JP2019197675A - Electrochemical reaction cell stack - Google Patents

Abstract

To provide an electrochemical reaction cell stack with a structure capable of suppressing a short-circuit between a non-connection conductive member and a fastening member.SOLUTION: An electrochemical reaction cell stack comprises: a plurality of single cells arranged to align in a first direction; a plurality of conductive members arranged between both sides of the plurality of single cells and both single cells, and in which a penetration hole is formed; and a fastening member 22 inserted into the penetration hole formed in the plurality of conductive members. A cylindrical member 300 having an insulation quality is arranged between the penetration hole formed in a plurality of non-connection conductive members which is not electrically connected to the fastening member and the fastening member. The cylindrical member surrounds an outer periphery of an axial periphery of the fastening member, and is extended from a first non-connection conductive member positioned at one end of a first direction to a second non-connection conductive member positioned at the other end of the first direction from the plurality of non-connection conductive members.SELECTED DRAWING: Figure 6

Description

  The technology disclosed herein relates to an electrochemical reaction cell stack.

  One type of fuel cell that generates electricity using an electrochemical reaction between hydrogen and oxygen is a solid oxide fuel cell (hereinafter referred to as “SOFC”) having an electrolyte layer containing a solid oxide. It has been. 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 facing each other in a predetermined direction (hereinafter referred to as “first direction”) across the electrolyte layer. Electrode and fuel electrode.

  The SOFC is generally used in the form of a fuel cell stack including 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 disposed on both sides of the plurality of single cells in the first direction and between the single cells. 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 a through hole formed in the plurality of conductive members, and the fuel cell stack is fastened by the fastening member.

Japanese Unexamined Patent Publication No. 2016-225078

  In the conventional fuel cell stack in which the fastening member is inserted into the through hole of the conductive member, for example, when a high voltage is generated, it is originally electrically connected to the fastening member among the plurality of conductive members. A discharge occurs between the inner wall of the through hole formed in the non-connected conductive member (for example, a conductive member disposed between the single cells) and the fastening member, and the non-conductive conductive member and the fastening member May be short-circuited. When the non-conductive conductive member and the fastening member are short-circuited, the performance of the fuel cell stack is reduced (for example, the output is reduced).

  In addition, such a subject is an electrolysis provided with a plurality of electrolytic single cells which are constituent units of a solid oxide electrolytic cell (hereinafter also referred to as “SOEC”) that generates hydrogen using an 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. Such a problem is not limited to SOFC and SOEC, but is common to other types of electrochemical reaction cell stacks.

  In this specification, the technique which can solve the subject mentioned above is disclosed.

  The technology disclosed in this specification can be implemented as the following forms.

(1) An electrochemical reaction cell stack disclosed in the present specification includes an electrolyte layer, an air electrode, and a fuel electrode, respectively, and a plurality of single cells arranged in a first direction, and the first direction. A plurality of conductive members disposed on both sides of the plurality of single cells and between the single cells, each having a through hole penetrating the plurality of conductive members in the first direction. And a fastening member extending in the first direction and inserted into the through holes formed in the plurality of conductive members, and the electrochemical reaction fastened by the fastening member In the cell stack, among the plurality of conductive members, an insulating property is provided between the through hole formed in the plurality of non-connected conductive members that are not electrically connected to the fastening member and the fastening member. A cylindrical member having The cylindrical member surrounds an outer periphery around the axis of the fastening member, and of the plurality of non-connected conductive members, a first non-conductive conductive member located at one end in the first direction To a second unconnected conductive member located at the other end in the first direction. According to this electrochemical reaction cell stack, a cylindrical member having insulating properties is disposed between the through hole formed in the plurality of non-connected conductive members and the fastening member. The cylindrical member surrounds the outer periphery around the axis of the fastening member, and among the plurality of non-connected conductive members that are not electrically connected to the fastening member among the plurality of conductive members, It extends from the first non-conductive conductive member located at one end to the second non-conductive conductive member located at the other end in the first direction. That is, a cylindrical member is interposed between the plurality of non-connected conductive members and the fastening member. Thereby, compared with the structure in which no member is interposed between the through hole formed in the non-connected conductive member and the fastening member, it is possible to suppress the short-circuit between the non-conductive conductive member and the fastening member. .

(2) In the electrochemical reaction cell stack, in a plane direction perpendicular to the first direction, a gap is formed between the inner wall of the through-hole formed in the plurality of non-connected conductive members and the cylindrical member. It is good also as a structure in which 1 clearance gap is formed. According to the electrochemical reaction cell stack, the first gap is formed between the inner wall of the through hole formed in the plurality of non-connected conductive members and the cylindrical member in the plane direction perpendicular to the first direction. Has been. As a result, compared to a configuration in which no gap is formed between the through hole and the cylindrical member, thermal stress due to the thermal expansion difference between the non-connected conductive member and the cylindrical member is generated in the cylindrical member. As a result, for example, cracking of the cylindrical member can be suppressed.

(3) In the electrochemical reaction cell stack, at least one of both ends of the cylindrical member in the first direction is separated from a member constituting the electrochemical reaction cell stack in the first direction. It is good also as composition which has. According to the electrochemical reaction cell stack, at least one of both ends of the cylindrical member in the first direction is separated from the member constituting the electrochemical reaction cell stack in the first direction. That is, the cylindrical member can be displaced in the first direction in the through hole. Thereby, compared with the structure which the both ends of the 1st direction in a cylindrical member are contacting the member which comprises an electrochemical reaction cell stack in a 1st direction, the heat | fever of an electroconductive member and a cylindrical member is carried out. It is suppressed that the thermal stress resulting from an expansion difference arises in a cylindrical member, As a result, the crack of a cylindrical member, etc. can be suppressed, for example.

(4) In the electrochemical reaction cell stack, a second gap may be formed between the fastening member and the cylindrical member in a plane direction perpendicular to the first direction. According to this electrochemical reaction cell stack, the second gap is formed between the fastening member and the cylindrical member in the plane direction perpendicular to the first direction. Thereby, compared with the structure in which no gap is formed between the fastening member and the tubular member, the occurrence of thermal stress due to the difference in thermal expansion between the fastening member and the tubular member is suppressed. As a result, for example, cracking of the cylindrical member can be suppressed.

  The technology disclosed in the present specification can be realized in various forms. For example, an electrochemical reaction cell stack (a fuel cell stack or an electrolytic cell stack) including a plurality of electrochemical reaction single cells, It can be realized in the form of its manufacturing method.

1 is a perspective view showing an external configuration of a fuel cell stack 100 in the present embodiment. It is explanatory drawing which shows the XZ cross-section structure of the fuel cell stack 100 in the position of II-II of FIG. FIG. 3 is an explanatory diagram showing a YZ cross-sectional configuration of a fuel cell stack 100 at a position of III-III in FIG. It is explanatory drawing which shows XZ cross-section structure of the two electric power generation units 102 adjacent to each other in the same position as the cross section shown in FIG. It is explanatory drawing which shows the YZ cross-section structure of the two electric power generation units 102 adjacent to each other in the same position as the cross section shown in FIG. 3 is an explanatory diagram showing a configuration for fastening the fuel cell stack 100. FIG. It is explanatory drawing which expands and shows the peripheral part of the flange part 228 of the volt | bolt 22 in FIG.

A. Embodiment:
A-1. Constitution:
(Configuration of fuel cell stack 100)
FIG. 1 is a perspective view showing an external configuration of a fuel cell stack 100 in the present embodiment, and FIG. 2 is an explanatory diagram showing an XZ cross-sectional configuration of the fuel cell stack 100 at a position II-II in FIG. FIG. 3 is an explanatory diagram showing a YZ cross-sectional configuration of the fuel cell stack 100 at the position of III-III in FIG. In each figure, XYZ axes orthogonal to each other for specifying the direction are shown. In this specification, for the sake of convenience, the positive direction of the Z axis is referred to as the upward direction, and the negative direction of the Z axis is referred to as the downward direction. However, the fuel cell stack 100 is actually different from such an orientation. It may be installed. The same applies to FIG.

  The fuel cell stack 100 includes a plurality of (seven in this embodiment) 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 assembly 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 that penetrate vertically are formed at the four corners of the outer periphery of each power generation unit 102 around the Z direction, and holes that are formed in each layer and that correspond to each other are vertically aligned. A bolt hole 109 extending in the vertical direction is formed in communication. Each bolt hole 109 has a conductive bolt 22 inserted therein, 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 in the claims.

  Further, as shown in FIGS. 1 to 3, a hole penetrating each power generation unit 102 in the vertical direction is formed near the middle point of the outer periphery around each Z direction of each power generation unit 102. The holes corresponding to each other formed in 102 communicate with each other in the vertical direction to form a communication hole 108 extending in the vertical direction across the plurality of power generation units 102. In the following description, a hole formed in each power generation unit 102 to configure the communication hole 108 may also be referred to as the communication hole 108.

  As shown in FIGS. 1 and 2, the fuel cell stack 100 is located near the midpoint of one side (the X-axis positive direction side of two sides parallel to the Y-axis) on the outer periphery around the Z-direction. The communication hole 108 to which the oxidant gas OG is introduced from the outside of the fuel cell stack 100 and the oxidant gas introduction manifold is a gas flow path for supplying the oxidant gas OG to an air chamber 166 described later of each power generation unit 102. The communication hole 108, which functions as 161, is located near the midpoint of the opposite side (the side on the negative X-axis side of the two sides parallel to the Y-axis). It functions as an oxidant gas discharge manifold 162 that is a gas flow path for discharging the oxidant off-gas OOG that is a gas discharged from the chamber 166 to the outside of the fuel cell stack 100. In the present 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 Y axis positive direction side of two sides parallel to the X axis) on the outer periphery of the fuel cell stack 100 around the Z direction A communication hole 108 located in the fuel cell stack 100 receives a fuel gas FG from the outside of the fuel cell stack 100 and supplies a fuel gas FG to a fuel chamber 176 (to be described later) of each power generation unit 102. The communication hole 108 located near the midpoint of the opposite side of the side (the side on the Y axis negative direction side of the two sides parallel to the X axis) is a fuel chamber of each power generation unit 102. It functions as a fuel gas discharge manifold 172 that is a gas flow path for discharging the fuel off-gas FOG that is the gas discharged from 176 to the outside of the fuel cell stack 100. In the present embodiment, as the fuel gas FG, for example, hydrogen-rich gas obtained by reforming city gas is used.

(Configuration of end plates 104 and 106)
The pair of end plates 104 and 106 are substantially rectangular flat plate-shaped conductive members, and are formed of, for example, stainless steel. One end plate 104 is disposed on the upper side of the power generation unit 102 located on the uppermost side, and the other end plate 106 is disposed on the lower side of the power generation unit 102 located on the lowermost side. 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. As shown in FIGS. 2 and 3, four passage through holes 107 are formed in the lower end plate 106. The four flow passage 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 cylindrical main body portion 28 and a hollow cylindrical branch portion 29 branched from the side surface of the main body portion 28. The hole of the branch part 29 communicates with the hole of the main body part 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 portion 28 of the gas passage member 27 disposed at the position of the oxidant gas introduction manifold 161 passes through the passage through hole 107 formed in the lower end plate 106. The hole of the main body portion 28 of the gas passage member 27 that communicates with the oxidant gas introduction manifold 161 and is disposed at the position of the oxidant gas discharge manifold 162 is for the flow path formed in the lower end plate 106. It communicates with the oxidant gas discharge manifold 162 through the through hole 107. As shown in FIG. 3, the hole of the main body portion 28 of the gas passage member 27 disposed at the position of the fuel gas introduction manifold 171 is interposed through the flow passage through hole 107 formed in the lower end plate 106. The hole of the main body portion 28 of the gas passage member 27 that communicates with the fuel gas introduction manifold 171 and is disposed at the position of the fuel gas discharge manifold 172 passes through the flow passage formed in the lower end plate 106. The fuel gas discharge manifold 172 communicates with 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 powder sheet, a glass sheet, a glass ceramic composite agent, or the like.

(Configuration of power generation unit 102)
4 is an explanatory diagram 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 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 structure of the two electric power generation units. As shown in FIGS. 4 and 5, each power generation unit 102 includes a unit cell 110, a separator 120, an air electrode side frame 130, an air electrode side current collector 134, a fuel electrode side frame 140, and a fuel electrode. A side current collector 144 and a pair of interconnectors 150 constituting the uppermost layer and the lowermost layer of the power generation unit 102 are provided. In the periphery of the separator 120, the air electrode side frame 130, the fuel electrode side frame 140, and the interconnector 150 around the Z direction, holes corresponding to the bolt holes 109 and manifolds 161, 162, 171, and 172 are provided. A hole corresponding to the communication hole 108 is formed.

  The interconnector 150 is a substantially rectangular flat plate-shaped conductive member, and is formed of, for example, ferritic stainless steel. The interconnector 150 ensures electrical continuity between the power generation units 102 and prevents reaction gas from being mixed 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 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 unit cell 110 includes an electrolyte layer 112, and an air electrode (cathode) 114 and a fuel electrode (anode) 116 that face each other in the vertical direction (the 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 electrode-supported single cell that supports the electrolyte layer 112 and the air electrode 114 with the fuel electrode 116.

  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 oxide It is formed with 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 (lanthanum strontium cobalt iron oxide), LSM (lanthanum strontium manganese oxide), LNF (lanthanum nickel iron)). Has been. The fuel electrode 116 is a substantially rectangular flat plate-like member, and is formed of, for example, Ni (nickel), cermet made of Ni and ceramic particles, Ni-based alloy, or the like. Thus, 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-like member in which a substantially rectangular hole 121 penetrating in the vertical direction is formed near the center, and is made of, for example, metal. The peripheral part of the hole 121 in the separator 120 is opposed to the peripheral part of the surface of the electrolyte layer 112 on the air electrode 114 side. The separator 120 is bonded to the single cell 110 by a bonding portion 124 formed of a brazing material (for example, Ag brazing) disposed in the facing portion. The separator 120 divides the air chamber 166 facing the air electrode 114 and the fuel chamber 176 facing the fuel electrode 116, and gas leaks from one electrode side to the other electrode side in the peripheral portion of the single cell 110. It is suppressed.

  The air electrode side frame 130 is a frame-like member in which a substantially rectangular hole 131 penetrating in the vertical direction is formed near the center, and is formed of an insulator such as mica, for example. The hole 131 of the air electrode side frame 130 forms an air chamber 166 that faces the air electrode 114. The air electrode side frame 130 is in contact with the peripheral edge portion of the surface of the separator 120 opposite to the side facing the electrolyte layer 112 and the peripheral edge portion of the surface of the interconnector 150 facing the air electrode 114. . The pair of interconnectors 150 included in the power generation unit 102 is electrically insulated by the air electrode side frame 130. The air electrode side frame 130 has an oxidant gas supply communication hole 132 communicating the oxidant gas introduction manifold 161 and the air chamber 166, and an oxidant gas communicating the air chamber 166 and the oxidant gas discharge manifold 162. A discharge communication hole 133 is formed.

  The fuel electrode side frame 140 is a frame-like member in which a substantially rectangular hole 141 penetrating in the vertical direction is formed near the center, and is made of, for example, metal. The hole 141 of the fuel electrode side frame 140 forms a fuel chamber 176 that faces the fuel electrode 116. The fuel electrode side frame 140 is in contact with the peripheral portion of the surface of the separator 120 facing the electrolyte layer 112 and the peripheral portion of the surface of the interconnector 150 facing the fuel electrode 116. Further, the fuel electrode side frame 140 has a fuel gas supply communication hole 142 that connects the fuel gas introduction manifold 171 and the fuel chamber 176, and a fuel gas discharge communication hole 143 that connects the fuel chamber 176 and the fuel gas discharge manifold 172. And are formed.

  The fuel electrode side current collector 144 is disposed in the fuel chamber 176. The fuel electrode side current collector 144 includes an interconnector facing portion 146, an electrode facing portion 145, and a connecting portion 147 that connects the electrode facing portion 145 and the interconnector facing portion 146. For example, nickel or a nickel alloy It is made of stainless steel or the like. The electrode facing portion 145 is in contact with the surface of the fuel electrode 116 on the side opposite to the side facing the electrolyte layer 112, and the interconnector facing portion 146 is on the surface of the interconnector 150 on the side facing the fuel electrode 116. In contact. Since the fuel electrode side current collector 144 has such a configuration, the fuel electrode 116 and the interconnector 150 are electrically connected. Note that a spacer 149 made of, for example, mica is disposed between the electrode facing portion 145 and the interconnector facing portion 146. Therefore, the fuel electrode side current collector 144 follows the deformation of the power generation unit 102 due to the temperature cycle or reaction gas pressure fluctuation, and the fuel electrode 116 and the interconnector 150 are electrically connected via the fuel electrode side current collector 144. Maintained well.

  The air electrode side current collector 134 is disposed in the air chamber 166. The air electrode side current collector 134 is composed of a plurality of current collector elements 135 having a substantially quadrangular prism shape, 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 facing the air electrode 114. Since the air electrode side current collector 134 has such a configuration, the air electrode 114 and the interconnector 150 are electrically connected. In the present embodiment, the air electrode side current collector 134 and the interconnector 150 are formed as an integral member. That is, a flat plate portion perpendicular to the vertical direction (Z-axis direction) of the integrated member functions as the interconnector 150 and is formed so as to protrude from the flat plate portion toward the air electrode 114. The current collector element 135 that is a plurality of convex portions functions as the air electrode side current collector 134. Moreover, the integral member of the air electrode side current collector 134 and the interconnector 150 may be covered with a conductive coat, and 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 the fuel cell stack 100:
As shown in FIGS. 2 and 4, the oxidant gas OG is supplied through 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 branch portion 29 of the gas passage member 27 and the hole of the main body portion 28, and the oxidant 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 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. Then, the fuel gas FG is supplied to the fuel gas introduction manifold 171 through the branch portion 29 of the gas passage member 27 and the hole of the main body portion 28, and the fuel gas supply communication of each power generation unit 102 from the fuel gas introduction manifold 171. The fuel chamber 176 is supplied 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 an electrochemical reaction between the oxidant gas OG and the fuel gas FG in the single cell 110. Is called. This power generation reaction is an exothermic reaction. In each power generation unit 102, the air electrode 114 of the single cell 110 is electrically connected to one interconnector 150 via the air electrode side current collector 134, and the fuel electrode 116 is connected via the fuel electrode side current collector 144. The other interconnector 150 is electrically connected. The plurality of power generation units 102 included in the fuel cell stack 100 are electrically connected in series. Therefore, electrical energy generated in each power generation unit 102 is taken out from the end plates 104 and 106 that function as output terminals of the fuel cell stack 100. Since SOFC generates power at a relatively high temperature (for example, 700 ° C. to 1000 ° C.), the fuel cell stack 100 is heated by a heater (after the start-up until the high temperature can be maintained by the heat generated by the power generation. (Not shown).

  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 via the oxidant gas discharge communication hole 133 as shown in FIGS. The fuel cell stack 100 is connected to the branch portion 29 via a gas pipe (not shown) through the holes of the main body portion 28 and the branch portion 29 of the gas passage member 27 provided at the position of the agent gas discharge manifold 162. Is discharged outside. 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 via the fuel gas discharge communication hole 143, and further to the fuel gas. The gas passage member 27 provided at the position of the discharge manifold 172 passes through the body portion 28 and the branch portion 29 and passes through a gas pipe (not shown) connected to the branch portion 29 to the outside of the fuel cell stack 100. 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 a cross-sectional configuration of the fuel cell stack 100 at the position VI-VI in FIG. As described above, the fuel cell stack 100 is fastened by the 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 an integral member. The flange portion 228 is a portion whose diameter (a dimension in a direction orthogonal to the axial direction of the shaft portion 226) is larger than the shaft portion 226, and has a seating surface 229. The seating surface 229 is a surface on the shaft portion 226 side among the surfaces orthogonal to the axial direction of the shaft portion 226 in the flange portion 228. A screw portion 224 is formed at the end of the shaft portion 226 of the bolt 22 opposite to the flange portion 228. A male screw is formed on the outer peripheral surface of the screw portion 224.

  The bolt hole 109 includes a through hole formed in each power generation unit 102 and a through hole formed in the upper end plate 104. Further, a screw hole 103 communicating with the bolt hole 109 is formed in the lower end plate 106. 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. The bolt hole 109 and the screw hole 103 correspond to a through hole in the claims.

  The bolt 22 is inserted into the bolt hole 109, and the screw portion 224 formed on 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 extends in the vertical direction (Z-axis direction). The flange portion 228 is positioned on the upper side (Z-axis positive direction side) with respect to the shaft portion 226, and the seating surface 229 of the flange portion 228 is in contact with the upper surface of the upper end plate 104.

  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 (the upper surface of the interconnector 150). Insulating sheet 210 is formed with holes 212 that form 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. An insulating sheet 220 is interposed between the upper surface of the lower end plate 106 and the lowermost power generation unit 102 (the lower surface of the interconnector 150). A hole 222 communicating with the bolt hole 109 is formed in the insulating sheet 220. 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 powder sheet, a glass sheet, a glass ceramic composite agent, or the like. Therefore, in this embodiment, the pair of end plates 104 and 106 are electrically connected to the bolts 22, but the separator 120, the fuel electrode side frame 140, and the interconnector 150 in each power generation unit 102 are the bolts 22. Is not electrically connected to. The pair of end plates 104, 106, the separator 120, the fuel electrode side frame 140, and the interconnector 150 correspond to the conductive members in the claims. The separator 120, the fuel electrode side frame 140, and the interconnector 150 are This corresponds to the non-connected conductive member in the claims.

A-4. Configuration for insulation between the unconnected conductive member and the bolt 22:
FIG. 7 is an explanatory diagram showing an enlarged 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 a protective tube 300 having insulating properties. The protective tube 300 is made of an insulating material such as alumina, zirconia, or silicon nitride. The protective tube 300 is formed in each non-connected conductive member constituting the bolt hole 109 formed in a plurality of non-connected conductive members (separator 120, fuel electrode side frame 140, interconnector 150). The inner wall of the through hole) and the bolt 22 are disposed. Specifically, the protective tube 300 surrounds the outer periphery around the axis of the shaft portion 226 of the bolt 22, and among the plurality of non-connected conductive members, the first non-connected conductive member (FIG. 6). The second unconnected conductive member located at the lower end from the upper interconnector 150 of the first power generation unit 102 from the top in FIG. 6 (the lower interconnector 150 of the seventh power generation unit 102 from the top in FIG. 6) It extends to. More specifically, the protective tube 300 is a substantially cylindrical member, and is inserted into a bolt hole 109 formed in a plurality of non-conductive members (separator 120, fuel electrode side frame 140, interconnector 150). Has been. A shaft portion 226 of the bolt 22 is inserted into the protective tube 300. In other words, the protective tube 300 is disposed 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 around the axis of the protective tube 300. The thickness of the protective tube 300 is preferably substantially uniform over the entire length of the protective tube 300. The thickness of the protective tube 300 is preferably 1/3 or more of the distance in the surface direction between the bolt 22 and the inner wall of the bolt hole 109 formed in the non-connected conductive member. / 2 or more is more preferable. The protective tube 300 corresponds to a cylindrical member in the claims.

  Further, in the plane direction (XY plane direction) perpendicular to the vertical direction (Z-axis direction), the protective tube 300 and a plurality of nonconductive members (separator 120, fuel electrode side frame 140, interconnector 150) are formed. A first gap S <b> 1 is formed between the inner wall of the bolt hole 109. 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. In the surface direction, a second gap S <b> 2 is formed between the protective 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 only need to 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 protective 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 hole 105 formed in the upper end plate 104 and constituting the bolt hole 109 includes a first hole 105 </ b> A and a second hole 105 </ b> B. And have. The first hole portion 105A opens on 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-connected conductive member. A step surface 105C is formed between the first hole 105A and the second hole 105B. As shown in FIG. 6, the vertical distance L <b> 2 between the step surface 105 </ b> C of the upper end plate 104 and the upper surface of the insulating sheet 220 is longer than the total length L <b> 1 of the protective tube 300. In FIG. 6, the lower end of the protective tube 300 is in contact with the peripheral portion of the hole 222 on the upper surface of the insulating sheet 220, and the upper end of the protective tube 300 is separated from the step surface 105 </ b> C in the upper end plate 104. ing. As described above, the insulating sheet 220 is interposed between the lower end of the protective tube 300 and the lower end plate 106, so that the fuel can be produced in comparison with the configuration in which the protective tube 300 and the lower end plate 106 are in direct contact. The withstand voltage of the battery stack 100 is improved.

  In the state of FIG. 6, the upper end of the protective tube 300 is preferably located above the uppermost non-connected 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. Thereby, for example, even if the power generation unit 102 expands relative to the protection tube 300 due to a difference in thermal expansion between the protection tube 300 and the power generation unit 102, a short circuit between the unconnected conductive member and the bolt 22 is performed. It can suppress more reliably. Further, the protective tube 300 is not fixed in the bolt hole 109, and is disposed so as to be displaceable in the vertical direction and the surface direction. Note that the vertical gap between the protective tube 300 and the members constituting the fuel cell stack 100 may be formed at least before the fuel cell stack 100 is operated.

  6 shows the 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 portions 224 of the bolts 22 are screwed into the respective screw holes 103. The fuel cell stack 100 is fastened by the bolts 22 screwed into the screw holes 103. Further, the protective tube 300 described above is arranged in each of the four bolt holes 109 formed in the fuel cell stack 100.

A-5. Effects 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-conductive members (separator 120, fuel electrode side frame 140, interconnector 150). A protective tube 300 having an insulating property is disposed between the bolt 22 and the bolt 22. The protective tube 300 surrounds the outer periphery around the axis of the bolt 22 and extends from the first non-conductive conductive member located at the upper end to the second non-conductive conductive member located at the lower end. That is, the protective tube 300 is interposed between the plurality of unconnected conductive members and the bolt 22. Thereby, compared with the structure in which no member is interposed between the through hole formed in the non-connected conductive member and the fastening member, it is possible to suppress the short-circuit between the non-conductive conductive member and the bolt 22. .

  Further, according to the present embodiment, in the surface direction, the first gap S1 is formed between the protective tube 300 and the inner wall of the bolt hole 109 formed in the plurality of nonconductive members. Thereby, compared with the configuration in which no gap is formed between the bolt hole 109 and the protective tube 300, the thermal stress in the surface direction due to the difference in thermal expansion between the non-connected conductive member and the protective tube 300 is protected. As a result, for example, cracking of the protective tube 300 can be suppressed.

  Further, according to the present embodiment, the 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, compared to a configuration in which no gap is formed between the protective tube 300 and the bolt 22, 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 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 protective tube 300 can be displaced in the vertical direction within the bolt hole 109. As a result, both ends of the protective tube 300 in the vertical direction are caused by a difference in thermal expansion between the conductive member and the protective tube 300 compared to a configuration in which the vertical ends of the protective tube 300 are in contact with members constituting the fuel cell stack 100. It is suppressed that the thermal stress of an up-down direction arises in the protective tube 300, As a result, the crack of the protective tube 300 etc. can be suppressed, for example.
B. Variations:
The technology disclosed in the present specification is not limited to the above-described embodiment, and can be modified into various forms without departing from the gist thereof. For example, the following modifications are possible.

  The configuration of the single cell 110 or the fuel cell stack 100 in the above embodiment is merely an example, and various modifications can be made. 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 combined. 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 portion of the shaft portion 226 of the bolt 22 may be screwed into a through hole formed in the upper end plate 104. In the above-described embodiment, the insulating sheet 210 may not be provided, and instead, an insulating sheet may be disposed between the seating 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 a non-connected conductive member in the claims.

  Moreover, in the said embodiment, the protective tube 300 is not restricted to a substantially cylindrical shape, For example, a substantially rectangular tube shape etc. may be sufficient. Moreover, in the said embodiment, the protective tube 300 should just be cylindrical. Even in such a configuration, a short circuit between the non-connected conductive member and the bolt 22 can be suppressed.

  In the above embodiment, the first gap S1 does not have to be formed over the entire circumference around the axis of the protective tube 300, 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 nonconductive member in the bolt hole 109 by being formed. 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. In the above embodiment, the second gap S2 does not need to be formed over the entire circumference around the axis of the protective tube 300, and the second gap S2 is partly around the axis of the protective tube 300. It is only necessary 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. 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. Alternatively, both ends of the protective tube 300 in the vertical direction (Z-axis direction) may be in contact with members constituting the fuel cell stack 100 in the vertical direction.

  Further, in the above embodiment, it is not necessary to employ a configuration in which the protective tube 300 is disposed in all the bolt holes 109 formed in the fuel cell stack 100, and the protective tube 300 is disposed in at least one bolt hole 109. Any configuration may be adopted.

  In the above embodiment, the number of unit cells 110 included in the fuel cell stack 100 is merely an example, and the number of unit cells 110 is appropriately determined according to the output voltage required for the fuel cell stack 100 or the like. Moreover, the material which comprises each member in the said embodiment is an illustration to the last, and each member may be comprised with the other material.

  In the above embodiment, the SOFC that generates electricity using the electrochemical reaction between hydrogen contained in the fuel gas and oxygen contained in the oxidant gas is targeted. The present invention can be similarly applied to an electrolytic single cell that is a constituent unit of a solid oxide electrolytic cell (SOEC) that generates hydrogen by using hydrogen, and an electrolytic cell stack including a plurality of electrolytic single cells. The configuration of the electrolytic cell stack is well known as described in, for example, Japanese Patent Application Laid-Open No. 2006-81813, and thus will not be described in detail here. 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, when the electrolysis cell stack is operated, a voltage is applied between the two electrodes so that the air electrode 114 is positive (anode) and the fuel electrode 116 is negative (cathode). Water vapor as a raw material gas is supplied. As a result, an electrolysis reaction of water occurs in each electrolysis cell unit, hydrogen gas is generated in the fuel chamber 176, and hydrogen is taken out of the electrolysis cell stack through the communication hole. Also in the electrolytic cell stack having such a configuration, as in the above embodiment, if a cylindrical member is disposed between the through hole formed in the electrolytic cell stack and the fastening member, the conductive member and the fastening member Short circuit can be suppressed.

  In the above embodiment, the solid oxide fuel cell (SOFC) has been described as an example. However, the present invention is applicable to other types of fuel cells (or electrolytic cells) such as a molten carbonate fuel cell (MCFC). Applicable.

22: Bolt 26: Insulating sheet 27: Gas passage member 28: Body portion 29: Branch portion 100: Fuel cell stack 102: Power generation unit 103: Screw hole 104, 106: End plate 105: Hole 105A: First hole portion 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 electrode 116: Fuel electrode 120: Separator 121: Hole 124: Joining Portion 130: Air electrode side frame 131: Hole 132: Oxidant gas supply communication hole 133: Oxidant gas discharge communication hole 134: Air electrode side current collector 135: Current collector element 140: Fuel electrode side frame 141: Hole 142 : Fuel gas supply communication hole 143: Fuel gas discharge communication hole 144: Fuel electrode side current collector 145: Electrode Direction portion 146: Interconnector facing portion 147: Connection portion 149: Spacer 150: Interconnector 161: Oxidant gas introduction manifold 162: Oxidant gas discharge manifold 166: Air chamber 171: Fuel gas introduction manifold 172: Fuel gas discharge manifold 176 : Fuel chamber 210, 220: Insulating sheet 212, 222: Hole 224: Screw 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: Full length L2: Distance L3: Length OG: Oxidant gas OOG: Oxidant offgas S1: First gap S2: Second gap

Claims (4)

A plurality of single cells each including an electrolyte layer, an air electrode, and a fuel electrode, arranged side by side in a first direction;
A plurality of conductive members respectively disposed between both sides of the plurality of single cells in the first direction and between the single cells, the through holes penetrating the plurality of conductive members in the first direction. A plurality of conductive members formed,
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, a cylindrical shape having an insulating property is provided between the through hole formed in the plurality of non-connected conductive members that are not electrically connected to the fastening member and the fastening member. The members are arranged,
The cylindrical member surrounds the outer periphery around the axis of the fastening member, and among the plurality of non-conductive members, the first non-conductive material located at one end in the first direction, Extending to a second unconnected conductive member located at the other end in the first direction,
An electrochemical reaction cell stack characterized by that. The electrochemical reaction cell stack according to claim 1,
In a plane direction perpendicular to the first direction, a first gap is formed between an inner wall of the through hole formed in the plurality of non-connected conductive members and the cylindrical member.
An electrochemical reaction cell stack characterized by that. The electrochemical reaction cell stack according to claim 1 or 2,
At least one of both ends of the cylindrical member in the first direction is separated from a member constituting the electrochemical reaction cell stack in the first direction.
An electrochemical reaction cell stack characterized by that. In the electrochemical reaction cell stack according to any one of claims 1 to 3,
In a surface direction perpendicular to the first direction, a second gap is formed between the fastening member and the tubular member.
An electrochemical reaction cell stack characterized by that.

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