Electrolytic cell stack, electrolytic cell cartridge, electrolytic cell module, and method for manufacturing electrolytic cell stack

Abstract

The purpose of the present disclosure is to provide an electrolytic cell stack capable of increasing the amount of product generated by electrolysis while suppressing the temperature rise of the cell stack. An electrolytic cell stack (101) according to the present disclosure comprises: an electrolysis unit cell (105) that has a hydrogen electrode containing Ni, an oxygen electrode, and a solid electrolyte membrane and is formed in the circumferential direction of a base tube; and an interconnector that electrically connects a plurality of electrolysis unit cells arranged in the axial direction of the base tube. When the distance between the ends of the oxygen electrode, oriented in the axial direction of the base tube, in each electrolysis unit cell is defined as the width W of the electrolysis unit cell, and the area on the base tube in which the plurality of electrolysis unit cells are arranged is divided into a first end portion (10), a central portion (11), and a second end portion (12) along the axial direction, the widths W1, W3 of the electrolysis single cells (105b, 105c) positioned in the first end portion and / or the second end portion is 1.5 to 3 times greater than the width W2 of the electrolysis unit cell (105a) positioned in the central portion.

Description

Electrolysis cell stack, electrolysis cell cartridge, electrolysis cell module, and method for manufacturing an electrolysis cell stack

[0001] The present disclosure relates to electrolysis cell stacks, electrolysis cell cartridges, electrolysis cell modules, and methods for manufacturing electrolysis cell stacks.

[0002] Electrolysis cells, which produce hydrogen and oxygen by electrochemically decomposing water, are a hydrogen production method that does not involve the emission of carbon dioxide and have excellent environmental characteristics. Among these, solid oxide electrolysis cells (SOECs) use ceramics such as yttria-stabilized zirconia as the electrolyte and use high-temperature steam as the raw material, making it possible to produce hydrogen more efficiently than other electrolysis cells. For the purpose of decarbonization, carbon dioxide (CO ２ Co-electrolysis is also possible, using ethylenediamine dinitrate (EDTA) as a raw material and electrolytic hydrogen as a reducing agent to directly produce carbon monoxide (CO).

[0003] Patent Document 1 discloses a hydrogen generation system including a cell stack in which a plurality of electrolytic cells, each having a hydrogen electrode, a solid electrolyte membrane, and an oxygen electrode, are arranged on a substrate tube. In this hydrogen generation system, the SOEC described in Patent Document 1 has a hydrogen electrode made of a composite oxide of Ni and a zirconia-based electrolyte material.

[0004] Patent No. 7282968

[0005] Increasing the current through the SOEC accelerates the electrochemical decomposition (electrolysis) of water and increases the amount of hydrogen produced. However, the current through the SOEC cannot be simply increased.

[0006] Water electrolysis is an endothermic reaction. However, when a current is passed through an SOEC, Joule heat is generated. At low currents, the endothermic reaction is dominant, so there is no problem. However, when operating at high currents, the SOEC itself generates Joule heat, causing a temperature rise. When an SOEC is exposed to high temperatures, the Ni in the hydrogen electrode sinters, increasing the internal resistance of the SOEC and making stable electrolysis over long periods of time difficult.

[0007] When a cell stack equipped with multiple electrolysis cells is operated at a high current, heat generated by the high current cannot be dissipated. As a result, the temperature rises at the outlet side of the raw material gas (e.g., water vapor) flow. Typically, both ends of the cell stack are held in place by holding members made of metal materials that can withstand high temperatures. However, the durability of these holding members decreases when exposed to high temperatures. Therefore, the current density passed through the SOEC is limited to a range that does not exceed the allowable temperature of the holding members.

[0008] The present disclosure has been made in consideration of the above circumstances, and aims to provide an electrolysis cell stack, an electrolysis cell cartridge, an electrolysis cell module, and a method for manufacturing an electrolysis cell stack that can increase the amount of product produced by electrolysis while suppressing a temperature rise in the cell stack.

[0009] In order to solve the above problems, the electrolysis cell stack, electrolysis cell cartridge, electrolysis cell module, and method for manufacturing an electrolysis cell stack according to the present disclosure employ the following measures.

[0010] The present disclosure provides an electrolysis cell stack comprising: an electrolysis unit cell having a hydrogen electrode containing Ni, an oxygen electrode, and a solid electrolyte membrane sandwiched between the hydrogen electrode and the oxygen electrode, the electrolysis unit cell being formed in the circumferential direction of a base tube; and an interconnector electrically connecting a plurality of the electrolysis unit cells arranged in the axial direction of the base tube, wherein the distance from one end of the oxygen electrode to the other end of the electrolysis unit cell facing in the axial direction of the base tube is defined as the width of the electrolysis unit cell, and when an area on the base tube in which the plurality of electrolysis unit cells are arranged is divided into a first end portion, a central portion, and a second end portion along the axial direction, the width of the electrolysis unit cell located at the first end portion and / or the second end portion is 1.5 to 3 times larger than the width of the electrolysis unit cell located in the central portion.

[0011] The present disclosure provides an electrolysis cell cartridge including the electrolysis cell stack described above.

[0012] The present disclosure provides an electrolysis cell module including the electrolysis cell cartridge described above.

[0013] The present disclosure provides a method for manufacturing an electrolysis cell stack including: electrolysis unit cells each having a Ni-containing hydrogen electrode, an oxygen electrode, and a solid electrolyte membrane disposed between the hydrogen electrode and the oxygen electrode, the electrolysis unit cells being formed in the circumferential direction of a base tube; and an interconnector that electrically connects a plurality of the electrolysis unit cells arranged in the axial direction of the base tube, wherein the distance from one end of the oxygen electrode to the other end of the electrolysis unit cell facing in the axial direction of the base tube is defined as the width of the electrolysis unit cell; the region on the base tube in which the plurality of electrolysis unit cells are arranged is divided along the axial direction into a first end portion, a central portion, and a second end portion; and the width of the electrolysis unit cells located at the first end portion and / or the second end portion is formed to be 1.5 to 3 times larger than the width of the electrolysis unit cells located in the central portion.

[0014] According to the present disclosure, by arranging electrolytic cells that are wider at the ends (first end and / or second end) of a plurality of electrolytic unit cells arranged on a substrate tube than at the central portion, it is possible to increase the amount of product produced by electrolysis while suppressing a temperature rise in the electrolytic cell stack.

[0015] FIG. 5B is a diagram showing an embodiment of an electrolysis cell stack according to an embodiment of the present disclosure; FIG. 5C is an enlarged schematic cross-sectional view of a first end of a cell stack; FIG. 5D is a diagram showing an embodiment of an electrolysis cell module according to an embodiment of the present disclosure; FIG. 5E is a diagram showing an embodiment of a cross-section of an electrolysis cell cartridge according to an embodiment of the present disclosure; FIG. 5F is a schematic view of a cell stack of Example 2; FIG. 5G is a diagram showing simulation results of the axial temperature distribution of the cell stack shown in FIG. 5A; FIG. 5H is a diagram showing width conditions and simulation results of electrolysis unit cells in Examples 3 to 5 and Comparative Examples 3 and 4; FIG. 5I is a diagram showing width conditions and simulation results of electrolysis unit cells in Examples 5 to 11; FIG. 5J is a diagram showing configuration conditions of the cell part length and simulation results in Examples 5 and 11 to 16;

[0016] Hereinafter, an embodiment of an electrolysis cell stack, an electrolysis cell cartridge, an electrolysis cell module, and a method for manufacturing an electrolysis cell stack according to the present disclosure will be described with reference to the drawings.

[0017] In this disclosure, "electrolysis" means "water electrolysis" or "co-electrolysis".

[0018] In the following, for the sake of convenience, the positional relationship of each component described using the expressions "upper" and "lower" with respect to the plane of the paper indicates the vertically upper side and the vertically lower side, respectively. In this embodiment, for components that can obtain similar effects in the vertical direction and the horizontal direction, the vertical direction on the plane of the paper is not necessarily limited to the vertically upper and lower directions, but may correspond to, for example, the horizontal direction perpendicular to the vertical direction.

[0019] First Embodiment (Cell Stack) First, referring to Figures 1 and 2, a cylindrical cell stack using a substrate tube will be described as an example of this embodiment. If a substrate tube is not used, for example, the hydrogen electrode may be formed thick and serve as the substrate tube, and the present invention is not limited to the use of a substrate tube. In this embodiment, the substrate tube is described as having a cylindrical shape, but the cross section of the substrate tube is not necessarily limited to a circular shape as long as it is tubular, and may be, for example, elliptical. A cell stack such as a flat tubular cylinder in which the peripheral side surface of a cylinder is crushed vertically may also be used.

[0020] Here, Fig. 1 shows one aspect of a cell stack (electrolysis cell stack) according to an embodiment. Fig. 2 is an enlarged schematic cross-sectional view of a first end of the cell stack. The cell stack 101 includes, as an example, a cylindrical base tube 103, a plurality of electrolysis unit cells 105 formed on the outer peripheral surface of the base tube 103 and arranged in the axial direction of the base tube 103, and interconnectors 107 formed between adjacent electrolysis unit cells 105.

[0021] The electrolytic unit cell 105 is formed by stacking a hydrogen electrode 109, a solid electrolyte membrane 111, and an oxygen electrode 113. The solid electrolyte membrane 111 is sandwiched between the hydrogen electrode 109 and the oxygen electrode 113. The electrolytic unit cell 105 is formed in the circumferential direction of a base tube. The outer diameter of the base tube is 10 mm to 50 mm. The overall length of the base tube is 500 mm to 3000 mm.

[0022] The cell stack 101 includes a lead film 115 electrically connected, via an interconnector 107, to the oxygen electrode 113 of the electrolytic unit cell 105 formed at one end, which is the outermost end in the axial direction of the base tube 103, among the plurality of electrolytic unit cells 105 formed on the outer peripheral surface of the base tube 103, and also includes a lead film 115 electrically connected to the hydrogen electrode 109 of the electrolytic unit cell 105 formed at the other outermost end.

[0023] In this embodiment, the region on the substrate tube 103 in which the plurality of electrolytic unit cells 105 are arranged is referred to as the cell section 104. For example, 50 to 350 electrolytic unit cells 105 can be arranged in the cell section 104. The cell section 104 is divided into three regions: a first end section 10, a central section 11, and a second end section 12. The first end section 10, the central section 11, and the second end section 12 are arranged in this order along the axial direction of the substrate tube 103. In FIG. 1 , the first end section 10 is located upstream of the feed gas flow, and the second end section 12 is located downstream of the feed gas flow.

[0024] Each of the regions of the first end portion 10, the central portion 11, and the second end portion 12 includes a plurality of electrolytic unit cells 105. The width of the electrolytic unit cell 105a located in the central portion 11 may be, for example, 3 mm to 20 mm. The distance between adjacent electrolytic unit cells 105 may be, for example, 0.3 mm to 2 mm.

[0025] The widths of the electrolytic unit cells 105b, 105c located at the first end 10 and the second end 12 are 1.5 to 3 times larger than the width of the electrolytic unit cell 105a located at the central portion 11. The "width of the electrolytic unit cell" (W) corresponds to the distance (width) from one end to the other of the oxygen electrode 113 in one electrolytic unit cell 105, which faces the axial direction of the base tube 103.

[0026] The width (W1) of the electrolytic unit cell 105b located at the first end 10 may be equal to the width (W3) of the electrolytic unit cell 105c located at the second end 12. The widths (W1) of the multiple electrolytic unit cells 105b located at the first end 10 may be the same or may gradually narrow toward the central portion 11.

[0027] The width of the electrolytic unit cell 105 c located at the second end 12 may be larger than the width of the electrolytic unit cell 105 b located at the first end 10. The widths (W3) of the multiple electrolytic unit cells 105 c located at the second end 12 may be the same or may gradually narrow toward the central portion 11.

[0028] The cell portion 104 has a length L extending along the axial direction of the substrate tube 103. The length L of the cell portion is preferably about 50% to 90% of the total length of the substrate tube 103. The length L of the cell portion may be, for example, 300 mm to 2500 mm.

[0029] The cell length L is divided into three parts: a first end length (L1), a central length (L2), and a second end length (L3).

[0030] The cell part length L is the distance between the electrolytic single cells 105 arranged at both ends of the electrolytic single cells arranged in the longitudinal direction on the base tube, and specifically, as shown in FIG. 1 , it is the distance from the outer end (upper side in FIG. 1 ) of the oxygen electrode 113 of the electrolytic single cell 105 arranged at the most upstream side in the feed gas flow to the outer end (lower side in FIG. 1 ) of the oxygen electrode 113 of the electrolytic single cell 105 arranged at the most downstream side in the feed gas flow.

[0031] The first end length L1 is the distance from the outer end (upper side in Figure 1 ) of the oxygen electrode 113 of the electrolytic unit cell 105 located at the end (for example, the most upstream side in the raw material gas flow in Figure 1 ) of the section (division) to the outer end (lower side in Figure 1 ) of the oxygen electrode 113 of the electrolytic unit cell 105 located at the opposite end (for example, the most downstream side in the raw material gas flow in Figure 1 ) of the section.

[0032] The second end length L3 is the distance from the outer end (lower side in Figure 1 ) of the oxygen electrode 113 of the electrolytic unit cell 105 located at the end (for example, the most downstream side in the raw material gas flow in Figure 1 ) of the section (division) to the outer end (upper side in Figure 1 ) of the oxygen electrode 113 of the electrolytic unit cell 105 located at the opposite end (for example, the upstream side in the raw material gas flow in Figure 1 ) of the section.

[0033] The central portion length L2 is the remaining portion obtained by subtracting L1 and L3 from the cell portion length L.

[0034] The first end length L1 may be 5% or more and 20% or less of the cell portion length L. The central portion length L2 may be 60% or more and 90% or less of the cell portion length L. The second end length L3 may be 5% or more and 20% or less of the cell portion length L. The second end length L3 may be longer than the first end length L1.

[0035] Next, each component of the electrolytic unit cell 105 will be described. The substrate tube 103 is made of a porous material, for example, CaO-stabilized ZrO ２ (CSZ), a mixture of CSZ and nickel oxide (NiO) (CSZ+NiO), or Y ２ O ３ Stabilized ZrO ２ (YSZ), or MgAl ２ O ４ The base tube 103 supports the electrolytic unit cell 105, the interconnector 107, and the lead film 115, and also diffuses the source gas supplied to the inner peripheral surface of the base tube 103 through the pores of the base tube 103 to the hydrogen electrode 109 formed on the outer peripheral surface of the base tube 103.

[0036] The hydrogen electrode 109 is made of a composite oxide of Ni and a zirconia-based electrolyte material, such as Ni / YSZ, and has a thickness of 50 μm to 250 μm. The hydrogen electrode 109 may be formed by screen printing a slurry.

[0037] Examples of raw material gases that can be supplied to the hydrogen electrode 109 of the cell stack 101 and used include water vapor, water vapor and carbon dioxide, hydrogen, nitrogen and hydrogen, and the like.

[0038] YSZ, which has gas-tightness that makes it difficult for gas to pass through and high oxygen ion conductivity at high temperatures, is mainly used for the solid electrolyte membrane 111. The thickness of the solid electrolyte membrane 111 located on the surface of the hydrogen electrode 109 is 10 μm to 100 μm, and the solid electrolyte membrane 111 may be formed by screen printing a slurry.

[0039] The oxygen electrode 113 is made of, for example, LaSrMnO ３ based oxides, or LaCoO ３The cathode 113 is made of a silicon dioxide-based oxide, and the slurry is applied to the cathode 113 by screen printing or by using a dispenser.

[0040] The oxygen electrode 113 may have a two-layer structure. In this case, the oxygen electrode layer (oxygen electrode intermediate layer) on the solid electrolyte membrane 111 side is made of a material that exhibits high ionic conductivity and excellent catalytic activity. The oxygen electrode layer (oxygen electrode intermediate layer) on the solid electrolyte membrane 111 side is made of Sm-doped ceria, and the oxygen electrode layer (oxygen electrode conductive layer) on the oxygen electrode intermediate layer is made of Sr- and Ca-doped LaMnO. ３ When the oxygen electrode 113 has a two-layer structure, the width of the electrolytic unit cell is determined based on the oxygen electrode conductive layer.

[0041] The interconnector 107 is made of SrTiO ３ M1-xLxTiO ３ (where M is an alkaline earth metal element and L is a lanthanoid element), and a slurry is screen-printed. The interconnector 107 is a dense film that prevents the raw material gas supplied to the hydrogen electrode 109 and the oxidizing gas supplied to the oxygen electrode 113 from mixing. The interconnector 107 has stable durability and electrical conductivity in both oxidizing and reducing atmospheres. In adjacent electrolytic unit cells 105, this interconnector 107 electrically connects the oxygen electrode 113 of one electrolytic unit cell 105 to the hydrogen electrode 109 of the other electrolytic unit cell 105, and connects the adjacent electrolytic unit cells 105 in series.

[0042] The oxidizing gas is a gas containing approximately 15% to 30% oxygen, and a representative example is air.

[0043] The lead film 115 must have electronic conductivity and a thermal expansion coefficient close to that of the other materials constituting the cell stack 101. For this reason, a composite material of Ni and a zirconia-based electrolyte material, such as Ni / YSZ, or SrTiO ３ M such as １－ｘ L ｘ TiO ３(M is an alkaline earth metal element, and L is a lanthanoid element.) The lead film 115 supplies DC power to the plurality of electrolytic unit cells 105 connected in series by the interconnectors 107.

[0044] When external power is supplied between the hydrogen electrode 109 and the oxygen electrode 113 via the lead film 115, part of the high-temperature raw material gas (e.g., water vapor) supplied to the hydrogen electrode 109 receives electrons and is separated into hydrogen and oxygen ions, generating hydrogen. The separated oxygen ions pass through the inside of the solid electrolyte membrane 111 and move to the oxygen electrode 113, where they release electrons and become oxygen.

[0045] Next, a method for manufacturing a cell stack will be described. The base tube 103 is formed, for example, by extrusion molding. A hydrogen electrode slurry is applied to the base tube 103. The application width of the hydrogen electrode slurry is appropriately changed depending on the application position (first end 10, central portion 11, or second end 12). The application width at the first end 10 and / or second end 12 is made larger than the application width at the central portion 11. The application width of the hydrogen electrode slurry is preferably adjusted so that the widths (W1, W3) of the electrolytic unit cells 105b, 105c located at the first end 10 and / or second end 12 after the cell stack is formed are 1.5 to 3 times the width (W2) of the electrolytic unit cell 105a located at the central portion 11.

[0046] After the application of the slurry for the hydrogen electrode, the slurry for the solid electrolyte membrane and the slurry for the interconnector are applied in this order, with the application width adjusted to match the application width of the slurry for the hydrogen electrode.

[0047] The substrate tube 103 on which the slurry film of the hydrogen electrode 109, the solid electrolyte membrane 111, and the interconnector 107 is formed is co-sintered in the atmosphere at a sintering temperature of, for example, 1350°C to 1450°C.

[0048] Next, the slurry for the oxygen electrode is applied onto the co-sintered substrate tube 103. The application width is adjusted to match the application width of the slurry for the hydrogen electrode.

[0049] The base tube 103 on which the slurry film of the oxygen electrode 113 has been formed is sintered in the atmosphere at a sintering temperature of, for example, 1100° C. to 1250° C. The sintering temperature here is set to be lower than the co-sintering temperature after forming the interconnector 107 from the base tube 103.

[0050] This provides a cell stack 101 in which the widths of the electrolytic single cells 105b, 105c located at the first end 10 and / or the second end 12 are 1.5 to 3 times the width (W2) of the electrolytic single cell 105a located in the central portion 11.

[0051] (SOEC Module) Next, the electrolysis cell cartridge and electrolysis cell module according to this embodiment will be described with reference to Fig. 3 and Fig. 4. Fig. 3 shows one embodiment of a solid oxide electrolysis (SOEC) module according to this embodiment. Fig. 4 shows a cross-sectional view of one embodiment of a solid oxide electrolysis (SOEC) cartridge according to this embodiment.

[0052] 3 , the electrolysis cell module 201 includes, for example, a plurality of SOEC cartridges 203 and a module container 205 that houses the plurality of SOEC cartridges 203. The SOEC module 201 includes a raw material gas supply pipe 207, a plurality of raw material gas supply branch pipes 207a, a raw material gas discharge pipe 209, and a plurality of raw material gas discharge branch pipes 209a. The SOEC module 201 also includes an oxidizing gas supply pipe (not shown), an oxidizing gas supply branch pipe (not shown), an oxidizing gas discharge pipe (not shown), and a plurality of oxidizing gas discharge branch pipes (not shown).

[0053] The raw material gas supply pipe 207 is provided inside the module container 205 and is connected to a raw material gas supply unit that supplies raw material gas with a predetermined gas composition and a predetermined flow rate corresponding to the amount of hydrogen generated by the SOEC module 201, and is also connected to a plurality of raw material gas supply branch pipes 207a. This raw material gas supply pipe 207 branches and guides the raw material gas supplied from the raw material gas supply unit at a predetermined flow rate to the plurality of raw material gas supply branch pipes 207a. The raw material gas supply branch pipes 207a are connected to the raw material gas supply pipe 207 and are also connected to the plurality of SOEC cartridges 203. This raw material gas supply branch pipe 207a guides the raw material gas supplied from the raw material gas supply pipe 207 to the plurality of SOEC cartridges 203 at a substantially uniform flow rate, thereby substantially uniforming the hydrogen generation capabilities of the plurality of SOEC cartridges 203.

[0054] The raw material gas discharge pipe 209a is connected to the plurality of SOEC cartridges 203 and is also connected to the raw material gas discharge pipe 209. This raw material gas discharge pipe 209a guides the exhaust raw material gas discharged from the SOEC cartridges 203 to the raw material gas discharge pipe 209. The raw material gas discharge pipe 209 is connected to the plurality of raw material gas discharge pipes 209a and is partially disposed outside the module container 205. This raw material gas discharge pipe 209 guides the exhaust raw material gas discharged at a substantially uniform flow rate from the raw material gas discharge pipe 209a to the outside of the module container 205.

[0055] The module container 205 is made of a material that is pressure-resistant and corrosion-resistant against oxidizing agents such as oxygen contained in oxidizing gases. For example, a stainless steel material such as SUS304 is suitable.

[0056] Here, in this embodiment, a configuration in which multiple SOEC cartridges 203 are grouped together and stored in a module container 205 is described, but this is not limited to this, and for example, a configuration in which the SOEC cartridges 203 are not grouped together but are stored in a module container 205 is also possible.

[0057] 4, the SOEC cartridge 203 includes a plurality of cell stacks 101, an electrolysis chamber 215, a raw material gas supply header 217, a raw material gas discharge header 219, an oxidizing gas (air) supply header 221, and an oxidizing gas discharge header 223. The SOEC cartridge 203 includes an upper tube plate 225a, a lower tube plate 225b, an upper insulator 227a, and a lower insulator 227b. In this embodiment, the SOEC cartridge 203 has a structure in which the raw material gas supply header 217, raw material gas discharge header 219, oxidizing gas supply header 221, and oxidizing gas discharge header 223 are arranged as shown in Figure 4, so that the raw material gas and oxidizing gas flow in opposite directions inside and outside the cell stack 101. However, this is not necessarily required, and for example, the raw material gas and oxidizing gas may flow in parallel inside and outside the cell stack 101, or the oxidizing gas may flow in a direction perpendicular to the longitudinal direction of the cell stack 101.

[0058] The electrolysis chamber 215 is a region formed between the upper insulator 227a and the lower insulator 227b. This electrolysis chamber 215 is a region in which the electrolysis unit cells 105 of the cell stack 101 are disposed, and is a region in which hydrogen is generated by electrochemically reacting a raw material gas with an oxidizing gas. The temperature near the center of the electrolysis chamber 215 in the longitudinal direction of the cell stack 101 may be monitored by a temperature measurement unit (such as a temperature sensor or a thermocouple). During steady-state operation of the electrolysis cell module 201, the electrolysis chamber 215 has a high-temperature atmosphere of approximately 700°C to 1000°C.

[0059] The raw material gas supply header 217 is an area surrounded by the upper casing 229a and upper tube plate 225a of the SOEC cartridge 203, and is connected to the raw material gas supply branch pipe 207a via raw material gas supply holes 231a provided in the upper part of the upper casing 229a. The multiple cell stacks 101 are joined to the upper tube plate 225a with seal members 237a, and the raw material gas supply header 217 guides the raw material gas, which is supplied from the raw material gas supply branch pipe 207a via the raw material gas supply holes 231a, into the interiors of the base tubes 103 of the multiple cell stacks 101 at a substantially uniform flow rate, thereby making the amount of hydrogen produced by the multiple cell stacks 101 substantially uniform.

[0060] The raw material gas discharge header 219 is an area surrounded by the lower casing 229b and lower tube plate 225b of the SOEC cartridge 203, and is connected to a raw material gas discharge branch pipe 209a (not shown) through a raw material gas discharge hole 231b provided in the lower casing 229b. The plurality of cell stacks 101 are joined to the lower tube plate 225b with a seal member 237b, and the raw material gas discharge header 219 collects the exhaust raw material gas that passes through the insides of the base tubes 103 of the plurality of cell stacks 101 and is supplied to the raw material gas discharge header 219, and leads it to the raw material gas discharge branch pipe 209a through the raw material gas discharge hole 231b.

[0061] An oxidizing gas having a predetermined gas composition and a predetermined flow rate corresponding to the amount of hydrogen generated by the SOEC module 201 is branched into an oxidizing gas supply branch pipe and supplied to a plurality of SOEC cartridges 203. The oxidizing gas supply header 221 is an area surrounded by a lower casing 229b, a lower tube sheet 225b, and a lower heat insulator 227b of the SOEC cartridge 203, and is connected to an oxidizing gas supply branch pipe (not shown) through an oxidizing gas supply hole 233a provided on the side surface of the lower casing 229b. The oxidizing gas supply header 221 guides the oxidizing gas at a predetermined flow rate, which is supplied from the oxidizing gas supply branch pipe (not shown) through the oxidizing gas supply hole 233a, to the electrolysis chamber 215 via an oxidizing gas supply gap 235a (described later).

[0062] The oxidizing gas discharge header 223 is an area surrounded by the upper casing 229a, upper tube plate 225a, and upper heat insulator 227a of the SOEC cartridge 203, and is connected to an oxidizing gas discharge branch pipe (not shown) through oxidizing gas discharge holes 233b provided on the side surface of the upper casing 229a. The oxidizing gas discharge header 223 guides the exhaust oxidizing gas supplied to the oxidizing gas discharge header 223 from the electrolysis chamber 215 through an oxidizing gas discharge gap 235b (described later) to the oxidizing gas discharge branch pipe (not shown) through the oxidizing gas discharge holes 233b.

[0063] The upper tube plate 225a is fixed to the side plate of the upper casing 229a between the top plate of the upper casing 229a and the upper insulator 227a so that the upper tube plate 225a, the top plate of the upper casing 229a, and the upper insulator 227a are approximately parallel to each other. The upper tube plate 225a has a plurality of holes corresponding to the number of cell stacks 101 provided in the SOEC cartridge 203, and the cell stacks 101 are inserted into the holes. The upper tube plate 225a airtightly supports one end of the plurality of cell stacks 101 via either or both of a sealing member 237a and an adhesive member, and also isolates the raw material gas supply header 217 from the oxidizing gas discharge header 223.

[0064] The upper heat insulator 227a is disposed at the lower end of the upper casing 229a so that the upper heat insulator 227a, the top plate of the upper casing 229a, and the upper tube plate 225a are substantially parallel to each other, and is fixed to the side plate of the upper casing 229a. The upper heat insulator 227a has a plurality of holes formed therein corresponding to the number of cell stacks 101 provided in the SOEC cartridge 203. The diameters of the holes are set larger than the outer diameters of the cell stacks 101. The upper heat insulator 227a has an oxidizing gas discharge gap 235b formed between the inner surface of the hole and the outer surface of the cell stack 101 inserted through the upper heat insulator 227a.

[0065] The upper heat insulator 227a separates the electrolysis chamber 215 from the oxidizing gas discharge header 223, and prevents the atmosphere surrounding the upper tube sheet 225a from becoming too hot, thereby reducing its strength and increasing corrosion caused by the oxidizing agent contained in the oxidizing gas. To prevent the upper tube sheet 225a and other components from being thermally deformed due to the temperature difference caused by exposure to the high temperature in the electrolysis chamber 215, a metal material with high temperature resistance, such as a Ni-based alloy, may be used. The upper heat insulator 227a guides the exhaust oxidizing gas, which has passed through the electrolysis chamber 215 and been exposed to high temperatures, through the oxidizing gas discharge gap 235b and into the oxidizing gas discharge header 223.

[0066] According to this embodiment, the structure of the SOEC cartridge 203 described above allows the raw material gas and the exhaust oxidizing gas to flow in opposite directions between the inside and outside of the cell stack 101. As a result, heat exchange occurs between the exhaust oxidizing gas and the raw material gas supplied to the electrolysis chamber 215 through the inside of the substrate tube 103, and the exhaust oxidizing gas is cooled to a temperature at which the upper tube plate 225a, etc., made of a metallic material, will not undergo deformation, such as buckling, before being supplied to the oxidizing gas discharge header 223. The raw material gas is heated by heat exchange with the exhaust oxidizing gas discharged from the electrolysis chamber 215 and is supplied to the electrolysis chamber 215. As a result, raw material gas preheated to a temperature suitable for hydrogen generation can be supplied to the electrolysis chamber 215 without using a heater or the like.

[0067] The lower tube sheet 225b is fixed to the side plate of the lower casing 229b between the bottom plate of the lower casing 229b and the lower insulator 227b so that the lower tube sheet 225b, the bottom plate of the lower casing 229b, and the lower insulator 227b are approximately parallel to each other. The lower tube sheet 225b has a plurality of holes corresponding to the number of cell stacks 101 provided in the SOEC cartridge 203, and the cell stacks 101 are inserted into the holes. The lower tube sheet 225b airtightly supports the other ends of the plurality of cell stacks 101 via either or both of a sealing member 237b and an adhesive member, and also isolates the raw material gas discharge header 219 from the oxidizing gas supply header 221.

[0068] The lower heat insulator 227b is disposed at the upper end of the lower casing 229b so that the lower heat insulator 227b, the bottom plate of the lower casing 229b, and the lower tube plate 225b are substantially parallel to each other, and is fixed to the side plate of the lower casing 229b. The lower heat insulator 227b has a plurality of holes formed therein corresponding to the number of cell stacks 101 provided in the SOEC cartridge 203. The diameters of the holes are set larger than the outer diameters of the cell stacks 101. The lower heat insulator 227b has an oxidizing gas supply gap 235a formed between the inner surface of the hole and the outer surface of the cell stack 101 inserted through the lower heat insulator 227b.

[0069] The lower heat insulator 227b separates the electrolysis chamber 215 from the oxidizing gas supply header 221, and prevents the atmosphere around the lower tube sheet 225b from becoming too hot, resulting in a decrease in strength and increased corrosion due to the oxidizing agent contained in the oxidizing gas. The lower tube sheet 225b and other components are made of a metal material that is resistant to high temperatures, such as Inconel, and this prevents the lower tube sheet 225b and other components from being thermally deformed due to increased temperature differences within the lower tube sheet 225b when exposed to high temperatures. The lower heat insulator 227b guides the oxidizing gas supplied to the oxidizing gas supply header 221 through the oxidizing gas supply gap 235a to the electrolysis chamber 215.

[0070] According to this embodiment, the structure of the SOEC cartridge 203 described above allows the exhaust feed gas and the oxidizing gas to flow in opposite directions between the inside and outside of the cell stack 101. As a result, the exhaust feed gas that passes through the inside of the substrate tube 103 and the electrolysis chamber 215 exchanges heat with the oxidizing gas supplied to the electrolysis chamber 215, and is cooled to a temperature at which the lower tube plate 225b made of a metal material and the like do not undergo deformation such as buckling, and is supplied to the feed gas discharge header 219. The oxidizing gas is heated by heat exchange with the exhaust feed gas and is supplied to the electrolysis chamber 215. As a result, the oxidizing gas heated to a temperature required for hydrogen generation can be supplied to the electrolysis chamber 215 without using a heater or the like.

[0071] Next, the basis for setting the width of the electrolytic single cell 105 and the length (L3) of the first end 10 (L1) and the second end 12 will be described.

[0072] (Test 1) The axial temperature distribution was simulated in a cell stack (Examples 1 and 2) in which the widths of the electrolytic unit cells 105b, 105c located at the first end 10 or the first end 10 and the second end 12 were larger than the width of the electrolytic unit cell 105a located at the central portion 11. As a control, a similar simulation was also performed on a conventional cell stack in which the widths of the electrolytic unit cells 105 located at the first end 10, the central portion 11, and the second end 12 were all the same (Comparative Examples 1 and 2). For the simulation, the change in cell resistance was calculated from the difference in electrode area due to the change in electrolytic cell width, and the change in heat balance was calculated based on the resistance value and the amount of heat generated by the current. The cell stack length was kept constant, and the amount of hydrogen produced was calculated from the current value and the number of cells, taking into account that the number of cells changed due to changes in cell dimensions.

[0073] The widths (W1, W2, W3) of the electrolytic single cells located at the first end 10, the central portion 11, and the second end 12 were set as follows: Comparative Example 1: W1 = W2 = W3 (standard current) Comparative Example 2: W1 = W2 = W3 (high current) Example 1: W1 > W2 = W3 (high current) Example 2: W1 = W3 > W2 (high current)

[0074] The width of the electrolytic single cells located in the same section was the same in Comparative Examples 1 and 2 and Examples 1 and 2. The size of the base tube 103, the axial length (L) of the cell section 104, and the axial lengths (L1, L2, L3) of the first end section 10, central section 11, and second end section 12 relative to the length (L) were all the same. The current passed through Comparative Example 2 and Examples 1 and 2 was higher than that passed through Comparative Example 1.

[0075] FIG. 5A is a schematic diagram of a cell stack of Example 2. FIG. 5B shows the results of a simulation of the axial temperature distribution of the cell stack shown in FIG. 5A. FIG. 5B also shows the temperature distributions of Examples 1 and 2 and Comparative Examples 1 and 2. In FIG. 5B, the horizontal axis represents the temperature of the cell stack (°C), and the vertical axis represents the axial length (mm) of the cell stack (substrate tube). The length on the vertical axis is set to 0 at the bottom of the second end (the end opposite to the central portion). The raw material gas flows from the first end side to the second end side of the cell stack. Note that the temperature of the cell stack may also refer to the temperature inside the electrolysis chamber 215, which is located at the same position as the axial length of the cell stack.

[0076] In both Comparative Examples 1 and 2 and Examples 1 and 2, the temperature tended to be low at the axial ends of the cell stack and highest in the central portion. Comparing Comparative Examples 1 and 2, the maximum temperature of the cell stack was higher in Comparative Example 2, which used a higher current. When a current is passed through the cell stack, Joule heat is generated, causing the temperature of the cell stack to rise. Joule heat is (current) ２ × resistance, so if you increase the current, more Joule heat will be generated.

[0077] Comparing Comparative Example 2 with Examples 1 and 2 in which the same current was passed, the maximum temperatures of Examples 1 and 2, which included wide electrolytic single cells, were lower than that of Comparative Example 2. It was confirmed that the maximum temperature of the cell stack can be reduced by arranging electrolytic single cells at the first end 10 and / or the second end 12 that are wider than the width of the electrolytic single cell 105a located in the central portion 11. If the temperature of the cell stack becomes too high, Ni in the hydrogen electrode will sinter, increasing the internal resistance of the electrolytic single cell and leading to a deterioration in the durability of the cell stack itself. Therefore, it is beneficial to be able to reduce the maximum temperature.

[0078] Both ends of the cell stack are held by tube sheets. If the temperature of the cell stack becomes too high, it will lead to deterioration of the tube sheets. The results in Fig. 5B suggest that by arranging electrolysis unit cells at the first end portion 10 and / or the second end portion 12 that are wider than the width of the electrolysis unit cell 105a located in the central portion 11, it is possible to suppress deterioration of the tube sheets that support the cell stack.

[0079] Comparing Examples 1 and 2, the maximum temperature was lower in Example 2, which included wide electrolytic single cells at both ends of the cell part 104. This result suggests that the temperature suppression effect can be increased by arranging wide electrolytic single cells at both the first end 10 and the second end 12, or by increasing the number of wide electrolytic single cells.

[0080] Increasing the current density flowing through the cell stack results in a corresponding increase in the decomposition of the source gas, resulting in an increase in the amount of hydrogen produced. In Examples 1 and 2, even when a higher current is passed through the cell stack, the maximum temperature of the cell stack can be kept lower than in the past. The maximum temperature in Example 2 was similar to that of Comparative Example 1, which had a lower current density.

[0081] (Test 2) For cell stacks (Examples 3 to 11) in which the widths of the electrolytic single cells located at the first end, center, and second end were varied, operation was simulated at an average voltage of 1.5 V and a maximum temperature setting of 950°C, and the current density, maximum temperature (°C) of the cell stack (substrate tube), lower tube sheet temperature (°C), and hydrogen production amount were calculated. The hydrogen production amount was expressed as a ratio, with the hydrogen production amount in Comparative Example 1 set to 1. The simulation was performed by calculating the change in cell resistance from the difference in electrode area due to the change in electrolytic cell width, and then calculating the change in heat balance based on the resistance value and the heat generation amount due to the current. The cell stack length was kept constant, and considering that the number of cells changes due to changes in cell dimensions, the hydrogen production amount was calculated from the current value and the number of cells. The percentages of the first end length (L1), center length (L2), and second end length (L3) relative to 100% cell length were 10%, 80%, and 10%, respectively.

[0082] 6 and 7 show the width conditions of the electrolytic single cell and the simulation results in each example.

[0083] In this test, the current density was set so that the maximum temperature of the cell stack would be 950°C. Fig. 6 shows that, compared to Comparative Examples 3 and 4 in which all of the electrolysis unit cells included in the cell portion had the same width, Examples 3 to 5 in which wider electrolysis unit cells were arranged at the first end and / or second end than at the central portion were able to pass a larger current and produce a larger amount of hydrogen. Comparing Examples 3 to 5 suggests that Example 5 in which wider electrolysis unit cells were arranged at both the first end and the second end was able to pass the largest current and produce the largest amount of hydrogen.

[0084] 7 shows that the current density and the amount of hydrogen production could be increased in Examples 5 to 9, in which the widths of the electrolysis unit cells located at the first end and the second end were 1.5 to 3 times larger than the width of the electrolysis unit cell located in the central portion. The lower tube sheet temperature in Examples 5 to 9 was also lower than that of Comparative Example 3.

[0085] Comparing Example 5 and Example 7, the current density and amount of hydrogen production were higher in Example 7, in which the width (W3) of the electrolytic single cell located at the second end was doubled and made larger than the width (W1) of the electrolytic single cell located at the first end, than in Example 5, in which the width of the electrolytic single cell was doubled at both the first end and the second end. This suggests that the width of the electrolytic single cell located at the second end has a greater effect on the current density and amount of hydrogen production.

[0086] Example 10, in which the width of the electrolytic single cells located at the first end and the second end was 1.3 times larger than that of the central portion, had the lowest allowable current density among Examples 5 to 11. Example 11 had the same current density as Examples 5 and 6, but the amount of hydrogen produced was low.

[0087] In Examples 5 to 11, the axial lengths (L1, L3) of the first end and the second end are the same. Increasing the width of the electrolysis unit cells reduces the number of electrolysis unit cells that can be placed within the first end and the second end, resulting in a reduction in the total number of electrolysis unit cells in the cell unit. The number of electrolysis unit cells affects the amount of hydrogen produced. In Example 11, the width of the electrolysis unit cells was increased too much, resulting in a reduction in the number of electrolysis unit cells, which is thought to have affected the amount of hydrogen produced. In Examples 8 and 9, as in Example 7, the number of electrolysis unit cells in the cell unit was reduced, but the increase in the current density that could be passed compensated for the effect on the amount of hydrogen produced of the reduction in the number of electrolysis unit cells, which is thought to have resulted in an increase in the amount of hydrogen produced.

[0088] 6 and 7 show a tendency that the lower tube sheet temperature decreases as the width of the electrolytic unit cells arranged at the first end and the second end increases.

[0089] (Test 3) For cell stacks in which the lengths of the first end, central portion, and second end of the cell portion (lengths in the axial direction of the substrate tube) were changed, operation was simulated at an average voltage of 1.5 V and a maximum temperature setting of 950°C, and the current density, maximum temperature (°C) of the cell stack (substrate tube), lower tube sheet temperature (°C), and hydrogen production amount were calculated. The size of the cell stack and the total length of the cell portion were the same in each example. The hydrogen production amount was expressed as a ratio, with the hydrogen production amount in Comparative Example 1 set to 1. The simulation was performed by calculating the change in cell resistance from the difference in electrode area due to changes in electrolytic cell width, and then calculating the change in heat balance based on the resistance value and heat generation amount due to current. The cell stack length was kept constant, and the hydrogen production amount was calculated from the current value and number of cells, taking into account that the number of cells changes due to changes in cell dimensions. The widths (W1, W3) of the electrolytic unit cells located at the first end and second end were twice as large as that of the central portion (W2).

[0090] FIG. 8 shows the configuration conditions of the cell section length and the simulation results in each example.

[0091] In Examples 5, 11 to 16, in which the widths of the electrolytic unit cells located at the first end and the second end were twice as large as that of the central portion, the results showed that the current density that could be passed through the cell portion and the amount of hydrogen produced in the cell portion were higher than those in Comparative Examples 3 and 4. In Examples 5, 11 to 16, the lower tube sheet temperature was also lower than that in Comparative Examples 3 and 4.

[0092] The amount of hydrogen generated was particularly high in Examples 5, 11 to 14, in which the first end length and the second end length were each 5% to 20% of the total length (100%) of the cell portion, and especially in Examples 5, 11, and 12, in which the first end length and the second end length were each 5% to 10%.

[0093] In Example 15, in which the length ratio of the first end and the second end to the total length of the cell unit was small, the number of electrolysis unit cells that could be arranged in the cell unit was large, but the current density that could be passed through the cell unit was not increased as much as in the other Examples. In Example 16, in which the length ratio of the first end and the second end to the total length of the cell unit was large, the current density that could be passed through the cell unit increased, but the number of electrolysis unit cells that could be arranged in the cell unit decreased. This decrease in the number of electrolysis unit cells is thought to be the reason why the amount of hydrogen produced in Example 16 was lower than in the other Examples.

[0094] In Example 11, the first end length was the same as in Example 5, but the second end length was longer than in Example 5. A longer second end length increases the number of electrolysis unit cells that can be arranged within the second end. That is, in Example 11, a larger number of wide electrolysis unit cells were arranged within the second end than in Example 5. The amount of hydrogen produced in Example 11 was greater than that in Example 5.

[0095] On the other hand, in Example 11, the second end length was the same as in Example 13, but the first end length was shorter than in Example 5. In Example 11, the amount of hydrogen produced was greater than in Example 13, despite the fact that the number of wide electrolysis unit cells arranged at the first end was smaller.

[0096] FIG. 8 shows that the lower tube sheet temperature tends to decrease when the first end length and the second end length are increased.

[0097] <Additional Notes> The electrolytic cell stack, electrolytic cell cartridge, electrolytic cell module, and method for manufacturing the electrolytic cell stack described in the above-described embodiments can be understood, for example, as follows.

[0098] The electrolysis cell stack (101) according to a first aspect of the present disclosure comprises electrolysis unit cells (105) each having a Ni-containing hydrogen electrode (109), an oxygen electrode (113), and a solid electrolyte membrane (111) and formed in the circumferential direction of a base tube (103), and an interconnector (107) that electrically connects a plurality of electrolysis unit cells arranged in the axial direction of the base tube, wherein the distance from one end of the oxygen electrode facing the axial direction of the base tube in one of the electrolysis unit cells is defined as the width (W) of the electrolysis unit cell, and when the region on the base tube in which the plurality of electrolysis unit cells are arranged is divided along the axial direction into a first end portion (10), a central portion (11), and a second end portion (12), the widths (W1, W3) of the electrolysis unit cells located at the first end portion and / or the second end portion are larger than the width (W2) of the electrolysis unit cells located in the central portion.

[0099] When the width of the electrolytic unit cell is large (wide), the amount of heat generated (Joule heat) per electrolytic unit cell decreases, but the amount of ion migration and current density per electrolytic unit cell remain unchanged. Therefore, by arranging electrolytic cells that are wider at the ends (first end and / or second end) of the multiple electrolytic unit cells arranged on the base tube than at the center, it becomes possible to increase the amount of product produced by electrolysis per electrolytic cell stack while suppressing the temperature rise in the electrolytic cell stack.

[0100] An electrolysis cell stack according to a second aspect of the present disclosure is, in the above-described first aspect, wherein a width of the electrolysis unit cell located at the first end and / or the second end is 1.5 to 3 times the width of the electrolysis unit cell located in the central portion.

[0101] If the width of the electrolysis unit cell is too small, the temperature of the cell stack is likely to rise, and if it is too large, the electrolysis capacity decreases. By making the width of the electrolysis unit cell located at the first end and / or the second end 1.5 to 3 times larger than that of the central part, it is possible to achieve a good balance between the ability to suppress temperature rise and the electrolysis capacity, and to obtain a large amount of electrolysis product.

[0102] An electrolysis cell stack according to a third aspect of the present disclosure is, in the first or second aspect described above, wherein a width of the electrolysis unit cell located at the first end is equal to a width of the electrolysis unit cell located at the second end.

[0103] By making the widths of the electrolytic unit cells at the first end and the second end equal, manufacturing becomes easier.

[0104] An electrolysis cell stack according to a fourth aspect of the present disclosure is, in the first or second aspect described above, wherein the first end is an end on the upstream side in the gas flow direction within the base tube, the second end is an end on the downstream side in the gas flow direction within the base tube, and the width of the electrolysis unit cell located at the second end is larger than the width of the electrolysis unit cell located at the first end.

[0105] The electrolysis cell stack has the highest temperature in the center, and the temperatures at both ends are lower than that of the center. However, because the temperature of the source gas increases when passing through the center, the temperature of the second end downstream in the gas flow direction is less likely to decrease than that of the first end upstream. By making the width of the electrolysis unit cell located at the second end larger than that of the first end and suppressing the generation of Joule heat at the second end, it becomes easier to ensure the allowable temperature of the members that hold the electrolysis cell stack even when the maximum temperature is set high.

[0106] An electrolysis cell stack according to a fifth aspect of the present disclosure is, in any one of the first to fourth aspects, such that the axial length (L1) of the first end is 5% or more and 20% or less of the total axial length (L) of the central portion, the first end, and the second end.

[0107] Increasing (lengthening) the region including the wide electrolysis unit cells reduces the number of electrolysis unit cells arranged in the entire electrolysis cell stack. If the total number of electrolysis unit cells is reduced, the total amount of electrolysis products also decreases accordingly. By setting the length of the first end within the above range, it is possible to compensate for the effect of the reduction in the number of electrolysis unit cells and increase the amount of electrolysis products.

[0108] An electrolysis cell stack according to a sixth aspect of the present disclosure is, in any one of the first to fifth aspects, such that the axial length (L3) of the second end is 5% or more and 20% or less of the sum of the axial lengths (L) of the central portion, the first end, and the second end.

[0109] By setting the length of the second end portion within the above range, it is possible to compensate for the influence of a decrease in the number of electrolysis unit cells and increase the amount of electrolysis products.

[0110] An electrolytic cell stack according to a seventh aspect of the present disclosure is any one of the first to sixth aspects, wherein the first end is an end upstream in the gas flow direction within the base tube, the second end is an end downstream in the gas flow direction within the base tube, and the axial length of the second end is greater than the axial length of the first end.

[0111] By making the length of the second end longer than the length of the first end, the generation of Joule heat at the second end can be more effectively suppressed.

[0112] An electrolytic cell cartridge according to an eighth aspect of the present disclosure includes the electrolytic cell stack according to any one of the first to seventh aspects.

[0113] An electrolysis cell module according to a ninth aspect of the present disclosure includes the electrolysis cell cartridge according to the eighth aspect.

[0114] A ninth aspect of the present disclosure provides a method for manufacturing an electrolysis cell stack including: an electrolysis unit cell having a Ni-containing hydrogen electrode, an oxygen electrode, and a solid electrolyte membrane disposed between the hydrogen electrode and the oxygen electrode, the electrolysis unit cell being formed in the circumferential direction of a base tube; and an interconnector electrically connecting a plurality of the electrolysis unit cells arranged in the axial direction of the base tube, wherein the distance from one end of the oxygen electrode to the other end of the electrolysis unit cell facing in the axial direction of the base tube is defined as the width of the electrolysis unit cell; an area on the base tube in which the plurality of electrolysis unit cells are arranged is divided into a first end portion, a central portion, and a second end portion along the axial direction; and the width of the electrolysis unit cells located at the first end portion and / or the second end portion is formed larger than the width of the electrolysis unit cells located in the central portion.

[0115] 10 First end 11 Central portion 12 Second end 101 Cell stack (electrolysis cell stack) 103 Substrate tube 105 Electrolysis unit cell 107 Interconnector 109 Hydrogen electrode 111 Solid electrolyte membrane 113 Oxygen electrode 115 Lead film 201 Electrolysis cell module (SOEC module) 203 Electrolysis cell cartridge (SOEC cartridge) 207 Raw material gas supply pipe 209 Raw material gas discharge pipe 215 Electrolysis chamber 217 Raw material gas supply header 219 Raw material gas discharge header 225a Upper tube plate 225b Lower tube plate

Claims

1. An electrolytic cell stack having a hydrogen electrode containing Ni, an oxygen electrode, and a solid electrolyte membrane sandwiched between the hydrogen electrode and the oxygen electrode, an electrolytic single cell formed in the circumferential direction of a substrate tube, and an interconnector for electrically connecting a plurality of the electrolytic single cells arranged in the axial direction of the substrate tube, wherein, in one of the electrolytic single cells, the distance from one end to the other end of the oxygen electrode facing the axial direction of the substrate tube is defined as the width of the electrolytic single cell, and when a region on the substrate tube where the plurality of electrolytic single cells are arranged is divided into a first end portion, a central portion, and a second end portion along the axial direction, the width of the electrolytic single cell located at the first end portion and / or the second end portion is 1.5 to 3 times larger than the width of the electrolytic single cell located at the central portion.

2. The electrolytic cell stack according to claim 1, wherein the width of the electrolytic single cell located at the first end portion is equal to the width of the electrolytic single cell located at the second end portion.

3. The electrolytic cell stack according to claim 1, wherein the first end portion is an end portion on the upstream side in the gas flow direction in the substrate tube, the second end portion is an end portion on the downstream side in the gas flow direction in the substrate tube, and the width of the electrolytic single cell located at the second end portion is larger than the width of the electrolytic single cell located at the first end portion.

4. The electrolytic cell stack according to claim 1, wherein the axial length of the first end portion is 5% or more and 20% or less with respect to the total of the axial lengths of the central portion, the first end portion, and the second end portion.

5. The electrolytic cell stack according to claim 1, wherein the axial length of the second end portion is 5% or more and 20% or less with respect to the total of the axial lengths of the central portion, the first end portion, and the second end portion.

6. The electrolytic cell stack according to claim 1, wherein the first end portion is an end portion on the upstream side in the gas flow direction in the substrate tube, the second end portion is an end portion on the downstream side in the gas flow direction in the substrate tube, and the axial length of the second end portion is larger than the axial length of the first end portion.

7. An electrolytic cell cartridge comprising the electrolytic cell stack according to any one of claims 1 to 6.

8. An electrolytic cell module comprising the electrolytic cell cartridge according to claim 7.

9. A method for manufacturing an electrolytic cell stack having a hydrogen electrode containing Ni, an oxygen electrode, and a solid electrolyte membrane disposed between the hydrogen electrode and the oxygen electrode, the electrolytic cell formed in the circumferential direction of a substrate tube, and an interconnector for electrically connecting a plurality of the electrolytic cells arranged in the axial direction of the substrate tube, wherein in one of the electrolytic cells, the distance from one end to the other end of the oxygen electrode facing the axial direction of the substrate tube is defined as the width of the electrolytic cell, and a region on the substrate tube where a plurality of the electrolytic cells are arranged is divided into a first end portion, a central portion, and a second end portion along the axial direction, and the width of the electrolytic cell located at the first end portion and / or the second end portion is formed to be 1.5 to 3 times larger than the width of the electrolytic cell located at the central portion.

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