Differential pressure electrolytic cells and differential pressure electrolytic stacks

Abstract

To provide a better differential pressure electrolysis cell and differential pressure electrolysis stack. [Solution] A differential pressure electrolytic cell 22 includes a membrane electrode assembly 54, a first separator 48a, a second separator 48b, a first current feeder 56, a second current feeder 62, and a pressing portion 66. The pressing portion includes a sheet portion 86 formed of an electrically insulating polymer material so as to be elastically deformable, and disposed between the second current feeder and the second separator in a state in which it is compressed and deformed in the stacking direction of the membrane electrode assembly.

Description

Technical Field

[0001] The present disclosure relates to a differential pressure type electrolytic cell and a differential pressure type electrolytic stack.

Background Art

[0002] In recent years, in order to enable more people to access affordable, reliable, sustainable and advanced energy, research and development has been carried out on differential pressure type electrolytic cells and differential pressure type electrolytic stacks that contribute to energy efficiency.

[0003] Japanese Patent Application Laid-Open No. 2019-157213 discloses a water electrolytic cell which is a differential pressure type electrolytic cell. The water electrolytic cell includes an electrolyte membrane-electrode structure (membrane electrode structure), an anode power supply, a cathode power supply, an anode separator, and a cathode separator.

[0004] The electrolyte membrane-electrode structure has an electrolyte membrane, a cathode electrode catalyst layer laminated on one surface of the electrolyte membrane, and an anode electrode catalyst layer laminated on the other surface of the electrolyte membrane. In the water electrolytic cell, by applying a voltage between the cathode power supply and the anode power supply, oxygen gas is generated in the anode electrode catalyst layer and Cathode electrode hydrogen gas is generated in the catalyst layer. The water electrolytic cell can Cathode electrode make the hydrogen gas generated in the catalyst layer Anode electrode have a higher pressure than the oxygen gas generated in the catalyst layer.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] Better differential pressure type electrolytic cells and differential pressure type electrolytic stacks have been long awaited.

[0007] The present disclosure aims to solve the above-described problems.

Means for Solving the Problems

[0008] A first aspect of the present disclosure includes a membrane electrode structure having an electrolyte membrane, a first electrode catalyst layer laminated on one surface of the electrolyte membrane, and a second electrode catalyst layer laminated on the other surface of the electrolyte membrane; a first separator located on the side opposite to the second electrode catalyst layer with respect to the electrolyte membrane; a second separator located on the side opposite to the first electrode catalyst layer with respect to the electrolyte membrane; a first power supply body disposed between the first separator and the first electrode catalyst layer; a second power supply body disposed between the second separator and the second electrode catalyst layer; and a pressing portion sandwiched between the second power supply body and the second separator for pressing the second power supply body toward the second electrode catalyst layer. By applying a voltage between the first power supply body and the second power supply body to electrolyze the fluid supplied to the membrane electrode structure, a differential pressure type electrolytic cell capable of generating gas in the second electrode catalyst layer and making the gas at a higher pressure than the fluid is provided. The pressing portion includes a sheet portion formed of an electrically insulating polymer material so as to be elastically deformable and disposed between the second power supply body and the second separator in a state of being compressed and deformed in the stacking direction of the membrane electrode structure.

[0009] A second aspect of the present disclosure is a differential pressure type electrolytic stack formed by laminating a plurality of differential pressure type electrolytic cells, wherein the differential pressure type electrolytic cell is a differential pressure type electrolytic cell according to the first aspect.

Advantages of the Invention

[0010] According to the present disclosure, better differential pressure type electrolytic cells and differential pressure type electrolytic stacks can be provided.

Brief Description of the Drawings

[0011] [Figure 1]FIG. 1 is a perspective view of an electrolysis apparatus including a differential pressure type electrolysis stack. [Figure 2] FIG. 2 is a cross-sectional view of a differential pressure type electrolysis cell. [Figure 3] FIG. 3 is a cross-sectional view of a differential pressure type electrolysis cell according to a first modification. [Figure 4] FIG. 4 is a cross-sectional view of a differential pressure type electrolysis cell according to a second modification. [Figure 5] FIG. 5 is a cross-sectional view of a differential pressure type electrolysis cell according to a third modification. [Figure 6] FIG. 6A is a cross-sectional explanatory view of the differential pressure type electrolysis cell of FIG. 2. FIG. 6B is a cross-sectional explanatory view of the differential pressure type electrolysis cell of FIG. 5.

MODE FOR CARRYING OUT THE INVENTION

[0012] In the above-described water electrolysis cell, for example, a metal leaf spring (pressing portion) is disposed between the anode separator and the anode feeder. The leaf spring presses the anode feeder toward the membrane electrode structure. In such a configuration, variations are likely to occur in the pressure acting on the electrolyte membrane from the leaf spring (surface pressure of the electrolyte membrane). Further, since an extra current flows through the metal leaf spring, power loss occurs. When variations occur in the surface pressure of the electrolyte membrane and power loss occurs, the electrolysis efficiency of the membrane electrode structure decreases.

[0013] Furthermore, since the anode separator is made of metal, the portion of its surface that comes into contact with the leaf spring is coated with a material having electrical insulation properties. The coating prevents metal ions (for example, iron ions) from eluting from the anode separator. Since the leaf spring makes line contact with the coating of the anode separator, a relatively large load acts on the coating. Then, the coating of the anode separator may be peeled off when the leaf spring repeatedly presses the coating of the anode separator.

[0014] When the coating of the anode separator peels off, metal ions may elute. When the eluted metal ions reach the electrolyte membrane, the electrolyte membrane deteriorates. Then, the durability of the differential pressure type electrolytic cell decreases. Further, when a voltage is applied between the cathode power supply and the anode power supply, a local current may flow between the leaf spring and the anode separator through the peeled-off part of the coating, and metal corrosion may progress. Then, the durability of the differential pressure type electrolytic cell decreases.

[0015] The present disclosure can provide a differential pressure type electrolytic cell and a differential pressure type electrolytic stack that can improve electrolysis efficiency and durability.

[0016] FIG. 1 is a perspective explanatory view of an electrolytic device 11 including a differential pressure type electrolytic stack 10. As shown in FIG. 1, the electrolytic device 11 includes a differential pressure type electrolytic stack 10 and a power supply 12. The differential pressure type electrolytic stack 10 has a cell laminate 14, a pair of terminal plates 16a and 16b, a pair of insulating plates 18a and 18b, and a pair of end plates 20a and 20b.

[0017] The cell laminate 14 is formed by laminating a plurality of differential pressure type electrolytic cells 22 on each other in the A direction. The plurality of differential pressure type electrolytic cells 22 are laminated, for example, in the vertical direction. The plurality of differential pressure type electrolytic cells 22 may be laminated in a direction intersecting the vertical direction (for example, the horizontal direction). The cell laminate 14 is provided with a fluid inlet portion 24 and a fluid outlet portion 26. The fluid inlet portion 24 introduces a fluid used for electrolysis into the interior of the cell laminate 14. The fluid outlet portion 26 discharges unreacted fluid and the like that did not react during electrolysis to the outside of the cell laminate 14.

[0018] The terminal plate 16a is disposed at one end (the end in the A1 direction) of the cell stack 14. The insulating plate 18a is adjacent to the terminal plate 16a in the A1 direction. The end plate 20a is adjacent to the insulating plate 18a in the A1 direction. The terminal plate 16b is disposed at the other end (the end in the A2 direction) of the cell stack 14. The insulating plate 18b is adjacent to the terminal plate 16b in the A2 direction. The end plate 20b is adjacent to the insulating plate 18b in the A2 direction.

[0019] The terminal plate 16a is provided with a terminal portion 28a. The terminal portion 28a is electrically connected to the power source 12 via the wiring 30a. The terminal plate 16b is provided with a terminal portion 28b. The terminal portion 28b is electrically connected to the power source 12 via the wiring 30b.

[0020] The pair of end plates 20a and 20b are connected by a plurality of connecting members 32. The connecting members 32 include a stud bolt 34 and a nut 36. One end portion of the stud bolt 34 is fastened to the end plate 20a. The stud bolt 34 is passed through a hole (not shown) formed in the end plate 20b. A nut 36 is fastened to the other end portion of the stud bolt 34. Thereby, since the pair of end plates 20a and 20b are tightened in a direction approaching each other by the plurality of connecting members 32, a tightening load is applied to the cell stack 14.

[0021] FIG. 2 is a cross-sectional view of the differential pressure type electrolytic cell 22. As shown in FIG. 2, a fluid supply communication hole 40, a fluid discharge communication hole 42, and a gas outlet communication hole 44 are formed to penetrate in the A direction in the differential pressure type electrolytic cell 22. The fluid supply communication hole 40 is formed in the outer peripheral portion (the radially outer end portion) of the differential pressure type electrolytic cell 22. The fluid supply communication holes 40 of the plurality of differential pressure type electrolytic cells 22 communicate with each other. The fluid supply communication hole 40 communicates with the fluid inlet portion 24 (see FIG. 1). The fluid supply communication hole 40 is a flow path for supplying the fluid introduced from the fluid inlet portion 24 to the first electrode catalyst layer 76 of the differential pressure type electrolytic cell 22.

[0022] The fluid discharge communication holes 42 are formed on the outer circumference (radially outward end) of the differential pressure electrolytic cell 22. The fluid discharge communication holes 42 of multiple differential pressure electrolytic cells 22 are in communication with each other. The fluid discharge communication holes 42 are in communication with the fluid outlet section 26 (see Figure 1). The fluid discharge communication holes 42 are flow paths for guiding unreacted fluids that did not react during electrolysis in each differential pressure electrolytic cell 22 to the fluid outlet section 26.

[0023] The gas outlet communication hole 44 is formed in the center of the differential pressure electrolytic cell 22. The fluid supply communication hole 40 and the fluid discharge communication hole 42 are positioned so as to sandwich the gas outlet communication hole 44. The gas outlet communication holes 44 of the multiple differential pressure electrolytic cells 22 are in communication with each other. The gas outlet communication hole 44 is also formed in the end plate 20b (see Figure 1). The gas generated in the second electrode catalyst layer 78 of the differential pressure electrolytic cell 22 is discharged to the outside through the gas outlet communication hole 44 of the differential pressure electrolytic cell 22 and the gas outlet communication hole 44 of the end plate 20b.

[0024] The differential pressure electrolytic cell 22 comprises a cell body 46, a pair of separators 48, and a frame member 50. The cell body 46 is held between the pair of separators 48. The frame member 50 is formed in an annular shape to surround the cell body 46. The frame member 50 is made of, for example, an electrically insulating resin material. A sealing member 52 is provided between each of the pair of separators 48 and the frame member 50 to prevent fluid from flowing out to the outside.

[0025] The separator 48 is made of a metal material such as stainless steel. Hereinafter, in the differential pressure electrolytic cell 22 of Figure 2, the separator 48 located in the A1 direction of the cell body 46 of the pair of separators 48 will be referred to as the "first separator 48a", and the separator 48 located in the A2 direction of the cell body 46 of the pair of separators 48 will be referred to as the "second separator 48b".

[0026] The cell body 46 includes a membrane electrode structure 54, a first power supply 56, a protective sheet 58, a flow path member 60, a second power supply 62, a conductive sheet 64, a pressing portion 66, a conductive member 68, a sealing member 70, and a pressure-resistant member 72.

[0027] The membrane electrode structure 54 is positioned between the first power supply 56 and the second power supply 62. A gas outlet communication hole 44 is formed in the central part of the membrane electrode structure 54. The membrane electrode structure 54 includes an electrolyte membrane 74, a first electrode catalyst layer 76, and a second electrode catalyst layer 78. The electrolyte membrane 74 is an ion-exchange membrane. The electrolyte membrane 74 is, for example, a proton exchange membrane (PEM). The proton exchange membrane is, for example, a fluorine-based polymer membrane. The electrolyte membrane 74 may also be an anion exchange membrane (AEM).

[0028] The first electrode catalyst layer 76 is laminated on one side of the electrolyte membrane 74 (the side facing the A1 direction). The first electrode catalyst layer 76 is formed in an annular (circular) shape. The fluid used for electrolysis is supplied to the first electrode catalyst layer 76. The outer diameter of the first electrode catalyst layer 76 is smaller than the outer diameter of the electrolyte membrane 74. The second electrode catalyst layer 78 is laminated on the other side of the electrolyte membrane 74 (the side facing the A2 direction). Gas is generated in the second electrode catalyst layer 78 by the electrolysis of the fluid. The second electrode catalyst layer 78 is formed in an annular shape. The outer diameter of the second electrode catalyst layer 78 is smaller than the outer diameter of the electrolyte membrane 74.

[0029] The first power supply unit 56 is formed in an annular (ring-shaped) form. The first power supply unit 56 also serves as a diffusion layer for supplying the fluid used for electrolysis to the first electrode catalyst layer 76. The first power supply unit 56 has a portion formed of a porous material. The protective sheet 58 is placed between the first electrode catalyst layer 76 and the first power supply unit 56. The protective sheet 58 prevents the membrane electrode structure 54 from being pressed against the first power supply unit 56 and damaged by the gas generated in the second electrode catalyst layer 78. The protective sheet 58 has a plurality of through holes 80 formed therein to allow the fluid used for electrolysis to pass through.

[0030] The flow channel member 60 is formed in an annular shape. The flow channel member 60 is positioned between the first separator 48a and the first power supply unit 56. The flow channel member 60 supports the first power supply unit 56. A communication passage 82 is formed in the flow channel member 60. The communication passage 82 guides the fluid introduced from the fluid supply communication hole 40 to the first power supply unit 56. The communication passage 82 also guides unreacted fluid that did not react during electrolysis to the fluid discharge communication hole 42.

[0031] The second power supply unit 62 is formed in an annular (ring-shaped) form. The second power supply unit 62 also serves as a gas diffusion layer for guiding the gas generated in the second electrode catalyst layer 78. The second power supply unit 62 has a portion formed of a porous material. The outer diameter of the second power supply unit 62 is smaller than the outer diameter of the membrane electrode structure 54. In other words, the outer diameter of the second power supply unit 62 is smaller than the outer diameter of the electrolyte membrane 74. The membrane electrode structure 54 has an outer peripheral portion 84 that protrudes outward in the planar direction from the second power supply unit 62.

[0032] The conductive sheet 64 is laminated on the surface of the second power supply 62 facing direction A2. The conductive sheet 64 is made of a metal sheet such as titanium or stainless steel. A gas outlet communication hole 44 is formed in the center of the conductive sheet 64. The outer diameter of the conductive sheet 64 is approximately the same as the outer diameter of the second power supply 62.

[0033] The pressing portion 66 is sandwiched between the second separator 48b and the second power supply 62. In other words, the pressing portion 66 is sandwiched between the second separator 48b and the conductive sheet 64. The pressing portion 66 presses the conductive sheet 64 and the second power supply 62 toward the second electrode catalyst layer 78. In other words, the pressing portion 66 presses the conductive sheet 64 toward the second power supply 62. The pressing portion 66 is formed in an annular shape (for example, a ring shape) and is positioned corresponding to the electrolyte membrane 74 and the second power supply 62.

[0034] The pressing portion 66 includes a sheet portion 86 and a metal plate 88. The sheet portion 86 is formed elastically deformable from an electrically insulating polymer material. In other words, the sheet portion 86 is formed from a rubber material. The sheet portion 86 is positioned between the second power supply body 62 (conductive sheet 64) and the second separator 48b in a state of compression deformation in the stacking direction (direction A) of the membrane electrode structure 54. The sheet portion 86 is in surface contact with the second separator 48b and also in surface contact with the conductive sheet 64. The sheet portion 86 is formed in an annular shape (for example, a ring shape). The outer diameter of the sheet portion 86 is approximately the same as the outer diameter of the second power supply body 62.

[0035] The metal plate 88 extends along the sheet portion 86. The metal plate 88 is made of, for example, stainless steel. The metal plate 88 is formed in an annular shape (for example, a ring shape). The metal plate 88 is located inside the sheet portion 86. In other words, the metal plate 88 is embedded in the sheet portion 86. In direction A, the metal plate 88 is located in the central part of the sheet portion 86. That is, the sheet portion 86 covers the metal plate 88 from both sides in the stacking direction of the film electrode structure 54. The sheet portion 86 covers the entire surface of the metal plate 88.

[0036] The conductive member 68 is positioned in the central hole 90 of the pressing portion 66. The conductive member 68 is in contact with the inner surface of the sealing member 70. The conductive member 68 electrically connects the second separator 48b and the conductive sheet 64. The conductive member 68 is made of, for example, a metal material. However, the conductive member 68 may also be made of carbon or the like. The conductive member 68 is sandwiched between the second separator 48b and the conductive sheet 64. A gas outlet communication hole 44 is formed in the central part of the conductive member 68. The conductive member 68 and the conductive sheet 64 have gas flow paths 92 formed therein for guiding the gas generated in the second electrode catalyst layer 78 to the gas outlet communication hole 44.

[0037] The sealing member 70 is formed in an annular shape. The sealing member 70 has a circular cross-section. The sealing member 70 seals the space between the outer periphery 84 of the membrane electrode structure 54 and the second separator 48b. That is, the sealing member 70 is in airtight and liquid-tight contact with the outer periphery 84 of the membrane electrode structure 54, and is also in airtight and liquid-tight contact with the second separator 48b. The inner surface of the sealing member 70 facing radially inward is in contact with the outer periphery end of the sheet portion 86. The sealing member 70 prevents the gas generated in the second electrode catalyst layer 78 from leaking to the outside. The second power supply body 62, the conductive sheet 64, and the pressing portion 66 are arranged inside the sealing member 70. The gas generated in the second electrode catalyst layer 78 is sealed inside the sealing member 70 (gas containment chamber 94).

[0038] In this embodiment, since the space between the sealing member 70 and the conductive member 68 is sealed by the pressing portion 66 (sheet portion 86), the volume of the gas containment chamber 94 can be reduced compared to the case where a leaf spring is used for the pressing portion 66. The sealing member 70 is made of a resin material such as rubber.

[0039] The pressure-resistant member 72 is formed in an annular shape. The pressure-resistant member 72 is made of, for example, a metal material. The pressure-resistant member 72 is positioned to surround the seal member 70 from the radially outward direction. The pressure-resistant member 72 is sandwiched between the outer periphery 84 of the membrane electrode structure 54 and the second separator 48b. The pressure-resistant member 72 contacts the radially outward end of the seal member 70. The pressure-resistant member 72 prevents the seal member 70 from expanding radially outward due to the gas (high-pressure gas) present in the gas containment chamber 94. The pressing portion 66 of the second separator 48b, and the portion facing the seal member 70 and the pressure-resistant member 72 are coated with an electrically insulating material. This coating prevents the elution of metal ions (for example, iron ions) from the second separator 48b.

[0040] Next, the basic operation of the differential pressure electrolytic stack 10 according to this embodiment will be briefly described. In this embodiment, as shown in Figures 1 and 2, humidified fluid is supplied to the fluid inlet 24 of the differential pressure electrolytic stack 10, and a voltage is applied between the first power supply 56 and the second power supply 62 by the power supply 12. At this time, since the sheet portion 86 has electrical insulation properties, no current flows through the pressing portion 66. That is, when current flows through the second power supply 62, the conductive sheet 64, the conductive member 68, and the second separator 48b, no excess current flows through the pressing portion 66.

[0041] The fluid supplied to the fluid inlet 24 is guided to the first electrode catalyst layer 76 of each differential pressure electrolytic cell 22 via the fluid supply communication hole 40. In each differential pressure electrolytic cell 22, gas is generated in the second electrode catalyst layer 78 (gas containment chamber 94) by electrolysis of the fluid. The gas generated in the second electrode catalyst layer 78 is guided to the gas outlet communication hole 44 via the gas flow path 92. The gas guided to the gas outlet communication hole 44 is discharged to an external flow path (not shown). A back pressure valve (not shown) is provided in the external flow path. The gas generated in the second electrode catalyst layer 78 is pressurized by being sealed by the back pressure valve. This makes it possible to make the gas generated in the second electrode catalyst layer 78 more pressurized than the fluid supplied to the first electrode catalyst layer 76. In this embodiment, compared to the case where a leaf spring is used as the pressing part 66, the volume of the gas containment chamber 94 is smaller, so the gas pressurization rate can be increased. In each differential pressure electrolytic cell 22, any unreacted fluid that did not react during electrolysis is guided to the fluid outlet section 26 via the fluid discharge communication hole 42.

[0042] In this embodiment, the differential pressure electrolytic cell 22 may be a differential pressure water electrolytic cell or an electrochemical hydrogen booster cell. Below, examples of cases where the differential pressure electrolytic cell 22 is a differential pressure water electrolytic cell and cases where the differential pressure electrolytic cell 22 is an electrochemical hydrogen booster cell will be described.

[0043] If the differential-pressure electrolytic cell 22 is a differential-pressure water electrolytic cell, for example, the electrolyte membrane 74 can be formed as a proton exchange membrane, the first electrode catalyst layer 76 as an anode electrode catalyst layer, and the second electrode catalyst layer 78 as a cathode electrode catalyst layer. In this case, when water is supplied to the first electrode catalyst layer 76, the water is electrolyzed in the first electrode catalyst layer 76 to produce hydrogen ions and oxygen gas. The hydrogen ions move along with the water through the electrolyte membrane 74 from the first electrode catalyst layer 76 to the second electrode catalyst layer 78. As a result, hydrogen ions are supplied to the second electrode catalyst layer 78 and the electrolyte membrane 74 is humidified. In the second electrode catalyst layer 78, hydrogen ions combine to produce hydrogen gas. The hydrogen gas produced in the second electrode catalyst layer 78 is led to the gas outlet communication hole 44. The unreacted water supplied to the first electrode catalyst layer 76 and the oxygen gas produced in the first electrode catalyst layer 76 are led to the fluid discharge communication hole 42.

[0044] Furthermore, if the differential-pressure electrolytic cell 22 is a differential-pressure water electrolytic cell, for example, the electrolyte membrane 74 may be formed as an anion exchange membrane, the first electrode catalyst layer 76 as an anode electrode catalyst layer, and the second electrode catalyst layer 78 as a cathode electrode catalyst layer. In this case, water supplied to the first electrode catalyst layer 76 moves through the electrolyte membrane 74 from the first electrode catalyst layer 76 to the second electrode catalyst layer 78. As a result, water is supplied to the second electrode catalyst layer 78 and the electrolyte membrane 74 is humidified. In the second electrode catalyst layer 78, water is electrolyzed to produce hydrogen gas and hydroxide ions. The hydrogen gas produced in the second electrode catalyst layer 78 is guided to the gas outlet communication hole 44. The hydroxide ions produced in the second electrode catalyst layer 78 move through the electrolyte membrane 74 from the second electrode catalyst layer 78 to the first electrode catalyst layer 76. In the first electrode catalyst layer 76, oxygen gas and water are produced from the hydroxide ions. The water present in the first electrode catalyst layer 76 and the oxygen gas generated in the first electrode catalyst layer 76 are guided to the fluid discharge communication hole 42.

[0045] Furthermore, if the differential-pressure electrolytic cell 22 is a differential-pressure water electrolytic cell, for example, the electrolyte membrane 74 may be formed as a proton exchange membrane, the first electrode catalyst layer 76 as a cathode electrode catalyst layer, and the second electrode catalyst layer 78 as an anode electrode catalyst layer. In this case, water supplied to the first electrode catalyst layer 76 moves through the electrolyte membrane 74 from the first electrode catalyst layer 76 to the second electrode catalyst layer 78. As a result, water is supplied to the second electrode catalyst layer 78 and the electrolyte membrane 74 is humidified. In the second electrode catalyst layer 78, water is electrolyzed to produce hydrogen ions and oxygen gas. The oxygen gas produced in the second electrode catalyst layer 78 is guided to the gas outlet communication hole 44. The hydrogen ions produced in the second electrode catalyst layer 78 move through the electrolyte membrane 74 from the second electrode catalyst layer 78 to the first electrode catalyst layer 76. In the first electrode catalyst layer 76, hydrogen ions combine to produce hydrogen gas. The water and hydrogen gas supplied to the first electrode catalyst layer 76 that did not react are guided to the fluid discharge communication hole 42.

[0046] Furthermore, if the differential-pressure electrolytic cell 22 is a differential-pressure water electrolytic cell, for example, the electrolyte membrane 74 may be formed as an anion exchange membrane, the first electrode catalyst layer 76 as a cathode electrode catalyst layer, and the second electrode catalyst layer 78 as an anode electrode catalyst layer. In this case, when water is supplied to the first electrode catalyst layer 76, the water is electrolyzed in the first electrode catalyst layer 76 to produce hydrogen gas and hydroxide ions. The hydroxide ions move along with the water through the electrolyte membrane 74 from the first electrode catalyst layer 76 to the second electrode catalyst layer 78. As a result, hydroxide ions are supplied to the second electrode catalyst layer 78 and the electrolyte membrane 74 is humidified. In the second electrode catalyst layer 78, oxygen gas and water are produced from the hydroxide ions. The oxygen gas produced in the second electrode catalyst layer 78 is led to the gas outlet communication hole 44. The unreacted water supplied to the first electrode catalyst layer 76 and the hydrogen gas produced in the first electrode catalyst layer 76 are led to the fluid discharge communication hole 42.

[0047] When the differential pressure electrolytic cell 22 is an electrochemical hydrogen boost cell, for example, the electrolyte membrane 74 can be formed as a proton exchange membrane, the first electrode catalyst layer 76 as an anode electrode catalyst layer, and the second electrode catalyst layer 78 as a cathode electrode catalyst layer. In this case, when hydrogen gas containing water is supplied to the first electrode catalyst layer 76, the hydrogen gas is electrolyzed in the first electrode catalyst layer 76 to generate hydrogen ions. The hydrogen ions, along with the water, move through the electrolyte membrane 74 from the first electrode catalyst layer 76 to the second electrode catalyst layer 78. As a result, hydrogen ions are supplied to the second electrode catalyst layer 78 and the electrolyte membrane 74 is humidified. In the second electrode catalyst layer 78, hydrogen ions combine to generate hydrogen gas. The hydrogen gas generated in the second electrode catalyst layer 78 is guided to the gas outlet communication hole 44. Unreacted hydrogen gas that was guided to the first electrode catalyst layer 76 and did not react is guided to the fluid discharge communication hole 42.

[0048] According to this embodiment, since the sheet portion 86 is formed to be elastically deformable using an electrically insulating polymer material, variations in the surface pressure of the electrolyte membrane 74 can be suppressed compared to the case where a leaf spring is used as the pressing portion 66. In addition, power loss due to excess current flowing through the sheet portion 86 can be avoided. Therefore, the electrolysis efficiency of the differential pressure electrolytic cell 22 can be improved.

[0049] Furthermore, such a sheet portion 86 makes surface contact with the second separator 48b. That is, compared to the case where a leaf spring is used as the pressing portion 66, the pressure acting on the coating of the second separator 48b can be reduced. Therefore, peeling of the coating by the pressing portion 66 can be suppressed. As a result, the generation of metal ions due to peeling of the coating is suppressed, and thus the deterioration of the electrolyte membrane 74 by metal ions can be suppressed. In addition, metal corrosion due to local current flow can be suppressed. Therefore, the durability of the differential pressure electrolytic cell 22 can be improved. Thus, a better differential pressure electrolytic cell 22 and differential pressure electrolytic stack 10 can be provided.

[0050] In this embodiment, the pressing portion 66 has a metal plate 88 that extends along the sheet portion 86. With this configuration, the amount of elastic deformation of the sheet portion 86 in direction A can be reduced compared to the case where the sheet portion 86 does not have a metal plate 88 (pressing portion 66a according to the first modified example described later). In other words, when the electrolyte membrane 74 expands due to water absorption, the amount of compressive deformation of the sheet portion 86 in direction A can be reduced. This makes it possible to suppress the expansion of the electrolyte membrane 74 due to water absorption. That is, it is possible to suppress the outward spreading of the electrolyte membrane 74 in the planar direction. In other words, it is possible to suppress blistering (water blistering) of the electrolyte membrane 74.

[0051] (First variation) Next, a differential pressure electrolytic cell 22a according to the first modified example will be described. Figure 3 is a cross-sectional view of the differential pressure electrolytic cell 22a according to the first modified example. Components of the differential pressure electrolytic cell 22a according to the first modified example that are the same as those of the differential pressure electrolytic cell 22 described above are given the same reference numerals, and their detailed explanations are omitted. The same applies to the differential pressure electrolytic cell 22b according to the second modified example and the differential pressure electrolytic cell 22c according to the third modified example, which will be described later.

[0052] As shown in Figure 3, in the differential pressure electrolytic cell 22a according to the first modified example, a pressing portion 66a is provided instead of the pressing portion 66 compared to the differential pressure electrolytic cell 22 described above. The pressing portion 66a is composed only of a sheet portion 86. In other words, the pressing portion 66a does not have the metal plate 88 described above.

[0053] This configuration makes it possible to provide a differential pressure electrolytic cell 22a that can improve electrolysis efficiency and durability. Furthermore, since there is no need to provide a metal plate 88 inside the sheet portion 86, the configuration of the pressing portion 66a can be simplified.

[0054] (Second variation) Next, a differential pressure electrolytic cell 22b according to the second modified example will be described. Figure 4 is a cross-sectional view of the differential pressure electrolytic cell 22b according to the second modified example. As shown in Figure 4, in the differential pressure electrolytic cell 22b according to the second modified example, a pressing portion 66b is provided in place of the pressing portion 66 compared to the differential pressure electrolytic cell 22 described above.

[0055] The pressing portion 66b has a sheet portion 86a and a metal plate 88. The sheet portion 86a includes a first sheet body 100 and a second sheet body 102. The first sheet body 100 is sandwiched between the metal plate 88 and the conductive sheet 64. The second sheet body 102 is sandwiched between the metal plate 88 and the second separator 48b. The outer end face of the metal plate 88 in the plane direction is not covered by the sheet portion 86a. The inner end face of the metal plate 88 in the plane direction is not covered by the sheet portion 86a.

[0056] This configuration can provide a differential pressure electrolytic cell 22b that can improve electrolysis efficiency and durability. Furthermore, since the pressing portion 66b has a metal plate 88, blistering of the electrolyte membrane 74 can be suppressed.

[0057] In the differential pressure electrolytic cell 22b according to the second modified example, the inner circumferential end of the first sheet body 100 and the inner circumferential end of the second sheet body 102 may be connected to each other. In this case, the inward end face of the metal plate 88 in the planar direction is covered by the sheet portion 86a. Therefore, it is possible to prevent current from flowing between the conductive member 68 and the metal plate 88.

[0058] (Third variation) Next, a differential pressure electrolytic cell 22c according to the third modified example will be described. Figure 5 is a cross-sectional view of the differential pressure electrolytic cell 22c according to the third modified example. As shown in Figure 5, in the differential pressure electrolytic cell 22c according to the third modified example, compared to the differential pressure electrolytic cell 22 described above, a pressing portion 66c is provided in place of the pressing portion 66, and the sealing member 70 described above is omitted.

[0059] The pressing portion 66c has a sheet portion 86, a metal plate 88, a sealing portion 104, and a reinforcing portion 106. The sealing portion 104 is made of the same material as the sheet portion 86. That is, the sealing portion 104 is formed to be elastically deformable from an electrically insulating polymer material. In other words, the sealing portion 104 is made of a rubber material.

[0060] The sealing portion 104 extends in an annular (ring-shaped) manner. The sealing portion 104 seals the space between the outer peripheral portion 84 of the membrane electrode structure 54, which protrudes outward in the planar direction from the second power supply body 62, and the second separator 48b. The sealing portion 104 is molded integrally with the sheet portion 86. In other words, the sealing portion 104 is connected to the outer peripheral end of the sheet portion 86.

[0061] The seal portion 104 is adjacent to the second power supply body 62 in the outward direction in the plane (outward in the radial direction). That is, the seal portion 104 is in contact with or close to the second power supply body 62. The seal portion 104 presses the portion of the electrolyte membrane 74 adjacent to the portion pressed by the second power supply body 62 (pressed portion 108) in the outward direction in the plane (adjacent portion 110) in the A1 direction (see Figure 6B). The pressure-resistant member 72 is in contact with the radially outward end of the seal portion 104.

[0062] The reinforcing portion 106 is provided inside the sealing portion 104. The reinforcing portion 106 is made of metal. The reinforcing portion 106 extends in an annular shape along the sealing portion 104. The reinforcing portion 106 is connected to the outer circumference of the metal plate 88. That is, the reinforcing portion 106 and the metal plate 88 are integrally molded. The reinforcing portion 106 has an L-shaped cross-section. The reinforcing portion 106 includes an annular extension portion 106a extending radially outward from the metal plate 88 and an annular projection portion 106b projecting in the A1 direction from the extension portion 106a.

[0063] Figure 6A is a cross-sectional explanatory diagram of the differential pressure electrolytic cell 22 shown in Figure 2. As shown in Figure 6A, in the differential pressure electrolytic cell 22, the sealing member 70 has a circular cross-section. Therefore, the portion of the membrane electrode structure 54 that is pressed by the sealing member 70 (seal portion 112) is located further outward in the planar direction than the pressing portion 108 of the membrane electrode structure 54. In this case, the adjacent portion 110 of the electrolyte membrane 74 is not pressed by the sealing member 70. If the pressing portion 108 is pressed in the A1 direction by the second power supply 62 in this state, the adjacent portion 110 may deform in the A2 direction, bulging towards the gap between the second power supply 62 and the sealing member 70.

[0064] Figure 6B is a cross-sectional explanatory diagram of the differential pressure electrolytic cell 22c of Figure 5. As shown in Figure 6B, in the differential pressure electrolytic cell 22c according to the third modified example, the seal portion 104 is integrally molded with the sheet portion 86, so that the seal portion 104 can press against the adjacent portion 110. That is, in the differential pressure electrolytic cell 22c, the seal portion 112 is adjacent to the pressing portion 108. As a result, the seal portion 104 prevents a gap from forming between the second power supply body 62 and the pressure-resistant member 72, and deformation of the adjacent portion 110 can be suppressed.

[0065] Furthermore, in the differential pressure electrolytic cell 22c according to the third modified example, since the seal portion 104 is integrally molded with the sheet portion 86, the outer diameter of the seal portion 104 can be reduced compared to the case where the seal member 70 is provided separately from the sheet portion 86, as in the differential pressure electrolytic cell 22 described above. This makes it possible to reduce the outer diameter of the differential pressure electrolytic cell 22c.

[0066] In the differential pressure electrolytic cell 22c, a metal reinforcing portion 106 is provided inside the seal portion 104. With this configuration, the seal portion 104 provides good sealing to the adjacent portion 110. Press It is possible to obtain it.

[0067] Furthermore, the reinforcing portion 106 extends in an annular shape along the sealing portion 104. With this configuration, the sealing portion 104 provides good sealing to the adjacent portion 110. Press It is possible to obtain it.

[0068] Furthermore, the reinforcing portion 106 is connected to the metal plate 88. This configuration allows for increased rigidity of the reinforcing portion 106.

[0069] In the differential pressure electrolytic cell 22c, the seal portion 104 is in contact with or close to the second power supply body 62. With this configuration, the volume of the gas containment chamber 94 can be reduced, and therefore the rate at which the gas generated in the second electrode catalyst layer 78 is pressurized can be increased.

[0070] The differential pressure electrolytic cell 22c according to the third modified example is not limited to the configuration described above. The reinforcing portion 106 may be separated from the metal plate 88.

[0071] The following additional information is disclosed regarding the above embodiments.

[0072] (Note 1) The differential pressure electrolytic cell of the present disclosure comprises a membrane electrode structure (54) having an electrolyte membrane (74), a first electrode catalyst layer (76) laminated on one side of the electrolyte membrane, and a second electrode catalyst layer (78) laminated on the other side of the electrolyte membrane; a first separator (48a) located on the side of the electrolyte membrane opposite to the second electrode catalyst layer; a second separator (48b) located on the side of the electrolyte membrane opposite to the first electrode catalyst layer; a first power supply (56) disposed between the first separator and the first electrode catalyst layer; a second power supply (62) disposed between the second separator and the second electrode catalyst layer; and the second power supply and the second separator A differential pressure electrolytic cell (22, 22a to 22c) is provided, comprising pressing portions (66, 66a to 66c) sandwiched between the first and second power supply bodies for pressing the second power supply body toward the second electrode catalyst layer, wherein a voltage is applied between the first and second power supply bodies to electrolyze the fluid supplied to the membrane electrode structure, thereby generating gas in the second electrode catalyst layer and making the gas higher than the fluid, wherein the pressing portions include sheet portions (86, 86a) formed elastically deformable from an electrically insulating polymer material and disposed between the second power supply body and the second separator in a state of compression deformation in the stacking direction of the membrane electrode structure.

[0073] With this configuration, since the sheet portion is formed from an electrically insulating polymer material that can be elastically deformed, variations in the surface pressure of the electrolyte can be suppressed compared to when a leaf spring is used as the pressing part. In addition, power loss due to excess current flowing through the sheet portion can be avoided. Therefore, the electrolysis efficiency of the differential pressure electrolytic cell can be improved.

[0074] Furthermore, this sheet portion makes surface contact with the second separator. That is, compared to the case where a leaf spring is used as the pressing part, the pressure acting on the coating of the second separator can be reduced. Therefore, peeling of the coating by the pressing part can be suppressed. As a result, the generation of metal ions due to peeling of the coating is suppressed, and thus the deterioration of the electrolyte membrane by metal ions can be suppressed. In addition, metal corrosion due to local current flow can be suppressed. Therefore, the durability of the differential pressure electrolytic cell can be improved. Consequently, a better differential pressure electrolytic cell and differential pressure electrolytic stack can be provided.

[0075] (Note 2) In the differential pressure electrolytic cell described in Appendix 1, the pressing portion may have a metal plate (88) provided inside the sheet portion.

[0076] With this configuration, the amount of elastic deformation of the sheet portion in the stacking direction of the membrane electrode structure can be reduced compared to a case where a metal plate is not provided in the sheet portion. In other words, the amount of compressive deformation of the sheet portion in the stacking direction when the electrolyte membrane expands due to water absorption can be reduced. This makes it possible to suppress the expansion of the electrolyte membrane due to water absorption. That is, it is possible to suppress the outward spreading of the electrolyte membrane in the planar direction. In other words, it is possible to suppress blistering (water blistering) of the electrolyte membrane. In addition, the outer diameter of the seal portion can be reduced compared to a case where the seal member is provided separately from the pressing portion, so the outer diameter of the differential pressure electrolytic cell can be reduced.

[0077] (Note 3) The differential pressure electrolytic cell described in Appendix 1, wherein the pressing portion has a metal plate extending along the planar direction of the membrane electrode structure, and the sheet portion may cover the metal plate from both sides in the stacking direction.

[0078] This configuration produces the same effect as the differential pressure electrolytic cell described in Appendix 2.

[0079] (Note 4) A differential pressure electrolytic cell according to any one of the appendices 1 to 3, further comprising an annular sealing portion (104) that seals the space between the outer peripheral portion (84) of the membrane electrode structure, which is elastically deformable and protrudes outward in the planar direction from the second power supply body, and the second separator, wherein the sealing portion may be integrally molded with the sheet portion.

[0080] With this configuration, since the sealing portion is integrally molded with the sheet portion, the sealing portion can press against the portion of the membrane electrode structure that is pressed by the second power supply (pressed portion) in the planar direction and adjacent portion (adjacent portion). Therefore, deformation of the adjacent portion (deformation in which the adjacent portion bulges toward the second separator) can be suppressed.

[0081] (Note 5) The differential pressure electrolytic cell described in Appendix 4 may have a metal reinforcing portion (106) inside the sealing portion.

[0082] With this configuration, the sealing portion can better press against adjacent parts.

[0083] (Note 6) In the differential pressure electrolytic cell described in Appendix 5, the reinforcing portion may extend in an annular shape along the sealing portion.

[0084] With this configuration, the sealing portion can hold adjacent parts together even more effectively.

[0085] (Note 7) The differential pressure electrolytic cell described in Appendix 5, wherein the pressing portion has a metal plate provided inside the sealing portion, and the reinforcing portion may be connected to the metal plate.

[0086] This configuration allows for increased rigidity of the reinforced section.

[0087] (Note 8) A differential pressure electrolytic cell as described in Appendix 4, further comprising an annular pressure-resistant member (72) that covers the seal portion from the outside in the planar direction, wherein the pressure-resistant member may be in contact with the seal portion.

[0088] With this configuration, the pressure-resistant member can suppress the outward expansion of the seal portion in the planar direction due to the gas generated in the second electrode catalyst layer.

[0089] (Note 9) The differential pressure electrolytic cell described in Appendix 4, wherein the sealing portion may be in contact with or in close proximity to the second power supply.

[0090] With this configuration, the volume of the gas containment chamber can be reduced, which in turn increases the rate at which the gas generated in the second electrode catalyst layer is pressurized.

[0091] (Note 10) The differential pressure electrolytic stack of the present disclosure is a differential pressure electrolytic stack (10) formed by stacking a plurality of differential pressure electrolytic cells, wherein the differential pressure electrolytic cell is a differential pressure electrolytic cell as described in any one of appendices 1 to 9.

[0092] While this disclosure has been described in detail, it is not limited to the individual embodiments described above. These embodiments can be added, replaced, modified, partially deleted, etc., in any way that does not depart from the gist of this disclosure or from the spirit of this disclosure derived from the claims and their equivalents. These embodiments can also be implemented in combination. For example, the order of operations and processes in the embodiments described above are given as examples only and are not limited thereto. The same applies when numerical values ​​or mathematical formulas are used in the description of the embodiments described above. [Explanation of Symbols]

[0093] 10... Differential pressure electrolytic stack 22, 22a~22c... Differential pressure electrolytic cell 48a...First separator 48b...Second separator 54...Membrane electrode structure 56...First power feeder 62...Second power supply unit 66, 66a~66c...Pressing part 72...Pressure-resistant component 74...Electrolyte membrane 76...First electrode catalyst layer 78...Second electrode catalyst layer 84...Peripheral portion of the membrane electrode structure 86, 86a...Sheet portion 88... Metal plate 104... Seal part 106…Reinforcement section

Claims

1. A membrane electrode structure having an electrolyte membrane, a first electrode catalyst layer laminated on one side of the electrolyte membrane, and a second electrode catalyst layer laminated on the other side of the electrolyte membrane, A first separator located on the opposite side of the electrolyte membrane from the second electrode catalyst layer, A second separator located on the opposite side of the electrolyte membrane from the first electrode catalyst layer, A first power supply unit disposed between the first separator and the first electrode catalyst layer, A second power supply unit disposed between the second separator and the second electrode catalyst layer, A pressing portion is sandwiched between the second power supply and the second separator and presses the second power supply toward the second electrode catalyst layer, Equipped with, A differential pressure electrolytic cell is provided which, by applying a voltage between the first power supply and the second power supply and electrolyzing the fluid supplied to the membrane electrode structure, gas is generated in the second electrode catalyst layer and the pressure of the gas is made higher than that of the fluid, The pressing portion includes a sheet portion formed elastically deformable from an electrically insulating polymer material and disposed between the second power supply and the second separator in a state of compression deformation in the stacking direction of the film electrode structure. It is formed elastically deformable from an electrically insulating polymer material and further comprises an annular sealing portion that seals the space between the outer peripheral portion of the film electrode structure that protrudes outward in the planar direction from the second power supply and the second separator, A differential pressure electrolytic cell in which the sealing portion is integrally molded with the sheet portion.

2. A differential pressure electrolytic cell according to claim 1, The pressing portion is a differential pressure electrolytic cell having a metal plate provided inside the sheet portion.

3. A differential pressure electrolytic cell according to claim 1, The pressing portion has a metal plate that extends along the planar direction of the film electrode structure. The sheet portion covers the metal plate from both sides in the stacking direction, in a differential pressure electrolytic cell.

4. A differential pressure electrolytic cell according to claim 1, A differential pressure electrolytic cell is provided with a metal reinforcing portion inside the aforementioned sealing portion.

5. A differential pressure electrolytic cell according to claim 4, The reinforcing portion extends in an annular shape along the sealing portion, in a differential pressure electrolytic cell.

6. A differential pressure electrolytic cell according to claim 4, The pressing portion has a metal plate provided inside the sealing portion, The reinforcing portion is a differential pressure electrolytic cell connected to the metal plate.

7. A differential pressure electrolytic cell according to claim 1, The sealing portion is further provided with an annular pressure-resistant member that covers it from the outside in the surface direction, The pressure-resistant member is in contact with the sealing portion of a differential pressure electrolytic cell.

8. A differential pressure electrolytic cell according to claim 1, The sealing portion is in contact with or close to the second power supply unit, in a differential pressure electrolytic cell.

9. A differential pressure electrolytic stack formed by stacking multiple differential pressure electrolytic cells, A differential pressure electrolytic stack, wherein the differential pressure electrolytic cell is the differential pressure electrolytic cell described in any one of claims 1 to 8.

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