Electrochemical cell stack, hot module, and hydrogen production device

Abstract

To provide an electrochemical cell stack constituted so that a sufficient amount of fuel gas can be made to flow even on the outlet side of a fuel chamber.SOLUTION: An anode current collector 312 of an electrochemical cell stack 1 includes an upper side part 311c in contact with an anode layer 312a, a lower side part 312C in contact with an interconnector 313, and a pair of coupling parts 312a connecting the upper side part 312C and the lower side part 312b, and is arranged in an anode chamber Sf. A projection part side 312A is formed by the upper side part side 312b and the pair of connecting part side 312A, and the combustion chamber Sf is partitioned into an inside space side 312A surrounded by the projection part side A1 and the interconnector 313, and an outside space side 312A surrounded by the projection part side A2 and the electrolytic cell 311. The connecting portion side 312b has an opening through which the inner space side A1 and the outer space side A2 communicate with each other. The opening ratio in the front half area FA of the connecting portion 312b is smaller than the opening ratio in the rear half area RA.SELECTED DRAWING: Figure 9

Description

[Technical Field]

[0001] The present disclosure relates to an electrochemical cell stack, a hot module, and a hydrogen production device. [Background technology]

[0002] An electrochemical cell is a cell that generates gases such as hydrogen and carbon monoxide or generates electricity by utilizing an electrochemical reaction. When generating gases or generating electricity using an electrochemical cell, an electrochemical cell stack is actually used, which is made up of electrochemical cell units stacked together, each of which includes an electrochemical cell, an interconnector, and an anode current collector. Patent Document 1 discloses an electrochemical cell stack made up of a plurality of electrochemical cell units stacked together. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 06756549 specification Summary of the Invention

[0004] The electrochemical cell stack is supplied with fuel gas required for the electrochemical reaction. This fuel gas is supplied into a fuel chamber formed within the electrochemical cell stack. As the fuel gas supplied into the fuel chamber flows from the inlet side to the outlet side of the fuel chamber, it is used in the electrochemical reaction that takes place in the anode layer exposed to the fuel chamber. At this time, fuel gas is consumed for the electrochemical reaction from the inlet side of the fuel chamber (upstream side of the fuel gas flow), so there is less fuel gas on the outlet side of the fuel chamber (downstream side of the fuel gas flow), and in some cases there may be a shortage of fuel gas near the outlet of the fuel chamber.

[0005] When the amount of fuel gas at the inlet side of the fuel chamber is large and the amount at the outlet side is small, the electrochemical reaction is promoted near the inlet side of the fuel chamber and suppressed near the outlet side. This imbalance in the reaction causes uneven current density of the current required for the reaction or the current generated by the reaction, resulting in a decrease in the performance of the electrochemical cell.

[0006] The present disclosure aims to solve the above-mentioned problems. That is, one of the objects of the present disclosure is to provide an electrochemical cell stack configured to be able to supply a sufficient amount of fuel gas also to the outlet side of the fuel chamber, a hot module including the electrochemical cell stack, and a hydrogen production device including the hot module.

[0007] The electrochemical cell stack according to the present disclosure is an electrochemical cell stack (1) formed by stacking a plurality of electrochemical cell units (31), each of which includes an electrochemical cell (311) including a solid electrolyte layer (311a), an air electrode layer (311b) stacked on one side of the solid electrolyte layer (311a), and an anode layer (311c) stacked on the other side of the solid electrolyte layer (311a), an anode current collector (312) formed of a conductive metal stacked on the electrochemical cell (311) so as to be in contact with the anode layer (311c), and an interconnector (313) stacked on the electrochemical cell (311) so as to be in contact with the anode current collector (312).

[0008] The fuel electrode current collector (312) is disposed in a fuel chamber (Sf) formed between the electrochemical cell (311) and the interconnector (313), through which fuel gas flows from one end (front end) to the other end (rear end) in a predetermined first direction (depth direction) perpendicular to the stacking direction of the electrochemical cell (311), and includes a first contact portion (312a) formed along the first direction (depth direction) and in contact with an adjacent fuel electrode layer (311c) in the stacking direction, a second contact portion (312C) formed along the first direction (depth direction) and in contact with an adjacent interconnector (313) in the stacking direction, and a pair of connecting portions (312b) formed from both end portions of the first contact portion (312a) along the first direction (depth direction) toward the second contact portion (312C) so as to connect the first contact portion (312a) and the second contact portion (312C). The first contact portion (312a) and the pair of connecting portions (312b) form a protrusion (312A) that protrudes from the second contact portion (312C) and extends in the first direction (depth direction). The fuel chamber (Sf) is divided by the connecting portion (312b) into an inner space (A1) surrounded by the protrusion (312A) and the interconnector (313) and an outer space (A2) surrounded by the protrusion (312A) and the electrochemical cell (311). The connecting portion (312b) has an opening that connects the inner space (A1) to the outer space (A2). When the connecting portion (312b) is divided into a front half region (FA) that includes one end in the first direction and a rear half region (RA) that includes the other end, the opening ratio in the front half region (FA) is smaller than the opening ratio in the rear half region (RA).

[0009] According to the above configuration, fuel gas flowing from one end to the other end in the first direction through the inner space surrounded by the protrusion and the interconnector flows from the inner space to the outer space through the opening formed in the connecting portion. The fuel gas flowing into the outer space contacts the fuel electrode layer of the electrochemical cell exposed in the outer space, causing an electrochemical reaction. In this case, the one end of the connecting portion in the first direction is located on the inlet side of the fuel chamber, and the other end is located on the outlet side of the fuel chamber. Furthermore, if the connecting portion is divided into a front half region that includes the one end in the first direction and a rear half region that includes the other end, the front half region is located on the inlet side of the fuel chamber and the rear half region is located on the outlet side of the fuel chamber. The opening ratio in the front half region of the connecting portion is smaller than the opening ratio in the rear half region. This allows more fuel gas to flow from the inner space to the outer space through the rear half region of the connecting portion, which has a larger opening ratio. This allows a sufficient amount of fuel gas to be supplied to the outlet side of the fuel chamber, thereby promoting the electrochemical reaction at the outlet side of the fuel chamber. This reduces bias in the electrochemical reaction, thereby suppressing performance degradation of the electrochemical cell.

[0010] In one embodiment of the electrochemical cell stack according to the present disclosure, The connecting portion (312b) has a plurality of openings formed along a first direction (depth direction), and the total opening area of ​​the openings formed in the front half region (FA) is smaller than the total opening area of ​​the openings formed in the rear half region (RA).

[0011] According to the above configuration, the opening ratio in the front half region of the connecting portion can be made smaller than the opening ratio in the rear half region.

[0012] In another embodiment of the electrochemical cell stack according to the present disclosure, The pitch (D) between the openings formed in the front half area (FA) is larger than the pitch (D) between the openings formed in the rear half area (RA).

[0013] According to the above configuration, by making the number of openings formed in the front half region of the connecting portion smaller than the number of openings formed in the rear half region, the opening ratio in the front half region of the connecting portion can be made smaller than the opening ratio in the rear half region.

[0014] In yet another embodiment of the electrochemical cell stack according to the present disclosure, The opening length (L) of the opening formed in the front half region (FA) is shorter than the opening length (L) of the opening formed in the rear half region (RA). Here, the opening length is the length in the in-plane direction of the opening surface formed in the connecting portion and in a direction parallel to the first direction.

[0015] According to the above configuration, by making the opening length of the opening formed in the front half region of the connecting portion shorter than the opening length of the opening formed in the rear half region, the opening ratio in the front half region of the connecting portion can be made smaller than the opening ratio in the rear half region.

[0016] In yet another embodiment of the electrochemical cell stack according to the present disclosure, The opening width (W) of the opening formed in the front half region (FA) is narrower than the opening width (W) of the opening formed in the rear half region (RA). Here, the opening width is the length in the in-plane direction of the opening surface formed in the connecting portion and in the direction perpendicular to the first direction.

[0017] According to the above configuration, by making the opening width of the opening formed in the front half region of the connecting portion narrower than the opening width of the opening formed in the rear half region, the opening ratio in the front half region of the connecting portion can be made smaller than the opening ratio in the rear half region.

[0018] In yet another embodiment of the electrochemical cell stack according to the present disclosure, No opening is formed in the front half area (FA), and an opening is formed in the rear half area (RA).

[0019] According to the above configuration, by forming the opening only in the rear region of the connecting portion, the ratio of the opening in the front region of the connecting portion can be made smaller than the ratio of the opening in the rear region.

[0020] In yet another embodiment of the electrochemical cell stack according to the present disclosure, The connecting portion (312b) has a plurality of openings formed along a first direction (depth direction), and at least the openings formed in the rear region (RA) have louvers (LV) formed therein for guiding fuel gas flowing through the inner space (A1) to the outer space (A2) through the openings.

[0021] According to the above configuration, by providing a louver in the opening formed in the rear half region of the connecting portion, it is possible to allow a larger amount of fuel gas to flow from the inner space to the outer space in the rear half region of the connecting portion.

[0022] In yet another embodiment of the electrochemical cell stack according to the present disclosure, The anode current collector (312) has a plurality of ridges (312A) arranged parallel to one another in a first direction.

[0023] According to the above configuration, in each of the plurality of protrusions, the opening ratio in the front half region of the connecting portion can be made smaller than the opening ratio in the rear half region.

[0024] In addition, another fuel electrode current collector (312) of the electrochemical cell stack according to the present disclosure is disposed in a fuel chamber (Sf) formed between the electrochemical cell (311) and the interconnector (313), through which fuel gas flows from one end to the other end in a predetermined first direction (depth direction) perpendicular to the stacking direction of the electrochemical cell (311), and includes a first contact portion (312a) formed along the first direction (depth direction) and in contact with an adjacent fuel electrode layer (311c) in the stacking direction, a second contact portion (312C) formed along the first direction (depth direction) and in contact with an adjacent interconnector (313) in the stacking direction, and a pair of connecting portions (312b) formed from both ends of the first contact portion (312a) along the first direction (depth direction) toward the second contact portion (312C) so as to connect the first contact portion (312a) and the second contact portion (312C). In addition, the first contact portion (312a) and the pair of connecting portions (312b) form a protrusion portion (312A) that protrudes from the second contact portion (312C) and extends in a first direction (depth direction), and the fuel chamber (Sf) is divided by the connecting portion (312b) into an inner space (A1) surrounded by the protrusion portion (312A) and the interconnector (313) and an outer space (A2) surrounded by the protrusion portion (312A) and the electrochemical cell (311).The connecting portion (312b) has a plurality of openings that connect the inner space (A1) and the outer space (A2), and each of the plurality of openings has a louver for guiding the fuel gas flowing through the inner space (A1) to the outer space (A2). When the connecting portion (312b) is divided into a front half region (FA), which is a half region including one end in the first direction (depth direction), and a rear half region (RA), which is a half region including the other end, the opening angle of the louvers formed at the opening in the front half region (FA) is smaller than the opening angle of the louvers formed at the opening in the rear half region (RA).

[0025] According to the above configuration, fuel gas flowing from one end to the other end in the first direction through the inner space surrounded by the protrusion portion and the interconnector flows from the inner space to the outer space through multiple openings formed in the connecting portion. The fuel gas flowing into the outer space comes into contact with the fuel electrode layer of the electrochemical cell exposed to the outer space, causing an electrochemical reaction. In this case, one end of the connecting portion in the first direction is located on the inlet side of the fuel chamber, and the other end is located on the outlet side of the fuel chamber. Furthermore, louvers are formed in each opening formed in the connecting portion, and these louvers guide the fuel gas flowing through the inner space to the outer space. When the connecting portion is divided into a front half region that includes one end in the first direction and a rear half region that includes the other end, the opening angle of the louvers formed in the openings in the front half region is smaller than the opening angle of the louvers formed in the openings in the rear half region. In other words, the opening angle of the louvers formed in the openings in the rear half region is larger than the opening angle of the louvers formed in the front half region. In the rear region where the louver opening angle is large, more fuel gas can flow from the inner space to the outer space, so a sufficient amount of fuel gas can be supplied to the outlet side of the fuel chamber and the electrochemical reaction at the outlet side of the fuel chamber can be promoted. This prevents the electrochemical reaction from becoming unevenly distributed, and as a result, prevents a decrease in the performance of the electrochemical cell.

[0026] In addition, the hot module (7) according to the present disclosure includes an electrochemical cell stack (1) having the above-described configuration, a vaporizer (2) that generates water vapor to be supplied to the electrochemical cell stack (1), heating devices (3, 4) that heat the gas to be supplied to the electrochemical cell stack (1), and a thermal insulator (5) in which the electrochemical cell stack (1), the vaporizer (2), and the heating devices (3, 4) are disposed.

[0027] According to the above configuration, it is possible to provide a hot module including an electrochemical cell stack configured to allow a sufficient amount of fuel gas to flow to the outlet side of the fuel chamber.

[0028] The hydrogen production device (100) according to the present disclosure includes the hot module (7) having the above-described configuration.

[0029] According to the above configuration, it is possible to provide a hydrogen production device equipped with a hot module including an electrochemical cell stack configured to allow a sufficient amount of fuel gas to flow to the outlet side of the fuel chamber. [Brief explanation of the drawings]

[0030] [Figure 1] FIG. 1 is a block diagram of a hydrogen production device. [Figure 2] FIG. 1 is a schematic perspective view of an electrochemical cell stack. [Figure 3] FIG. 3 is a cross-sectional view taken along line III-III in FIG. 2. [Figure 4] FIG. 4 is a cross-sectional view of the cell cassette shown in FIG. [Figure 5] FIG. 4 is a cross-sectional view taken along line VV in FIG. [Figure 6] FIG. 6 is a cross-sectional view of the cell cassette shown in FIG. 5. [Figure 7] FIG. 2 is a cross-sectional view of an anode current collector. [Figure 8] FIG. 6 is a cross-sectional view showing the details of a portion E in FIG. 5. [Figure 9] FIG. 2 is a perspective view of one protrusion and a lower side portion connected to the protrusion of the fuel electrode current collector according to the first embodiment. [Figure 10] FIG. 10 is a perspective view of one protrusion and a lower side portion connected to the protrusion of the fuel electrode current collector according to Modification 1. [Figure 11] FIG. 10 is a perspective view of one protrusion and a lower side portion connected to the protrusion of an anode current collector according to a second embodiment. [Figure 12] FIG. 10 is a perspective view of one protrusion and a lower side portion connected to the protrusion of an anode current collector according to Modification 2. [Figure 13] FIG. 10 is a perspective view of one protrusion and a lower side portion connected to the protrusion of an anode current collector according to a third embodiment. [Figure 14] FIG. 11 is a perspective view of one protrusion and a lower side portion connected to the protrusion of an anode current collector according to Modification 3. [Figure 15]FIG. 10 is a perspective view of one protrusion and a lower side portion connected to the protrusion of an anode current collector according to a fourth embodiment. [Figure 16] FIG. 11 is a perspective view of one protrusion and a lower side portion connected to the protrusion of an anode current collector according to a fifth embodiment. [Figure 17] FIG. 17 is a cross-sectional view taken along line AA in FIG. 16. [Figure 18] FIG. 13 is a perspective view of one protrusion and a lower side portion connected to the protrusion of an anode current collector according to a sixth embodiment. [Figure 19] FIG. 13 is a perspective view of one protrusion and a lower side portion connected to the protrusion of an anode current collector according to a seventh embodiment. [Figure 20] FIG. 13 is a perspective view of one protrusion and a lower side portion connected to the protrusion of an anode current collector according to an eighth embodiment. [Figure 21] FIG. 13 is a perspective view of one protrusion and a lower side portion connected to the protrusion of an anode current collector according to a ninth embodiment. [Figure 22] 22 is a cross-sectional view of the first inclined portion of the connecting portion shown in FIG. 21 cut along the depth direction so as to pass through each opening. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0031] (First embodiment) 1 is a block diagram of a hydrogen production device 100 according to the present disclosure. The hydrogen production device 100 is a device that produces hydrogen by electrolyzing water vapor. As shown in FIG. 1, the hydrogen production device 100 includes a hot module 7 and a condenser 8.

[0032] The hot module 7 is constructed by covering with insulating material the main components that become hot among the elements that make up the hydrogen production device 100, and is a device in which the main components are concentrated within the insulating material so that they can be kept at a high temperature. This hot module 7 includes an electrochemical cell stack 1, a vaporizer 2, a heat exchanger 3, a heater 4, and an insulating material 5.

[0033] As shown in Fig. 1, water (H2O) is supplied to the vaporizer 2. The vaporizer 2 is configured to heat the supplied water to a temperature of 100°C or higher using a heat source. Therefore, the water supplied to the vaporizer 2 evaporates within the vaporizer 2, generating water vapor. The water vapor generated in the vaporizer 2 is supplied to the heat exchanger 3.

[0034] In addition to the water vapor described above, air is supplied to the heat exchanger 3. In addition, high-temperature hydrogen (H2) and high-temperature oxygen (O2) generated in the electrochemical cell stack 1 are supplied to the heat exchanger 3. These high-temperature gases exchange heat with the water vapor and air in the heat exchanger 3, thereby heating (raising the temperature) the water vapor and air supplied from the vaporizer 2 in the heat exchanger 3.

[0035] The water vapor and air heated by the heat exchanger 3 are further heated by the heater 4 to the operating temperature of the electrochemical cell stack 1 (i.e., the temperature required to operate the electrochemical cell stack 1). The water vapor and air are then supplied to the electrochemical cell stack 1. The heat exchanger 3 and the heater 4 are temperature-raising devices for raising the temperature of the gases (water vapor and air) supplied to the electrochemical cell stack 1 to the operating temperature of the electrochemical cell stack 1.

[0036] The electrochemical cell stack 1 is formed by stacking cell cassettes, each including an electrochemical cell unit having a solid oxide electrolysis cell (hereinafter referred to as an electrolysis cell). The electrochemical cell stack 1 is heated to its operating temperature by a heat source (such as a burner), not shown. A predetermined voltage is applied to the electrochemical cell stack 1. As a result, water vapor supplied to the electrochemical cell stack 1 is electrolyzed to produce high-temperature hydrogen and oxygen. The high-temperature hydrogen produced in the electrochemical cell stack 1 is supplied to the heat exchanger 3 together with unreacted water vapor, where it is used to heat the water vapor and air supplied from the vaporizer 2 to the heat exchanger 3, and then introduced into the condenser 8. The unreacted water vapor is condensed in the condenser 8. The condensed water produced in the condenser 8 is supplied to the vaporizer 2. Meanwhile, the hydrogen separated by the condensation of the water vapor in the condenser 8 is recovered. Furthermore, the high-temperature oxygen generated in the electrochemical cell stack 1 is supplied to the heat exchanger 3 and used to heat the water vapor and air, and then supplied to the vaporizer 2 to heat the water to be supplied to the vaporizer 2. The oxygen discharged from the vaporizer 2 is then recovered (or released to the atmosphere).

[0037] The electrochemical cell stack 1, vaporizer 2, heat exchanger 3, and heater 4 are disposed inside a thermal insulation material 5. This suppresses heat radiation from each of the components 1, 2, 3, and 4. Heat-resistant fibers such as ceramic wool, refractory ceramic fiber (RCF), and biosoluble fiber (AES), and / or a heat-resistant container formed from these heat-resistant fibers, can be used for the thermal insulation material 5. The heat-resistant fibers are disposed so as to fill the gaps between the electrochemical cell stack 1, vaporizer 2, heat exchanger 3, and heater 4.

[0038] FIG. 2 is a perspective view of the electrochemical cell stack 1. When directions are used to describe the electrochemical cell stack 1 and its components, the three directions shown in FIG. 2, the up-down direction, the width direction, and the depth direction, are used. The up-down direction, the width direction, and the depth direction are perpendicular to one another. The plane extending in the width direction and the depth direction is a horizontal plane perpendicular to the up-down direction. Furthermore, one side of the depth direction is defined as the front, and the other side is defined as the rear.

[0039] As shown in Fig. 2, the electrochemical cell stack 1 includes a cell cassette group formed by stacking multiple rectangular flat cell cassettes 30 in the vertical direction, an upper insulating plate 20 stacked on the upper surface of the cell cassette group, an upper end plate 10 stacked on the upper surface of the upper insulating plate 20, a terminal plate 40 stacked on the lower surface of the cell cassette group, a lower insulating plate 50 stacked on the lower surface of the terminal plate 40, and a lower end plate 60 stacked on the lower surface of the lower insulating plate 50, and is a laminate formed by stacking these plate-like members in the thickness direction. The thickness direction of each member corresponds to the vertical direction in Fig. 2. Therefore, the above-mentioned members are stacked in the vertical direction.

[0040] Each of the above-mentioned components is formed in a rectangular plate shape with sides aligned in the width and depth directions. The components are fastened to one another by bolts B inserted through the four corners in the stacking direction and nuts (not shown). The upper end plate 10, terminal plate 40, and lower end plate 60 are rectangular flat-plate components that have the same outer shape as the cell cassette 30 when viewed from above and below, and are all made of metal (e.g., stainless steel). A rectangular opening is formed in the center of the upper end plate 10. The upper insulating plate 20 and lower insulating plate 50 also have the same outer shape as the cell cassette 30 when viewed from above and below, and are plate-shaped and made of insulating material, such as mica or resin. For ease of explanation, the proportions of the components in the drawings may differ from their actual proportions.

[0041] Two gas supply passages Pfi, Pai and two gas exhaust passages Pfo, Pao are formed in the stacking direction of the multiple cell cassettes 30, terminal plate 40, lower insulating plate 50, and lower end plate 60 that make up the cell cassette group. The gas supply passage Pfi is formed near one corner of side E1, which is one of the four sides that make up the outer periphery of the electrochemical cell stack 1. The gas exhaust passage Pfo is formed near the other corner of side E2 that faces side E1 (the corner located diagonally from one corner of side E1). The gas supply passage Pai is formed near one corner of side E2, and the gas exhaust passage Pao is formed near the other corner of side E1. The gas supply passage Pfi forms a passage through which water vapor supplied to the electrochemical cell stack 1 passes, and the gas supply passage Pai forms a passage through which air supplied to the electrochemical cell stack 1 passes. The gas exhaust passage Pfo forms a passage through which hydrogen and water vapor discharged from the electrochemical cell stack 1 pass, and the gas exhaust passage Pao forms a passage through which oxygen and air discharged from the electrochemical cell stack 1 pass.

[0042] Fig. 3 is a cross-sectional view taken along line III-III in Fig. 2. Fig. 3 is a cross-sectional view of the electrochemical cell stack 1 cut along the depth direction so as to reveal cross sections of the gas supply passages Pfi and the gas discharge passages Pfo. As shown in Fig. 3, the multiple cell cassettes 30 constituting the cell cassette group are stacked between an upper end plate 10 and a lower end plate 60, with an upper insulating plate 20, a lower insulating plate 50, and a terminal plate 40 interposed therebetween.

[0043] FIG. 4 shows a cross-sectional view of the cell cassette 30 shown in FIG. 3. Note that the gas supply passages Pfi and gas discharge passages Pfo shown in FIG. 3 are omitted in FIG. 4. As shown in FIG. 4, the cell cassette 30 includes an electrochemical cell unit 31, a separator section 32, and a frame section 33. The electrochemical cell unit 31 is a reaction section where an electrochemical reaction takes place, and includes a solid oxide electrolysis cell (hereinafter referred to as an electrolysis cell) as an electrochemical cell. Specifically, the electrochemical cell unit 31 includes an electrolysis cell 311, an anode current collector 312, and an interconnector 313.

[0044] In this embodiment, the electrolysis cell 311 is a plate-like member having a substantially rectangular shape. The electrolysis cell 311 includes a solid electrolyte layer 311a, an air electrode layer 311b stacked on the upper surface (one surface) of the solid electrolyte layer 311a, and an anode layer 311c stacked on the lower surface (other surface) of the solid electrolyte layer 311a, and is formed by stacking these in the thickness direction. The air electrode layer 311b has a smaller outer shape than the solid electrolyte layer 311a and the anode layer 311c, and is located at the center of the upper surface of the solid electrolyte layer 311a in a plan view of the electrolysis cell 311. Therefore, the upper surface of the outer periphery of the solid electrolyte layer 311a is exposed.

[0045] The solid electrolyte layer 311a is a layer made of a solid oxide electrolyte. The solid electrolyte layer 311a is a rectangular flat layer containing YSZ (yttria-stabilized zirconia) and is formed by sintering. The solid electrolyte layer 311a has high oxide ion conductivity. The solid electrolyte layer 311a is a dense layer and is designed so that the atmosphere on the air electrode layer 311b side (air atmosphere) and the atmosphere on the fuel electrode layer 311c side (reducing atmosphere) do not leak into each other through the solid electrolyte layer 311a.

[0046] The air electrode layer 311b is also a rectangular flat layer containing a perovskite oxide such as lanthanum strontium cobalt iron oxide (LSCF) and is formed by sintering. The air electrode layer 311b has a functional layer and a current collecting layer. The current collecting layer is thicker than the functional layer and is disposed on top of the functional layer. The air electrode layer 311b has high electronic conductivity and effectively collects electrons from the current collecting layer. The air electrode layer 311b is a porous layer with pores inside.

[0047] The anode layer 311c is also a rectangular flat layer. The anode layer 311c is formed to be thicker than the solid electrolyte layer 311a and the air cathode layer 311b. The anode layer 311c supports the solid electrolyte layer 311a and the air cathode layer 311b. In other words, the electrolysis cell 311 is an anode-supported electrochemical cell. The outer shape of the anode layer 311c in a plan view matches the outer shape of the solid electrolyte layer 311a. The anode layer 311c also includes an anode functional layer and an anode support layer. The anode support layer is formed to be significantly thicker than the anode functional layer, and the thickness ratio can be set to, for example, approximately 16 to 40 times. The anode functional layer and the anode support layer are stacked on the lower surface of the solid electrolyte layer 311a in this order.

[0048] The anode support layer is primarily composed of a cermet of Ni and YSZ (yttria-stabilized zirconia). The anode support layer is a porous layer configured to have a porous structure containing multiple micropores (not shown). The micropores have a diameter on the order of several micrometers, ensuring water vapor permeability (gas diffusibility). The anode functional layer is also primarily composed of a cermet of Ni and YSZ. Like the anode support layer, the anode functional layer is also a porous layer configured to have a porous structure containing multiple micropores (not shown). The anode functional layer is formed to be denser than the anode support layer. That is, the anode functional layer and the anode support layer are formed so that the porosity of the anode functional layer is smaller than that of the anode support layer. The anode layer 311c is also formed by sintering, similar to the solid electrolyte layer 311a and the air cathode layer 311b. Note that the components of the anode functional layer and the anode support layer are not limited to those described above. For example, the main components of the anode functional layer can be composed of Ni and GDC (gadolinia-doped ceria).

[0049] Anode current collector 312 is a rectangular flat member made of a conductive metal plate, and is stacked below electrolytic cell 311 so as to be in contact with anode layer 311c of electrolytic cell 311. The configuration of anode current collector 312 will be described later.

[0050] The interconnector 313 is a metal (e.g., stainless steel) member having a rectangular, flat main body 313a and a protruding portion 313b protruding downward from the underside of the main body 313a. The protruding portion 313b is formed by a plurality of ridges arranged parallel to one another in a direction perpendicular to the paper surface of Figures 3 and 4 (the width direction). As shown in Figure 3, the interconnector 313 is stacked on the electrolysis cell 311 so that the main body 313a contacts the anode current collector 312 disposed above it, and the protruding portion 313b connects to the air cathode layer 311b of the adjacent electrolysis cell 311 disposed below it.

[0051] The frame section 33 includes an anode frame 331 and a cathode frame 332. The anode frame 331 is a rectangular plate-shaped metal (e.g., stainless steel) member with a rectangular opening formed in its center. The cathode frame 332 is disposed below the anode frame 331. The cathode frame 332 is a rectangular plate-shaped insulating member and may be formed from, for example, a mica sheet. The cathode frame 332 also has a rectangular opening formed in its center, similar to that of the anode frame 331. The shape of the frame section 33 viewed from the top and bottom matches the shapes of the upper end plate 10 and the lower end plate 60.

[0052] As can be seen from FIG. 4 , the electrochemical cell unit 31 is disposed inside an opening formed in the center of the frame part 33. In other words, the frame part 33 is disposed around the electrochemical cell unit 31 so as to surround the outer periphery of the electrochemical cell unit 31. A predetermined gap is formed between the frame part 33 and the electrochemical cell unit 31, and the separator part 32 is disposed to close this gap. The separator part 32 includes a cell-side separator 321 and an interconnector-side separator 322. The cell-side separator 321 is a rectangular plate-shaped metal (e.g., stainless steel) member, and has a rectangular opening formed in its center. The periphery (i.e., inner periphery) of the opening of the cell-side separator 321 is brazed to the upper surface of the outer periphery of the solid electrolyte layer 311a of the electrolysis cell 311 with brazing material (e.g., Ag brazing), not shown. On the other hand, the outer peripheral portion of the cell-side separator 321 is disposed on the upper surface of the fuel electrode frame 331 and is joined to the fuel electrode frame 331 by, for example, welding.

[0053] Like the cell-side separator 321, the interconnector-side separator 322 is a rectangular plate-shaped metal (e.g., stainless steel) member with a rectangular opening formed in its center. The periphery (i.e., inner periphery) of the opening of the interconnector-side separator 322 is joined to the upper surface of the main body 313a of the interconnector 313, for example, by welding. The outer peripheral portion of the interconnector-side separator 322 is sandwiched between the lower surface of the anode frame 331 and the upper surface of the cathode frame 332, and is joined to the upper anode frame 331, for example, by welding. In this way, the separator section 32 (cell-side separator 321 and interconnector-side separator 322) is configured to be able to connect the electrochemical cell unit 31 and the frame section 33.

[0054] The cell cassettes 30 configured as described above are stacked on the terminal plate 40 to form an electrochemical cell stack 1 in which multiple electrochemical cell units 31 are stacked vertically. At this time, the separator sections 32 (cell-side separators 321 and interconnector-side separators 322) separate the spaces between adjacent separators. This creates multiple fuel chambers Sf and air chambers Sa within the electrochemical cell stack 1, with gas flow blocked between them. Specifically, the fuel chamber Sf is formed by the anode frame 331, the cell-side separator 321 joined to the anode frame 331, the electrolysis cell 311 connected to the cell-side separator 321, the interconnector-side separator 322 joined to the anode frame 331, and the interconnector 313 connected to the interconnector-side separator 322. The fuel chamber Sf is formed between the electrolysis cell 311 and the interconnector 313. Furthermore, the fuel electrode layer 311c of the electrolysis cell 311 is exposed to the fuel chamber Sf. An air chamber Sa is formed by the air electrode frame 332, the interconnector-side separator 322 in contact with the air electrode frame 332, the interconnector 313 connected to the interconnector-side separator 322, the cell-side separator 321 of the cell cassette 30 adjacent to the air electrode frame 332, and the electrolysis cell 311 connected to the cell-side separator 321. The air electrode layer 311b of the electrolysis cell 311 is exposed to the air chamber Sa. Steam is supplied to the fuel chamber Sf as a fuel gas. Air is supplied to the air chamber Sa.

[0055] 3, the gas supply passages Pfi and the gas discharge passages Pfo are formed to penetrate the lower end plate 60, the lower insulating plate 50, the terminal plate 40, and the frame portion 33 of each cell cassette 30 constituting the cell cassette group in the stacking direction. The gas supply passages Pfi communicate with the fuel chamber Sf via horizontal holes 331a formed in the fuel electrode frame 331 of each cell cassette 30. The gas discharge passages Pfo communicate with the fuel chamber Sf via horizontal holes 331b formed in the fuel electrode frame 331 of each cell cassette 30.

[0056] The gas supply passages Pai and gas discharge passages Pao are also formed to penetrate the lower end plate 60, the lower insulating plate 50, the terminal plate 40, and the frame portion 33 of each cell cassette 30 constituting the cell cassette group in the stacking direction. The gas supply passages Pai and gas discharge passages Pao each communicate with the air chamber Sa via a horizontal hole (not shown) formed in the air electrode frame 332 of each cell cassette 30.

[0057] The cell cassette 30 (30A) located at the top of the cell cassette group is a dummy cell cassette provided with a metal plate PL instead of the electrolysis cell 311. The fuel electrode frame 331 of this dummy cell cassette 30A functions as a terminal plate.

[0058] The operation of the electrochemical cell stack 1 will be described. First, a voltage is applied to the electrochemical cell stack 1. In this case, the negative electrode of the power supply is connected to the terminal plate 40, and the positive electrode is connected to the fuel electrode frame 331 of the dummy cell cassette 30A. Next, high-temperature water vapor is supplied from the gas supply passage Pfi. The water vapor supplied to the gas supply passage Pfi flows into the fuel chamber Sf of each cell cassette 30 through the horizontal hole 331a. In addition, high-temperature air is supplied from the gas supply passage Pai. The air supplied to the gas supply passage Pai flows into the air chamber Sa of each cell cassette 30 through a horizontal hole (not shown). The reason for supplying high-temperature air to the air chamber Sa is to control the temperature of the electrochemical cell stack 1.

[0059] The water vapor that flows into the fuel chamber Sf flows through the fuel chamber Sf from the front side (one end) to the rear side (the other end) in the depth direction, as shown in FIG. 3 . Therefore, the front side in the depth direction is the inlet side of the fuel chamber Sf, and the rear side in the depth direction is the outlet side of the fuel chamber Sf. The water vapor in the fuel chamber Sf comes into contact with the anode layer 311c exposed to the fuel chamber Sf and reacts with electrons supplied to the anode layer 311c via the interconnector 313, the anode current collector 312, and the like. This causes the water vapor to decompose into hydrogen and oxide ions (water vapor electrolysis reaction). The hydrogen generated by the water vapor electrolysis reaction flows further to the rear side in the depth direction within the fuel chamber Sf and is discharged from the gas discharge passage Pfo via the horizontal hole 331b. At this time, unreacted water vapor is discharged from the gas discharge passage Pfo together with the hydrogen. Meanwhile, the oxide ions move through the solid electrolyte layer 311a to the air electrode layer 311b exposed to the air chamber Sa, where they release electrons in the functional layer of the air electrode layer 311b and become oxygen. The oxygen diffuses within the air chamber Sa and is discharged from the gas discharge passage Pao via a horizontal hole (not shown) together with the air that has flowed into the air chamber Sa.

[0060] Electrons emitted from the functional layer of the air electrode layer 311b are collected by the interconnector 313 via the current collecting layer, and then return to the positive electrode of the power supply device through the dummy cell cassette 30A.

[0061] Next, the anode current collector 312 will be described. Fig. 5 is a cross-sectional view taken along line VV in Fig. 3, and Fig. 5 is a cross-sectional view of the electrochemical cell stack 1 cut along the width direction. Fig. 6 shows a cross-section of one cell cassette 30 shown in Fig. 5. As shown in Figs. 5 and 6, the anode current collector 312 is disposed between the electrolysis cell 311 and the interconnector 313. Because a fuel chamber Sf is formed between the electrolysis cell 311 and the interconnector 313, the anode current collector 312 is disposed within the fuel chamber Sf.

[0062] Anode current collector 312 is constructed by forming multiple upwardly protruding ridges on a single conductive metal plate. The ridges are formed at regular intervals in the width direction and extend in the depth direction. Anode current collector 312 is disposed between electrolysis cell 311 and interconnector 313 so that the portion connecting adjacent ridges in the width direction is in surface contact with main body 313a of interconnector 313 and the upper surface of each ridge is in surface contact with anode layer 311c of electrolysis cell 311.

[0063] Fig. 7 shows a cross section of the anode current collector 312 shown in Fig. 5. As shown in Fig. 7, the anode current collector 312 has a plurality of protrusions 312A aligned in the width direction and a bottom side 312C connecting adjacent protrusions 312A in the width direction. The plurality of protrusions 312A are formed so as to be arranged parallel to each other in the depth direction at predetermined intervals in the width direction.

[0064] FIG. 8 shows a detail of portion E in FIG. 5. FIG. 8 shows a cross section of a protrusion 312A formed on an anode current collector 312 and its vicinity. As shown in FIG. 8, the protrusion 312A is formed by an upper edge portion 312a and a pair of connecting portions 312b, 312b. The upper edge portion 312a constitutes the upper end portion of the protrusion 312A. The upper edge portion 312a is formed along the depth direction. The upper surface S1 of the upper edge portion 312a is formed flat and parallel to a plane perpendicular to the up-down direction. The upper surface S1 is formed along the depth direction (first direction) and is in surface contact with the lower surface of the anode layer 311c of the electrolysis cell 311 stacked immediately above it. Therefore, the upper edge portion 312a is a first contact portion that is in surface contact with the anode layer 311c of the electrolysis cell 311 adjacent in the stacking direction.

[0065] Like the upper side portion 312a, the lower side portion 312C is also formed along the depth direction. A lower surface S2 of the lower side portion 312C is formed flat so as to be parallel to a plane perpendicular to the up-down direction. The lower surface S2 is formed along the depth direction and comes into surface contact with the upper surface of the main body portion 313a of the interconnector 313 stacked directly below it. Therefore, the lower side portion 312C is a second contact portion that comes into surface contact with the interconnector 313 adjacent in the stacking direction.

[0066] The connecting portion 312b is formed from both depthwise ends (i.e., both widthwise ends) of the upper side portion 312a toward the lower side portion 312C so as to connect the upper side portion 312a and the lower side portion 312C. The connecting portion 312b includes a first inclined portion P1, a second inclined portion P2, and a step portion P3. The first inclined portion P1 is formed so as to slope obliquely downward and widen from the side end (widthwise end) along the extension direction (depth direction) of the upper side portion 312a. The step portion P3 is connected to the lower end of the first inclined portion P1. The step portion P3 has a flat surface parallel to a plane perpendicular to the up-down direction. The upper end of the second inclined portion P2 is connected to the widthwise end of the step portion P3, which is opposite the end to which the first inclined portion P1 is connected. The second inclined portion P2 is formed so as to slope obliquely downward and widen from the end of the step portion P3. The lower end of the second inclined portion P2 is connected to the lower side portion 312C.

[0067] The protrusion 312A is formed by an upper side portion 312a and a pair of connecting portions 312b, 312b connected to both side ends of the upper side portion 312a along the extension direction (depth direction), and its cross-sectional shape is a two-tiered mountain shape that widens toward the end, as can be seen in Figure 8. The protrusion 312A is formed to protrude from the lower side portion 312C and extend in the depth direction. The pair of connecting portions 312b, 312b each connects the upper side portion 312a and the lower side portion 312C.

[0068] When the electrochemical cell stack 1 is fastened with the bolts B and nuts, the fastening force acts to compress the anode current collector 312 in the vertical direction. This fastening force is absorbed by the elastic deformation of the connecting portions 312b of the protrusions 312A of the anode current collector 312. At this time, the elastic force of the connecting portions 312b acts on the upper side portion 312a and the lower side portion 312C, so that the upper side portion 312a is pressed firmly against the anode layer 311c, and the lower side portion 312C is pressed firmly against the main body portion 313a of the interconnector 313. This makes it possible to maintain good contact between the upper surface S1 of the upper side portion 312a and the anode layer 311c, and between the lower surface S2 of the lower side portion 312C and the main body portion 313a of the interconnector 313.

[0069] During operation of the electrochemical cell stack 1, water vapor is supplied to the fuel chamber Sf as described above. As shown in FIG. 3 , the water vapor supplied to the fuel chamber Sf flows through the fuel chamber Sf from the front side in the depth direction, which is the inlet side of the fuel chamber Sf, to the rear side in the depth direction, which is the outlet side of the fuel chamber Sf. An anode current collector 312 is disposed within the fuel chamber Sf, and this anode current collector 312 is provided with a plurality of protrusions 312A extending in the depth direction. Therefore, water vapor within the fuel chamber Sf flows from the inlet side (front side in the depth direction) of the fuel chamber Sf to the outlet side (rear side in the depth direction) along the extension direction of the protrusions 312A.

[0070] 5, the fuel chamber Sf is divided into an inner space A1, which is a space surrounded by the protrusions 312A and the interconnector 313 directly below the protrusions 312A, and an outer space A2, which is surrounded by the protrusions 312A and the fuel electrode layer 311c of the electrolysis cell 311 directly above the protrusions 312A. The inner space A1 and the outer space A2 are separated by the connecting portion 312b of the protrusions 312A. Water vapor in the fuel chamber Sf flows from the front to the rear in the depth direction through either the inner space A1 or the outer space A2 within the fuel chamber Sf.

[0071] The water vapor flowing through the outer space A2 comes into direct contact with the fuel electrode layer 311c exposed to the outer space A2 so as to form the upper wall of the outer space A2, and is utilized in the water vapor electrolysis reaction. As a result, water vapor is consumed from the front side in the depth direction (the inlet side of the fuel chamber Sf), and the amount of water vapor decreases toward the rear side in the depth direction, and the amount of water vapor is small near the rear end in the depth direction (near the outlet side of the fuel chamber Sf). As a result, there is a risk of a shortage of water vapor at the outlet side of the fuel chamber Sf.

[0072] On the other hand, the inner space A1 is surrounded by the protrusion 312A and the interconnector 313, so the anode layer 311c is not exposed to the inner space A1. Therefore, water vapor does not come into contact with the anode layer 311c in the inner space A1. In other words, the steam electrolysis reaction does not occur in the inner space A1. However, the connecting portion 312b of the protrusion 312A has an opening penetrating through the thickness direction, which connects the inner space A1 with the outer space A2. Therefore, the water vapor in the inner space A1 flows out to the outer space A2 through the opening formed in the connecting portion 312b. The water vapor that flows out to the outer space A2 comes into contact with the anode layer 311c and is used in the steam electrolysis reaction.

[0073] FIG. 9 is a perspective view showing one protrusion 312A formed on an anode current collector 312 according to the first embodiment and lower edge portions 312C provided on both sides of the protrusion 312A. As shown in FIG. 9, water vapor (H2O) is supplied to the inner space A1 of the protrusion 312A from the front side in the depth direction. Furthermore, multiple openings OP are formed along the depth direction in the connecting portion 312b of the protrusion 312A. In this example, multiple openings are formed along the depth direction in each of the first inclined portion P1 and the second inclined portion P2 of the connecting portion 312b. Furthermore, in this embodiment, each opening OP has a rectangular shape with sides parallel to the depth direction and sides perpendicular to the depth direction. The sizes of these rectangular openings OP are different. Specifically, the openings OP formed in the first inclined portion P1 and the second inclined portion P2 are formed so that the opening area increases from the front side to the rear side in the depth direction. In this embodiment, all openings have the same opening width W. The opening width W is the length in the in-plane direction of the opening surface of the opening OP, in a direction perpendicular to the depth direction. Meanwhile, the opening length L of each opening OP is longer the further back the opening OP is formed. More specifically, each opening is formed so that the opening length L of the nth opening OP from the front in the depth direction is shorter than the opening length L of the (n+1)th opening from the front in the depth direction. The opening length L of the opening OP formed furthest back is the longest. The opening length L is the length in the in-plane direction of the opening surface of the opening OP, in a direction parallel to the depth direction. Furthermore, the pitch D between each opening (the length in the direction parallel to the depth direction between the rear end of an opening OP and the front end of an opening OP adjacent to the rear of that opening OP) is all the same.

[0074] Here, the connecting portion 312b is divided into a front half region FA, which includes the front end (one end) in the extension direction (depth direction) of the connecting portion 312b and is located forward of the midpoint of its length in the extension direction, and a rear half region RA, which includes the rear end (the other end) in the extension direction (depth direction) and is located rearward of the midpoint of its length in the extension direction. When the connecting portion 312b is divided into the front half region FA and the rear half region RA, the surface areas of the front half region FA and the rear half region RA are equal. Furthermore, since the connecting portion 312b is disposed within the fuel chamber Sf and water vapor within the fuel chamber Sf flows from the front side (one end) to the rear side (the other end) in the extension direction (depth direction) of the connecting portion 312b, the front half region FA, which includes the front end of the connecting portion 312b, is located near the inlet of the fuel chamber Sf, and the rear half region RA, which includes the rear end of the connecting portion 312b, is located near the outlet of the fuel chamber Sf.

[0075] Furthermore, the ratio of the total opening area of ​​the openings formed in the front half region FA to the surface area (area including the opening area) of the front half region FA is defined as the opening ratio in the front half region FA, and the ratio of the total opening area of ​​the openings formed in the rear half region RA to the surface area (area including the opening area) of the rear half region RA is defined as the opening ratio in the rear half region RA.

[0076] The opening length L of the openings OP formed in the connecting portion 312b is longer as the openings OP are formed further rearward in the depth direction. Therefore, the opening length L of the openings OP formed in the front half region FA of the connecting portion 312b is shorter than the opening length L of the openings OP formed in the rear half region RA of the connecting portion 312b. Furthermore, all openings OP have the same opening width W. Therefore, the opening area of ​​each opening OP increases as the openings OP are formed further rearward in the depth direction (i.e., toward the outlet of the fuel chamber Sf). Furthermore, the pitch D between all openings is the same. Therefore, openings with smaller opening areas are formed in the front half region FA of the connecting portion 312b, and openings with larger opening areas are formed in the rear half region RA of the connecting portion 312b. Therefore, the total opening area of ​​the openings formed in the front half region FA of the connecting portion 312b is smaller than the total opening area of ​​the openings formed in the rear half region RA of the connecting portion 312b. In other words, the opening ratio in the front half region FA of the connecting portion 312b is smaller than the opening ratio in the rear half region RA of the connecting portion 312b.

[0077] Water vapor flowing from the front side to the rear side in the depth direction within the inner space A1 can only flow into the outer space A2 through the opening OP and come into contact with the fuel electrode layer 311c. In this embodiment, as described above, the opening ratio of the connecting portion 312b in the front half region FA is smaller than the opening ratio in the rear half region RA, so the amount of water vapor flowing from the inner space A1 to the outer space A2 in the front half region FA is small. On the other hand, the opening ratio of the connecting portion 312b in the rear half region RA is larger than the opening ratio in the front half region FA, so the amount of water vapor flowing from the inner space A1 to the outer space A2 in the rear half region RA is large. Therefore, more water vapor flows from the inner space A1 to the outer space A2 in the rear half region RA, which is located in the area on the outlet side of the fuel chamber Sf, thereby compensating for the shortage of water vapor near the outlet of the fuel chamber Sf (outer space A2). This promotes the steam electrolysis reaction near the outlet of the fuel chamber Sf.

[0078] Thus, according to this embodiment, the openings are formed in the connecting portion 312b so that the opening ratio in the front region FA of the connecting portion 312b is smaller than the opening ratio in the rear region RA. This allows a sufficient amount of steam to be supplied near the rear end of the connecting portion 312b, i.e., near the outlet of the fuel chamber Sf (outer space A2), thereby promoting the steam electrolysis reaction near the outlet of the fuel chamber Sf. This prevents bias in the steam electrolysis reaction (electrochemical reaction) in the depth direction. Since bias in the steam electrolysis reaction can be prevented in this way, degradation of the electrochemical cell performance can be prevented.

[0079] Furthermore, according to this embodiment, a plurality of openings OP are formed in the connecting portion 312b, and the opening length L of the openings OP formed in the front half region FA of the connecting portion 312b is shorter than the opening length L of the openings OP formed in the rear half region RA. By adjusting the opening length L of each opening OP in this manner, the opening ratio in the front half region FA of the connecting portion 312b can be made smaller than the opening ratio in the rear half region RA.

[0080] Furthermore, according to this embodiment, the anode current collector 312 has multiple protrusions 312A arranged parallel to the depth direction (first direction). Therefore, in each of the multiple protrusions 312A, the opening ratio of the connecting portion 312b in the front half region FA can be made smaller than the opening ratio in the rear half region RA. This allows more of the water vapor flowing through the inner space A1 of each protrusion 312A to flow into the outer space A2 near the rear end in the depth direction (i.e., near the outlet of the fuel chamber). This further reduces bias in the water vapor electrolysis reaction.

[0081] (Variation 1) In the above first embodiment, an example was shown in which a plurality of openings OP are formed in the first inclined portion P1 and the second inclined portion P2 of the connecting portion 312b of the fuel electrode current collector 312 such that the opening length L gradually increases toward the rear side in the depth direction. However, there may be openings having the same opening length among the plurality of openings. For example, as shown in FIG. 10, a plurality of openings may be formed in the connecting portion 312b. According to FIG. 10, among the plurality of openings formed in the first inclined portion P1 and the second inclined portion P2 of the connecting portion 312b (rib portion 312A) of the fuel electrode current collector 312, the opening lengths of the foremost and the second foremost openings OP 1, OP 2 are the same, the opening lengths of the third and fourth openings OP 3, OP 4 from the front are the same, the opening lengths of the fifth and sixth openings OP 5, OP 6 from the front are the same, and the opening lengths of the seventh and eighth openings OP 7, OP 8 from the front are the same. And the opening lengths of the respective openings are in the relationship of OP 1, OP 2 opening length < OP 3, OP 4 opening length < OP 5, OP 6 opening length < OP 7, OP 8 opening length.

[0082] Even in the case where the respective openings are formed in this way, the opening ratio in the front half region FA of the connecting portion 312b can be made smaller than the opening ratio in the rear half region RA.

[0083] (Second Embodiment) The fuel electrode current collector according to the present embodiment also has a shape in which a plurality of upwardly convex rib portions extend in parallel in the depth direction, similar to the fuel electrode current collector according to the first embodiment. FIG. 11 is a perspective view showing one rib portion formed in the fuel electrode current collector according to the second embodiment and a pair of lower side portions connected to the rib portion. The basic shape and structure of the fuel electrode current collector according to the present embodiment are the same as the shape and structure of the fuel electrode current collector according to the first embodiment, and the difference is the shape and pitch of the plurality of openings formed in the connecting portion of the fuel electrode current collector. Hereinafter, the description will focus on the differences.

[0084] 11 , like the anode current collector 312 according to the first embodiment, the anode current collector 312 according to this embodiment has an upper side portion 312a, a connecting portion 312b, and a lower side portion 312C. The upper side portion 312a and a pair of connecting portions 312b, 312b connected to the upper side portion 312a form a two-tiered, mountain-shaped protrusion 312A that protrudes from the lower side portion 312C and extends in the depth direction. The external shapes of these portions are the same as the external shapes of the upper side portion 312a, the connecting portion 312b, and the lower side portion 312C of the anode current collector 312 according to the first embodiment.

[0085] Furthermore, a plurality of openings penetrating the thickness direction are formed along the depth direction in each of the first and second inclined portions P1 and P2 of the connecting portion 312b. In FIG. 11, ten openings OP1 to OP10 are formed in the first and second inclined portions P1 and P2, respectively. These openings OP1 to OP10 are all identical rectangular shapes with sides parallel to the depth direction and sides perpendicular to the depth direction. That is, all openings OP1 to OP10 have the same opening width W and opening length L. Therefore, all openings OP1 to OP10 have the same opening area. However, the pitch D between each opening decreases toward the rear. According to FIG. 11, the openings are formed so that the pitch Dn between the nth (n=1 to 8) opening OPn from the front in the depth direction and the n+1th opening OPn+1 from the front is longer than the pitch Dn+1 between the n+1th opening OPn+1 and the n+2th opening OPn+2 from the front. The rearmost pitch D9 is the shortest.

[0086] In the anode current collector 312 according to this embodiment, the pitch D on the front side in the depth direction is longer than the pitch D on the rear side, so the number of openings formed in the front region FA of the connecting portion 312b is smaller than the number of openings formed in the rear region RA. Furthermore, because all openings have the same opening area, the opening ratio in the front region FA of the connecting portion 312b is smaller than the opening ratio in the rear region RA. Therefore, the opening ratio in the rear region RA of the connecting portion 312b is larger, so more water vapor flows from the inner space A1 to the outer space A2 in the rear region RA located in the region on the outlet side of the fuel chamber Sf. This compensates for the lack of water vapor near the outlet of the fuel chamber Sf (outer space A2). This promotes the steam electrolysis reaction near the outlet of the fuel chamber Sf.

[0087] As described above, according to this embodiment, the steam electrolysis reaction near the outlet of the fuel chamber Sf can be promoted, which can prevent the steam electrolysis reaction (electrochemical reaction) from becoming uneven in the depth direction, thereby preventing the performance degradation of the electrochemical cell.

[0088] Furthermore, according to this embodiment, a plurality of openings OP are formed in the connecting portion 312b, and the pitch D between the openings formed in the front half region FA of the connecting portion 312b is longer than the pitch D between the openings formed in the rear half region RA. By adjusting the pitch between the openings in this manner, the ratio of openings in the front half region FA of the connecting portion 312b can be made smaller than the ratio of openings in the rear half region RA.

[0089] (Variation 2) In the second embodiment, a plurality of openings OP are formed in the connecting portion 312b of the anode current collector 312 such that the pitch D between the openings gradually decreases toward the rear. However, the anode current collector 312 (protrusion 312A) may be configured as shown in FIG. 12, for example. As shown in FIG. 12, a plurality of openings OP (OP1 to OP11) are formed in each of the first inclined portion P1 and the second inclined portion P2 of the connecting portion 312b of the anode current collector 312 (protrusion 312A). These openings are formed in the depth direction. In addition, the first and second pitches from the front side in the depth direction are the same pitch D1, the third and fourth pitches are the same pitch D2, the fifth and sixth pitches are the same pitch D3, the seventh and eighth pitches are the same pitch D4, and the ninth and tenth pitches are the same pitch D5. The pitches have a relationship of D1>D2>D3>D4>D5.

[0090] Even when the openings are formed in this manner, the ratio of the openings in the front region FA of the connecting portion 312b can be made smaller than the ratio of the openings in the rear region RA.

[0091] (Third embodiment) Like the anode current collector according to the first embodiment, the anode current collector according to this embodiment also has a shape in which a plurality of upwardly protruding ridges extend parallel to each other in the depth direction. Figure 13 is a perspective view showing one ridge formed on an anode current collector according to a third embodiment and a pair of lower edge portions connected to the ridge. The basic shape and structure of the anode current collector according to this embodiment are the same as those of the anode current collector according to the first embodiment, with the only difference being the opening length and opening width of the plurality of openings formed in the connecting portion of the anode current collector. The following description will focus on these differences.

[0092] 13, like the anode current collector 312 according to the first embodiment, the anode current collector 312 according to this embodiment has an upper side portion 312a, a connecting portion 312b, and a lower side portion 312C. The upper side portion 312a and a pair of connecting portions 312b, 312b connected to the upper side portion 312a form a two-tiered, mountain-shaped protrusion 312A that protrudes from the lower side portion 312C and extends in the depth direction. The external shapes of these portions are the same as the external shapes of the upper side portion 312a, the connecting portion 312b, and the lower side portion 312C of the anode current collector 312 according to the first embodiment.

[0093] Furthermore, a plurality of openings penetrating the thickness direction are formed along the depth direction in each of the first inclined portion P1 and the second inclined portion P2 of the connecting portion 312b. In FIG. 13, ten openings OP1 to OP10 are formed in each of the first inclined portion P1 and the second inclined portion P2. The opening lengths L of these openings OP1 to OP10 are all the same. The pitches D between the openings are also all the same. However, the opening widths W of the openings gradually increase as they are formed further rearward in the depth direction. Specifically, the openings are formed such that the opening width W of the nth (n=1 to 9) opening OPn from the front in the depth direction is narrower than the opening width W of the n+1th opening OPn+1. The opening width W of the rearmost opening OP10 is the widest.

[0094] In the anode current collector 312 according to this embodiment, the opening width W of the opening formed on the front side in the depth direction is narrower than the opening width W of the opening formed on the rear side. Therefore, the opening area of ​​the opening formed in the front half region FA of the connecting portion 312b is smaller than the opening area of ​​the opening formed in the rear half region RA. That is, the opening ratio in the front half region FA of the connecting portion 312b is smaller than the opening ratio in the rear half region RA. Because the opening ratio in the rear half region RA of the connecting portion 312b is thus large, more water vapor flows from the inner space A1 to the outer space A2 in the rear half region RA, which is located in the area on the outlet side of the fuel chamber Sf. This compensates for the shortage of water vapor near the outlet of the fuel chamber Sf (outer space A2). This promotes the steam electrolysis reaction near the outlet of the fuel chamber Sf.

[0095] As described above, according to this embodiment, the steam electrolysis reaction near the outlet of the fuel chamber Sf can be promoted, which can prevent the steam electrolysis reaction (electrochemical reaction) from becoming uneven in the depth direction, thereby preventing the performance degradation of the electrochemical cell.

[0096] Furthermore, according to this embodiment, multiple openings OP are formed in the connecting portion 312b, and the opening width W of the openings formed in the front half region FA of the connecting portion 312b is narrower than the opening width W of the openings formed in the rear half region RA. In this way, by adjusting the opening width W, the opening ratio in the front half region FA of the connecting portion 312b can be made smaller than the opening ratio in the rear half region RA.

[0097] (Variation 3) In the third embodiment described above, an example was shown in which a plurality of openings are formed in the connecting portion 312b of the anode current collector 312 such that the opening width W gradually increases toward the rear. However, some of the openings may have the same opening width. For example, the anode current collector 312 (protrusion 312A) may be configured as shown in FIG. 14. As shown in FIG. 14, a plurality of openings OP (OP1 to OP10) are formed along the depth direction in each of the first inclined portion P1 and the second inclined portion P2 of the connecting portion 312b of the anode current collector 312 (protrusion 312A). Furthermore, the first and second openings (OP1, OP2) from the front in the depth direction have the same opening width, the third and fourth openings (OP3, OP4) have the same opening width, the fifth and sixth openings (OP5, OP6) have the same opening width, the seventh and eighth openings (OP7, OP8) have the same opening width, and the ninth and tenth openings (OP9, OP10) have the same opening width. The opening widths have the following relationship: (opening width of openings OP1, OP2)<(opening width of openings OP3, OP4)<(opening width of openings OP5, OP6)<(opening width of openings OP7, OP8)<(opening width of openings OP9, OP10).

[0098] Even when the openings are formed in this manner, the ratio of the openings in the front region FA of the connecting portion 312b can be made smaller than the ratio of the openings in the rear region RA.

[0099] (Fourth embodiment) Like the anode current collector according to the first embodiment, the anode current collector according to this embodiment also has a shape in which a plurality of upwardly protruding ridges extend parallel to each other in the depth direction. FIG. 15 is a perspective view showing one ridge formed on the anode current collector according to the fourth embodiment and a pair of lower edge portions connected to the ridge. The basic shape and structure of the anode current collector according to this embodiment are the same as those of the anode current collector according to the first embodiment, except for the arrangement of openings formed in the connecting portions of the anode current collector. The following description will focus on these differences.

[0100] 15, like the anode current collector 312 according to the first embodiment, the anode current collector 312 according to this embodiment has an upper side portion 312a, a connecting portion 312b, and a lower side portion 312C. The upper side portion 312a and a pair of connecting portions 312b, 312b connected to the upper side portion 312a form a two-tiered, mountain-shaped protrusion 312A that protrudes from the lower side portion 312C and extends in the depth direction. The external shapes of these portions are the same as the external shapes of the upper side portion 312a, the connecting portion 312b, and the lower side portion 312C of the anode current collector 312 according to the first embodiment.

[0101] Furthermore, a plurality of openings OP are formed in each of the first inclined portion P1 and the second inclined portion P2 of the connecting portion 312b, penetrating in the thickness direction. However, the openings OP are formed only in the rear region RA of the connecting portion 312b, and no openings are formed in the front region FA of the connecting portion 312b. In FIG. 15, the shapes of the plurality of openings OP formed in the rear region RA of the first inclined portion P1 of the connecting portion 312b are all the same, and the pitch D between the openings is also constant. Furthermore, the shapes of the plurality of openings OP formed in the rear region RA of the second inclined portion P2 of the connecting portion 312b are all the same, and the pitch D between the openings is also constant. However, the shapes of the plurality of openings formed in the rear region RA do not have to be the same, and any shape may be used.

[0102] In the anode current collector 312 according to this embodiment, openings OP are formed only in the rear region RA of the connecting portion 312b, and no openings are formed in the front region FA of the connecting portion 312b. Therefore, the opening ratio (=0) in the front region FA is smaller than the opening ratio in the rear region RA. In particular, because the opening ratio in the front region FA is 0, water vapor does not flow from the inner space A1 to the outer space A2 in the front region FA. Therefore, more water vapor flows from the inner space A1 to the outer space A2 in the rear region RA, which is located in the region on the outlet side of the fuel chamber Sf. This makes it possible to compensate for the shortage of water vapor near the outlet of the fuel chamber Sf and promote the steam electrolysis reaction near the outlet of the fuel chamber Sf.

[0103] As described above, according to this embodiment, the steam electrolysis reaction can be promoted near the outlet of the fuel chamber Sf, thereby suppressing bias in the electrochemical reaction in the depth direction, and as a result, suppressing performance degradation of the electrochemical cell.

[0104] Furthermore, according to this embodiment, by adjusting the arrangement of the plurality of openings formed in the connecting portion 312b, the opening ratio in the front region FA of the connecting portion 312b can be made smaller than the opening ratio in the rear region RA.

[0105] Fifth Embodiment Like the anode current collector according to the first embodiment, the anode current collector according to this embodiment also has a shape in which a plurality of upwardly protruding ridges extend parallel to each other in the depth direction. Fig. 16 is a perspective view showing one ridge formed on the anode current collector according to the fifth embodiment and a pair of lower edge portions connected to the ridge. The anode current collector according to this embodiment differs from the above-described embodiments in the structure of the connecting portion. The following description will focus on these differences.

[0106] 16, like the anode current collector 312 according to the first embodiment, the anode current collector 312 according to this embodiment has an upper side portion 312a, a connecting portion 312b, and a lower side portion 312C. The upper side portion 312a and a pair of connecting portions 312b, 312b connected to the upper side portion 312a form a protrusion 312A that protrudes from the lower side portion 312C and extends in the depth direction. However, the cross-sectional shape of the protrusion 312A according to this embodiment differs from the cross-sectional shapes of the protrusions according to the above embodiments.

[0107] FIG. 17 is a cross-sectional view taken along line AA in FIG. 16. FIG. 17 also shows anode current collector 312, anode layer 311c positioned above and below it, and part of main body 313a of interconnector 313. As shown in FIG. 17, connecting portions 312b, 312b are connected to both ends in the width direction of upper side portion 312a. The lower end of connecting portion 312b is connected to lower side portion 312C. Thus, connecting portion 312b connects upper side portion 312a and lower side portion 312C. The cross-sectional shape of connecting portion 312b is an arc shape that bulges outward from internal space A1.

[0108] When a fastening force acts from above or below on anode current collector 312 having the above-described shape, connecting portion 312b, which has an arc-shaped cross section, bends and elastically deforms, thereby absorbing the fastening force. At this time, the elastic force of connecting portion 312b acts on upper side portion 312a and lower side portion 312C, so that upper side portion 312a is pressed firmly against anode layer 311c, and lower side portion 312C is pressed firmly against main body portion 313a of interconnector 313. This makes it possible to maintain good contact between upper surface S1 of upper side portion 312a and anode layer 311c, and between lower surface S2 of lower side portion 312C and main body portion 313a of interconnector 313.

[0109] 16, the connecting portion 312b has a plurality of openings OP formed along the depth direction. These openings OP are formed so that the opening length L increases toward the rear side in the depth direction. The opening width W of each opening is the same, and the pitch D between each opening is also the same.

[0110] According to this embodiment, the plurality of openings OP are formed in the connecting portion 312b so that the opening length L increases toward the rear in the depth direction, and therefore the opening ratio in the front half region FA of the connecting portion 312b is smaller than the opening ratio in the rear half region RA. Therefore, because the opening ratio in the rear half region RA of the connecting portion 312b is large, more water vapor flows from the inner space A1 to the outer space A2 in the rear half region RA, which is located in the area on the outlet side of the fuel chamber Sf. This compensates for the lack of water vapor near the outlet of the fuel chamber Sf (outer space A2). This promotes the steam electrolysis reaction near the outlet of the fuel chamber Sf.

[0111] As described above, this embodiment can promote the steam electrolysis reaction near the outlet of the fuel chamber Sf. This can prevent the steam electrolysis reaction (electrochemical reaction) from becoming uneven in the depth direction. Because the unevenness of the steam electrolysis reaction can be prevented in this way, the deterioration of the performance of the electrochemical cell can be prevented.

[0112] In addition, since the surface of the connecting portion 312b in this embodiment is curved (arcuate in cross section), the opening area of ​​the opening formed in the connecting portion 312b having such a surface shape may be the surface area of ​​the portion removed to form the opening, or may be the projected area when the opening is projected onto a specified plane.

[0113] (Sixth embodiment) Like the anode current collector according to the first embodiment, the anode current collector according to this embodiment also has a shape in which a plurality of upwardly protruding ridges extend parallel to each other in the depth direction. FIG. 18 is a perspective view showing one ridge formed on the anode current collector according to the sixth embodiment and a pair of lower edge portions connected to the ridge. The basic shape and structure of the anode current collector according to this embodiment are the same as those of the anode current collector according to the first embodiment, except that louvers are formed in openings formed in the connecting portions of the anode current collector. The following mainly describes the differences.

[0114] 18, like the anode current collector 312 according to the first embodiment, the anode current collector 312 according to this embodiment has an upper side portion 312a, a connecting portion 312b, and a lower side portion 312C. The upper side portion 312a and a pair of connecting portions 312b, 312b connected to the upper side portion 312a form a two-tiered, mountain-shaped protrusion 312A that protrudes from the lower side portion 312C and extends in the depth direction. The external shapes of these portions are the same as the external shapes of the upper side portion 312a, the connecting portion 312b, and the lower side portion 312C of the anode current collector 312 according to the first embodiment.

[0115] Furthermore, a plurality of openings OP are formed along the depth direction in each of the first inclined portion P1 and the second inclined portion P2 of the connecting portion 312b, penetrating in the thickness direction. The size, shape, and pitch of these openings are the same as the size, shape, and pitch of the plurality of openings formed in each of the first inclined portion P1 and the second inclined portion P2 of the connecting portion 312b according to the first embodiment. That is, the openings formed in the first inclined portion P1 and the openings formed in the second inclined portion P2 are formed so that the opening length L is longer as the opening OP is formed further rearward in the depth direction.

[0116] Each opening OP is provided with a louver LV. When forming each opening OP, the louver LV can be formed by cutting out the opening in a U-shape so that the rear end of the opening remains, and bending the base end (rear end) of the cutout piece so that the cutout piece is inclined from the opening toward the inner space A1 (inside). This louver LV has the same shape as the shape of the opening OP in which it is provided, and is formed so as to open inward from the rear end toward the front end in the depth direction.

[0117] When such louvers LV are formed in the opening OP, water vapor in the inner space A1 flows along the wall surface of the louvers LV, forming a flow path that guides the water vapor in the inner space A1 to the outer space A2. In other words, the louvers LV function to guide the water vapor in the inner space A1 from the inner space A1 to the outer space A2. Therefore, by forming the louvers LV in the opening OP, it is possible to make it easier for the water vapor in the inner space A1 to flow out to the outer space A2. This reduces the amount of water vapor that does not flow out from the inner space A1 to the outer space A2, allowing the water vapor to be used effectively.

[0118] Also in this embodiment, the opening ratio of the connecting portion 312b in the front region FA is smaller than the opening ratio in the rear region RA. Therefore, more water vapor flows from the inner space A1 to the outer space A2 in the rear region RA located in the region on the outlet side of the fuel chamber Sf, thereby compensating for the shortage of water vapor near the outlet of the fuel chamber Sf (outer space A2). This promotes the steam electrolysis reaction near the outlet of the fuel chamber Sf. Therefore, it is possible to suppress the bias of the steam electrolysis reaction (electrochemical reaction) in the depth direction. Furthermore, because the bias of the steam electrolysis reaction can be suppressed, it is possible to suppress the deterioration of the performance of the electrochemical cell.

[0119] Seventh Embodiment Like the anode current collector according to the first embodiment, the anode current collector according to this embodiment also has a shape in which a plurality of upwardly protruding ridges extend parallel to each other in the depth direction. Figure 19 is a perspective view showing one ridge formed on the anode current collector according to the seventh embodiment and a pair of lower edge portions connected to the ridge. The basic shape and structure of the anode current collector according to this embodiment are the same as those of the anode current collector according to the sixth embodiment, except that louvers are formed only in the openings formed in the rear region of the connecting portion of the anode current collector. The following mainly describes the differences.

[0120] 19, like the anode current collector 312 according to the first embodiment, the anode current collector 312 according to this embodiment has an upper side portion 312a, a connecting portion 312b, and a lower side portion 312C. The upper side portion 312a and a pair of connecting portions 312b, 312b connected to the upper side portion 312a form a two-tiered, mountain-shaped protrusion 312A that protrudes from the lower side portion 312C and extends in the depth direction. The external shapes of these portions are the same as the external shapes of the upper side portion 312a, connecting portion 312b, and lower side portion 312C of the anode current collector 312 according to the first embodiment.

[0121] Furthermore, a plurality of openings OP are formed along the depth direction in each of the first inclined portion P1 and the second inclined portion P2 of the connecting portion 312b, penetrating in the thickness direction. The size, shape, and pitch between these openings are the same as the size, shape, and pitch between the plurality of openings formed in each of the first inclined portion P1 and the second inclined portion P2 of the connecting portion 312b according to the first embodiment. That is, the openings formed in the first inclined portion P1 and the openings formed in the second inclined portion P2 are formed so that the opening length L is longer as the opening OP is formed closer to the rear.

[0122] A louver LV is formed in each opening OP formed in the rear region RA of the connecting portion 312b. Like the louvers LV according to the sixth embodiment, these louvers LV have the same shape as the openings in which they are provided, and are formed so as to open inward (toward the inner space A1) from the rear end to the front end in the depth direction.

[0123] If such louvers are formed only in the openings OP formed in the rear region RA of the connecting portion 312b, more water vapor in the inner space A1 can flow into the outer space A2 in the rear region RA of the connecting portion 312b. This allows a sufficient amount of water vapor to be supplied near the rear end of the connecting portion 312b, i.e., near the outlet of the fuel chamber Sf (outer space A2), and makes up for the shortage of water vapor near the outlet of the fuel chamber Sf. This promotes the water vapor electrolysis reaction near the outlet of the fuel chamber Sf. This prevents uneven distribution of the water vapor electrolysis reaction (electrochemical reaction) in the depth direction, and prevents performance degradation of the electrochemical cell.

[0124] Eighth Embodiment The anode current collector according to this embodiment has a shape in which a plurality of upwardly protruding ridges extend parallel to each other in the depth direction, similar to the anode current collector according to the first embodiment. Fig. 20 is a perspective view showing one ridge formed on the anode current collector according to the eighth embodiment and a pair of bottom edges connected to the ridge.

[0125] The structure of the anode current collector 312 according to this embodiment is a structure in which louvers LV are formed in each of the openings (OP1 to OP10) formed in the connecting portion 312b of the protrusion 312A of the anode current collector 312 according to the second embodiment shown in Fig. 11. Therefore, the structure other than the louvers LV is the same as the structure shown in Fig. 11, and therefore detailed description thereof will be omitted.

[0126] Like the louvers LV according to the sixth embodiment, the louvers LV have the same shape as the opening in which they are provided, and are formed so as to open inward (toward the inner space A1) from the rear end to the front end in the depth direction. By forming such louvers LV in the opening OP, a flow path is formed through which water vapor in the inner space A1 flows along the wall surface of the louvers LV and is guided to the outer space A2. This reduces the amount of water vapor that does not flow from the inner space A1 to the outer space A2, allowing for effective use of the water vapor.

[0127] Ninth embodiment The anode current collector according to this embodiment also has a shape in which a plurality of upwardly convex protrusions extend parallel to each other in the depth direction, similar to the anode current collector according to the first embodiment. Fig. 21 is a perspective view showing one protrusion formed on the anode current collector according to the ninth embodiment and a pair of bottom edges connected to the protrusion.

[0128] 21 , like the anode current collector 312 according to the first embodiment, the anode current collector 312 according to this embodiment has an upper side portion 312a, a connecting portion 312b, and a lower side portion 312C. The upper side portion 312a and a pair of connecting portions 312b, 312b connected to the upper side portion 312a form a two-tiered, mountain-shaped protrusion 312A that protrudes from the lower side portion 312C and extends in the depth direction. The external shapes of these portions are the same as the external shapes of the upper side portion 312a, the connecting portion 312b, and the lower side portion 312C of the anode current collector 312 according to the first embodiment.

[0129] Furthermore, a plurality of openings OP (OP1 to OP10) are formed along the depth direction in each of the first inclined portion P1 and the second inclined portion P2 of the connecting portion 312b. The shape of these openings is rectangular with sides parallel to the depth direction and sides perpendicular to the depth direction. All of the openings OP formed in the first inclined portion P1 have the same shape and size, and all of the openings OP formed in the second inclined portion P2 have the same shape and size. Furthermore, the pitches D between the openings formed in the first inclined portion P1 are all the same, and the pitches D between the openings formed in the second inclined portion P2 are also all the same.

[0130] Furthermore, louvers LV (LV1 to LV10) are formed in all of the openings OP. These louvers can be formed by cutting out the opening in a U-shape so that the rear end of the opening OP remains, and bending the base end (rear end) of the cutout piece so that the cutout piece is inclined from the opening toward the inner space A1 (inside). The louvers LV (LV1 to LV10) have the same shape as the shape of the opening OP in which they are provided, and are formed so as to open inward from the rear end toward the front end in the depth direction.

[0131] FIG. 22 is a cross-sectional view of the first inclined portion P1 of the connecting portion 312 shown in FIG. 21, cut along the depth direction so as to pass through the openings OP1 to OP10. As shown in FIGS. 21 and 22, the opening angles of the louvers LV formed in the openings OP become larger as the louvers are formed in the openings further back in the depth direction. Specifically, the opening angle of the louvers LVn formed in the nth (n=1 to 9)th opening OPn from the front in the depth direction is smaller than the opening angle of the (n+1)th opening OPn+1 from the front in the depth direction, and the opening angle of the louvers LV10 formed in the rearmost opening OP10 is the largest. The opening angle of a louver is the angle between the opening plane of the opening in which the louver is formed and the surface of the louver, as shown by angle θ in FIG. 22.

[0132] When louvers LV (LV1 to LV10) are formed as shown in Figure 21, the opening angle of louvers LV (LV1 to LV5) formed in the opening of the front half area FA of connecting portion 312b is smaller than the opening angle of louvers LV (LV6 to LV10) formed in the opening of the rear half area RA.

[0133] According to this embodiment, the opening angle of the louvers formed at the openings of the front half region FA of the connecting portion 312b is smaller than the opening angle of the louvers formed at the openings of the rear half region RA. Therefore, a small amount of water vapor flows along the louvers provided at the openings of the front half region FA and is discharged into the outer space A2. On the other hand, the opening angle of the louvers formed at the openings of the rear half region RA of the connecting portion 312b is larger. Therefore, more water vapor flows from the inner space A1 to the outer space A2 in the rear half region RA, which is located in the area on the outlet side of the fuel chamber Sf. This compensates for the lack of water vapor near the outlet of the fuel chamber Sf (outer space A2). This promotes the steam electrolysis reaction near the outlet of the fuel chamber Sf, thereby suppressing the bias of the steam electrolysis reaction (electrochemical reaction) in the depth direction. This suppression of the bias of the steam electrolysis reaction reduces the performance degradation of the electrochemical cell.

[0134] Although the embodiments of the present disclosure have been described above, the technology according to the present disclosure is not limited to the above embodiments. For example, the technology according to the present disclosure may be applied by combining the embodiments. For example, the openings formed in the connecting portion 312b may be formed so that the opening ratio in the front region FA of the connecting portion 312b is smaller than the opening ratio in the rear region RA by adjusting the opening length, opening width, and pitch of the openings. Furthermore, although the above embodiments describe examples in which the openings are rectangular, the openings may have any shape. For example, circular openings may be formed in the connecting portion 312b. Furthermore, although the above embodiments and their modifications describe examples in which an opening is formed in one of the pair of connecting portions 312b constituting the protrusion 312A, openings may be formed in both of the pair of connecting portions 312b. Furthermore, the above embodiments and their modifications describe examples in which multiple openings are formed in both the first inclined portion P1 and the second inclined portion P2 of the connecting portion 312b, openings may be formed only in the first inclined portion P1 or only in the second inclined portion P2. Furthermore, in the above embodiment, an example was shown in which openings are formed in the inclined portions (first inclined portion P1, second inclined portion P2) of the connecting portion, but multiple openings may be formed along the depth direction in the step portion P3. Furthermore, the cross-sectional shape of the connecting portion is not limited to the shape shown in the above embodiment, and any cross-sectional shape can be adopted.

[0135] Furthermore, although the above embodiment illustrates an electrochemical cell stack that generates hydrogen using water vapor as a fuel gas, the present technology can also be applied to an electrochemical cell stack that generates other gases, such as carbon monoxide, an electrochemical cell stack that generates hydrogen and carbon monoxide, or an electrochemical cell stack that generates electricity using hydrogen. In this way, the technology according to the present disclosure can be modified without departing from the spirit thereof.

[0136] Furthermore, the present disclosure may include the following aspects. [1] an electrochemical cell stack formed by stacking a plurality of electrochemical cell units, each of which includes an electrochemical cell including a solid electrolyte layer, an air cathode layer stacked on one side of the solid electrolyte layer, and an anode layer stacked on the other side of the solid electrolyte layer; an anode current collector formed of a conductive metal stacked on the electrochemical cell so as to be in contact with the anode layer; and an interconnector stacked on the electrochemical cell so as to be in contact with the anode current collector, The fuel electrode current collector is the electrochemical cell is disposed in a fuel chamber formed between the electrochemical cell and the interconnector, through which a fuel gas flows from one end to the other end in a predetermined first direction perpendicular to a stacking direction of the electrochemical cells; a first contact portion formed along the first direction and in contact with the anode layer adjacent to the first contact portion in the stacking direction, a second contact portion formed along the first direction and in contact with the interconnector adjacent to the first contact portion in the stacking direction, and a pair of connecting portions formed from both side ends of the first contact portion along the first direction toward the second contact portion to connect the first contact portion and the second contact portion, a protrusion portion that protrudes from the second contact portion and extends in the first direction is formed by the first contact portion and the pair of connecting portions, the fuel chamber is partitioned by the connecting portion into an inner space surrounded by the protrusion portion and the interconnector and an outer space surrounded by the protrusion portion and the electrochemical cell, An opening that communicates the inner space with the outer space is formed in the connecting portion, When the connecting portion is divided into a front half region that is a half region including one end in the first direction and a rear half region that is a half region including the other end, the opening ratio in the front half region is smaller than the opening ratio in the rear half region. Electrochemical cell stack. [2] [1] The electrochemical cell stack according to [1], A plurality of openings are formed in the connecting portion along the first direction, a total opening area of ​​the openings formed in the front half region is smaller than a total opening area of ​​the openings formed in the rear half region; Electrochemical cell stack. [3] The electrochemical cell stack according to [1] or [2], the pitch between the openings formed in the front half region is larger than the pitch between the openings formed in the rear half region; Electrochemical cell stack. [4] The electrochemical cell stack according to [1] or [2], an opening length of the opening formed in the front half region is shorter than an opening length of the opening formed in the rear half region; Electrochemical cell stack. [5] The electrochemical cell stack according to [1] or [2], the opening width of the opening formed in the front half region is narrower than the opening width of the opening formed in the rear half region; Electrochemical cell stack. [6] [1] to [5], an electrochemical cell stack according to any one of [1] to [5], No opening is formed in the front half region, and an opening is formed in the rear half region. Electrochemical cell stack. [7] [1] to [6], an electrochemical cell stack according to any one of [1] to [6], A plurality of openings are formed in the connecting portion along the first direction, At least the opening formed in the rear half region is provided with a louver for guiding the fuel gas flowing through the inner space to the outer space through the opening. Electrochemical cell stack. [8] [1] to [7], an electrochemical cell stack according to any one of [1] to [7], the anode current collector includes a plurality of the protrusions arranged in parallel to the first direction; Electrochemical cell stack. [9] an electrochemical cell stack formed by stacking a plurality of electrochemical cell units, each of which includes an electrochemical cell including a solid electrolyte layer, an air cathode layer stacked on one side of the solid electrolyte layer, and an anode layer stacked on the other side of the solid electrolyte layer; an anode current collector formed of a conductive metal stacked on the electrochemical cell so as to be in contact with the anode layer; and an interconnector stacked on the electrochemical cell so as to be in contact with the anode current collector, The fuel electrode current collector is the electrochemical cell is disposed in a fuel chamber formed between the electrochemical cell and the interconnector, through which a fuel gas flows from one end to the other end in a predetermined first direction perpendicular to a stacking direction of the electrochemical cells; a first contact portion formed along the first direction and in contact with the anode layer adjacent to the first contact portion in the stacking direction, a second contact portion formed along the first direction and in contact with the interconnector adjacent to the first contact portion in the stacking direction, and a pair of connecting portions formed from both side ends of the first contact portion along the first direction toward the second contact portion to connect the first contact portion and the second contact portion, a protrusion portion that protrudes from the second contact portion and extends in the first direction is formed by the first contact portion and the pair of connecting portions, the fuel chamber is partitioned by the connecting portion into an inner space surrounded by the protrusion portion and the interconnector and an outer space surrounded by the protrusion portion and the electrochemical cell, The connecting portion has a plurality of openings that communicate between the inner space and the outer space, Each of the plurality of openings is formed with a louver for guiding the fuel gas flowing through the inner space to the outer space, When the connecting portion is divided into a front half region that is a half region including one end in the first direction and a rear half region that is a region including the other end, an opening angle of the louvers formed in the opening of the front half region is smaller than an opening angle of the louvers formed in the opening of the rear half region. Electrochemical cell stack.

[10] [1] to [9], and an electrochemical cell stack according to any one of [1] to [9]. a vaporizer that generates water vapor to be supplied to the electrochemical cell stack; a heating device for heating the gas supplied to the electrochemical cell stack; a thermal insulator in which the electrochemical cell stack, the vaporizer, and the heating device are disposed; Equipped with Hot module.

[11] A hydrogen production device comprising the hot module according to

[10] . [Explanation of symbols]

[0137] 1...electrochemical cell stack, 2...evaporator, 3...heat exchanger, 4...heater (heating device), 5...insulating material (heating device), 7...hot module, 8...condenser, 30...cell cassette, 31...electrochemical cell unit, 311...electrolysis cell (electrochemical cell), 311a...solid electrolyte layer, 311b...air electrode layer, 311c...fuel electrode layer, 312...fuel electrode current collector, 312A...protrusion portion, 312a...upper edge portion (first contact portion), 312b...connecting portion, 312 C...lower side portion (second contact portion), 313...interconnector, 313a...main body portion, 313b...protrusion portion, 32...separator portion, 321...cell side separator, 322...interconnector side separator, 33...frame portion, 331...fuel electrode frame, 332...air electrode frame, 100...hydrogen production device, A1...inner space, A2...outer space, FA...front half region, LV...louver, OP...opening, RA...rear half region, Sa...air chamber, Sf...fuel chamber

Claims

1. an electrochemical cell stack formed by stacking a plurality of electrochemical cell units, each of which includes an electrochemical cell including a solid electrolyte layer, an air cathode layer stacked on one side of the solid electrolyte layer, and an anode layer stacked on the other side of the solid electrolyte layer; an anode current collector formed of a conductive metal stacked on the electrochemical cell so as to be in contact with the anode layer; and an interconnector stacked on the electrochemical cell so as to be in contact with the anode current collector, The fuel electrode current collector is the electrochemical cell is disposed in a fuel chamber formed between the electrochemical cell and the interconnector, through which a fuel gas flows from one end to the other end in a predetermined first direction perpendicular to a stacking direction of the electrochemical cells; a first contact portion formed along the first direction and in contact with the anode layer adjacent to the first contact portion in the stacking direction, a second contact portion formed along the first direction and in contact with the interconnector adjacent to the first contact portion in the stacking direction, and a pair of connecting portions formed from both side ends of the first contact portion along the first direction toward the second contact portion to connect the first contact portion and the second contact portion, a protrusion portion that protrudes from the second contact portion and extends in the first direction is formed by the first contact portion and the pair of connecting portions, the fuel chamber is partitioned by the connecting portion into an inner space surrounded by the protrusion portion and the interconnector and an outer space surrounded by the protrusion portion and the electrochemical cell, An opening that communicates the inner space with the outer space is formed in the connecting portion, When the connecting portion is divided into a front half region that is a half region including one end in the first direction and a rear half region that is a half region including the other end, the opening ratio in the front half region is smaller than the opening ratio in the rear half region. Electrochemical cell stack.

2. 10. The electrochemical cell stack of claim 1, A plurality of openings are formed in the connecting portion along the first direction, a total opening area of ​​the openings formed in the front half region is smaller than a total opening area of ​​the openings formed in the rear half region; Electrochemical cell stack.

3. 3. The electrochemical cell stack of claim 2, the pitch between the openings formed in the front half region is larger than the pitch between the openings formed in the rear half region; Electrochemical cell stack.

4. 3. The electrochemical cell stack of claim 2, an opening length of the opening formed in the front half region is shorter than an opening length of the opening formed in the rear half region; Electrochemical cell stack.

5. 3. The electrochemical cell stack of claim 2, the opening width of the opening formed in the front half region is narrower than the opening width of the opening formed in the rear half region; Electrochemical cell stack.

6. 10. The electrochemical cell stack of claim 1, No opening is formed in the front half region, and an opening is formed in the rear half region. Electrochemical cell stack.

7. 10. The electrochemical cell stack of claim 1, A plurality of openings are formed in the connecting portion along the first direction, At least the opening formed in the rear half region is provided with a louver for guiding the fuel gas flowing through the inner space to the outer space through the opening. Electrochemical cell stack.

8. 10. The electrochemical cell stack of claim 1, the anode current collector includes a plurality of the protrusions arranged in parallel to the first direction; Electrochemical cell stack.

9. an electrochemical cell stack formed by stacking a plurality of electrochemical cell units, each of which includes an electrochemical cell including a solid electrolyte layer, an air cathode layer stacked on one side of the solid electrolyte layer, and an anode layer stacked on the other side of the solid electrolyte layer; an anode current collector formed of a conductive metal stacked on the electrochemical cell so as to be in contact with the anode layer; and an interconnector stacked on the electrochemical cell so as to be in contact with the anode current collector, The fuel electrode current collector is the electrochemical cell is disposed in a fuel chamber formed between the electrochemical cell and the interconnector, through which a fuel gas flows from one end to the other end in a predetermined first direction perpendicular to a stacking direction of the electrochemical cells; a first contact portion formed along the first direction and in contact with the anode layer adjacent to the first contact portion in the stacking direction, a second contact portion formed along the first direction and in contact with the interconnector adjacent to the first contact portion in the stacking direction, and a pair of connecting portions formed from both side ends of the first contact portion along the first direction toward the second contact portion to connect the first contact portion and the second contact portion, a protrusion portion that protrudes from the second contact portion and extends in the first direction is formed by the first contact portion and the pair of connecting portions, the fuel chamber is partitioned by the connecting portion into an inner space surrounded by the protrusion portion and the interconnector and an outer space surrounded by the protrusion portion and the electrochemical cell, The connecting portion has a plurality of openings that communicate between the inner space and the outer space, Each of the plurality of openings is formed with a louver for guiding the fuel gas flowing through the inner space to the outer space, When the connecting portion is divided into a front half region that is a half region including one end in the first direction and a rear half region that is a region including the other end, an opening angle of the louvers formed in the opening of the front half region is smaller than an opening angle of the louvers formed in the opening of the rear half region. Electrochemical cell stack.

10. An electrochemical cell stack according to any one of claims 1 to 9; a vaporizer that generates water vapor to be supplied to the electrochemical cell stack; a heating device for heating the gas supplied to the electrochemical cell stack; a thermal insulator in which the electrochemical cell stack, the vaporizer, and the heating device are disposed; Equipped with Hot module.

11. A hydrogen production device comprising the hot module according to claim 10.

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