CN110552014A

CN110552014A - electrochemical pump

Info

Publication number: CN110552014A
Application number: CN201910211884.8A
Authority: CN
Inventors: 川畑德彦; 后川和也
Original assignee: Panasonic Intellectual Property Management Co Ltd
Current assignee: Panasonic Intellectual Property Management Co Ltd
Priority date: 2018-06-04
Filing date: 2019-03-20
Publication date: 2019-12-10
Also published as: US20190368512A1

Abstract

In an electrochemical hydrogen pump (24), an anode separator (7), an anode diffusion layer (5), an electrolyte membrane (2), a cathode diffusion layer (6), and a cathode separator (8) are laminated in this order, the anode separator (7) has a first recess (25) that houses the anode diffusion layer (5), the bottom surface (25a) of the first recess (25) is an -shaped curved surface that protrudes from the center, the cathode separator (8) has a second recess (27) that houses the cathode diffusion layer (6), and the bottom surface (27a) of the second recess (27) is a -shaped curved surface that is recessed from the center.

Description

Electrochemical pump

Technical Field

The present invention relates to an electrochemical hydrogen pump. And more particularly to an electrochemical hydrogen pump for compressing hydrogen.

Background

In recent years, development and popularization of a fuel cell for home use using hydrogen as a fuel have been promoted. Further, mass production and sale of fuel cell vehicles using hydrogen as fuel have been started, as in the case of domestic fuel cells.

while fuel cells for domestic use are able to utilize existing city gas and existing commercial electricity, fuel cell vehicles require a hydrogen infrastructure. Therefore, in order to widely spread fuel cell vehicles in the future, expansion of a hydrogen station as a hydrogen infrastructure is required.

However, the construction of hydrogen stations requires large-scale facilities and land. Therefore, enormous expenses are required. This problem is a major problem to be solved for the widespread use of fuel cell vehicles.

Therefore, as an alternative to a large-sized hydrogen station, development of a compact and low-cost small hydrogen filling device for home use is desired. The most important of the development of such small hydrogen filling devices is the development of a compressor for compressing hydrogen, and an electrochemical hydrogen pump capable of electrochemically boosting the pressure of hydrogen is currently focused.

Compared with a conventional mechanical hydrogen compressor, the electrochemical hydrogen pump has many advantages such as compactness, high pressure-increasing efficiency, no maintenance because of no mechanical operation part, and little noise. Therefore, the practical use of the electrochemical hydrogen pump is strongly desired.

Currently, consideration is given to electrochemically compressing hydrogen generated by a fuel reforming apparatus using a household fuel cell using an electrochemical hydrogen pump.

If such an electrochemical hydrogen pump is used for a small hydrogen filling apparatus, there are the following advantages in addition to the above-described advantages. That is, although the concentration of hydrogen generated using the fuel reforming device is about 75%, it is theoretically possible to purify it to almost 100% hydrogen and boost it to an ultra-high pressure that can be filled in the fuel cell vehicle.

Further, the electrochemical hydrogen pump is constructed similarly to a power generation laminate of a household fuel cell. Unlike a power generation laminate of a household fuel cell, the pressure of the cathode needs to be ultra high pressure to the extent that hydrogen can be filled in a fuel cell vehicle, compared to the anode that supplies low-pressure hydrogen. Therefore, when the power generation laminate of the household fuel cell is used as an electrochemical hydrogen pump, it is necessary to use a support structure for the electrolyte membrane interposed between the two electrodes as a special structure.

Fig. 1 is a diagram illustrating a structure of a power generation laminate 1 of a conventional fuel cell. As shown in fig. 1, in the power generation laminated body 1, each surface of the electrolyte membrane 102 on which the anode electrode layer 103 and the cathode electrode layer 104 are formed is sandwiched by the anode diffusion layer 105 and the cathode diffusion layer 106.

Further, the outside thereof is sandwiched by an anode separator 107 and a cathode separator 108. Further, the outer side is sandwiched by an anode insulating plate 111 and a cathode insulating plate 112. Further, the outer side thereof is sandwiched by an anode terminal plate 113 and a cathode terminal plate 114. Further, the anode end plate 113 and the cathode end plate 114 are sandwiched by the bolt 115 and the nut 110, and the bolt 115 and the nut 110 are fastened to each other.

a seal 109 is mounted around the anode diffusion layer 105 and the cathode diffusion layer 106 so that gas does not leak to the outside. When the power generation laminate 1 of the fuel cell is used as a hydrogen pump, the anode inlet 116 is used to supply low-pressure hydrogen, the anode outlet 117 is used to recover excess low-pressure hydrogen, and the cathode inlet 118 is used to take out high-pressure hydrogen, and is sealed because the cathode outlet 119 is not used.

Here, a case where the power generation laminate 1 is configured by one unit cell including the electrolyte membrane 102, the anode diffusion layer 105, the cathode diffusion layer 106, the anode separator 107, the cathode separator 108, and the like will be described. However, in general, a plurality of unit cells of the above-described configuration are included in the power generation laminate 1.

In a state where low-pressure hydrogen is supplied from the anode inlet 116 and the low-pressure hydrogen flows into the flow channel groove 107a on the anode side, a voltage is applied between the anode separator 107 and the cathode separator 108 by the power supply 20. Then, in the anode electrode layer 103, hydrogen is dissociated into protons and electrons as shown in formula (1).

h ₂ (Low pressure) → 2H ⁺ +2e ^- (1)

the protons dissociated in the anode electrode layer 103 move in the electrolyte membrane 102 with water molecules, and the electrons pass from the anode diffusion layer 105 through the anode separator 107, and move to the cathode electrode layer 104 via the power source 20 to the cathode separator 108 and the cathode diffusion layer 106.

in the cathode electrode side, as shown in formula (2), a reduction reaction occurs due to protons moving through the electrolyte membrane 102 and electrons moving through the cathode diffusion layer 106, and hydrogen is generated. At this time, when the cathode inlet 118 is sealed, the hydrogen pressure in the cathode-side flow channel 108a increases, and high-pressure hydrogen gas is generated.

2H ⁺ +2e ^- → H ₂ (high pressure) (2)

Here, the relationship between the pressure P1 of hydrogen on the anode side, the pressure P2 of hydrogen on the cathode side, and the voltage E is expressed by expression (3).

E＝(RT/2F)ln(P2/P1)+ir (3)

In the equation (3), R represents a gas constant (8.3145J/K · mol), T represents a temperature (K) of the cell constituting the power generation laminated body 1, F represents a faraday constant (96485C/mol), P2 represents a cathode-side pressure (MPa), P1 represents an anode-side pressure (Pa), i represents a current density (a/cm ²), and R represents a cell resistance (Ω · cm ²).

As is clear from equation (3), if the voltage is increased, the cathode-side pressure P2 increases.

Fig. 2A is a perspective view of conventional anode diffusion layer 105. Fig. 2B is a perspective view of conventional anode separator 107. Fig. 3 is a perspective view of a conventional anode diffusion layer 105 and anode separator 107 combined.

in the conventional power generation laminate 1, in order to accommodate the anode diffusion layer 105 in the concave portion of the anode separator 107, a gap is required between the outer periphery of the anode diffusion layer 105 and the side surface of the concave portion of the anode separator 107. In order to accommodate the cathode diffusion layer 106 in the recessed portion of the cathode separator 108, a gap is required between the outer periphery of the cathode diffusion layer 106 and the side surface of the recessed portion of the cathode separator 108.

In order to fit the disk-shaped anode diffusion layer 105 having a diameter D shown in fig. 2A into the recess having an inner diameter D formed in the anode separator 107 shown in fig. 2B, the inner diameter D needs to be larger than the diameter D. When the inner diameter D of the concave portion is larger than the diameter D of the anode diffusion layer 105, as shown in fig. 3, an anode-side gap 121 having a width Δ is formed between the outer periphery of the anode diffusion layer 105 and the side surface of the concave portion of the anode separator 107. The width Δ of the anode-side gap 121 is about half the difference between the diameter D and the inner diameter D.

when the size of the anode diffusion layer 105 is 100mm, the reference dimensions of the diameter D and the inner diameter D are set so that the width Δ of the anode-side gap 121 is, for example, about 0.1 mm.

If the difference between the diameter D and the inner diameter D is set to be less than 0.1mm, the dimensional relationship between the diameter D and the inner diameter D is reversed due to dimensional variations in the fabrication of the anode diffusion layer 105 and the anode separator 107, and the anode diffusion layer 105 may not be fitted into the recess of the anode separator 107.

It is also conceivable to set the width Δ of the anode-side gap 121 to less than 0.1mm, and to use only non-defective products by performing a dimensional inspection after the anode diffusion layer 105 and the anode separator 107 are manufactured. However, this leads to a problem that the yield of the anode diffusion layer 105 and the anode separator 107 is reduced and the cost is high. Therefore, it is necessary to set an anode-side gap 121 having a width of about 0.1mm between the anode diffusion layer 105 and the anode separator 107.

reference dimensions of the diameter D of the cathode diffusion layer 106 and the inner diameter D of the concave portion of the cathode separator 108 are set so that the width of the cathode-side gap 122 formed between the cathode diffusion layer 106 and the cathode separator 108 is also about 0.1mm (see fig. 1).

when the power generation laminate 1 of the fuel cell having the anode-side gap 121 and the cathode-side gap 122 is used as a hydrogen pump and the pressure of hydrogen is increased, the electrolyte membrane 102 is pushed from the high-pressure side (cathode side) to the low-pressure side (anode side) by the pressure of hydrogen applied to the cathode-side gap 122 as the pressure on the high-pressure side increases. That is, the electrolyte membrane 102 is deformed to hang down from the cathode-side gap 122 on the high-pressure side to the anode-side gap 121 on the low-pressure side. If this deformation increases, cracks are generated in the electrolyte membrane 102, and eventually the electrolyte membrane 102 is broken.

Therefore, the pressure of hydrogen that can be boosted by using the power generation laminate 1 of a general fuel cell as a hydrogen pump is not so high, and the filling of hydrogen into the fuel cell vehicle is insufficient.

Therefore, a structure has been proposed in which a power generation laminate of a general fuel cell is used as a hydrogen pump, and an electrolyte membrane is supported so that the electrolyte membrane is not damaged even when a pressure difference between a high-pressure side and a low-pressure side exists (patent document 1).

Fig. 4 is a longitudinal sectional view of a conventional electrochemical hydrogen pump 23. In the conventional electrochemical hydrogen pump 23, the anode diffusion layer 205 in the low-pressure region is configured to be wider than the cathode diffusion layer 206 to which a high pressure is applied. Therefore, the anode-side gap 221 and the cathode-side gap 222 are not disposed at positions facing each other across the electrolyte membrane 202.

Therefore, even if a high voltage is applied to the electrolyte membrane 202, the highly rigid anode diffusion layer 205 on the low-voltage side can support the electrolyte membrane 202. Therefore, the electrolyte membrane 202 is not subjected to bending force or shearing force, which is an important factor for breakage. Therefore, even if there is a difference between the pressure generated in the anode-side gap 221 and the pressure generated in the cathode-side gap 222, the electrolyte membrane 202 can be supported safely.

Prior art documents

Patent document

Patent document 1: japanese patent No. 6246203

disclosure of Invention

Problems to be solved by the invention

however, in the structure described in patent document 1, only the portion corresponding to the area of the cathode diffusion layer 206 is effectively used for increasing the pressure of hydrogen, and the portion of the anode diffusion layer 205 wider than the cathode diffusion layer 206 is an expensive diffusion layer of a metal sintered body of Ti, but is an unnecessary portion that cannot be effectively used. Therefore, it is an object to reduce the manufacturing cost of the electrochemical hydrogen pump 23.

Further, it has been found through recent studies that the above-described structure causes a problem in performance due to the cathode-side gap 222 on the high-pressure side and the anode-side gap 221 on the low-pressure side. Namely, there are the following problems: during operation of the electrochemical hydrogen pump 23, a part of the high-pressure hydrogen diffuses in the reverse direction from the cathode-side gap 222 on the high-pressure side to the anode-side gap 221 on the low-pressure side, and the pressure of the boosted hydrogen decreases. That is, the pressure-increasing efficiency of the electrochemical hydrogen pump 23 decreases.

Further, it is apparent that the following problem occurs when the pressure of hydrogen is increased in order to fill the fuel cell vehicle with hydrogen. That is, as the pressure of hydrogen filled in the gaps between the flow channel grooves 208a of the cathode separator 208 and the cathode diffusion layer 206 increases, the center portions of the cathode separator 208, the cathode insulating plate 212, and the cathode end plate 214 are displaced in the Y1 direction in fig. 4. Further, the central portions of the electrolyte membrane 202, the anode diffusion layer 205, the anode separator 207, the anode insulating plate 211, and the anode end plate 213 are displaced in the Y2 direction.

from this, it is apparent that the contact surface pressure in the vicinity of the center of the cathode diffusion layer 206 and the cathode electrode layer 204 and the cathode diffusion layer 206 and the cathode separator 208 is lower than the surrounding pressure, and as a result, the contact resistance increases and the voltage rises. In general, a measure is taken to increase the plate thickness of the cathode end plate 214 and the anode end plate 213 to increase the rigidity so that such a phenomenon does not occur. However, this measure has a problem that the weight of the member is extremely heavy and it is difficult to handle the respective members.

The purpose of the present invention is to provide an electrochemical hydrogen pump in which the size of an anode diffusion layer and the size of a cathode diffusion layer are made the same so as not to be an obstacle to cost reduction, and in which the breakage of an electrolyte membrane 2 due to the differential pressure between the pressure on the anode side and the pressure on the cathode side is prevented without causing a reduction in compression performance and a high weight of each member.

means for solving the problems

In order to solve the above problems, in the electrochemical pump of the present invention, an anode separator, an anode diffusion layer, an electrolyte membrane, a cathode diffusion layer, and a cathode separator are laminated in this order, the anode separator has a first concave portion that houses the anode diffusion layer, a bottom surface of the first concave portion is an -shaped curved surface whose central portion protrudes, the cathode separator has a second concave portion that houses the cathode diffusion layer, and a bottom surface of the second concave portion is a -shaped curved surface whose central portion is recessed.

Effects of the invention

according to the present invention, the anode-side gap between the anode diffusion layer and the anode separator and the cathode-side gap between the cathode diffusion layer and the cathode separator can be eliminated. Therefore, a decrease in compression performance due to concentration diffusion of hydrogen from the cathode-side gap to the anode-side gap through the electrolyte membrane is suppressed.

Drawings

fig. 1 is a diagram illustrating the structure of a power generation stack of a conventional fuel cell.

fig. 2A is a perspective view of a conventional anode diffusion layer.

fig. 2B is a perspective view of a conventional anode separator.

Fig. 3 is a perspective view of a conventional anode diffusion layer and an anode separator combined together.

Fig. 4 is a longitudinal sectional view of a conventional electrochemical hydrogen pump.

Fig. 5 is a longitudinal sectional view of the electrochemical hydrogen pump in embodiment 1.

fig. 6A is a sectional perspective view of the anode diffusion layer in embodiment 1.

Fig. 6B is a sectional perspective view of the cathode diffusion layer in embodiment 1.

Fig. 7A is a sectional perspective view of the anode separator without processing the flow channel.

Fig. 7B is a sectional perspective view of the anode separator after the channel groove is processed.

Fig. 7C is a sectional perspective view of the cathode separator without processing the flow channel groove.

Fig. 7D is a sectional perspective view of the cathode separator after the flow channel groove is processed.

fig. 8A is a longitudinal sectional view illustrating an assembly step of the electrochemical hydrogen pump.

Fig. 8B is a longitudinal sectional view illustrating an assembly step of the electrochemical hydrogen pump.

Fig. 9 is a circuit diagram of an evaluation device of the electrochemical hydrogen pump.

Fig. 10 is a graph showing the evaluation results of the electrochemical hydrogen pump.

Fig. 11 is a longitudinal sectional view of an electrochemical hydrogen pump according to embodiment 2.

Fig. 12 is a longitudinal sectional view of an electrochemical hydrogen pump according to embodiment 3.

fig. 13 is a longitudinal sectional view of an electrochemical hydrogen pump in a comparative example.

Description of the reference numerals

1 a power generation laminate;

2. 102, 202 electrolyte membranes;

3. 103 an anode electrode layer;

4. 104, 204 cathode electrode layers;

5. 105, 205 anode diffusion layer;

5a, 6a outer peripheral surface;

6. 106, 206 cathode diffusion layer;

7. 107, 207 anode separators;

7a, 8a, 107a, 108a, 208a flow channel;

8. 108, 208 cathode separators;

9. 109 a seal;

10. 110 nuts;

11. 111, 211 anode insulating plates;

12. 112, 212 cathode insulating plates;

13. 113, 213 anode end plate;

14. 114, 214 cathode end plate;

15. 115 bolts;

116 an anode inlet;

117 an anode outlet;

118 a cathode inlet;

119 cathode outlet;

20. 120 power supply;

121. 221, 321, 421 anode side gap;

122. 222 cathode side gap;

23. 24, 24A, 24B, 46 electrochemical hydrogen pumps;

25. 27a recess;

25a, 27a bottom surface;

25b, 27b sides;

26 bolt holes;

28 grooves;

29. 30 curved surfaces;

31 an evaluation device;

A 32 hydrogen bottle;

33 a regulator;

34 a diffuser;

35 a heater;

36 gas-liquid separation device;

37 a cooling device;

A 38 manometer;

39 an exhaust valve;

40 nitrogen bottles;

41 a dilution device;

42 an exhaust port;

43 a three-way valve;

A 44 valve;

45, and (4) a valve.

Detailed Description

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(embodiment mode 1)

Fig. 5 is a longitudinal sectional view of the electrochemical hydrogen pump 24 in embodiment 1.

< overall Structure >

In the electrochemical hydrogen pump 24 according to embodiment 1, the electrolyte membrane 2 on which the anode electrode layer 3 and the cathode electrode layer 4 are formed is sandwiched between the anode diffusion layer 5 and the cathode diffusion layer 6 on both sides, and the anode separator 7 and the cathode separator 8 on the outside.

Further, the outer sides of the anode separator 7 and the cathode separator 8 are sandwiched by an anode insulating plate 11 and a cathode insulating plate 12, respectively, and further, the outer sides thereof are sandwiched by an anode terminal plate 13 and a cathode terminal plate 14. Further, the above members are pressed by a press from the outside of the anode terminal plate 13 and the cathode terminal plate 14 so as to be in close contact with each other.

This pressurized state is maintained by the bolt 15 and the nut 10. Further, around the anode diffusion layer 5 and the cathode diffusion layer 6, a seal 9 is attached so that gas does not leak to the outside.

The electrolyte membrane 2 is a cation-permeable membrane, and for example, nafion (registered trademark, manufactured by dupont) or Aciplex (trade name, manufactured by asahi chemical co. The electrolyte membrane 2 is provided on the face of the anode side with an anode electrode layer 3 comprising, for example, a RuIrFeOx catalyst, and on the face of the cathode side with a cathode electrode layer 4 comprising, for example, a platinum catalyst.

Further, the anode diffusion layer 5 needs to withstand the pressing of the electrolyte membrane 2 by the high-pressure hydrogen of the flow channel 8a in the cathode separator 8. Therefore, for the anode diffusion layer 5, for example, a porous body having sufficient rigidity and conductivity, such as a titanium fiber sintered body or a titanium powder sintered body having a platinum plating applied to the surface thereof, is used.

Further, as the cathode diffusion layer 6, for example, a highly elastic graphitized carbon fiber (for example, a carbon fiber treated at a high temperature of 2000 ℃ or higher and graphitized) having platinum plating applied to the surface thereof, a porous body such as a titanium fiber sintered body or a titanium powder sintered body, or the like is used in a paper form.

Further, as the seal 9, one obtained by producing a fluororubber by compression molding is used. For the anode separator 7 and the cathode separator 8, for example, a plate material of SUS316L on which the flow channel grooves 7a, 8a, and the like were formed by cutting was used.

< anode diffusion layer 5 and cathode diffusion layer 6>

fig. 6A is a sectional perspective view of the anode diffusion layer 5 in embodiment 1, and fig. 6B is a sectional perspective view of the cathode diffusion layer 6 in embodiment 1.

As shown in fig. 6A, the anode diffusion layer 5 is formed substantially in a disk shape having a plate thickness t1 and a diameter d 1. In a state where no force is applied from the outside, the anode diffusion layer 5 has a shape in which the center portion of the circle has an -type projecting dimension α 1. For example, a disk having a thickness t1 and formed by platinum plating on the surface of the titanium fiber sintered body or the titanium powder sintered body is deformed by press forming, and the anode diffusion layer 5 is formed into such a shape. The anode diffusion layer 5 is used in a range of elastic deformation so that even if it is deformed by applying a force from the outside, if the force from the outside is removed, it returns to its original shape.

As shown in fig. 6B, the cathode diffusion layer 6 is formed substantially in a disk shape having a plate thickness t1 and a diameter d 1. In a state where no force is applied from the outside, the cathode diffusion layer 6 has a shape in which the center portion protrudes upward by a dimension α 3 of type after the dimension α 2 protrudes downward in fig. 6B from the outer peripheral portion of the circle toward the center portion.

The height of the -shaped apex at the center is lower than the outer peripheral portion by a dimension β. For the cathode diffusion layer 6, for example, a disk having a thickness t1 obtained by plating the surface of a titanium fiber sintered body or a titanium powder sintered body with platinum is used. Further, the cathode diffusion layer 6 is formed into such a shape by press forming. The cathode diffusion layer 6 is used in a range of elastic deformation so that even if it is deformed by applying force from the outside, if the force applied from the outside is removed, it returns to its original shape.

Fig. 7A is a sectional perspective view of the anode separator 7 when the channel groove 7A is not machined, and fig. 7B is a sectional perspective view of the anode separator 7 after the channel groove 7A is machined. Fig. 7C is a sectional perspective view of the cathode separator 8 when the channel groove 8a is not machined, and fig. 7D is a sectional perspective view of the cathode separator 8 after the channel groove 8a is machined.

< Anode separator 7>

As shown in fig. 7A, the anode separator 7 is formed in a disk shape having a plate thickness t2 and a diameter d 2. The anode separator 7 has a concave portion 25 for accommodating the anode diffusion layer 5 having a diameter D1 on a surface thereof in contact with the anode diffusion layer 5. The depth near the side surface of the recess 25 is T1. On the other hand, the central portion of the recess 25 is raised by a dimension δ from the bottom surface 25a adjacent to the side surface. That is, the bottom surface 25a is an -shaped curved surface.

As shown in fig. 7B, a meandering channel groove 7a through which the anode gas (low-pressure hydrogen gas) flows is formed in the bottom surface 25a of the anode separator 7. Further, a bolt hole 26 through which the bolt 15 passes is provided outside the recess 25.

The cathode separator 8 is formed in a disk shape having a plate thickness t3 and a diameter d2 as shown in fig. 7C. The cathode separator 8 has a concave portion 27 for accommodating the cathode diffusion layer 6 having a diameter D1 on the surface facing the cathode diffusion layer 6. The depth near the side surface of the recess 27 is T1. On the other hand, the central portion of the recess 25 is recessed by a dimension δ from the bottom surface 27a adjacent to the side surface, and the bottom surface 27a is an -shaped curved surface.

As shown in fig. 7D, a meandering channel groove 8a through which the cathode gas (high-pressure hydrogen gas) flows is formed in the bottom surface 27a of the cathode separator 8. Further, outside the recess 27, a bolt hole 26 through which the bolt 15 passes and a groove 28 for housing the seal 9 are provided.

Preferably, the diameter D1 of the concave portion 25 of the anode separator 7 and the diameter D1 of the concave portion 27 of the cathode separator 8 are larger than the diameter D1 of the anode diffusion layer 5 and the diameter D1 of the cathode diffusion layer 6. Preferably, the protrusion dimension α 1 of the central portion of the anode diffusion layer 5 is larger than the protrusion dimension δ of the surface of the anode separator 7 in contact with the anode diffusion layer 5.

In addition, it is preferable that the area of the curved surface 29 in contact with the anode separator 7 of the anode diffusion layer 5 is larger than the area of the bottom surface 25a of the recess 25 of the anode separator 7 before the machining of the flow path groove 7a in a state where no external force is applied to the anode diffusion layer 5.

Preferably, the area of the curved surface 30 in contact with the cathode separator 8 of the cathode diffusion layer 6 is larger than the area of the bottom surface 27a of the recess 27 of the cathode separator 8 before the flow channel groove 8a is machined, in a state where no external force is applied to the cathode diffusion layer 6.

preferably, the thickness T1 of the anode diffusion layer 5 and the cathode diffusion layer 6 is about 10% thicker than the depth T1 in the vicinity of the side faces of the recess 25 of the anode separator 7 and the recess 27 of the cathode separator 8.

< assembling step >

Next, the assembly procedure of the electrochemical hydrogen pump 24 will be explained. Fig. 8A and 8B are vertical sectional views illustrating steps of assembling the electrochemical hydrogen pump 24.

First, the anode end plate 13 is placed on an assembly table (not shown). On which an anode insulating plate 11, an anode separator 7 are stacked. An anode diffusion layer 5 is placed on the anode separator 7, and an electrolyte membrane 2 is stacked thereon. At this time, the anode diffusion layer 5 having the diameter D1 is fitted inside the concave portion 25 of the anode separator 7 having the diameter D1.

Further, a cathode diffusion layer 6, a cathode separator 8, a cathode insulating plate 12, and a cathode end plate 14 are stacked in this order on the electrolyte membrane 2. At this time, the seal 9 is embedded in the groove 28 of the cathode separator 8 in advance. Further, the cathode diffusion layer 6 of diameter D1 is embedded inside the recess 27 of the cathode separator 8 of diameter D1.

< compression operation >

next, an assembly table (not shown) on which the anode end plate 13 is placed is set in a press (not shown), and the cathode end plate 14 is pressed downward toward the assembly table, thereby applying a compressive force. In a state where the cathode end plate 14 is pressed toward the assembly table, the anode separator 7 and the cathode separator 8 press the anode diffusion layer 5 and the cathode diffusion layer 6 toward the electrolyte membrane 2.

Fig. 8A shows the electrochemical hydrogen pump 24A in a state where no compression force is applied. The anode diffusion layer 5 of diameter D1 is embedded inside the recess 25 of the anode separator 7 of diameter D1. Further, the cathode diffusion layer 6 of diameter D1 is embedded inside the recess 27 of the cathode separator 8 of diameter D1.

the curved surface 29 near the outer periphery of the anode diffusion layer 5 is in contact with the anode separator 7, but is not in contact with the central portion. Similarly, the curved surface 30 near the outer peripheral portion of the cathode diffusion layer 6 is in contact with the cathode separator 8, but is not in contact with the central portion.

Further, the outer peripheral surface 5a of the anode diffusion layer 5 is not in contact with the side surface 25b of the concave portion 25 of the anode separator 7, and the outer peripheral surface 6a of the cathode diffusion layer 6 is not in contact with the side surface 27b of the concave portion 27 of the cathode separator 8.

fig. 8B shows the electrochemical hydrogen pump 24B in a state in the middle of compression. When a further compressive force is applied from the state shown in fig. 8A, the outer peripheral surface 5a of the anode diffusion layer 5 comes into contact with the side surface 25B of the recess 25 of the anode separator 7 as shown in fig. 8B. Further, the outer peripheral surface 6a of the cathode diffusion layer 6 is in contact with the side surface 27b of the recess 27 of the cathode separator 8.

However, even at this stage, the curved surface 29 of the central portion of the anode diffusion layer 5 is not in contact with the anode separator 7. Similarly, the curved surface 30 of the central portion of the cathode diffusion layer 6 does not contact the cathode separator 8.

If the compressive force is directly applied further, the curved surface 29 of the anode diffusion layer 5 is in contact with the anode separator 7 over the entire surface as shown in fig. 5. Likewise, the curved surface 30 of the cathode diffusion layer 6 is in contact with the cathode separator 8 over the entire surface.

Before the compressive force is applied, the area of the curved surface 29 of the anode diffusion layer 5 in contact with the anode separator 7 is larger than the area of the bottom surface 25a of the recess 25 before the flow channel groove 7a of the anode separator 7 is machined. In other words, the diameter D1 of the anode diffusion layer 5 is smaller than the diameter D1 of the recess 25 of the anode separator 7 before the compressive force is applied.

Therefore, at the time of compression, the anode diffusion layer 5 is compressed in the direction orthogonal to the thickness and pressed into the concave portion 25 of the anode separator 7. In other words, the anode diffusion layer 5 is disposed in the concave portion 25 in a pressurized state. Due to this compressive force, the outer peripheral surface 5a of the anode diffusion layer 5 abuts against the side surface 25b of the concave portion 25 of the anode separator 7, and therefore the anode-side gap 221 (fig. 4) between the anode diffusion layer 5 and the anode separator 7 can be eliminated. That is, the diameter D1 of the anode diffusion layer 5 becomes equal to the diameter D1 of the concave portion 25 of the anode separator 7. At this time, the height of the anode diffusion layer 5 becomes lower than the height of the anode diffusion layer 5 before the compressive force is applied. The anode diffusion layer 5 is also compressed in the thickness direction, and the thickness is equal to the depth T1 near the side surface 25b of the recess 25 of the anode separator 7.

Similarly, the area of the curved surface 30 of the cathode diffusion layer 6 in contact with the cathode separator 8 before the compressive force is applied is larger than the area of the bottom surface 27a of the recess 27 of the cathode separator 8 before the flow channel groove 8a is machined. In other words, the diameter D1 of the cathode diffusion layer 6 is smaller than the diameter D1 of the recess 27 of the cathode separator 8 before the compressive force is applied.

Thus, the cathode diffusion layer 6 is compressed in the direction orthogonal to the thickness and pressed into the recess 27 of the cathode separator 8. In other words, the cathode diffusion layer 6 is disposed in the concave portion 27 in a pressurized state. Due to this compressive force, the outer peripheral surface 6a of the cathode diffusion layer 6 abuts against the side surface 27b of the recess 27 of the cathode separator 8, and therefore the cathode-side gap 222 (see fig. 4) between the cathode diffusion layer 6 and the cathode separator 8 can be eliminated. That is, the diameter D1 of the cathode diffusion layer 6 becomes equal to the diameter D1 of the recess 27 of the cathode separator 8. At this time, the height of the cathode diffusion layer 6 becomes lower than the height of the cathode diffusion layer 6 before the compressive force is applied. The cathode diffusion layer 6 is also compressed in the thickness direction, and the thickness is equal to the depth T1 near the side surface 27b of the recess 27 of the cathode separator 8.

In the electrochemical hydrogen pump 24, as the pressure of hydrogen filled in the flow channel 8a and the gaps of the cathode diffusion layer 6 increases, the electrolyte membrane 2 compresses the anode diffusion layer 5 in the thickness direction (Y2 direction). Further, the anode diffusion layer 5 presses down the central portion of the anode separator 7 (presses in the Y2 direction). At this time, the pressure of the high-pressure hydrogen acts on the anode diffusion layer 5 in the direction (Y2 direction) in which the anode diffusion layer 5 is in a state of being close to a flat plate.

Therefore, the surface pressure of the outer peripheral surface 5a of the anode diffusion layer 5 and the side surface 25b of the concave portion 25 of the anode separator 7 increases with the increase in the pressure of hydrogen. Therefore, even if the hydrogen in the cathode separator 8 becomes a high pressure, the anode-side gap 121 between the anode diffusion layer 5 and the anode separator 7 can be maintained in a state where it does not exist.

< evaluation apparatus >

Fig. 9 is a circuit diagram of the evaluation device 31 of the electrochemical hydrogen pump 24. The power supply 120 flows current to the electrochemical hydrogen pump 24. The hydrogen cylinder 32 and the regulator 33 supply low-pressure hydrogen to the electrochemical hydrogen pump 24. The low-pressure hydrogen is humidified by the diffuser 34 and the heater 35.

The gas-liquid separation device 36 and the cooling device 37 lower the dew point of the excess hydrogen that is not used by the electrochemical hydrogen pump 24. On the high pressure side, the pressure is measured by the pressure gauge 38, and the exhaust valve 39 downstream of the pressure gauge 38 is always kept in a closed state, and is opened when the pressure becomes equal to or higher than a constant value.

however, the opening degree of the exhaust valve 39 is adjusted so as to sufficiently generate the pressure loss. That is, the opening degree of the exhaust valve 39 is set so that the pressure of the hydrogen after passing through the exhaust valve 39 is reduced to approximately atmospheric pressure (about 1.05 times the atmospheric pressure) by the pressure loss generated by the exhaust valve 39.

the dew point of hydrogen reduced to substantially atmospheric pressure is lowered by the gas-liquid separation device 36 and the cooling device 37. The decompressed hydrogen is diluted by nitrogen supplied from the nitrogen bottle 40 in the dilution device 41 and then released to the exhaust port 42 that leads to the outside.

In the following evaluation process, the temperature of the heater 35 was set to 65 (deg.C) and the temperature of the cooler 37 was set to 20 (deg.C).

< evaluation Process >

a process for evaluating the electrochemical hydrogen pump 24 is explained.

(1) As shown in fig. 9, the electrochemical hydrogen pump 24 in embodiment 1 is connected to an evaluation device 31.

(2) The three-way valve 43 is switched from the atmosphere open position (arrow a) to the closed side (arrow B).

(3) the valve 44 of the diluting nitrogen bottle 40 is operated to flow nitrogen to the diluting device 41.

(4) the valve 45 and the regulator 33 of the hydrogen cylinder 32 are operated to supply hydrogen at a low pressure (pressure ratio of 0.05) to the electrochemical hydrogen pump 24. In addition, the pressure ratio refers to a ratio of the actually applied pressure with respect to a given pressure.

(5) the power source 120 was turned ON, and the current value was set so that the current density was 1.0(A/cm2) by calculation from the electrode area.

(6) The voltage displayed in power supply 120 is recorded each time the pressure ratio rises by 0.05 until gauge 38 reaches the target pressure (pressure ratio 1.0).

(7) The power supply 120 is turned OFF, and the valves are operated to stop the supply of hydrogen, and then the supply of nitrogen for dilution is stopped.

(8) Finally, the three-way valve 43 is switched from the closed position (arrow B) to the atmosphere open side (arrow a).

(9) The electrochemical hydrogen pump 24 in embodiment 1 is removed.

< evaluation results >

Fig. 10 is a graph showing the evaluation results of the electrochemical hydrogen pump 24. In fig. 10, the horizontal axis represents the pressure ratio, and the vertical axis represents the voltage ratio. Fig. 10 a shows the evaluation result of the conventional electrochemical hydrogen pump 23 described in patent document 1. Note that b in fig. 10 shows the evaluation result of the electrochemical hydrogen pump 24 in embodiment 1. In addition, the voltage ratio refers to a ratio of a voltage actually applied with respect to a given reference voltage.

in the conventional electrochemical hydrogen pump 23 described in patent document 1, the voltage ratio is gradually increased from the pressure ratio of 0.05 to the pressure ratio of 0.6, and the voltage ratio is rapidly increased from the pressure ratio of 0.6 to the pressure ratio of 1.0. In the electrochemical hydrogen pump 24 in embodiment 1, the voltage ratio is slowly increased to the pressure ratio of 0.6, and thereafter, the voltage ratio is sharply increased. This tendency is the same as that of the conventional electrochemical hydrogen pump 23.

However, the electrochemical hydrogen pump 24 in embodiment 1 has a voltage ratio lower by about 0.2 point than that in the range of 0.05 to 0.6, and is superior in performance to the conventional electrochemical hydrogen pump 23. In addition, the difference between the voltage ratio of the electrochemical hydrogen pump 24 in embodiment 1 and the voltage ratio of the conventional electrochemical hydrogen pump 23 is increased in the range of the pressure ratio of 0.6 to 1.0. That is, when comparing the electrochemical hydrogen pump 24 of embodiment 1 with the conventional electrochemical hydrogen pump 23, it can be said that the electrochemical hydrogen pump 24 is excellent in performance particularly when the pressure on the cathode side is increased.

the reason why the voltage ratio of the conventional electrochemical hydrogen pump 23 is high is considered to be that diffusion of hydrogen concentration occurs from the cathode-side gap 222 to the anode-side gap 221 of the electrochemical hydrogen pump 23. That is, it is considered that the electrochemical hydrogen pump 24 in embodiment 1 is improved in this point, and thus the performance is improved.

Further, c is data showing the evaluation results of the electrochemical hydrogen pump according to embodiment 2. For this, it will be described later.

(embodiment mode 2)

Fig. 11 is a longitudinal sectional view of the electrochemical hydrogen pump 46 in embodiment 2. Fig. 11 shows a state at the time of assembly of the electrochemical hydrogen pump 46 and before the application of the compressive force. The assembled state of the electrochemical hydrogen pump 46 according to embodiment 2 is the same as the electrochemical hydrogen pump 24 according to embodiment 1.

< overall Structure >

In the electrochemical hydrogen pump 46, since it is necessary to accumulate high-pressure hydrogen on the cathode side, the following problems occur. That is, as the pressure of hydrogen filled in the flow channel grooves 8a of the cathode separator 8 and the gaps of the cathode diffusion layer 6 increases, the center portions of the cathode end plate 14, the cathode insulating plate 12, and the cathode separator 8 are displaced upward in fig. 11 (direction Y1). The center portions of the electrolyte membrane 2, the anode diffusion layer 5, the anode separator 7, the anode insulating plate 11, and the anode end plate 13 are displaced downward in fig. 11 (Y2 direction).

due to these displacements, the contact surface pressures near the centers of the cathode diffusion layer 6 and the cathode electrode layer 4 and the cathode diffusion layer 6 and the cathode separator 8 are lower than the surroundings, so the contact resistance increases, and the voltage rises. As a result, there is a problem that the performance of the electrochemical hydrogen pump is degraded.

as shown in fig. 10, the evaluation results of the electrochemical hydrogen pump 23 in patent document 1 and the electrochemical hydrogen pump 24 in embodiment 1 are considered to be caused by a sudden increase in the voltage ratio from the pressure ratio of 0.6 to the pressure ratio of 1.0.

In general, the plate thickness of the cathode end plate 14 and the anode end plate 13 is increased to increase the rigidity so that the displacement does not affect the performance. However, this measure has a problem that the weight of the member is extremely heavy and it is difficult to handle the respective members.

Therefore, in the electrochemical hydrogen pump 46 according to embodiment 2, the cathode diffusion layer 6 is formed to have a larger thickness as it approaches the center.

The thickness of the outer peripheral portion of the cathode diffusion layer 6 was t1, and the thickness of the central portion was t4(t1 < t 4). t4 is for example 1.05 times t 1. By so doing, the contact surface pressure of the cathode diffusion layer 6 and the cathode electrode layer 4, and the cathode diffusion layer 6 and the cathode separator 8 becomes large at the central portion of the cathode diffusion layer 6.

Therefore, even if the pressure of hydrogen on the cathode side increases and the members shift in the Y1 direction and the Y2 direction, the contact surface pressures of the cathode diffusion layer 6 and the cathode separator 8, and the cathode diffusion layer 6 and the cathode electrode layer 4 can be set to be almost equal in the outer peripheral portion and the central portion of the cathode diffusion layer 6. Therefore, the performance of the electrochemical hydrogen pump 46 is not degraded. That is, the performance of the electrochemical hydrogen pump 46 can be suppressed from being degraded without increasing the thicknesses of the cathode end plate 14 and the anode end plate 13.

< evaluation >

Fig. 10 c shows the evaluation results of the electrochemical hydrogen pump 46 in embodiment 2.

As shown in fig. 10, although the electrochemical hydrogen pump 46 of embodiment 2 has some voltage ratio rise throughout the entire region of the pressure ratio of 0.05 to 1.0, no sharp increase in the voltage ratio is seen.

This is considered because, as compared with embodiment 1, even if the pressure of hydrogen on the cathode side rises, a decrease in the contact surface pressure of the cathode diffusion layer 6 and the cathode separator 8, and the cathode diffusion layer 6 and the cathode electrode layer 4 is suppressed.

That is, in the electrochemical hydrogen pump 46 according to embodiment 2, it is not necessary to increase the plate thickness of the cathode end plate 14 and the anode end plate 13.

(example 3)

fig. 12 is a longitudinal sectional view of an electrochemical hydrogen pump 46 according to embodiment 3. Fig. 12 shows the assembled state. Fig. 13 is a longitudinal sectional view of an electrochemical hydrogen pump of a comparative example.

< overall Structure >

in embodiment 1, as shown in fig. 5, the side surface 25B (fig. 8B) of the recess of the anode separator 7 and the outer peripheral surface 5a (fig. 8A) of the anode diffusion layer 5 are prepared so as to be in close contact with each other. However, due to variations in the production of the anode separator 7 and the anode diffusion layer 5, as shown in fig. 13, an anode-side gap 321 may be formed between the side surface 25b of the recess of the anode separator 7 and the outer peripheral surface 5a of the anode diffusion layer 5 on the electrolyte membrane 2 side. If such an anode-side gap 321 is formed, the electrolyte membrane 2 may hang down to the anode-side gap 321 as the pressure of hydrogen on the cathode side increases, and eventually the electrolyte membrane 2 may be damaged.

Therefore, as shown in fig. 12, in the electrochemical hydrogen pump 46 according to embodiment 3, the side surface 25b of the recessed portion 25 of the anode separator 7 and the outer peripheral surface 5a of the anode diffusion layer 5 are inclined with respect to the compression direction, so that an anode-side gap 421 is formed on the opposite side of the electrolyte membrane 2 in the vicinity of the contact portion between the side surface 25b of the recessed portion of the anode separator 7 and the outer peripheral surface 5a of the anode diffusion layer 5.

By doing so, the outer peripheral surface 5a of the anode diffusion layer 5 on the electrolyte membrane 2 side is reliably brought into close contact with the side surface 25b of the concave portion 25 of the anode separator 7 at the ridge of the anode diffusion layer 5 on the electrolyte membrane 2 side. With this configuration, even if there is variation in production, the outer peripheral surface 5a of the anode diffusion layer 5 can be reliably brought into close contact with the side surface 25b of the recess of the anode separator 7 on the electrolyte membrane 2 side, and therefore, even if the hydrogen pressure on the cathode side becomes high, the risk of the electrolyte membrane 2 sagging into the gap and being damaged can be avoided.

< evaluation >

Fig. 10 e shows the evaluation results of the electrochemical hydrogen pump 46 in embodiment 3.

As shown in fig. 10, as the pressure ratio approaches 1, the voltage of the electrochemical hydrogen pump 46 in embodiment 3 becomes higher than that of the electrochemical hydrogen pump 46 in embodiment 2. This is considered because the contact resistance of the electrolyte membrane 2 and the cathode diffusion layer 6 increases by the electrolyte membrane 2 pressing the anode diffusion layer 5 in the opposite direction of the electrolyte membrane 2 as the pressure of hydrogen of the cathode becomes higher, whereby the anode diffusion layer 5 is slightly dented. However, this voltage rise is extremely small, and there is no practical problem in view.

the electrochemical hydrogen pump of the present invention has the following features.

The anode diffusion layer 5 is substantially in the shape of a circular disk, but in a state where no external force is applied, the anode diffusion layer 5 has a shape in which the center portion of the circle protrudes in an pattern.

The cathode diffusion layer 6 is substantially disc-shaped, but in a state where no external force is applied, the cathode diffusion layer 6 is shaped such that the vicinity of the center protrudes in the opposite direction in the pattern after protruding in the thickness direction from the end portion toward the center portion of the circle. The center -shaped apex is located at a lower height than the outer peripheral portion.

The anode separator 7 is substantially disc-shaped. The surface in contact with the anode diffusion layer 5 has a recess 25 for accommodating the anode diffusion layer 5. The depth of the recess 25 is not constant, and the bottom surface 25a is an -shaped curved surface protruding at the center.

The cathode separator 8 is substantially disc-shaped. The surface in contact with the cathode diffusion layer 6 has a recess 27 for accommodating the cathode diffusion layer 6. The depth of the recess 27 is not constant, and the bottom surface 27a is an -shaped curved surface with a depressed central portion.

The area of the curved surface 29 of the anode diffusion layer 5 in contact with the anode separator 7 is larger than the area of the bottom surface 25a of the recess 25 of the anode separator 7 before the flow path groove 7a is machined.

The area of the curved surface 30 of the cathode diffusion layer 6 in contact with the cathode separator 8 is larger than the area of the bottom surface 27a of the recess 27 of the cathode separator 8 before the flow channel groove 8a is machined.

Further, the thickness of the anode diffusion layer 5 or the cathode diffusion layer 6 increases from the outer peripheral portion to the center.

an anode-side gap 421 is provided on the opposite side of the electrolyte membrane 2 in the vicinity of the contact portion between the side surface 25b of the recess 25 of the anode separator and the outer peripheral surface 5a of the anode diffusion layer 5.

According to the above feature, no gap is generated between the anode diffusion layer 5 and the anode separator 7 and between the cathode diffusion layer 6 and the cathode separator 8, and the electrolyte membrane 2 is not exposed to hydrogen. Therefore, the performance degradation of the electrochemical hydrogen pump caused by the concentration diffusion of hydrogen from the high-pressure side to the low-pressure side is suppressed.

further, even if the pressure of hydrogen on the cathode side rises, a decrease in the contact surface pressure of the cathode diffusion layer 6 and the cathode separator 8 and the contact surface pressure of the cathode diffusion layer 6 and the cathode electrode layer 4 is suppressed. Therefore, the electrochemical hydrogen pump of the present invention is most suitable as a hydrogen compressor for a small-sized hydrogen filling device for home use.

[ Industrial Applicability ]

The electrochemical hydrogen pump of the present invention can be used as a hydrogen compression device for a hydrogen filling device. Furthermore, the structure of the electrochemical hydrogen pump of the present invention can also be used as an electrochemical water electrolysis apparatus that electrolyzes water to produce hydrogen and oxygen.

Claims

1. an electrochemical pump is provided, which comprises a pump body,

an anode separator, an anode diffusion layer, an electrolyte membrane, a cathode diffusion layer, and a cathode separator are sequentially laminated,

the anode separator has a first recess for accommodating the anode diffusion layer, the bottom surface of the first recess is an -shaped curved surface protruding from the center,

the cathode separator has a second recess for accommodating the cathode diffusion layer, and the bottom surface of the second recess is an -shaped curved surface with a depressed central portion.

2. The electrochemical pump of claim 1,

the first concave part is provided with a flow channel for gas to flow,

The second recess has a flow channel through which gas flows.

3. The electrochemical pump of claim 1,

The anode diffusion layer is disposed in the first concave portion in a pressurized state,

The cathode diffusion layer is disposed in the second recess under a pressurized state.

4. The electrochemical pump of claim 1,

The anode diffusion layer is shaped so that the central portion thereof protrudes in an -shape when no external force is applied,

The cathode diffusion layer is shaped to protrude in a thickness direction from the outer peripheral portion toward the central portion and protrude in an opposite direction toward the central portion in an -type shape in a state where no external force is applied.

5. the electrochemical pump of claim 2,

an area of a curved surface of the anode diffusion layer in contact with the anode separator is larger than an area of the curved surface of the anode separator before the flow channel groove is processed in a state where no external force is applied to the anode diffusion layer,

In a state where no external force is applied to the cathode diffusion layer, an area of a curved surface of the cathode diffusion layer in contact with the cathode separator is larger than an area of the curved surface of the cathode separator before the flow channel groove is machined.

6. The electrochemical pump of claim 1,

The anode diffusion layer or the cathode diffusion layer has a thickness that increases from the outer peripheral portion to the central portion.

7. An electrochemical pump in which, in the case of a pump,

Comprising:

An electrolyte membrane;

A pair of plate-like diffusion layers disposed adjacent to both surfaces of the electrolyte membrane; and

A pair of separators that have a recess portion that accommodates one of the diffusion layers and that press the diffusion layer accommodated in the recess portion toward the electrolyte membrane;

a diameter of the diffusion layer is smaller than a diameter of the recess in a state where the diffusion layer is not pressurized by the spacer, the diameter of the diffusion layer is equal to the diameter of the recess in a state where the diffusion layer is pressurized by the spacer,

The height of the diffusion layer in a state of being pressurized by the spacer is lower than the height of the diffusion layer in a state of not being pressurized by the spacer.

8. The electrochemical pump of claim 7,

the diffusion layer has a central portion thicker than an outer peripheral portion thereof in a state of being pressurized by the separator.

9. The electrochemical pump of claim 1,

The side surface of the first recess of the anode separator and the side surface of the anode diffusion layer are inclined with respect to the stacking direction so that a space can be formed on the side opposite to the electrolyte membrane at the contact portion between the anode separator and the side surface of the anode diffusion layer.