JP7044593B2 - Water electrolyzer - Google Patents

Description

The present invention relates to a water electrolyzer that electrolyzes water to generate oxygen and hydrogen.

The water electrolyzer is well known as a device that electrolyzes water to generate hydrogen (and oxygen), and the obtained hydrogen is supplied to a fuel cell, for example, and used as a fuel gas.

More specifically, the water electrolyzer has an electrolyte membrane / electrode structure in which an anode electrode catalyst layer is formed on one surface of an electrolyte membrane made of a solid polymer and a cathode electrode catalyst layer is formed on the other surface. The electrolyte membrane / electrode structure is sandwiched between the anode electrode catalyst layer and the feeding body arranged outside the cathode electrode catalyst layer, respectively. When electric power is supplied to the electrolyte membrane / electrode structure via the feeder, water is electrolyzed in the anode electrode catalyst layer, whereby hydrogen ions (protons) and oxygen are generated. The protons in this permeate through the electrolyte membrane, move to the cathode electrode catalyst layer, combine with electrons, and change to hydrogen. On the other hand, the oxygen generated in the anode electrode catalyst layer is discharged from the water electrolyzer together with the excess water.

Here, hydrogen generated in the cathode electrode catalyst layer may be obtained as having a higher pressure than oxygen generated in the anode electrode catalyst layer. In this water electrolyzer, since the internal pressure on the cathode side becomes large, a seal member (for example, an O-ring) for preventing hydrogen from leaking to the cathode side and a pressure resistant member surrounding the seal member from the outside thereof. Is provided.

Further, as shown in Patent Document 1, an insulating reinforcing member may be provided to prevent the electrolyte membrane from being damaged. In this case, the insulating reinforcing member is made of a thin film and is adhered to the pressure resistant member.

Japanese Patent No. 6091012

The present invention has been made in connection with the above-mentioned prior art, and an object of the present invention is to provide a water electrolyzer capable of more effectively avoiding damage to an electrolyte membrane or a sealing member.

In order to achieve the above object, the present invention uses an anode-side separator and
Cathode side separator and
The anode electrode catalyst layer and the cathode electrode catalyst layer are provided on the electrolyte membrane, and the electrolyte membrane / electrode structure located between the anode side separator and the cathode side separator,
A sealing member sandwiched between the cathode side separator and the electrolyte membrane / electrode structure and surrounding the cathode electrode catalyst layer,
A pressure-resistant member that surrounds the seal member from the outside,
It is a water electrolyzer with
Concavities and convexities are formed on the first end surface of the pressure-resistant member facing the electrolyte membrane / electrode structure and the second end surface facing the cathode side separator.
Further, it is characterized by further having an insulator interposed between the pressure-resistant member and the electrolyte membrane / electrode structure.

That is, in the present invention, the first end surface and the second end surface of the pressure resistant member are roughened so as to have a predetermined surface roughness. Therefore, the first end surface abuts on the insulator not by surface contact but by a plurality of point contacts via only the tip of the convex portion. Similarly, the second end surface also abuts on the cathode side separator by a plurality of point contacts. Therefore, a slight clearance is formed between the insulator and the pressure-resistant member, and between the pressure-resistant member and the cathode-side separator.

When high-pressure hydrogen is generated at the cathode on the inner peripheral side of the seal member, the outer peripheral side (pressure resistant member) of the seal member is at normal pressure, so hydrogen that has permeated the inside of the seal member and hydrogen that has permeated the electrolyte membrane. Hydrogen may enter between the insulator and the first end face of the pressure resistant member, and between the second end face and the cathode side separator. However, in the present invention, a clearance is formed at the relevant portion as described above. Therefore, when the cathode is depressurized after the production of hydrogen is stopped, the hydrogen that has entered the clearance is quickly discharged.

As a result, high-pressure hydrogen is prevented from staying between the insulator and the first end face and between the second end face and the cathode side separator, so that a differential pressure is generated on the inner peripheral side and the outer peripheral side of the sealing member. It is avoided to occur. Therefore, due to this differential pressure, the sealing member is caught between the insulator and the pressure-resistant member, and between the pressure-resistant member and the cathode side separator, and the sealing member is pressed against the electrolyte membrane / electrode structure side to seal. It is avoided that a gap is formed between the member and the electrolyte membrane / electrode structure. This makes it possible to effectively prevent damage to the electrolyte membrane and the sealing member.

The surface roughness of the first end surface of the pressure-resistant member, that is, the end surface that makes point contact with the insulator is preferably set so that the maximum height is in the range of 1.5 to 13.0 μm. In this case, it becomes easy to discharge hydrogen, and it becomes easy to prevent the sealing member from getting caught between the insulator and the pressure-resistant member.

Further, it is preferable to interpose a surface pressure applying member between the seal member and the pressure resistant member to apply pressure to the electrolyte membrane / electrode structure by receiving pressure from the seal member. This surface pressure applying member is pressed by the sealing member during the generation of hydrogen. For this reason,
It is converted into a force (surface pressure) that presses down the electrolyte membrane / electrode structure. Therefore, it is possible to effectively prevent the electrolyte membrane / electrode structure from being displaced when the sealing member is compressed or expanded / contracted due to the generation / stop of hydrogen production.

Moreover, when hydrogen is generated, the outer peripheral wall of the seal member abuts on the surface pressure applying member and is compressed, so that the outer peripheral wall of the seal member is effectively prevented from being bitten between the insulator and the pressure resistant member. ..

In the above configuration, it is preferable that the insulator is not adhered to the pressure resistant member and the electrolyte membrane / electrode structure. When bonding, the unevenness and thus the clearance may be filled with an adhesive. This is because it is not easy to discharge hydrogen in such a state.

According to the present invention, the pressure-resistant member that surrounds the seal member from the outer peripheral side has irregularities formed on the first end surface facing the electrolyte membrane / electrode structure and the second end surface facing the cathode side separator. Therefore, it is possible to prevent the seal member from getting caught between the insulator and the pressure-resistant member and between the pressure-resistant member and the cathode-side separator, and the seal member from being separated from the pressure-resistant member. This makes it possible to prevent the electrolyte membrane and the sealing member from being damaged.

It is a schematic whole perspective view of the differential pressure type high pressure water electrolyzer (water electrolyzer) which concerns on embodiment of this invention. It is an exploded perspective view of the high pressure water electrolysis cell constituting the differential pressure type high pressure water electrolysis apparatus of FIG. FIG. 3 is a cross-sectional view taken along the line III-III in FIG. It is an enlarged sectional view of the main part of a high-pressure water electrolysis cell. It is an enlarged sectional view of the main part which shows the state which the pressing force of high pressure hydrogen acted on the large O-ring (seal member). It is a graph which showed the time-dependent change of the pressure (hydrogen pressure) in a stack, and the hydrogen concentration outside the stack when the unevenness having the maximum height of 0.4 μm was formed. It is a graph which showed the time-dependent change of the pressure inside a stack, and the hydrogen concentration outside the stack when the unevenness having a maximum height of 1.68 μm was formed. It is a graph which showed the time-dependent change of the pressure in the laminated body and the hydrogen concentration outside the laminated body when the unevenness with the maximum height of 8.0 μm was formed.

Hereinafter, suitable embodiments of the water electrolyzer according to the present invention will be given, and will be described in detail with reference to the accompanying drawings.

FIG. 1 is a schematic overall perspective view of a differential pressure type high-pressure water electrolyzer 10 (water electrolyzer) according to the present embodiment. The differential pressure type high-pressure water electrolyzer 10 includes a laminated body 14 in which a plurality of high-pressure water electrolyzer cells 12 are laminated. Although the high-pressure water electrolysis cells 12 are laminated along the vertical direction (arrow A direction) in FIG. 1, they may be laminated along the horizontal direction (arrow B direction).

At one end (upper end) of the laminated body 14 in the stacking direction, a terminal plate 16a, an insulating plate 18a, and an end plate 20a, each having a substantially disk shape, are arranged in this order from the lower side to the upper side. Similarly, the terminal plate 16b, the insulating plate 18b, and the end plate 20b, each of which has a substantially disk shape, are arranged in this order from the upper side to the lower side on the other end (lower end) of the laminated body 14 in the stacking direction.

The differential pressure type high-pressure water electrolyzer 10 is integrally tightened and held between the end plates 20a and 20b via four tie rods 22 extending in the direction of arrow A, and is fastened in the stacking direction. The differential pressure type high-pressure water electrolyzer 10 may adopt a configuration in which the end plates 20a and 20b are integrally held by a box-shaped casing (not shown) including the end plates. Further, although the differential pressure type high-pressure water electrolyzer 10 has a substantially cylindrical shape as a whole, it can be set to various shapes such as a cubic shape.

Terminal portions 24a and 24b are provided on the side portions of the terminal plates 16a and 16b so as to project outward. The electrolytic power supply 28 is electrically connected to the terminal portions 24a and 24b via the conducting wires 26a and 26b.

As shown in FIGS. 2 and 3, the high-pressure water electrolysis cell 12 includes a substantially disk-shaped electrolyte membrane / electrode structure 30, an anode-side separator 32 and a cathode-side separator 34 that sandwich the electrolyte membrane / electrode structure 30. And. A resin frame member 36 having a substantially annular shape is arranged between the anode-side separator 32 and the cathode-side separator 34. The electrolyte membrane / electrode structure 30 and the like are housed in the hollow inside of the resin frame member 36.

Seal members 37a and 37b are provided on the bottom of the upper opening and the bottom of the lower opening of the resin frame member 36. The anode-side separator 32 and the cathode-side separator 34 close the upper opening bottom and the lower opening bottom of the resin frame member 36 via the sealing members 37a and 37b, respectively.

A water supply communication hole 38a for supplying water (pure water) is provided at one end of the resin frame member 36 in the radial direction so as to communicate with each other in the stacking direction (arrow A direction). Further, at the other end of the resin frame member 36 in the radial direction, a water discharge communication hole 38b for discharging oxygen generated by the reaction and unreacted water (mixed fluid) is provided.

As shown in FIG. 1, a water supply port 39a communicating with the water supply communication hole 38a is connected to the side portion of the resin frame member 36 arranged at the lowermost position in the stacking direction. Further, a water discharge port 39b communicating with the water discharge communication hole 38b is connected to the side portion of the resin frame member 36 arranged at the uppermost position in the stacking direction.

At the center of the high-pressure water electrolysis cell 12, a high-pressure hydrogen communication hole 38c that penetrates substantially the center of the electrolysis region and communicates with each other in the stacking direction is provided (see FIGS. 2 and 3). The high-pressure hydrogen communication hole 38c is generated by the reaction and discharges hydrogen having a higher pressure (for example, 1 MPa to 80 MPa) than oxygen also generated by the reaction.

The anode-side separator 32 and the cathode-side separator 34 have a substantially disk shape and are composed of, for example, a carbon member or the like. The anode-side separator 32 and the cathode-side separator 34 are obtained by press-molding a steel plate, a stainless steel plate, a titanium plate, an aluminum plate, a plated steel plate, or a metal plate having a surface treatment for corrosion protection on the metal surface thereof. You may do so. Alternatively, it may be configured by subjecting it to a surface treatment for anticorrosion after cutting.

The electrolyte membrane / electrode structure 30 includes an electrolyte membrane 40 made of a solid polymer membrane having a substantially ring shape. The electrolyte membrane 40 is sandwiched between the anode feeding body 42 for electrolysis and the cathode feeding body 44 having a ring shape. The electrolyte membrane 40 is composed of, for example, a hydrocarbon (HC) -based membrane or a fluorine-based solid polymer membrane.

An anode electrode catalyst layer 42a having a ring shape is provided on one surface of the electrolyte membrane 40. A ring-shaped cathode electrode catalyst layer 44a is formed on the other surface of the electrolyte membrane 40. As the anode electrode catalyst layer 42a, for example, a Ru (ruthenium) -based catalyst is used, and as the cathode electrode catalyst layer 44a, for example, a platinum catalyst is used. A high-pressure hydrogen communication hole 38c is formed in a substantially central portion of the electrolyte membrane 40, the anode electrode catalyst layer 42a, and the cathode electrode catalyst layer 44a.

The anode feeding body 42 and the cathode feeding body 44 are composed of, for example, a sintered body (porous conductor) of spherical atomized titanium powder. The anode feeding body 42 and the cathode feeding body 44 are provided with a smooth surface portion to be etched after grinding, and the porosity is set within the range of 10% to 50%, more preferably 20% to 40%. The frame portion 42e is fitted into the outer peripheral edge portion of the anode feeding body 42. The frame portion 42e is configured more precisely than the anode feeding body 42. By precisely forming the outer peripheral portion of the anode feeding body 42, the outer peripheral edge portion can be used as the frame portion 42e.

The hollow inside of the resin frame member 36 and the anode-side separator 32 form an anode chamber 45an in which the anode feeding body 42 is housed. On the other hand, the hollow inside of the resin frame member 36 and the cathode side separator 34 form a cathode chamber 45ca in which the cathode feeding body 44 is housed.

A water flow path member 46 is interposed between the anode side separator 32 and the anode feeding body 42 (anode chamber 45an), and a protective sheet is provided between the anode feeding body 42 and the anode electrode catalyst layer 42a. The member 48 is interposed. As shown in FIG. 2, the water flow path member 46 has a substantially disk shape, and an inlet protrusion 46a and an outlet protrusion 46b are formed on the outer peripheral portion with a phase difference of approximately 180 °.

A supply connecting path 50a communicating with the water supply communication hole 38a is formed in the inlet protrusion 46a. The supply connecting path 50a communicates with the water flow path 50b (see FIG. 3). Further, a plurality of holes 50c communicate with the water flow path 50b, and the holes 50c open toward the anode feeding body 42. On the other hand, the outlet protrusion 46b is formed with a discharge connecting path 50d communicating with the water flow path 50b, and the discharge connecting path 50d communicates with the water discharge communication hole 38b.

The inner circumference of the protective sheet member 48 is arranged inward from the inner circumferences of the anode feeding body 42 and the cathode feeding body 44, and the outer peripheral positions thereof are the electrolyte membrane 40, the anode feeding body 42, and the water flow path member 46. It is set to the same position as the outer peripheral position. Further, the protective sheet member 48 has a plurality of through holes 48a provided in a range (electrolysis region) facing the stacking direction of the anode electrode catalyst layer 42a, and has a frame portion 48b on the outer side of the electrolytic region. For example, a rectangular hole portion (not shown) is formed in the frame portion 48b.

A communication hole member 52 surrounding the high-pressure hydrogen communication hole 38c is arranged between the anode-side separator 32 and the electrolyte membrane 40. The communication hole member 52 has a substantially cylindrical shape, and seal chambers 52a and 52b having a ring-shaped notch are provided at both ends in the axial direction. Sealing members (small O-rings) 54a and 54b that circulate and seal the high-pressure hydrogen communication holes 38c are arranged in the sealing chambers 52a and 52b. Grooves 52s in which the protective sheet member 48 is arranged are formed on the end surface of the communication hole member 52 facing the electrolyte membrane 40.

A cylindrical porous member 56 is disposed between the seal chambers 52a and 52b and the high-pressure hydrogen communication hole 38c. A high-pressure hydrogen communication hole 38c is formed in the central portion of the porous member 56. The porous member 56 is interposed between the anode-side separator 32 and the electrolyte membrane 40. The porous member 56 is formed of a ceramic porous body, a resin porous body, or a porous body made of a mixed material of ceramic and resin, but various other materials may be used.

As shown in FIGS. 2 and 3, a load applying mechanism 58 that presses the cathode feeding body 44 toward the electrolyte membrane 40 is arranged in the cathode chamber 45ca. The load applying mechanism 58 includes an elastic member, for example, a leaf spring 60, and the leaf spring 60 applies a load to the cathode feeding body 44 via a metal leaf spring holder (shim member) 62. .. As the elastic member, in addition to the leaf spring 60, a disc spring, a coil spring, or the like can be used.

A conductive sheet 66 is arranged between the cathode feeding body 44 and the leaf spring holder 62. The conductive sheet 66 is made of, for example, a metal sheet such as titanium, SUS, or iron, has a ring shape, and has a diameter substantially the same as that of the cathode feeding body 44.

An insulating member, for example, a resin sheet 68, is arranged between the conductive sheet 66 and the electrolyte membrane 40 in the central portion of the cathode feeding body 44. The resin sheet 68 fits on the inner peripheral surface of the cathode feeding body 44. The resin sheet 68 is set to have substantially the same thickness as the cathode feeding body 44. As the resin sheet 68, for example, PEN (polyethylene naphthalate), a polyimide film, or the like is used.

A communication hole member 70 is arranged between the resin sheet 68 and the cathode side separator 34. The communication hole member 70 has a cylindrical shape, and a high-pressure hydrogen communication hole 38c is formed in the central portion. A hydrogen discharge passage 71 that communicates the cathode chamber 45ca and the high-pressure hydrogen communication hole 38c is formed at one end of the communication hole member 70 in the axial direction.

In the cathode chamber 45ca, a large O-ring 72 (seal member) that circulates around the outer periphery of the cathode feeding body 44, the leaf spring holder 62, and the conductive sheet 66 is arranged. A pressure-resistant member 74 having a hardness higher than that of the large O-ring 72 is arranged on the outer periphery of the large O-ring 72. The pressure-resistant member 74 has a substantially ring shape, and the outer peripheral portion is fitted to the inner peripheral portion of the resin frame member 36.

The cross section of the large O-ring 72 is close to a perfect circle or an ellipse. Therefore, as shown in FIG. 3, a gap 76 is formed between the large O-ring 72 and the cathode electrode catalyst layer 44a. As will be described later, hydrogen generated in the cathode electrode catalyst layer 44a enters the void 76.

A backup ring 78 as a surface pressure applying member is interposed between the large O-ring 72 and the pressure resistant member 74. As can be understood from FIG. 4, which is an enlarged cross-sectional view of a main part, the backup ring 78 has a substantially triangular cross section along the radial direction, and is formed between the large O-ring 72 and the lower half of the pressure-resistant member 74. Fills the approximately triangular voids. The backup ring 78 having such a shape abuts on the first contact surface 80a that abuts on the electrolyte membrane / electrode structure 30, the second contact surface 80b that abuts on the pressure resistant member 74, and the large O-ring 72. It has a third contact surface 80c. Hereinafter, the side forming the first contact surface 80a, the side forming the second contact surface 80b, and the side forming the third contact surface 80c are referred to as the first side 82a, the second side 82b, and the third side 82c, respectively. write. The first side 82a is the bottom side, and the third side 82c is the hypotenuse connected to both the first side 82a and the second side 82b, so that the radial cross section of the backup ring 78 becomes a substantially triangular shape.

The backup ring 78 is preferably made of a material having a low coefficient of friction. A suitable example of such a material is a polytetrafluoroethylene resin.

The lower surface (first end surface) of the pressure resistant member 74 facing the electrolyte membrane / electrode structure 30 and the upper surface (second end surface) facing the cathode side separator 34 are roughened. Therefore, the lower surface and the upper surface are not smooth, and unevenness including the concave portion 90 and the convex portion 92 is formed. The surface roughness of the lower surface and the upper surface is preferably set so that the maximum height (Rz) is in the range of 1.5 to 13.0 μm. The more suitable surface roughness is in the range of the maximum height (Rz) of 1.5 to 8.0 μm.

An insulating annular body 94 as an insulator is interposed between the electrolyte membrane 40 constituting the electrolyte membrane / electrode structure 30 and the pressure resistant member 74. In other words, the insulating torus 94 is sandwiched between the electrolyte membrane 40 and the pressure resistant member 74. The insulating torus 94 is made of, for example, a PEN, a polyimide film, or the like, like the resin sheet 68.

In the prior art, the pressure resistant member 74 and the insulator (insulating ring 94) are bonded by an adhesive. On the other hand, in the present embodiment, the insulating torus 94 is not adhered to the pressure resistant member 74. In addition, they are not joined by other joining methods, but merely come into contact with each other.

The differential pressure type high-pressure water electrolyzer 10 according to the present embodiment is basically configured as described above, and next, the operation and effect thereof are the same as the operation of the differential pressure type high-pressure water electrolyzer 10. I will explain in relation.

When starting the electrolysis of water, as shown in FIG. 1, water is supplied from the water supply port 39a to the water supply communication hole 38a, and the lead wires 26a are connected to the terminal portions 24a and 24b of the terminal plates 16a and 16b. Power from the electrolytic power source 28 is applied via 26b. Therefore, as shown in FIG. 3, in each high-pressure water electrolysis cell 12, water is supplied from the water supply communication hole 38a to the water flow path 50b of the water flow path member 46 through the supply connection path 50a. Water is supplied to the anode feeding body 42 from the plurality of holes 50c and moves into the anode feeding body 42 which is a porous body.

Water further passes through the through hole 48a and reaches the anode electrode catalyst layer 42a. Water is electrolyzed in the anode electrode catalyst layer 42a, and an anodic reaction is generated in which protons, electrons and oxygen are generated. The protons in this permeate through the electrolyte membrane 40 and move to the cathode electrode catalyst layer 44a side, causing a cathode reaction that binds to electrons. As a result, hydrogen as a gas phase is obtained.

Hydrogen flows into the cathode chamber 45ca along the hydrogen flow path inside the cathode feeding body 44, and is further discharged from the hydrogen discharge passage 71 into the high-pressure hydrogen communication hole 38c. Hydrogen can flow out of the differential pressure type high-pressure water electrolyzer 10 through the high-pressure hydrogen communication hole 38c while being maintained at a higher pressure than the water supply communication hole 38a. On the other hand, the oxygen generated by the anodic reaction and the unreacted water are discharged from the water discharge communication hole 38b to the outside of the differential pressure type high-pressure water electrolyzer 10 through the water discharge port 39b.

A part of the hydrogen generated in the cathode electrode catalyst layer 44a enters the void 76. Since the hydrogen that has entered the void 76 and the cathode chamber 45ca has a high pressure as described above, in each high-pressure water electrolysis cell 12, the inside of the large O-ring 72 has a high pressure and the outside has a low pressure. Therefore, as shown in FIG. 5, a pressing force F that moves and compresses the large O-ring 72 so as to press it against the pressure-resistant member 74 acts on the large O-ring 72. The backup ring 78 receives this pressing force F.

That is, in the backup ring 78, the third contact surface 80c in contact with the large O-ring 72 is pressed by the large O-ring 72. Since the third side 82c forming the third contact surface 80c is a hypotenuse, the pressing force F of the large O-ring 72 acts along a direction substantially orthogonal to the third side 82c. The pressing force F is further distributed in a direction substantially orthogonal to each of the first side 82a and the second side 82b. Therefore, the first side 82a (first contact surface 80a) presses the electrolyte membrane 40 with the distribution force f1, and the second side 82b (second contact surface 80b) presses the pressure resistant member 74 with the distribution force f2. .. In this way, the pressing force F generated by the expansion of the diameter of the large O-ring 72 is converted into a force f1 that presses the electrolyte membrane 40 against the protective sheet member 48 by the backup ring 78.

By forming the void 76 on the inner side of the backup ring 78 in this way, the pressure of hydrogen is surely transmitted to the large O-ring 72. As a result, the pressing force F of the large O-ring 72 is transmitted to the electrolyte membrane 40 via the first contact surface 80a of the backup ring 78, so that the surface pressure (from the backup ring 78 to the electrolyte membrane / electrode structure 30) ( Distributing power f2) is given. Therefore, the electrolyte membrane / electrode structure 30 is strongly pressed against the protective sheet member 48. That is, the electrolyte membrane 40 is directed toward the protective sheet member 48 and pressed.

This pressing makes it difficult for the electrolyte membrane / electrode structure 30 to be displaced with respect to the protective sheet member 48. Therefore, even if the large O-ring 72 moves, the electrolyte membrane 40 is prevented from being pulled accordingly. Therefore, the concern that wrinkles are generated in the electrolyte membrane 40 is eliminated.

In addition, since the large O-ring 72 is compressed while being blocked by the backup ring 78, a part of the outer peripheral wall of the large O-ring 72 is formed by the electrolyte membrane 40 or the insulating torus 94 and the pressure resistant member 74. It is prevented from getting caught in between.

Here, high-pressure hydrogen is generated on the inner peripheral side (cathode) of the large O-ring 72, and the differential pressure from the outer peripheral side (pressure resistant member 74), which is the normal pressure, is large. Therefore, hydrogen generated in the cathode electrode catalyst layer 44a and permeating the inside of the large O-ring 72 and hydrogen permeating the electrolyte membrane 40 proceed to the pressure-resistant member 74 side, and the insulating torus 94 and the pressure-resistant member 74 There is a possibility that it may enter and stay between the lower surface of the pressure-resistant member 74 and between the upper surface of the pressure-resistant member 74 and the cathode-side separator 34.

When stopping the operation of the differential pressure type high pressure water electrolysis device 10 to stop electrolysis, the cathode chamber is used to eliminate the differential pressure between the anode chamber 45an on the low pressure (normal pressure) side and the cathode chamber 45ca on the high pressure side. Depressurization (decompression) treatment is applied to 45ca. As described above, when hydrogen stays between the insulating torus 94 and the pressure resistant member 74 and between the pressure resistant member 74 and the cathode side separator 34, the inner peripheral side of the large O-ring 72 has a low pressure and the outer circumference. A differential pressure is generated because the side becomes high pressure.

When the large O-ring 72 is pressed toward the inner peripheral side based on this differential pressure, the large O-ring 72 is separated from the pressure-resistant member 74, or the insulating ring 94 or the electrolyte membrane 40 and the pressure-resistant member 74 are separated from each other. In the meantime, it may get caught between the pressure resistant member 74 and the cathode side separator 34. As a result, there is a concern that the electrolyte membrane 40 and the large O-ring 72 may be damaged.

However, in the present embodiment, first, the lower surface and the upper surface of the pressure-resistant member 74 are roughened to form unevenness including the concave portion 90 and the convex portion 92. Therefore, between the insulating torus 94 and the lower surface of the pressure-resistant member 74, and between the upper surface of the pressure-resistant member 74 and the cathode-side separator 34, a plurality of points are not in surface contact but via the tip of the convex portion 92. They are in contact with each other. In other words, except for the tip of the convex portion 92, it is separated from the insulating torus 94 or the pressure resistant member 74. Due to this separation, a clearance is formed between the insulating torus 94 and the lower surface of the pressure-resistant member 74, and between the upper surface of the pressure-resistant member 74 and the cathode-side separator 34.

The surface roughness of the lower surface and the upper surface of the pressure-resistant member 74 is preferably set so that the maximum height (Rz) is in the range of 1.5 to 13.0 μm. If the maximum height is less than 1.5 μm, it will not be easy to form a sufficient clearance. If it exceeds 13.0 μm, when the large O-ring 72 receives the pressing force F and is pressed against the pressure resistant member 74 during the above hydrogen generation, the large O-ring 72 is between the pressure resistant member 74 and the cathode side separator 34. There is a concern that it will bite. A more preferred maximum height (Rz) is in the range of 1.5 to 8.0 μm.

Moreover, in the present embodiment, the insulating torus 94 is only brought into contact with the pressure resistant member 74, and is not adhered. Therefore, the adhesive does not fill the clearance.

Therefore, when hydrogen enters between the insulating torus 94 and the lower surface of the pressure resistant member 74, and between the upper surface of the pressure resistant member 74 and the cathode side separator 34, when the cathode is depressurized, hydrogen is applied. Can be distributed through the clearance. That is, the pressure-resistant member 74 is between the insulating annular body 94 and the lower surface of the pressure-resistant member 74 by performing a roughening treatment in which the concave portion 90 and the convex portion 92 (concavo-convex) are provided on the lower surface and the upper surface of the pressure-resistant member 74. Hydrogen that has entered between the upper surface of the torus and the cathode side separator 34 is quickly discharged.

In other words, hydrogen is prevented from staying after depressurization. Therefore, it is avoided that a differential pressure is generated on the inner peripheral side and the outer peripheral side of the large O-ring 72. This eliminates the concern that the electrolyte membrane 40 and the large O-ring 72 will be damaged due to the differential pressure between the inner peripheral side and the outer peripheral side of the large O-ring 72.

6 to 8 show the pressure (hydrogen pressure) inside the laminate 14 and the hydrogen concentration outside the laminate 14 over time when the maximum heights are 0.4 μm, 1.68 μm, and 8.0 μm, respectively. It is a graph showing the change. In FIG. 6, the hydrogen concentration gradually decreases as the pressure in the laminate 14 decreases, whereas in FIGS. 7 and 8, the hydrogen concentration momentarily increases during depressurization. I understand. This means that in FIGS. 7 and 8, hydrogen that has entered between the insulating torus 94 and the lower surface of the pressure resistant member 74, and between the upper surface of the pressure resistant member 74 and the cathode side separator 34 is discharged. On the other hand, FIG. 6 shows that it remains stagnant.

That is, when FIG. 6 is compared with FIGS. 7 and 8, the lower surface and the upper surface of the pressure resistant member 74 are roughened so as to have a predetermined surface roughness, so that after depressurization of the cathode, It is clear that hydrogen can be prevented from staying between the insulating torus 94 and the pressure resistant member 74, and between the pressure resistant member 74 and the cathode side separator 34.

By depressurizing, the pressure inside and outside the backup ring 78 becomes the same. For this reason, the large O-ring 72 is released from the pressing force F, so that the large O-ring 72 expands and returns to its original shape and moves to its original position.

Even at this time, the state in which the second contact surface 80 b of the backup ring 78 is in contact with the insulating torus 94 continues. Therefore, it is difficult for the electrolyte membrane / electrode structure 30 to be displaced with respect to the protective sheet member 48 in the same manner as described above, and it is possible to avoid pulling the electrolyte membrane 40 with the movement of the large O-ring 72. To. That is, the concern that wrinkles are generated in the electrolyte membrane 40 is eliminated.

The present invention is not particularly limited to the above-described embodiment, and various modifications can be made without departing from the gist of the present invention.

For example, it is not necessary to use the backup ring 78.

10 ... Differential pressure type high pressure water electrolyzer 12 ... High pressure water electrolysis cell 14 ... Laminated body 28 ... Electrolyte power supply 30 ... Electrolyte film / electrode structure 32 ... Anode side separator 34 ... Anode side separator 36 ... Resin frame member 37a, 37b ... Seal Member 38a ... Water supply communication hole 38b ... Water discharge communication hole 38c ... High-pressure hydrogen communication hole 39a ... Water supply port 39b ... Water discharge port 40 ... Electrolyte film 42 ... Anode feeding body 42a ... Anode electrode catalyst layer 44 ... Cathode feeding body 44a ... Cathode electrode catalyst layer 45an ... Anode chamber 45ca ... Cathode chamber 46 ... Water flow path member 52, 70 ... Communication hole member 52a, 52b ... Seal chamber 56 ... Porous member 58 ... Load application mechanism 60 ... Leaf spring 62 ... Leaf spring holder 71 ... Hydrogen discharge passage 72 ... Large O-ring 74 ... Pressure-resistant member 76 ... Void 78 ... Backup ring 80a ... First contact surface 80b ... Second contact surface 80c ... Third contact surface 82a ... First side 82b ... First side 2 sides 82c ... 3rd side 90 ... concave 92 ... convex 94 ... insulating annular body

Claims (2)

Anode side separator and
Cathode side separator and
An electrolyte membrane / electrode structure configured by providing an anode electrode catalyst layer and a cathode electrode catalyst layer on an electrolyte membrane and located between the anode-side separator and the cathode-side separator.
A seal member sandwiched between the cathode side separator and the electrolyte membrane / electrode structure and surrounding the cathode electrode catalyst layer, and
A pressure-resistant member that surrounds the seal member from the outside,
It is a water electrolyzer with
Concavities and convexities are formed on the first end surface of the pressure resistant member facing the electrolyte membrane / electrode structure and the second end surface facing the cathode side separator.
The surface roughness of the first end surface and the second end surface is 1.5 to 13.0 μm at the maximum height.
Further, it further has an insulator interposed between the pressure-resistant member and the electrolyte membrane / electrode structure.
A water electrolyzer characterized in that the insulator is not adhered to the pressure resistant member and the electrolyte membrane / electrode structure . In the water electrolyzer according to claim 1 , a surface pressure applying member that is interposed between the seal member and the pressure resistant member and receives pressure from the seal member to apply pressure to the electrolyte membrane / electrode structure. A water electrolyzer characterized by further having.

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