150 correspond to conductive members within the scope of the claims, and the separator 120, the fuel electrode side frame 140, and the interconnector 150 correspond to each other. , Corresponds to a non-connecting conductive member within the scope of claims.

A-4. Configuration for insulation between the non-connecting conductive member and the bolt 22:
FIG. 7 is an enlarged explanatory view showing a peripheral portion of the flange portion 228 of the bolt 22 in FIG. As shown in FIGS. 6 and 7, the fuel cell stack 100 further includes an insulating protective tube 300. The protective tube 300 is made of an insulating material such as alumina, zirconia, or silicon nitride. The protective tube 300 is formed in the bolt holes 109 (each non-connecting conductive member constituting the bolt hole 109) formed in the plurality of non-connecting conductive members (separator 120, fuel electrode side frame 140, interconnector 150). It is arranged between the inner wall of the through hole) and the bolt 22. Specifically, the protective tube 300 surrounds the outer periphery of the shaft portion 226 of the bolt 22 around the axis, and is the first non-connecting conductive member located at the upper end of the plurality of non-connecting conductive members (FIG. 6). From the upper interconnector 150 of the first power generation unit 102 from the top to the second non-connecting conductive member located at the lower end (the lower interconnector 150 of the seventh power generation unit 102 from the top in FIG. 6). Extends to. More specifically, the protective tube 300 is a substantially cylindrical member, and is inserted into bolt holes 109 formed in a plurality of non-connecting conductive members (separator 120, fuel electrode side frame 140, interconnector 150). Has been done. The shaft portion 226 of the bolt 22 is inserted into the protective tube 300. In other words, the protective tube 300 is arranged so as to surround the entire circumference of the shaft portion 226 of the bolt 22. Further, the thickness of the protective tube 300 is preferably substantially uniform over the entire circumference of the protective tube 300 around the axis. Further, the thickness of the protective tube 300 is preferably substantially uniform over the entire length of the protective tube 300. Further, the thickness of the protective tube 300 is preferably 1/3 or more with respect to the distance in the surface direction between the bolt 22 and the inner wall of the bolt hole 109 formed in the non-connecting conductive member. More preferably, it is / 2 or more. The protective tube 300 corresponds to a tubular member within the scope of the claims.

Further, in a plane direction (XY plane direction) perpendicular to the vertical direction (Z-axis direction), the protective tube 300 and a plurality of non-conductive members (separator 120, fuel electrode side frame 140, interconnector 150) are formed. A first gap S1 is formed between the bolt hole 109 and the inner wall. Specifically, as shown in FIG. 7, the outer diameter D3 of the protective tube 300 is smaller than the diameter D4 of the bolt hole 109. Further, in the surface direction, a second gap S2 is formed between the protection tube 300 and the shaft portion 226 of the bolt 22. Specifically, as shown in FIG. 7, the inner diameter D2 of the protective tube 300 is larger than the outer diameter (maximum outer diameter) D1 of the shaft portion 226 of the bolt 22. The first gap S1 and the second gap S2 may be formed at least before the operation of the fuel cell stack 100.

Further, at least one of the upper end and the lower end of the protection tube 300 is separated from the members constituting the fuel cell stack 100 in the vertical direction (Z-axis direction). Specifically, as shown in FIGS. 6 and 7, the holes 105 formed in the upper end plate 104 and forming the bolt holes 109 are the first hole 105A and the second hole 105B. And have. The first hole 105A is open to the surface (lower surface) of the end plate 104 on the power generation unit 102 side. The diameter D4 of the first hole 105A is larger than the outer diameter D3 of the protective tube 300. In the present embodiment, the diameter D4 of the first hole 105A is substantially the same as the diameter of the bolt hole 109 formed in the non-connecting conductive member. A stepped surface 105C is formed between the first hole 105A and the second hole 105B. As shown in FIG. 6, the vertical distance L2 between the stepped surface 105C on the upper end plate 104 and the upper surface of the insulating sheet 220 is longer than the total length L1 of the protective tube 300. FIG. 6 shows a state in which the lower end of the protective tube 300 is in contact with the peripheral portion of the hole 222 in the upper surface of the insulating sheet 220, and the upper end of the protective tube 300 is separated from the stepped surface 105C of the upper end plate 104. ing. In this way, by interposing the insulating sheet 220 between the lower end of the protective tube 300 and the lower end plate 106, the fuel is compared with the configuration in which the protective tube 300 and the lower end plate 106 are in direct contact with each other. The withstand voltage of the battery stack 100 is improved.

Further, in the state of FIG. 6, the upper end of the protective tube 300 is preferably located above the uppermost non-connecting conductive member (the upper surface of the interconnector 150 above the first power generation unit 102). .. In other words, the total length L1 of the protective tube 300 is longer than the total length L3 in the vertical direction of the plurality of power generation units 102 sandwiched between the upper end plate 104 and the lower end plate 106. As a result, for example, even if the power generation unit 102 expands relative to the protection tube 300 due to the difference in thermal expansion between the protection tube 300 and the power generation unit 102, the non-connecting conductive member and the bolt 22 are short-circuited. It can be suppressed more reliably. Further, the protective tube 300 is not fixed in the bolt hole 109, but is arranged so as to be displaceable in the vertical direction and the surface direction. The vertical gap between the protection pipe 300 and the members constituting the fuel cell stack 100 may be formed at least before the operation of the fuel cell stack 100.

Although FIG. 6 shows a cross section of the fuel cell stack 100 at the position of one bolt hole 109, the cross section of the fuel cell stack 100 at the position of the other three bolt holes 109 has the same configuration. .. Therefore, a total of four screw holes 103 are formed in the lower end plate 106, and the screw portion 224 of the bolt 22 is screwed into each screw hole 103. The fuel cell stack 100 is fastened by the bolts 22 screwed into the screw holes 103. Further, the above-mentioned protection tube 300 is arranged in each of the four bolt holes 109 formed in the fuel cell stack 100.

A-5. Effect of this embodiment:
As described above, according to the fuel cell stack 100 of the present embodiment, through holes (bolt holes 109) formed in a plurality of non-connecting conductive members (separator 120, fuel electrode side frame 140, interconnector 150). A protective tube 300 having an insulating property is arranged between the bolt 22 and the bolt 22. The protective tube 300 surrounds the outer circumference of the bolt 22 around the axis and extends from the first non-connecting conductive member located at the upper end to the second non-connecting conductive member located at the lower end. That is, a protective tube 300 is interposed between the plurality of non-connecting conductive members and the bolt 22. As a result, it is possible to prevent the non-connecting conductive member and the bolt 22 from being short-circuited, as compared with a configuration in which no member is interposed between the through hole formed in the non-connecting conductive member and the fastening member. ..

Further, according to the present embodiment, a first gap S1 is formed between the protective tube 300 and the inner walls of the bolt holes 109 formed in the plurality of non-conductive members in the plane direction. As a result, the thermal stress in the surface direction due to the difference in thermal expansion between the non-connecting conductive member and the protective tube 300 is protected as compared with the configuration in which a gap is not formed between the bolt hole 109 and the protective tube 300. It is possible to suppress what occurs in the tube 300, and as a result, for example, cracking of the protective tube 300 can be suppressed.

Further, according to the present embodiment, a second gap S2 is formed between the protective tube 300 and the shaft portion 226 of the bolt 22 in the surface direction. As a result, a thermal stress in the surface direction due to the difference in thermal expansion between the protective tube 300 and the bolt 22 is generated in the protective tube 300 as compared with a configuration in which a gap is not formed between the protective tube 300 and the bolt 22. As a result, for example, cracking of the protective tube 300 can be suppressed.

Further, according to the present embodiment, at least one of the upper end and the lower end of the protective tube 300 is separated from the members constituting the fuel cell stack 100 in the vertical direction (Z-axis direction). That is, the protection tube 300 can be displaced in the vertical direction in the bolt hole 109. This is due to the difference in thermal expansion between the conductive member and the protective tube 300 as compared with the configuration in which both ends of the protective tube 300 in the vertical direction are in contact with the members constituting the fuel cell stack 100 in the vertical direction. It is possible to suppress the occurrence of thermal stress in the vertical direction on the protective tube 300, and as a result, for example, cracking of the protective tube 300 can be suppressed.
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, and for example, the following modifications are also possible.

The configuration of the single cell 110 or the fuel cell stack 100 in the above embodiment is merely an example and can be variously modified. For example, in the above embodiment, the lower end portion of the shaft portion 226 of the bolt 22 penetrates the lower end plate 106 and protrudes downward, and the nut is screwed into the screw portion 224 formed at the protruding lower end portion. It may be correct. Further, in the above embodiment, a screw is formed on the outer peripheral surface of the upper end portion of the shaft portion 226 of the bolt 22, and a female screw is formed on the inner peripheral surface of the through hole formed in the upper end plate 104. , The upper end of the shaft portion 226 of the bolt 22 may be screwed into the through hole formed in the upper end plate 104. Further, in the above embodiment, the insulating sheet 210 may not be provided, and instead, the insulating sheet may be arranged between the seat surface 229 of the bolt 22 and the upper end plate 104. In this case, in addition to the interconnector 150 and the like, the upper end plate 104 also corresponds to the non-connecting conductive member within the scope of the claims.

Further, in the above embodiment, the protective tube 300 is not limited to a substantially cylindrical shape, and may be, for example, a substantially square tubular shape. Further, in the above embodiment, the protective tube 300 may be tubular. Even with such a configuration, a short circuit between the non-connecting conductive member and the bolt 22 can be suppressed.

Further, in the above embodiment, the above-mentioned first gap S1 does not have to be formed over the entire circumference of the protective tube 300 around the axis, and the first gap S1 is partly around the axis of the protective tube 300. It is sufficient that the protective tube 300 can be displaced in the surface direction with respect to the non-conductive member in the bolt hole 109 by being formed. Further, in the above embodiment, the first gap S1 may not be formed between the protective tube 300 and the inner wall of the bolt hole 109 formed in the non-conductive member. Further, in the above embodiment, the above-mentioned second gap S2 does not have to be formed over the entire circumference of the protective tube 300 around the axis, and the second gap S2 is partly around the axis of the protective tube 300. It is sufficient that the protective tube 300 can be displaced in the surface direction with respect to the bolt 22 in the bolt hole 109 by being formed. Further, in the above embodiment, the second gap S2 may not be formed between the protective tube 300 and the inner wall of the bolt hole 109 formed in the non-conductive member. Further, both ends of the protective tube 300 in the vertical direction (Z-axis direction) may be in contact with the members constituting the fuel cell stack 100 in the vertical direction.

Further, in the above embodiment, it is not necessary to adopt the configuration in which the protective pipe 300 is arranged in all the bolt holes 109 formed in the fuel cell stack 100, and the protective pipe 300 is arranged in at least one bolt hole 109. The configuration may be adopted.

Further, in the above embodiment, the number of single cells 110 included in the fuel cell stack 100 is only an example, and the number of single cells 110 is appropriately determined according to the output voltage and the like required for the fuel cell stack 100. Further, the material constituting each member in the above embodiment is merely an example, and each member may be composed of another material.

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 single cell, which is a constituent unit of a solid oxide fuel cell (SOEC) that uses it to generate hydrogen, and an electrolytic cell stack including a plurality of electrolytic single cells. The configuration of the electrolytic cell stack is not described in detail here because it is known as described in, for example, 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 a configuration. 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 of the electrolytic cell stack through the communication hole 108. In the electrolytic cell stack having such a configuration, as in the above embodiment, if the tubular member is arranged between the through hole formed in the electrolytic cell stack and the fastening member, the conductive member and the fastening member can be connected. Short circuit can be suppressed.

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 a molten carbonate fuel cell (MCFC). Applicable.

22: Bolt 26: Insulation sheet 27: Gas passage member 28: Main body 29: Branch 100: Fuel cell stack 102: Power generation unit 103: Screw hole 104, 106: End plate 105: Hole 105A: First hole 105B : Second hole 105C: Step surface 107: Through hole for flow path 108: Communication hole 109: Bolt hole 110: Single cell 112: Electrolyte layer 114: Air pole 116: Fuel pole 120: Separator 121: Hole 124: Join Part 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 element 140: Fuel pole side frame 141: Hole 142 : Fuel gas supply communication hole 143: Fuel gas discharge communication hole 144: Fuel electrode side current collector 145: Electrode facing part 146: Interconnector facing part 147: Connecting part 149: Spacer 150: Interconnector 161 1: 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, 220: Insulation sheet 212, 222: Hole 224: Thread part 226: Shaft part 228: Flange part 229: Seat surface 300: Protective tube D1, D3: Outer diameter D2: Inner diameter D4: Diameter FG: Fuel gas FOG: Fuel off gas L1: Overall length L2: Distance L3: Length OG: Oxidizing agent gas OOG: Oxidizing agent off gas S1: First gap S2: Second gap

Claims (3)

A plurality of single cells arranged side by side in the first direction, including an electrolyte layer, an air electrode, and a fuel electrode, respectively.
A plurality of conductive members arranged on both sides of the plurality of single cells in the first direction and between the single cells, and through holes penetrating the plurality of conductive members in the first direction. With a plurality of conductive members in which
A fastening member extending in the first direction and inserted into the through holes formed in the plurality of conductive members.
In an electrochemical reaction cell stack fastened by the fastening member.
Among the plurality of conductive members, there is an insulating tubular shape between the through hole formed in the plurality of non-connecting conductive members that are not electrically connected to the fastening member and the fastening member. The members are arranged,
The tubular member surrounds the outer circumference around the axis of the fastening member, and from the first non-connecting conductive member located at one end in the first direction among the plurality of non-connecting conductive members, the said It extends to a second non-connecting conductive member located at the other end of the first direction .
In the plane direction perpendicular to the first direction, a first gap is formed between the inner wall of the through hole formed in the plurality of non-connecting conductive members and the tubular member .
It is characterized by an electrochemical reaction cell stack. In the electrochemical reaction cell stack according to claim 1,
At least one of both ends of the tubular member in the first direction is separated from the member constituting the electrochemical reaction cell stack in the first direction.
It is characterized by an electrochemical reaction cell stack. In the electrochemical reaction cell stack according to claim 1 or 2.
A second gap is formed between the fastening member and the tubular member in the plane direction perpendicular to the first direction.
It is characterized by an electrochemical reaction cell stack.

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