Differential pressure electrolysis apparatus

Abstract

To provide a differential pressure electrolysis apparatus in which occurrence of wrinkles (permanent deformation) in an electrolyte membrane subjected to gas pressure is avoided.SOLUTION: A differential pressure electrolysis apparatus comprises a resin frame member 110 joined to a peripheral portion of an electrolyte membrane 40A. A first member 166 is interposed between a first separator 32 and the resin frame member 110, and a second member 168 is interposed between the resin frame member 110 and a second separator 34. The differential pressure electrolysis apparatus comprises a positioning member 160. The positioning member 160 positions the resin frame member 110 with respect to the first member 166 or the second member 168. However, the positioning member 160 allows the resin frame member 110 to move along a plane direction.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a differential pressure electrolysis device for obtaining high-pressure gas by electrolysis. [Background technology]

[0002] One example of a differential pressure electrolysis device is a differential pressure water electrolysis device that electrolyzes water to obtain hydrogen and oxygen (see, for example, Patent Document 1). Another example of a differential pressure electrolysis device is an electrochemical hydrogen booster device that electrolyzes low-pressure hydrogen at one electrode and produces high-pressure hydrogen at the other electrode. Such a differential pressure electrolysis device includes an electrolysis cell. The electrolysis cell has a membrane electrode assembly and a first separator and a second separator that sandwich the membrane electrode assembly between them. The membrane electrode assembly has a first electrode, a second electrode, and an electrolyte membrane interposed between the first and second electrodes. The first electrode is either an anode or a cathode, and the second electrode is the other of the anode and the cathode.

[0003] When the electrolyte membrane is a proton conductor and water is supplied to the anode, electrons, protons, and oxygen are produced at the anode, and hydrogen is produced at the cathode. The hydrogen is pressurized relative to the oxygen. A similar reaction occurs when water is supplied to the cathode, but the oxygen is pressurized relative to the hydrogen. In contrast, when the electrolyte membrane is an anion conductor and water is supplied to the cathode, hydrogen and hydroxide ions are produced at the cathode, and oxygen and electrons are produced at the anode. The oxygen is pressurized relative to the hydrogen. A similar reaction occurs when water is supplied to the anode, but the hydrogen is pressurized relative to the oxygen. Thus, in a differential pressure water electrolysis device, the pressure of the gas generated at one electrode is greater than the pressure of the gas generated at the other electrode. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2019-157213 Summary of the Invention [Problem to be solved by the invention]

[0005] The electrolyte membrane has a first surface facing the first electrode and a second surface facing the second electrode. When high-pressure gas is generated at the second electrode, the second surface is subjected to pressure from the gas. This may cause wrinkles (deformation) in the electrolyte membrane. Furthermore, while a configuration in which the electrolyte membrane is bonded to a resin frame member is known for fuel cells, applying this configuration to a differential pressure electrolysis device may cause the electrolyte membrane to peel off from the resin frame member when the electrolyte membrane swells.

[0006] The present invention aims to solve the above-mentioned problems. [Means for solving the problem]

[0007] One aspect of the present invention is a differential pressure electrolysis device comprising an electrolysis cell having a membrane electrode assembly in which an electrolyte membrane is interposed between a first electrode and a second electrode, and a first separator and a second separator that sandwich the membrane electrode assembly between them. In the differential pressure electrolysis device, gas obtained at the second electrode has a higher pressure than the gas obtained at the first electrode.

[0008] The differential pressure electrolysis device includes a resin frame member joined to a peripheral portion of the electrolyte membrane, a first member interposed between the first separator and the resin frame member in a stacking direction of the first electrode, the electrolyte membrane, and the second electrode, a second member interposed between the resin frame member and the second separator in the stacking direction, and a positioning member that positions the resin frame member relative to the first member or the second member in a planar direction perpendicular to the stacking direction. The positioning member allows the resin frame member to move along the planar direction. [Effects of the Invention]

[0009] When the electrolyte membrane expands along the surface, the resin frame member moves along the surface, which prevents wrinkles (permanent deformation) from occurring in the electrolyte membrane under gas pressure. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 is a schematic perspective view of a differential pressure electrolysis device (water electrolysis device) according to one embodiment of the present invention. [Figure 2] FIG. 2 is a schematic cross-sectional view of an electrolysis cell constituting the water electrolysis apparatus, viewed from the radial direction. [Figure 3] FIG. 3 is a cross-sectional view of the main part of the electrolysis cell as viewed from the radial direction. [Figure 4] FIG. 4 is a schematic plan view of the framed structure as viewed from above in the stacking direction. [Figure 5] FIG. 5 is a schematic plan view of a framed structure of another embodiment, as viewed from above in the stacking direction. [Figure 6] FIG. 6 is a cross-sectional view of a main part of an electrolysis cell of a water electrolysis apparatus according to a second embodiment, viewed from the radial direction. [Figure 7] FIG. 7 is a cross-sectional view of a main part of an electrolysis cell of a water electrolysis apparatus according to a third embodiment, viewed from the radial direction. [Figure 8] FIG. 8 is a cross-sectional view of a main part of an electrolysis cell of a water electrolysis apparatus according to a fourth embodiment, viewed from the radial direction. [Figure 9] FIG. 9 is a cross-sectional view of a main part of an electrolysis cell of a water electrolysis apparatus according to a first modified example of the fourth embodiment, viewed from the radial direction. [Figure 10] FIG. 10 is a cross-sectional view of a main part of an electrolysis cell of a water electrolysis apparatus according to a second modification of the fourth embodiment, viewed from the radial direction. DETAILED DESCRIPTION OF THE INVENTION

[0011] The following description will be given taking as an example a case where the electrolytic cells 12 shown in FIG. 1 are stacked in the vertical direction (the direction of arrow A). Therefore, "bottom" and "top" refer to the top and bottom in the stacking direction, respectively. However, this is a convenient orientation for simplifying the description. The stacking direction of the differential pressure electrolysis device 300 is not limited to the up-down direction. The stacking direction of the electrolytic cells 12 may also be the horizontal direction (the direction of arrow B) perpendicular to the vertical direction.

[0012] 1 is a schematic perspective view of a differential pressure electrolysis device 300. In the first embodiment, the differential pressure electrolysis device 300 is a water electrolysis device 10 that electrolyzes water. Therefore, in the first embodiment, the water electrolysis device 10 will be described in detail. The same applies to the second to fourth embodiments described below. However, the differential pressure electrolysis device 300 is not limited to the water electrolysis device 10 as long as it is a device that generates gas at the second electrode 43b shown in FIG. 2.

[0013] In the water electrolysis device 10, water is electrolyzed to generate a first gas at the first electrode 43a and a second gas at the second electrode 43b shown in FIG. 2. The second gas is pressurized higher than the first gas. In this specification, the second electrode 43b refers to an electrode for obtaining a high-pressure gas. For simplicity and ease of understanding, the first embodiment illustrates an example in which oxygen is generated as the first gas at the first electrode 43a and hydrogen is generated as the second gas at the second electrode 43b. In this example, the first electrode 43a is an anode where an oxidation reaction occurs, and the second electrode 43b is a cathode where a reduction reaction occurs. The electrolyte membrane 40A is a proton exchange membrane through which protons can move, such as a hydrocarbon (HC)-based polymer membrane or a fluorine-based polymer membrane.

[0014] The water electrolysis device 10 includes electrolytic cells 12. As shown in Fig. 1, the water electrolysis device 10 includes a stack of multiple electrolytic cells 12 to form a stack 14. At one end (upper end) of the stack 14 in the stacking direction, a terminal plate 16a, an insulating plate 18a, and an end plate 20a are arranged from bottom to top. At the other end (lower end) of the stack 14 in the stacking direction, a terminal plate 16b, an insulating plate 18b, and an end plate 20b are arranged from top to bottom.

[0015] The electrolysis cell 12 has a substantially perfect circular shape in plan view. In this case, the planar direction perpendicular to the stacking direction corresponds to the diameter direction. Therefore, hereinafter, the planar direction may also be referred to as the radial direction. The direction of arrow B is an example of the radial direction.

[0016] A pipe (not shown) is connected to the end plate 20a. This pipe is provided with a back pressure mechanism (not shown) that can restrict the discharge of hydrogen from the hydrogen communication holes 38c (described later). The end plate 20a and the end plate 20b are fastened together via tie rods 22. This applies a fastening load to the multiple electrolysis cells 12.

[0017] Terminal portions 24a and 24b are provided on the sides of terminal plates 16a and 16b, respectively, so as to protrude outward in the diameter direction. Terminal portions 24a and 24b are electrically connected to a power source 28 for electrolysis via wires 26a and 26b, respectively.

[0018] As shown in FIG. 2, the electrolysis cell 12 includes a framed structure 100A including a substantially disk-shaped membrane electrode assembly 30A, a first separator 32, and a second separator 34. The first separator 32 and the second separator 34 sandwich the framed structure 100A between them. A resin cylinder 36 is disposed between the first separator 32 and the second separator 34. The cylinder 36 surrounds the outer periphery of the membrane electrode assembly 30A. A seal member 37a seals between the first separator 32 and the cylinder 36, and a seal member 37b seals between the cylinder 36 and the second separator 34.

[0019] Fluid supply communication holes 38a that communicate with each other in the stacking direction (arrow A direction) are provided at one end in the radial direction (arrow B direction) of the cylinder 36. A fluid supply unit 90 is connected to the fluid supply communication holes 38a. The fluid supply unit 90 (see FIG. 1) supplies water, which is a fluid, to the fluid supply communication holes 38a.

[0020] A fluid discharge passage 38b is provided at the other radial end (direction of arrow B) of the cylinder 36 for discharging oxygen produced by the electrode reaction and unreacted water. As shown in FIG. 1, a supply joint 92a is connected to the cylinder 36 located at the other end (lowest end) in the stacking direction. A fluid supply port 39a of the supply joint 92a communicates with the fluid supply passage 38a shown in FIG. 2. As shown in FIG. 1, a discharge joint 92b is connected to the cylinder 36 located at one end (upper end) in the stacking direction. A fluid discharge port 39b of the discharge joint 92b communicates with the fluid discharge passage 38b shown in FIG. 2.

[0021] 2, the electrolysis cell 12 has a hydrogen communication hole 38c that penetrates the center in the radial direction along the stacking direction. Hydrogen generated by electrolysis of water flows through the hydrogen communication hole 38c. The pressure of the hydrogen is increased to, for example, 1 MPa to 80 MPa.

[0022] As shown in detail in FIG. 3, the framed structure 100A includes a resin frame member 110 and a membrane electrode assembly 30A supported by the resin frame member 110. The resin frame member 110 is flexible and can be slightly stretched. The membrane electrode assembly 30A includes an electrolyte membrane 40A, a first electrode 43a, and a second electrode 43b. The electrolyte membrane 40A, the first electrode 43a, and the second electrode 43b are sandwiched between a first power feeder 44a and a second power feeder 44b. Each of the electrolyte membrane 40A, the first electrode 43a, the second electrode 43b, the first power feeder 44a, and the second power feeder 44b is generally ring-shaped. In the first embodiment, the electrolyte membrane 40A is formed from a single ion exchange membrane 41.

[0023] In the first embodiment, the outer diameter of the first electrode 43a and the outer diameter of the second electrode 43b are substantially equal. The outer diameter of the electrolyte membrane 40A is larger than the outer diameters of the first electrode 43a and the second electrode 43b. Therefore, the peripheral edge 42A of the electrolyte membrane 40A is exposed outward beyond the peripheral edges of the first electrode 43a and the second electrode 43b. The resin frame member 110 is joined to a membrane-side joining portion 200 of the electrolyte membrane 40A. The membrane-side joining portion 200 is part of the peripheral edge 42A of the electrolyte membrane 40A and forms the joining portion between the electrolyte membrane 40A and the resin frame member 110.

[0024] The electrolyte membrane 40A has a first surface 201 facing the first electrode 43a and a second surface 202 facing the second electrode 43b. The membrane-side joint 200 has a first joint 203 formed on the first surface 201 and a second joint 204 formed on the second surface 202. The first joint 203 and the second joint 204 form an annular shape.

[0025] The membrane-side joint 200 has a large number of minute recesses 210 and protrusions 212. Therefore, in the electrolyte membrane 40A, the surface roughness of the membrane-side joint 200 is greater than that of portions other than the membrane-side joint 200. In addition, the surface roughness of the second joint 204 is greater than that of the first joint 203.

[0026] The membrane-side bonding portion 200 can be formed, for example, by performing a surface treatment on a portion of the electrolyte membrane 40A that will become the membrane-side bonding portion 200 (hereinafter referred to as a "preliminary bonding portion"). One example of the surface treatment is an alkali treatment. Specifically, the preliminary bonding portion that will become the first bonding portion 203 is selectively immersed in a strong base such as NaOH, KOH, or Ca(OH)2. This etches the preliminary bonding portion, forming the first bonding portion 203. To neutralize the strong base remaining in the first bonding portion 203, the first bonding portion 203 is preferably washed with a strong acid. Examples of strong acids include H2SO4, HCl, and HNO3.

[0027] Next, the preliminary bonding portion that will become the second bonding portion 204 is selectively immersed in the strong base described above. The immersion time is longer than the immersion time when obtaining the first bonding portion 203. Thereafter, the second bonding portion 204 is washed with the strong acid described above. As a result, the second bonding portion 204, which has a greater surface roughness than the first bonding portion 203, is obtained.

[0028] The first bonding portion 203 may be formed as a plurality of concentric ring-shaped portions. In this case, predetermined locations of the preliminary bonding portion are masked with a ring-shaped masking material, and then the first surface 201 is subjected to the above-described alkali treatment. The locations where the masking material is not provided are etched, and the locations masked with the masking material are not etched. As a result, a plurality of second bonding portions 204 are formed on the outer circumferential side and the inner circumferential side of the masking material, respectively. In a similar manner, a plurality of concentric second bonding portions 204 can also be formed.

[0029] The relationship between the surface roughness of the first bonding portion 203 and the surface roughness of the second bonding portion 204 is not limited to the above. For example, the surface roughness of the second bonding portion 204 may be approximately the same as that of the first bonding portion 203. In addition, it is not essential to set the surface roughness of the membrane-side bonding portion 200 to be greater than that of other portions.

[0030] The resin frame member 110 has a first member element 120 and a second member element 130. The first member element 120 and the second member element 130 are stacked in the stacking direction. An annular recess 140 is formed on the inner peripheral edge of the stacked first member element 120 and the second member element 130. A membrane-side joining portion 200 of the electrolyte membrane 40A is inserted into the annular recess 140. Alternatively, as in FIG. 7 , the membrane-side joining portion 200 may be sandwiched between a flat first member element 122 and a flat second member element 132.

[0031] The membrane-side bonding portion 200 is bonded to the resin frame member 110 via, for example, an adhesive AS. Specifically, in the first member element 120, the adhesive AS is interposed between a first inner surface forming the annular recess 140 and a first bonding portion 203 facing the first inner surface. Similarly, in the second member element 130, the adhesive AS is interposed between a second inner surface forming the annular recess 140 and a second bonding portion 204 facing the second inner surface. When the surface roughness of the first bonding portion 203 and the second bonding portion 204 is greater than that of other portions, the anchor effect of the adhesive AS firmly bonds the first inner surface to the first bonding portion 203 and also firmly bonds the second inner surface to the second bonding portion 204.

[0032] As shown in FIG. 2, a space surrounded by the first separator 32, the cylinder 36, and the electrolyte membrane 40A is formed inside the electrolysis cell 12. This space is the first electrode chamber 45a. The first electrode chamber 45a houses a flow path forming member 46 and a first power feeder 44a. The flow path forming member 46 and the first power feeder 44a are interposed between the first separator 32 and the electrolyte membrane 40A. The flow path forming member 46 is sandwiched between the first separator 32 and the first power feeder 44a in the stacking direction.

[0033] The flow passage forming member 46 has an inlet protrusion 46a and an outlet protrusion 46b on the outer periphery thereof. The inlet protrusion 46a and the outlet protrusion 46b face each other in the radial direction.

[0034] A supply connection passage 50a is formed in the inlet protrusion 46a. The supply connection passage 50a communicates with the fluid supply communication hole 38a and the fluid flow path 50b. A plurality of holes 50c communicate with the fluid flow path 50b. The holes 50c open toward the first power feed body 44a. A discharge connection passage 50d is formed in the outlet protrusion 46b. The discharge connection passage 50d communicates with the fluid flow path 50b and the fluid discharge communication hole 38b.

[0035] A protective sheet member 48 is disposed between the first power supply body 44a and the first electrode 43a. The protective sheet member 48 has a plurality of through holes 48a extending in the stacking direction.

[0036] A substantially cylindrical, perforated body 52 is disposed in the radial center between the first separator 32 and the electrolyte membrane 40A. The perforated body 52 has an inner cylinder 54 made of a porous material in which hydrogen through holes 38c are formed, and an outer cylinder 55 that surrounds the outer periphery of the inner cylinder 54. The space between the inner cylinder 54 and the outer cylinder 55 is sealed by O-rings 56a and 56b.

[0037] An annular step 55s is formed on the outer peripheral end of the outer tubular body 55, facing the electrolyte membrane 40A. The inner peripheral portion of the protective sheet member 48 is inserted into the annular step 55s.

[0038] The space surrounded by the electrolyte membrane 40A, the cylinder 36, and the second separator 34 is the second electrode chamber 45b. The second electrode chamber 45b accommodates the second power supply body 44b and the load-applying mechanism 58. The second power supply body 44b and the load-applying mechanism 58 are interposed between the electrolyte membrane 40A and the second separator 34 in the stacking direction.

[0039] The load-applying mechanism 58 includes, for example, a conductive elastic member such as a leaf spring 60. The leaf spring 60 applies a load to the second power supply body 44b via a metal shim member 62. The load is applied in a direction that presses the second power supply body 44b toward the second electrode 43b, that is, downward in the stacking direction.

[0040] A conductive sheet 66 and an insulating sheet 68 are disposed between the second current feeder 44b and the shim member 62. The conductive sheet 66 is formed, for example, from a metal sheet with a hydrogen communication hole 38c provided approximately at the radial center. The inner and outer diameters of the conductive sheet 66 are approximately equal to the inner and outer diameters of the second current feeder 44b, respectively. The surface of the conductive sheet 66 facing the second current feeder 44b has a recess 66a. The insulating sheet 68 is housed in the recess 66a.

[0041] A cylindrical member 70 is disposed radially inward of the load-applying mechanism 58. The cylindrical member 70 is interposed between the conductive sheet 66 and the second separator 34 in the stacking direction. A hydrogen communication hole 38c is formed in the radial center of the cylindrical member 70. A hydrogen discharge passage 71 is formed in one end face of the cylindrical member 70 facing the second separator 34. The hydrogen discharge passage 71 connects the second electrode chamber 45b and the hydrogen communication hole 38c.

[0042] In the stacking direction, a seal member 80 and a pressure-resistant member 84 are interposed between the electrolyte membrane 40A and the second separator 34. The pressure-resistant member 84 is located on the outer periphery of the seal member 80 in the radial direction.

[0043] Furthermore, the joining point between the resin frame member 110 and the membrane-side joining portion 200 using the adhesive AS is located outward from the outer peripheral end 80o of the seal member 80. However, the joining point is not limited to this position. The joining point may be located outward from the outer peripheral end 80o of the seal member 80.

[0044] The electrolytic cell 12 has an insertion hole 150 formed from the first power supply body 44a to the second member element 130. In the example shown in FIG. 4, which is a cross section taken along the direction of arrow B, the insertion hole 150 includes a first insertion hole 150a to a third insertion hole 150c arranged in a circumferential direction. In the circumferential direction, the second insertion hole 150b is adjacent to the first insertion hole 150a, and the third insertion hole 150c is adjacent to the second insertion hole 150b. The first insertion hole 150a and the second insertion hole 150b are spaced apart by 90°, and the second insertion hole 150b and the third insertion hole 150c are also spaced apart by 90°. In contrast, the third insertion hole 150c and the first insertion hole 150a are spaced apart by 180°.

[0045] A positioning member 160 is inserted through each of the first through-holes 150a to third through-holes 150c. In the first embodiment, the positioning member 160 is a knock pin 162. In the illustrated example, the lower end of the knock pin 162 is supported by the flow path forming member 46. The upper end of the knock pin 162 is inserted into a positioning hole 164 formed in the pressure resistant member 84, and is thereby supported by the pressure resistant member 84. In this configuration, the flow path forming member 46 and the pressure resistant member 84 are a first member 166 and a second member 168, respectively, that support the knock pin 162.

[0046] The first member 166 is not limited to the flow path forming member 46. The first member 166 may be the first power feeder 44a or the protective sheet member 48. The second member 168 is not limited to the pressure-resistant member 84. The second member 168 may be the cylindrical body 36 or the first power feeder 44a. Furthermore, the knock pin 162, which is the positioning member 160, may be supported by either the first member 166 or the second member 168. It is not essential that the knock pin 162 be supported by both the first member 166 and the second member 168.

[0047] In the example shown in FIG. 4, the first insertion hole 150a has an elongated hole shape extending in the direction of the arrow S. The second insertion hole 150b has an elongated hole shape extending in the direction of the arrow T. The third insertion hole 150c has a substantially perfect circular shape. On the other hand, the cross section of the knock pin 162 has a substantially perfect circular shape. The cross-sectional areas of the first insertion hole 150a to the third insertion hole 150c in the planar direction are larger than the cross-sectional area of ​​the knock pin 162 in the planar direction.

[0048] Specifically, the extension length L1 of the first insertion hole 150a in the direction of arrow T is greater than the diameter D1 of the knock pin 162. Therefore, the resin frame member 110 is permitted to move in the direction of arrow T using the knock pin 162 and the first insertion hole 150a as guides. Similarly, the resin frame member 110 is permitted to move in the direction of arrow S using the knock pin 162 and the third insertion hole 150c as guides. Furthermore, the diameter D2 of the second insertion hole 150b is greater than the diameter D1 of the knock pin 162. Therefore, the resin frame member 110 is permitted to move in the radial direction. In this way, the knock pin 162 passed through each of the first to third insertion holes 150a to 150c is permitted to move along the surface direction of the resin frame member 110.

[0049] 5, the distance between the first insertion hole 150a and the second insertion hole 150b, the distance between the second insertion hole 150b and the third insertion hole 150c, and the distance between the third insertion hole 150c and the first insertion hole 150a are all 120°. The cross section of each of the first through hole 150a to the third insertion hole 150c is substantially circular. The cross section of the knock pin 162 is also substantially circular, but the diameter D2 of each of the first through hole 150a to the third insertion hole 150c is larger than the diameter D1 of the knock pin 162. Therefore, even in this embodiment, the cross-sectional area of ​​the first through hole 150a to the third insertion hole 150c in the planar direction is larger than the cross-sectional area of ​​the knock pin 162 in the planar direction. Therefore, the knock pins 162 inserted through the first through-holes 150a to the third through-holes 150c are allowed to move along the surface direction of the resin frame member 110.

[0050] The cross-sectional shape of the first through-hole 150a to the third through-hole 150c in the planar direction may be, for example, an elongated hole extending in the radial direction. Also, in Figures 4 and 5, the through-holes 150 are formed in the annular portion of the resin frame member 110, but the formation location of the through-holes 150 is not limited to the annular portion of the resin frame member 110. For example, as shown by imaginary lines in Figures 4 and 5, a tab-shaped portion may be provided that protrudes in the radial direction from the outer circumferential edge of the annular portion of the resin frame member 110, and the through-hole 150 may be formed in the tab-shaped portion.

[0051] As can be seen from the above, the knock pins 162, which are the positioning members 160, position the resin frame member 110 in the planar direction relative to the flow path forming member 46 and the pressure-resistant member 84. On the other hand, the knock pins 162 allow the resin frame member 110 to move along the planar direction.

[0052] Next, the operation of the water electrolysis device 10 will be described.

[0053] A voltage is applied from a power supply 28 to the terminal portion 24a of the terminal plate 16a and the terminal portion 24b of the terminal plate 16b shown in FIG. 1. Furthermore, water is supplied as a fluid from a fluid supply unit 90. The water flows through a fluid supply port 39a and into a fluid supply passage 38a (see FIG. 2) of the electrolysis cell 12. Within the electrolysis cell 12, the water flows through the fluid supply passage 38a and the supply connecting channel 50a and into a fluid flow passage 50b of the flow passage forming member 46. The water is then supplied to the first power supply body 44a through a plurality of holes 50c.

[0054] Water is electrolyzed at the first electrode 43a. As a result, protons, electrons, and oxygen are produced. That is, water participates in an electrode reaction (oxidation reaction) at the first electrode 43a. The protons are transferred through the electrolyte membrane 40A to the second electrode 43b, where they combine with electrons. As a result, hydrogen is produced. This hydrogen is discharged from the second electrode chamber 45b to the hydrogen communication hole 38c via the pores in the second power supply body 44b and the hydrogen discharge passage 71.

[0055] The back pressure mechanism restricts the discharge of hydrogen from the hydrogen communication hole 38c. Therefore, as the water electrolysis reaction progresses in the electrolysis cell 12, the generated hydrogen increases the internal pressure of the second electrode chamber 45b. As a result, the internal pressure of the second electrode chamber 45b becomes higher than the internal pressure of the first electrode chamber 45a, and the hydrogen in the hydrogen communication hole 38c is maintained at high pressure. This allows high-pressure hydrogen that has reached a predetermined pressure to be discharged from the water electrolysis device 10. Meanwhile, oxygen generated by the electrode reaction (reduction reaction) at the first electrode 43a is entrained with unreacted water and discharged at normal pressure to the outside of the water electrolysis device 10 via the fluid discharge communication hole 38b and the fluid discharge port 39b.

[0056] As the electrolysis reaction described above occurs, the electrolyte membrane 40A swells. Furthermore, the inner circumferential surface of the seal member 80 is pressed by the high-pressure hydrogen in the second electrode chamber 45b. As a result, the electrolyte membrane 40A is pulled by the lower surface of the seal member 80, which is moving radially outward. Furthermore, the second surface 202 of the electrolyte membrane 40A is subjected to pressure from the high-pressure hydrogen in the second electrode chamber 45b. For these reasons, the electrolyte membrane 40A stretches (expands) radially outward.

[0057] When the resin frame member 110 is positioned and fixed, the resin frame member 110 inhibits the electrolyte membrane 40A from extending radially outward. In this case, wrinkles may occur in the peripheral edge portion 42A of the electrolyte membrane 40A. That is, deformation of the electrolyte membrane 40A may occur.

[0058] In contrast, in the first embodiment, as shown in FIGS. 4 and 5, the knock pins 162 can move radially within the insertion holes 150. Therefore, when the electrolyte membrane 40A expands in diameter, the resin frame member 110 supporting the membrane electrode assembly 30A moves radially outward. This prevents the resin frame member 110 from hindering the radially outward expansion of the electrolyte membrane 40A. As a result, the occurrence of wrinkles in the peripheral edge portion 42A of the electrolyte membrane 40A is prevented. In other words, deformation of the electrolyte membrane 40A can be prevented.

[0059] Furthermore, at the joint between the membrane side joints 200 and the resin frame member 110, the membrane side joints 200 and the resin frame member 110 are firmly joined together due to the anchor effect of the adhesive AS. Furthermore, the joint between the membrane side joints 200 and the resin frame member 110 is located outward from the outer peripheral end 80o of the seal member 80. Therefore, it is difficult for high-pressure hydrogen to reach the joint. In other words, it is difficult for high-pressure hydrogen to apply pressure to the adhesive AS. For these reasons, peeling of the membrane side joints 200 from the resin frame member 110 is prevented. Therefore, the electrolyte membrane 40A and the resin frame member 110 can move together.

[0060] Even if high-pressure hydrogen reaches the joint between the second joint portion 204 and the second member element 130, the anchoring effect of the adhesive AS is also large because the surface roughness of the second joint portion 204 is large. Therefore, even in this case, it is difficult for the second joint portion 204 to peel off from the second member element 130.

[0061] Because deformation of the electrolyte membrane 40A is suppressed in this manner, an increase in the amount of high-pressure hydrogen produced at the second electrode 43b that permeates the first electrode 43a is suppressed. Therefore, a decrease in the amount of hydrogen recovered through the hydrogen communication holes 38c is avoided. Furthermore, because hydrogen is prevented from interfering with the electrode reaction at the first electrode 43a, a decrease in reaction efficiency is avoided. For these reasons, sufficient amounts of hydrogen and oxygen can be obtained by electrolysis of water.

[0062] The first embodiment has the following advantages.

[0063] 2 and 3, the water electrolysis apparatus 10 includes a resin frame member 110 joined to the peripheral edge portion 42A of the electrolyte membrane 40A, a first member 166, a second member 168, and knock pins 162 serving as positioning members 160. The knock pins 162 position the resin frame member 110 relative to the first member 166 or the second member 168 in a planar direction (radial direction) perpendicular to the stacking direction. In this configuration, the knock pins 162 allow the resin frame member 110 to move along the planar direction (radial direction). In the embodiment shown in FIG. 2, the first member 166 is the flow path forming member 46, and the second member 168 is the pressure-resistant member 84.

[0064] When the electrolyte membrane 40A swells radially outward during operation of the water electrolysis system 10, the resin frame member 110 moves radially outward. Similarly, when the electrolyte membrane 40A is subjected to pressure in the stacking direction by high-pressure hydrogen generated at the second electrode 43b and thus stretches radially outward, the resin frame member 110 moves radially outward.

[0065] As described above, in the above configuration, the resin frame member 110 moves radially outward in response to the outward radial extension of the electrolyte membrane 40A, thereby preventing the electrolyte membrane 40A from wrinkling (deforming) when subjected to the pressure of high-pressure hydrogen.

[0066] 4 and 5, the resin frame member 110 has insertion holes 150 (first insertion hole 150a to third insertion hole 150c) through which the knock pins 162 are inserted. The cross-sectional area of ​​the insertion holes 150 in the radial direction is larger than the cross-sectional area of ​​the knock pins 162 in the radial direction.

[0067] Therefore, the resin frame member 110 can easily move in the radial direction relative to the knock pin 162.

[0068] 2, the electrolysis cell 12 includes a seal member 80 that surrounds the outer periphery of the second electrode 43b and is interposed between the resin frame member 110 and the second separator 34 in the stacking direction. The peripheral edge 42A of the electrolyte membrane 40A and the resin frame member 110 are joined at a joining location using an adhesive AS. This joining location is located outward from the outer peripheral end 80o of the seal member 80.

[0069] Inside the seal member 80, the high-pressure hydrogen generated at the second electrode 43b is blocked by the seal member 80. This prevents the high-pressure hydrogen from reaching the joining location. This also prevents the high-pressure hydrogen from pressing against the adhesive AS. This prevents the electrolyte membrane 40A from peeling off from the resin frame member 110 due to the adhesive AS being subjected to gas pressure.

[0070] The electrolyte membrane 40A has membrane-side joints 200 to which the resin frame member 110 is joined via an adhesive AS. In the electrolyte membrane 40A, the surface roughness of the membrane-side joints 200 is greater than that of other portions.

[0071] Since the surface roughness of the membrane-side joints 200 is large, the anchor effect of the adhesive AS firmly joins the membrane-side joints 200 and the resin frame member 110. In other words, peeling of the electrolyte membrane 40A from the resin frame member 110 is further prevented.

[0072] The electrolyte membrane 40A has a first surface 201 facing the first electrode 43a and a second surface 202 facing the second electrode 43b. The membrane-side joint 200 has a first joint 203 formed on the first surface 201 and a second joint 204 formed on the second surface 202. In this configuration, the surface roughness of the second joint 204 is greater than that of the first joint 203.

[0073] In this configuration, the adhesive AS has a large anchoring effect on the second surface 202 facing the second electrode 43b. This allows the second surface 202 to be firmly bonded to the resin frame member 110. This further prevents the electrolyte membrane 40A from peeling off from the resin frame member 110. Furthermore, by reducing the surface roughness of the first surface 201, it is possible to prevent the thickness of the membrane-side joint 200 in the stacking direction from becoming excessively small.

[0074] The above effects can also be obtained in the second to fourth embodiments described later.

[0075] Next, a second embodiment will be described with reference to Fig. 6. Note that the same components as those shown in Figs. 1 to 5 are given the same reference numerals, and detailed description thereof will be omitted.

[0076] 6, in the second embodiment, the electrolysis cell 12 has a framed structure 100B. The framed structure 100B has a membrane electrode assembly 30A and a resin frame member 111. In the membrane electrode assembly 30A, a peripheral edge 42A of the electrolyte membrane 40A is exposed from the peripheral edge of the first electrode 43a and the peripheral edge of the second electrode 43b.

[0077] The electrolyte membrane 40A has a first surface 201 facing the first electrode 43a and a second surface 202 facing the second electrode 43b. In the embodiment shown in Fig. 6, the membrane-side joint 200 is only a first joint 203 formed on the first surface 201. Although not essential, it is preferable to make the surface roughness of the first joint 203 greater than that of the portions other than the first joint 203, as in the first embodiment.

[0078] As shown in Fig. 6, in the second embodiment, the resin frame member 111 is formed from a single member element 121. In the aspect shown in Fig. 6, the resin frame member 111 is disposed below the electrolyte membrane 40A in the stacking direction. In this state, the inner edge of the resin frame member 111, at a location facing the first bonding portion 203 of the electrolyte membrane 40A, is bonded to the first bonding portion 203 via an adhesive AS. The bonding location is preferably located outward from the outer peripheral end 80o of the seal member 80.

[0079] In this configuration, it is difficult for the high-pressure hydrogen generated at the second electrode 43b to reach the outer periphery of the seal member 80, but even if the high-pressure hydrogen does reach the outer periphery of the seal member 80, the adhesive AS will not be subjected to the pressure of the high-pressure hydrogen on the second surface 202. This is because there is no joint portion with the resin frame member 111 on the second surface 202.

[0080] 6, the membrane-side bonding portion 200 may be formed only by the second bonding portion 204 (see FIG. 3) formed on the second surface 202. In this configuration, the resin frame member 111 (member element 121) is disposed above the electrolyte membrane 40A in the stacking direction. The inner edge of the resin frame member 111, which faces the second bonding portion 204 of the electrolyte membrane 40A, is bonded to the second bonding portion 204 via an adhesive AS.

[0081] In this embodiment as well, it is preferable that the joining location be outside the outer peripheral end 80o of the seal member 80. As described above, it is difficult for the high-pressure hydrogen generated at the second electrode 43b to reach the outer periphery of the seal member 80, and therefore the adhesive AS is prevented from being subjected to the pressure of the high-pressure hydrogen.

[0082] 3 to 5, insertion holes 150 (first to third insertion holes 150a to 150c) are formed outward from the joining portion in the resin frame member 111. A knock pin 162 is inserted into each of the first to third insertion holes 150a to 150c.

[0083] The second embodiment is similar to the first embodiment in other respects, and the operation of the water electrolysis apparatus 10 is also similar to that of the first embodiment. Therefore, a description of the other components and operations will be omitted.

[0084] The second embodiment has the following advantages.

[0085] The electrolyte membrane 40A has a first surface 201 facing the first electrode 43a and a second surface 202 facing the second electrode 43b, and the resin frame member 111 is joined to only one of the first surface 201 (first joint 203) or the second surface 202 (second joint 204).

[0086] As shown in FIG. 3 , the resin frame member 110, which is simultaneously bonded to both the first surface 201 (first bonding portion 203) and the second surface 202 (second bonding portion 204), has a first member element 120 bonded to the first surface 201 and a second member element 130 bonded to the second surface 202. In contrast, in the second embodiment, the resin frame member 111 can be formed using only either the member element 121 bonded to the first surface 201 (first bonding portion 203) or the member element 121 bonded to the second surface 202 (second bonding portion 204). This allows the number of member elements 121 constituting the resin frame member 111 to be reduced. This simplifies the configuration of the electrolysis cell 12.

[0087] Next, a third embodiment will be described with reference to Fig. 7. Note that the same components as those shown in Figs. 1 to 6 are given the same reference numerals, and detailed description thereof will be omitted.

[0088] 7, in the third embodiment, the electrolysis cell 12 has a framed structure 100C. The framed structure 100C has a membrane electrode assembly 30C and a resin frame member 112. The membrane electrode assembly 30C has an electrolyte membrane 40C, a first electrode 43a, and a second electrode 43b.

[0089] The electrolyte membrane 40C includes a first ion exchange membrane 41a, a second ion exchange membrane 41b, and a support membrane 41c. The first ion exchange membrane 41a contacts the first electrode 43a. The second ion exchange membrane 41b contacts the second electrode 43b. The support membrane 41c is interposed between the first ion exchange membrane 41a and the second ion exchange membrane 41b. Therefore, the first ion exchange membrane 41a is interposed between the first electrode 43a and the support membrane 41c, and the second ion exchange membrane 41b is interposed between the support membrane 41c and the second electrode 43b.

[0090] The first ion exchange membrane 41a is a proton exchange membrane through which protons can move, such as a hydrocarbon (HC)-based polymer membrane or a fluorine-based polymer membrane. The polymer that is the material of the first ion exchange membrane 41a has a functional group involved in proton conduction. In the case of a fluorine-based polymer, the functional group is a sulfonic acid group.

[0091] The second ion exchange membrane 41b is formed from the same material as the first ion exchange membrane 41a. The concentration of functional groups involved in proton conduction in the second ion exchange membrane 41b may be the same as that in the first ion exchange membrane 41a, but is preferably higher than that in the first ion exchange membrane 41a.

[0092] The support membrane 41c is more flexible and bends more easily than the first ion exchange membrane 41a and the second ion exchange membrane 41b. Therefore, the support membrane 41c has a greater tensile strength than the first ion exchange membrane 41a and the second ion exchange membrane 41b. A suitable example of the material for such a support membrane 41c is expanded polytetrafluoroethylene (ePTFE). However, the material for the support membrane 41c is not limited to ePTFE.

[0093] Functional groups migrated from the first ion exchange membrane 41a and the second ion exchange membrane 41b are bonded to the polymer that forms the support membrane 41c. As a result, proton conduction also occurs in the support membrane 41c. When the concentration of functional groups in the second ion exchange membrane 41b is higher than that in the first ion exchange membrane 41a, the concentration of functional groups in the support membrane 41c decreases in the stacking direction from the second ion exchange membrane 41b toward the first ion exchange membrane 41a. In other words, a concentration gradient of functional groups is formed in the support membrane 41c.

[0094] The peripheral portion 42C of the support membrane 41c is exposed outside the peripheral portions of the first electrode 43a, the first ion exchange membrane 41a, the second ion exchange membrane 41b, and the second electrode 43b. The first surface 205 of the electrolyte membrane 40C is the surface of the support membrane 41c that faces the first electrode 43a and to which the first ion exchange membrane 41a is bonded. The second surface 206 of the electrolyte membrane 40C is the surface of the support membrane 41c that faces the second electrode 43b and to which the second ion exchange membrane 41b is bonded. The membrane-side bonding portion 200 of the electrolyte membrane 40C is formed on the support membrane 41c. In the embodiment shown in FIG. 7, the support membrane 41c has a first bonding portion 207 formed on the first surface 205 and a second bonding portion 208 formed on the second surface 206. Although not essential, the surface roughness of the first bonding portion 207 may be made larger than that of the portion other than the first bonding portion 207, as in the first embodiment.

[0095] The resin frame member 112 has a first member element 122 and a second member element 132. The first member element 122 is bonded to a first bonding portion 207 (first surface 205) from the inner periphery to the outer periphery via an adhesive AS. The second member element 132 is bonded to a second bonding portion 208 (second surface 206) from the inner periphery to the outer periphery via an adhesive AS. Alternatively, as in FIG. 3 , an annular recess 140 may be formed in the inner peripheral edge portions of the first member element 122 and the second member element 132, and the peripheral edge portion 42C of the support film 41c may be inserted into the annular recess 140.

[0096] In the third embodiment, the lower part of the seal member 80 abuts against the second surface 206 of the support film 41c. Note that the joining point of the resin frame member 112 to the support film 41c is preferably located outward from the outer peripheral end 80o of the seal member 80. As described above, it is difficult for the high-pressure hydrogen generated at the second electrode 43b to reach the outer periphery of the seal member 80, and therefore the adhesive AS of the second joint portion 208 is prevented from being subjected to the pressure of the high-pressure hydrogen.

[0097] An example of a process for obtaining such an electrolyte membrane 40C will now be briefly described. First, a first electrode 43a is formed on one end surface of the first ion exchange membrane 41a. Meanwhile, a second electrode 43b is formed on one end surface of the second ion exchange membrane 41b. Next, a resin frame member 112 is bonded, via an adhesive AS, to a peripheral portion 42C of the support membrane 41c, which has a larger area than the first ion exchange membrane 41a and the second ion exchange membrane 41b.

[0098] Next, a support membrane 41c is laminated on the other end surface of the first ion exchange membrane 41a. The surface of the support membrane 41c facing the other end surface of the first ion exchange membrane 41a is a first surface 205. Furthermore, the other end surface of the second ion exchange membrane 41b is laminated on the support membrane 41c. The surface of the support membrane 41c facing the other end surface of the second ion exchange membrane 41b is a second surface 206.

[0099] As a result of the above, a laminate of the first electrode 43a, the first ion exchange membrane 41a, the support membrane 41c, the second ion exchange membrane 41b, and the second electrode 43b is obtained. Next, this laminate is subjected to a heat press. This heat press firmly bonds each membrane from the first electrode 43a to the second electrode 43b, and firmly bonds the first member element 122 and the second member element 132 to the peripheral edge portion 42C of the support membrane 41c. In addition, some of the functional groups of the first ion exchange membrane 41a migrate to the support membrane 41c, and some of the functional groups of the second ion exchange membrane 41b migrate to the support membrane 41c.

[0100] Alternatively, a laminate may be formed using a support film 41c to which the resin frame member 112 is not bonded, and then the resin frame member 112 may be bonded to the peripheral edge portion 42C of the support film 41c. Alternatively, the laminate may be heat-pressed, and then the resin frame member 112 may be bonded to the peripheral edge portion 42C of the support film 41c.

[0101] 3 to 5, insertion holes 150 (first to third insertion holes 150a to 150c) are formed outward from the joining portion in the resin frame member 112. A knock pin 162 is inserted into each of the first to third insertion holes 150a to 150c.

[0102] The configuration of the third embodiment is the same as that of the first embodiment except for the above-described configuration. The operation of the water electrolysis device 10 is also the same as that of the first embodiment. Therefore, a description of the configuration and operation other than the above-described configuration will be omitted.

[0103] The third embodiment has the following advantages.

[0104] The electrolyte membrane 40C includes a first ion exchange membrane 41a in contact with the first electrode 43a, a second ion exchange membrane 41b in contact with the second electrode 43b, and a support membrane 41c interposed between the first ion exchange membrane 41a and the second ion exchange membrane 41b. The support membrane 41c has a greater tensile strength than both the first ion exchange membrane 41a and the second ion exchange membrane 41b. The resin frame member 112 is joined to a peripheral edge 42C of the support membrane 41c.

[0105] Since the support membrane 41c has a high tensile strength, the electrolyte membrane 40C is further prevented from being deformed by the pressure of high-pressure hydrogen.

[0106] In a preferred embodiment, the material of the support membrane 41c is ePTFE (expanded polytetrafluoroethylene) having functional groups, which are the same as the functional groups involved in ion exchange in the first ion exchange membrane 41a and the second ion exchange membrane 41b.

[0107] ePTFE exhibits excellent tensile strength. Moreover, in the third embodiment, ePTFE has functional groups involved in ion conduction, ensuring ion conduction between the first electrode 43a and the second electrode 43b via the electrolyte membrane 40C.

[0108] In a preferred embodiment, the concentration of functional groups in the second ion exchange membrane 41b is higher than that in the first ion exchange membrane 41a.

[0109] The second ion exchange membrane 41b contains moisture. If the second ion exchange membrane 41b has a high concentration of functional groups involved in ion exchange, it can retain a large amount of moisture. Therefore, even when the second ion exchange membrane 41b is pressed by high-pressure hydrogen, the second ion exchange membrane 41b can retain a certain amount of moisture. Therefore, sufficient ion conduction occurs in the second ion exchange membrane 41b even after high-pressure hydrogen is generated at the second electrode 43b.

[0110] Next, a fourth embodiment will be described with reference to Fig. 8. Note that the same components as those shown in Figs. 1 to 7 are given the same reference numerals, and detailed description thereof will be omitted.

[0111] 8, in the fourth embodiment, the electrolysis cell 12 has a framed structure 100D. The framed structure 100D has a membrane electrode assembly 30D and a resin frame member 113. The membrane electrode assembly 30D includes an electrolyte membrane 40D.

[0112] Like the electrolyte membrane 40C, the electrolyte membrane 40D has a first ion exchange membrane 41a, a second ion exchange membrane 41b, and a support membrane 41c. A suitable example of the material for the support membrane 41c is ePTFE, as in the third embodiment. Also in the fourth embodiment, the concentration of functional groups involved in proton conduction in the second ion exchange membrane 41b is preferably higher than that in the first ion exchange membrane 41a.

[0113] The area of ​​the second ion exchange membrane 41b is larger than that of the first ion exchange membrane 41a and is approximately equal to that of the support membrane 41c, so that a peripheral edge 42C of the support membrane 41c and a peripheral edge 42E of the second ion exchange membrane 41b are exposed outside the peripheral edges of the first electrode 43a, the first ion exchange membrane 41a, and the second electrode 43b.

[0114] The support membrane 41c constituting the electrolyte membrane 40D has a first surface 205 facing the first electrode 43a and the first ion exchange membrane 41a and a second surface 206 facing the second electrode 43b and the second ion exchange membrane 41b. In the embodiment shown in Fig. 8, the membrane-side joint 200 is only a first joint 207 formed on the first surface 205. Although not essential, it is preferable to make the surface roughness of the first joint 207 greater than that of the portions other than the first joint 207, as in the first embodiment.

[0115] In the fourth embodiment, the resin frame member 113 is formed from a single member element 123, as in the second embodiment. In the aspect shown in FIG. 8, the resin frame member 113 is disposed below the electrolyte membrane 40D in the stacking direction. In this state, the inner edge of the resin frame member 113, at a location facing the first bonding portion 207 of the electrolyte membrane 40D, is bonded to the first bonding portion 207 via adhesive AS. The bonding location is preferably located outward from the outer peripheral end portion 80o of the seal member 80. In the fourth embodiment, the lower portion of the seal member 80 abuts against the upper surface of the peripheral portion 42E of the second ion exchange membrane 41b.

[0116] Contrary to the embodiment shown in FIG. 8, the membrane-side bonding portion 200 may consist only of the second bonding portion 208 (see FIG. 7) formed on the second surface 206 of the support membrane 41c. In this configuration, the resin frame member 113 is disposed above the support membrane 41c in the stacking direction. Furthermore, the inner edge of the resin frame member 113, at a location facing the second bonding portion 208 of the support membrane 41c, is bonded to the second bonding portion 208 via adhesive AS. In this embodiment, too, it is preferable that the bonding location be outward from the outer peripheral end 80o of the seal member 80.

[0117] 7, the area of ​​the first ion exchange membrane 41a may be substantially equal to that of the second ion exchange membrane 41b, and the peripheral portion 42C of the support membrane 41c may be exposed from the peripheral portions of the first electrode 43a, the first ion exchange membrane 41a, the second ion exchange membrane 41b, and the second electrode 43b. The lower part of the seal member 80 abuts against the second surface 206 of the peripheral portion 42C of the support membrane 41c.

[0118] 9 as a first modification, the electrolyte membrane 40E may be configured such that the area of ​​the first ion exchange membrane 41a is slightly smaller than the area of ​​the second ion exchange membrane 41b. In this case, a membrane electrode assembly 30E including the electrolyte membrane 40E and a framed structure 100E including the membrane electrode assembly 30E are configured.

[0119] The first ion exchange membrane 41a has a peripheral edge 42D exposed from the peripheral edges of the first electrode 43a and the second electrode 43b. The peripheral edge 42D of the first ion exchange membrane 41a, the peripheral edge 42C of the support membrane 41c, and the peripheral edge 42E of the second ion exchange membrane 41b overlap in the stacking direction.

[0120] 10 as a second modification, the electrolyte membrane 40F may be configured such that the area of ​​the first ion exchange membrane 41a is larger than the area of ​​the second ion exchange membrane 41b and slightly smaller than the area of ​​the support membrane 41c. In this case, a membrane electrode assembly 30F including the electrolyte membrane 40F and a framed structure 100F including the membrane electrode assembly 30F are configured.

[0121] In this configuration, the peripheral edge 42D of the first ion exchange membrane 41a and the peripheral edge 42C of the support membrane 41c overlap in the stacking direction. The lower part of the seal member 80 abuts against the second surface 206 of the peripheral edge 42C of the support membrane 41c.

[0122] Furthermore, a resin frame member 112 shown in FIG. 7 may be joined to the electrolyte membrane 40E or the electrolyte membrane 40F.

[0123] 3 to 5, insertion holes 150 (first to third insertion holes 150a to 150c) are formed outward from the joining portion in the resin frame member 113. A knock pin 162 is inserted into each of the first to third insertion holes 150a to 150c.

[0124] The fourth embodiment is similar to the first embodiment in other respects, and the operation of the water electrolysis apparatus 10 is also similar to the first embodiment. Therefore, a description of the other configurations and operations will be omitted.

[0125] According to the fourth embodiment, similar to the electrolyte membrane 40C in the third embodiment, the effect of further suppressing deformation of the electrolyte membrane 40D due to the pressure of high-pressure hydrogen is obtained. Furthermore, in the fourth embodiment, the resin frame member 113 can be formed using only either the member elements 123 joined to the first surface 205 (first joints 207) or the member elements 123 joined to the second surface 206 (second joints 208). This allows the number of members constituting the resin frame member 113 to be reduced. This simplifies the configuration of the water electrolysis apparatus 10.

[0126] The first to fourth embodiments described above exemplify a configuration in which oxygen is generated as the first gas at the first electrode 43a and hydrogen is generated as the second gas at the second electrode 43b. However, a configuration in which hydrogen is generated as the first gas at the first electrode 43a and oxygen is generated as the second gas at the second electrode 43b can also be used. This configuration will be briefly described below. Note that the electrolyte membranes 40A, 40C, and 40D are proton conductors, as in the above configurations.

[0127] In this embodiment, the first electrode 43a serves as a cathode and the second electrode 43b serves as an anode. Water is supplied to the first electrode 43a, which serves as the cathode. The water permeates the electrolyte membranes 40A, 40C, and 40D and contacts the second electrode 43b, which serves as the anode. At the second electrode 43b, the water is electrolyzed to generate protons, oxygen, and electrons. The protons move through the electrolyte membranes 40A, 40C, and 40D to the first electrode 43a, which serves as the cathode. At the first electrode 43a, the protons and electrons combine to generate hydrogen. The pressure of the oxygen is increased to a predetermined pressure by a back pressure mechanism. That is, oxygen at a higher pressure than hydrogen is obtained at the second electrode 43b.

[0128] In the above-described first to fourth embodiments, the material of the electrolyte membranes 40A, 40C, and 40D is a proton conductor. However, the material of the electrolyte membranes 40A, 40C, and 40D may be an anion conductor. This embodiment will be briefly described below.

[0129] When electrolyte membranes 40A, 40C, and 40D made of an anion conductor are used and the first electrode 43a is used as a cathode and water is supplied to the first electrode 43a, a reduction reaction occurs at the first electrode 43a (cathode) to produce hydrogen and hydroxide ions from the water. The hydroxide ions are conducted through the electrolyte membranes 40A, 40C, and 40D and move to the second electrode 43b, which is the anode. At the second electrode 43b (anode), an oxidation reaction occurs to produce oxygen, water, and electrons from the hydroxide ions. The pressure of the oxygen is increased to a predetermined pressure by a backpressure mechanism. In other words, oxygen at a higher pressure than hydrogen is obtained.

[0130] In contrast, when water is supplied to the first electrode 43a as an anode, the water permeates the electrolyte membranes 40A, 40C, and 40D and comes into contact with the second electrode 43b, which serves as the cathode. At the second electrode 43b, a reduction reaction occurs in which hydrogen and hydroxide ions are produced from the water. The hydroxide ions are conducted through the electrolyte membranes 40A, 40C, and 40D and move to the second electrode 43b, which serves as the cathode. At the second electrode 43b (cathode), an oxidation reaction occurs in which oxygen, water, and electrons are produced from the hydroxide ions. The pressure of the hydrogen is increased to a predetermined pressure by the back pressure mechanism. In other words, hydrogen at a higher pressure than oxygen is obtained.

[0131] Furthermore, as described above, the differential pressure electrolysis device 300 according to the present invention is not limited to the water electrolysis device 10 that electrolyzes water. In other words, the present invention can be applied to a differential pressure electrolysis device 300 that electrolyzes substances (fluids) other than water.

[0132] The following additional notes are further disclosed regarding the above embodiment.

[0133] (Appendix 1) The differential pressure electrolysis device (300) of the present disclosure is a differential pressure electrolysis device that includes an electrolysis cell (12) having a membrane electrode assembly (30A, 30C, 30D) in which an electrolyte membrane (40A, 40C, 40D) is interposed between a first electrode (43a) and a second electrode (43b), and a first separator (32) and a second separator (34) that sandwich the membrane electrode assembly therebetween, and that obtains, at the second electrode, a gas having a higher pressure than the gas obtained at the first electrode. The differential pressure electrolysis device includes a resin frame member (110-113) joined to the peripheral edge portion (42A, 42C) of the electrolyte membrane, a first member (166) interposed between the first separator and the resin frame member in the stacking direction of the first electrode, the electrolyte membrane, and the second electrode, a second member (168) interposed between the resin frame member and the second separator in the stacking direction, and a positioning member (160) that positions the resin frame member relative to the first member or the second member in a plane direction perpendicular to the stacking direction. The positioning member allows the resin frame member to move along the plane direction.

[0134] In this configuration, the resin frame member supports the electrolyte membrane. Furthermore, when the electrolyte membrane swells along a surface direction perpendicular to the stacking direction during operation of the differential pressure electrolytic device, the resin frame member can move along the surface direction. Similarly, when the electrolyte membrane expands along the surface direction due to pressure along the stacking direction caused by gas generated at the second electrode, the resin frame member can move along the surface direction. As described above, when the electrolyte membrane expands along the surface direction, the resin frame member moves along the surface direction. This prevents wrinkles (permanent deformation) from occurring in the electrolyte membrane when subjected to gas pressure.

[0135] (Appendix 2) In the differential pressure electrolysis device described in Appendix 1, the resin frame member may have an insertion hole (150) through which the positioning member is inserted, and the cross-sectional area of ​​the insertion hole in the surface direction may be larger than the cross-sectional area of ​​the positioning member in the surface direction.

[0136] With this configuration, the resin frame member can easily move in the planar direction relative to the positioning member.

[0137] (Appendix 3) In the differential pressure electrolysis device described in Appendix 1 or 2, the electrolyte membrane may have a first surface (201, 205) facing the first electrode and a second surface (202, 206) facing the second electrode, and the resin frame member may be bonded to only one of the first surface or the second surface.

[0138] Since the resin frame member is joined to only one of the first surface or the second surface, the number of resin frame members can be reduced, resulting in a simpler configuration.

[0139] (Appendix 4) The differential pressure electrolysis device according to any one of Appendices 1 to 3 may further include a sealing member (80) that surrounds the outer periphery of the second electrode and is interposed between the resin frame member and the second separator in the stacking direction, and an adhesive (AS) that joins the peripheral edge of the electrolyte membrane to the resin frame member, and the joining point between the resin frame member and the electrolyte membrane via the adhesive may be located outward from the outer periphery end (80o) of the sealing member.

[0140] The inside of the seal member becomes high pressure due to the gas generated in the second electrode. In contrast, the outside of the seal member is blocked by the seal member, so high pressure is avoided. With the above configuration, the joining point is prevented from being located inside the seal member where high pressure would be generated. This prevents the electrolyte membrane from peeling off from the resin frame member due to the adhesive being subjected to gas pressure.

[0141] (Appendix 5) In the differential pressure electrolytic device described in any one of Appendices 1 to 4, an adhesive (AS) is provided to join the peripheral portion of the electrolyte membrane and the resin frame member, the electrolyte membrane has a membrane side joint (200) to which the resin frame member is joined via the adhesive, and the surface roughness of the membrane side joint of the electrolyte membrane may be greater than that of a portion other than the membrane side joint.

[0142] Since the surface roughness of the membrane-side joint is large, the membrane-side joint and the resin frame member are firmly joined together by the anchor effect of the adhesive.

[0143] (Appendix 6) In the differential pressure electrolysis device described in Appendix 5, the electrolyte membrane has a first surface (201, 205) facing the first electrode and a second surface (202, 206) facing the second electrode, and the membrane-side joint has a first joint (203, 207) formed on the first surface and a second joint (204, 208) formed on the second surface, and the surface roughness of the second joint may be greater than that of the first joint.

[0144] The adhesive has a strong anchoring effect on the second surface facing the second electrode where high-pressure gas is generated, allowing the second surface to be firmly bonded to the resin frame member.

[0145] (Appendix 7) In the differential pressure electrolysis device according to any one of Supplementary Notes 1 to 6, the electrolyte membrane may include a first ion exchange membrane (41a) in contact with the first electrode, a second ion exchange membrane (41b) in contact with the second electrode, and a support membrane (41c) interposed between the first ion exchange membrane and the second ion exchange membrane and having a tensile strength greater than those of the first ion exchange membrane and the second ion exchange membrane, and the resin frame member may be joined to a peripheral portion (42C) of the support membrane.

[0146] The support membrane has a high tensile strength, which further suppresses deformation of the electrolyte membrane. Furthermore, the support membrane is less susceptible to the effects of moisture than the electrolyte membrane. In other words, the support membrane is less likely to swell than the electrolyte membrane even when it comes into contact with moisture. This suppresses embrittlement of the adhesive bonding of the electrolyte membrane to the resin frame member. This eliminates concerns about the electrolyte membrane peeling off from the resin frame member.

[0147] (Appendix 8) In the differential pressure electrolysis device described in Appendix 7, the material of the support membrane may be expanded polytetrafluoroethylene having the same functional groups as functional groups involved in ion exchange in the first ion exchange membrane and the second ion exchange membrane.

[0148] This configuration ensures that ionic conduction occurs between the first electrode and the second electrode via the electrolyte membrane.

[0149] (Appendix 9) In the differential pressure electrolysis device described in Appendix 8, the second ion exchange membrane may have a higher concentration of the functional group than the first ion exchange membrane.

[0150] The second ion exchange membrane contains water. If the concentration of functional groups involved in ion exchange in the second ion exchange membrane is high, it can retain a large amount of water. Therefore, even when the second ion exchange membrane is pressed by high-pressure gas, the second ion exchange membrane contains a certain amount of water. Therefore, ionic conduction occurs in the second ion exchange membrane.

[0151] The present invention is not limited to the above disclosure, and various configurations can be adopted without departing from the gist of the present invention. [Explanation of symbols]

[0152] 10...water electrolysis device 12...electrolysis cell 30A, 30C to 30F... membrane electrode assembly 32... first separator 34... Second separator 40A, 40C to 40F... Electrolyte membrane 41, 41a, 41b... Ion exchange membrane 41c... Support membrane 43a...First electrode 43b...Second electrode 46...flow path forming member 80...sealing member 80o...Outer edge 100A~100F...Framed structure 110 to 113... Resin frame members 150, 150a to 150c... Insertion holes 160... Positioning member 162... Knock pin 166...First member 168...Second member 200...Membrane side joint part 201, 205...First surface 202, 206...Second surface 203, 207...First joint part 204, 208... Second joint portion 300... Differential pressure electrolysis device AS...adhesive

Claims

1. A differential pressure electrolysis device comprising an electrolysis cell having a membrane electrode assembly in which an electrolyte membrane is interposed between a first electrode and a second electrode, and a first separator and a second separator sandwiching the membrane electrode assembly therebetween, wherein a gas having a higher pressure at the second electrode than a gas obtained at the first electrode is obtained, a resin frame member joined to a peripheral edge portion of the electrolyte membrane; a first member interposed between the first separator and the resin frame member in a stacking direction of the first electrode, the electrolyte membrane, and the second electrode; a second member interposed between the resin frame member and the second separator in the stacking direction; a positioning member that positions the resin frame member relative to the first member or the second member in a surface direction perpendicular to the stacking direction; Equipped with The positioning member allows the resin frame member to move along the surface direction.

2. 2. The differential pressure electrolysis device according to claim 1, wherein the resin frame member has an insertion hole through which the positioning member is inserted, and the cross-sectional area of ​​the insertion hole in the planar direction is larger than the cross-sectional area of ​​the positioning member in the planar direction.

3. 2. The differential pressure electrolysis device according to claim 1, wherein the electrolyte membrane has a first surface facing the first electrode and a second surface facing the second electrode, The resin frame member is joined to only one of the first surface and the second surface.

4. 4. The differential pressure electrolysis device according to claim 1, further comprising: a sealing member that surrounds an outer periphery of the second electrode and is interposed between the resin frame member and the second separator in the stacking direction; an adhesive that bonds the peripheral edge portion of the electrolyte membrane and the resin frame member; Equipped with a pressure difference electrolysis device, wherein the joining portion between the resin frame member and the electrolyte membrane via the adhesive is located outward from an outer peripheral end of the seal member.

5. 2. The differential pressure electrolysis device according to claim 1, further comprising an adhesive that bonds the peripheral edge of the electrolyte membrane to the resin frame member, the electrolyte membrane has a membrane-side joining portion to which the resin frame member is joined via the adhesive, The differential pressure electrolysis device, wherein the electrolyte membrane has a surface roughness greater at the membrane-side joint than at a portion other than the membrane-side joint.

6. 6. The differential pressure electrolysis device according to claim 5, wherein the electrolyte membrane has a first surface facing the first electrode and a second surface facing the second electrode, The membrane-side joint has a first joint formed on the first surface and a second joint formed on the second surface, A differential pressure electrolysis device, wherein the second joint portion has a larger surface roughness than the first joint portion.

7. 4. The differential pressure electrolysis device according to claim 1, wherein the electrolyte membrane comprises a first ion exchange membrane in contact with the first electrode; a second ion exchange membrane in contact with the second electrode; a support membrane interposed between the first ion exchange membrane and the second ion exchange membrane, the support membrane having a tensile strength greater than that of each of the first ion exchange membrane and the second ion exchange membrane; and The resin frame member is joined to the peripheral edge of the support membrane.

8. 8. The differential pressure electrolysis apparatus according to claim 7, wherein the material of the support membrane is expanded polytetrafluoroethylene having the same functional groups as functional groups involved in ion exchange in the first ion exchange membrane and the second ion exchange membrane.

9. 9. The differential pressure electrolysis apparatus according to claim 8, wherein the second ion exchange membrane has a higher concentration of the functional group than the first ion exchange membrane.

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