JPH05242850A - Electrochemical gas compressor - Google Patents

Abstract

PURPOSE:To laminate alternately proton electroconductive films and gas diffusive electrodes bearing catalyst, construct a plurality of unitary cells consolidatedly, putting in a gas capable of ionizing. and thereby acquiring a compressed gas. CONSTITUTION:A gas capable of ionizing is put in a battery formed by laying gas diffusive electrodes 2, 3 bearing catalyst on both sides of a proton electroconductive film 1, and a specified potential is given to the two electrodes 2, 3. Thereby gas is ionized on one of the electrodes 2 and moves with the electroconductive film 1 as ions to return to gas on the counter-electrode 3, and thereby gas compressed on the counter-electrode 3 side is obtained. Between the electrodes 2, 3, electroconductive films 1, 11, 12 and gas diffusive electrodes 8, 18 are laminated alternately, and three unitary cells are structured solidly. This provides the resultant device with mechanical reliability, excellent electric characteristics, and the capability of emitting a large output from its light and compact construction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrochemical gas compressor for compressing gas by utilizing an electrochemical reaction.

[0002]

2. Description of the Related Art Conventional gas compressors compress gas by sealing the gas in a space and reducing the volume of the space with mechanical movement. In such a compressor, vibration and mechanical deterioration due to mechanical movement have been problems. Therefore, an electrochemical gas compressor using an ion conductive film has been proposed as a compressor that does not use mechanical parts. For example, FIG. 7 shows US Pat.
It is a figure which expands and shows the cross section of the conventional electrochemical hydrogen compressor disclosed by No. 71080. In the figure, 1 is about 0.
An ion conductive film having a thickness of 2 mm, 2 is a gas diffusion electrode of an anode carrying a catalyst such as platinum, 3 is a gas diffusion electrode of a cathode carrying a similar catalyst, 4 is a gas flow path on the anode side, 5
Is a gas flow path on the cathode side, 6 is a metal current collector on the anode side, and 7 is a metal current collector on the cathode side.

Next, the operation will be described. The hydrogen gas that has entered the gas flow path 4 on the gas diffusion electrode 2 side loses electrons on the gas diffusion electrode 2 and produces hydrogen ions according to the following chemical formula 1. H ₂ + 2H ₂ O → 2e ~ + 2H ₃ O ⁺

The hydrogen ions accompany the water in the ion conductive film 1 and travel to the other gas diffusion electrode 3 with a voltage as a driving force,
Electrons are received on the gas diffusion electrode 3 and returned to hydrogen gas according to the following Chemical formula 2. 2e ~ + 2H ₃ O ⁺ → H ₂ + 2H ₂ O

Since the hydrogen gas generated on the gas diffusion electrode 3 cannot pass through the ion conductive film 1 and the moving force of the ions due to the voltage is large, the hydrogen gas gradually flows toward the gas diffusion electrode 3 side. The pressure of hydrogen gas is accumulated and rises. At this time, the metal current collectors 6 and 7 are connected to the gas diffusion electrodes 2 and
A voltage is applied to 3 and the gas diffusion electrodes 2 and 3 and the ion conductive film 1 are mechanically reinforced.

[0006]

The conventional electrochemical hydrogen compressor is constructed as described above, and the voltage applied between the gas diffusion electrodes 2 and 3 is given by the following formula 1. E = E ₀ + (RT / 2F) × ln (P ₂ / P ₁ ) + ir

However, in _equation 1, E ₀ is the ionization potential of hydrogen, R is the gas constant, T is the temperature, F is the Faraday constant,
P ₁ is the hydrogen pressure on the gas diffusion electrode 2 side, P ₂ is the hydrogen pressure on the gas diffusion electrode 3 side, i is the current, and r is the electrical resistance.

Looking at the breakdown of the voltages applied to the both electrodes 2 and 3, the ionization potential E0 of the first term on the right side is 0.
02V, the second term is the so-called Nernst applied voltage, which is determined by the gas pressure of both electrodes 2, 3, but the gas pressure is 1
It is 0.06V even when compressed to 00 atm. However, the resistance of the third term is as large as 0.1 V even at a current of about 400 mA / cm ² , and accounts for 55% of the total voltage. That is, there is a problem that the voltage efficiency of this compressor is extremely small because the electric resistance of the ion conductive film 4 is large. The resistance of the ion conductive film 4 is about 0.2 mm.
However, in order to reduce the electric resistance of the ion conductive film 4, the film thickness may be reduced. However, if the film thickness is reduced, the mechanical strength of the ion conductive film 4 is reduced.
With a film thickness of 1, the film can withstand a pressure difference of 100 atm, but at a film thickness of 0.025 mm, it can withstand a pressure difference of 20 atm, and with a film thickness of 0.13 mm, it can withstand a pressure difference of about 7 atm. Therefore, in the conventional electrochemical hydrogen gas compressor, there is a problem that the mechanical reliability is deteriorated when the electrical characteristics are increased.

Further, in the conventional electrochemical hydrogen gas compressor, in order to maintain the ionic conductivity of the ionic conductive film 4, the ionic conductive film 4 needs to have a sufficient amount of water, but the hydrogen ion is a film. When moving inside, the water moves together with the water as described above, so it is necessary to replenish the water on the positive electrode 2. However, when the current is small, the water on the negative electrode 3 flows back through the membrane 4 by diffusion and returns to the positive electrode 2. However, if water is not separately supplied, it is difficult to continuously flow a large current. there were.

The present invention has been made to solve the above problems, and is an electrochemical gas compression system which has mechanical reliability and excellent electrical characteristics, and is lightweight, compact and capable of obtaining a large output. The purpose is to provide a machine.

[0011]

A first aspect of the present invention has a structure in which a plurality of unit cells are integrated by alternately laminating a plurality of ion conductive solid electrolyte bodies and gas diffusion electrodes between both gas diffusion electrodes. Is.

A second aspect of the invention is the provision of a moisture replenishing passage for replenishing moisture to the gas diffusion electrodes located between the individual cells in the first aspect of the invention.

According to a third aspect of the present invention, an external electric circuit is connected to the gas diffusion electrodes located between the unit cells of the first or second aspect of the invention to make the voltage applied to each of the unit cells variable. It was done.

A fourth aspect of the present invention is an ion-conductive solid electrolyte body integrally provided with a reinforcing body.

A fifth aspect of the invention is to provide the reinforcing body of the fourth aspect with a moisture replenishing passage for replenishing moisture.

[0016]

According to the first invention, the ion conductive solid electrolyte body is mechanically reinforced by the gas diffusion electrodes interposed between the individual cells, and the ion conductive solid electrolyte body is filled with the water contained in each electrode. Can retain the water content of.

According to the second aspect of the invention, water is directly replenished from the water replenishment path to the gas diffusion electrodes located between the individual cells to keep these electrodes always in a wet state and at the same time through the gas diffusion electrodes. This water can be replenished to the ion conductive solid electrolyte body.

According to the third invention, a voltage suitable for the gas pressure at the time of compression of the gas compressor can be applied to each unit cell.

According to the fourth aspect of the invention, the mechanical strength of the unit cell can be reinforced by the reinforcing body integrated with the ion conductive solid electrolyte body.

According to the fifth aspect, it is possible to directly replenish water from the water replenishing passage to the reinforcing body to retain the water in the ion conductive solid electrolyte body.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the embodiments shown in FIGS.

Example 1. As shown in FIG. 1, the electrochemical gas compressor of this embodiment is a gas in which a conventionally known catalyst such as platinum is carried on both sides of a conventionally known ion conductive solid electrolyte body (proton conductive membrane) 1. Ionizable hydrogen gas is charged into a battery having diffusion electrodes 2 and 3 to give a predetermined potential to both gas diffusion electrodes 2 and 3, so that the charged gas is on one gas diffusion electrode 2. It is configured so that the compressed gas can be obtained on the side of the other gas diffusion electrode 3 by being ionized by moving in the proton conductive membrane 1 as ions and returning to the gas on the other gas diffusion electrode 3. There is. The gas diffusion electrode 2 constitutes an anode and the gas diffusion electrode 3 constitutes a cathode, and the metal current collector 6 in which the gas flow paths 4 and 5 of hydrogen gas are formed on the outer surfaces of the gas diffusion electrodes 2 and 3, respectively. , 7 are provided as in the conventional case.

Thus, the electrochemical gas compressor has three proton conductive membranes 1 between the gas diffusion electrodes 2 and 3.
11 and 12 and the two gas diffusion electrodes 8 and 18 are alternately pressure-bonded and laminated to form three unit cells, and these three unit cells are integrally configured. Then, the gas diffusion electrodes 8 and 18 interposed between the gas diffusion electrodes 2 and 3
Are shared by the cells above and below each. Further, spacers 9 are formed around the gas diffusion electrode 8 at the peripheral portions of the proton conductive membranes 1 and 11 so as to form grooves. Similarly, the spacer 9 is provided around the gas diffusion electrode 18.

Next, the operation of the electrochemical gas compressor will be described. First, the hydrogen gas flowing into the gas flow path 4 loses its electrons and is ionized on the gas diffusion electrode 2 as shown in the following Chemical Formula 3 to generate hydrogen ions. H ₂ + 2H ₂ O → 2e ~ + 2H ₃ O ⁺

The hydrogen ions travel to the gas diffusion electrode 8 with the voltage in the proton conductive film 1 as a driving force with the water, receive the electrons on the gas diffusion electrode 8 and return to the gas according to the following chemical formula 4. 2e ~ + 2H ₃ O ⁺ → H ₂ + 2H ₂ O

The hydrogen returned to the gas on the gas diffusion electrode 8 again loses electrons near the proton conductive film 11 on the gas diffusion electrode 8 to generate hydrogen ions, and the proton conductive film 11 is hydronium. It moves to the gas diffusion electrode 18 as ions, receives electrons again on the gas diffusion electrode 18, and returns to hydrogen gas. Further, in the vicinity of the proton conductive film 12, electrons are again lost to generate hydrogen ions, and the proton conductive film 12 is used as hydronium ions to form the gas diffusion electrode 3
It moves to and receives electrons on the gas diffusion electrode 3 to become hydrogen gas. Thus, the hydrogen gas is gradually accumulated on the side of the gas diffusion electrode 3 which is the cathode, and the hydrogen gas is gradually compressed.

Therefore, according to the first embodiment, since the gas diffusion electrodes 8 and 18 are interposed between the proton conductive membranes 1, 11 and 12, these proton conductive membranes 1 and 11 are formed by these electrodes 8 and 18. , 12 can be mechanically reinforced, and the mechanical reliability of the electrochemical gas compressor can be improved. Further, the film thickness of each of the proton conductive membranes 1, 11, 12 whose mechanical strength is reinforced in this way can be made thin, and each of the water moving from the gas diffusion electrodes 2, 8, 18 can be made thin. The diffusive force in the membranes 1, 11, 12 can be significantly improved to improve the electrical properties of the electrochemical gas compressor.

In the above electrochemical gas compressor, the voltage E applied between the gas diffusion electrodes 2 and 3 is given by the following equation 2. E = E ₀ × 3 + (RT / 2F) × ln (P ₂ / P ₁ ) + i
r

Comparing the applied voltage of the electrochemical gas compressor of this embodiment with that of the conventional one, the Nernst addition of the second term on the right-hand side of the above equation 1 showing the applied voltage of the electrochemical gas compressor of this embodiment is shown. The voltage is 0.06V, which is not different from the conventional Nernst applied voltage, but the ionization potential E ₀ of the first term on the right side is
Is 0.06V, which is three times that of conventional cells. Regarding the resistance of the third term, the film thickness of each of the proton conductive films 1, 11 and 12 can be made thinner as described above, and the total thickness can be made thinner than the conventional film thickness. Further, as described above, moisture is sufficiently supplied to each of these films 1, 11 and 12 by diffusion thereof, so that the resistance of each film itself becomes small and the total applied voltage is made small to improve the electrical characteristics. Can be made

As described above, according to the first embodiment, there is provided an electrochemical gas compressor which has mechanical reliability and excellent electrical characteristics, and which is lightweight and compact and can obtain a large output. can do.

Example 2. In the electrochemical gas compressor of this embodiment, as shown in FIGS. 2 and 3, two water supply paths 20 and 21 are provided in the metal current collector 7 of the electrochemical gas compressor of the first embodiment. ing. The holes 11A and 12 are formed in the proton conductive membranes 11 and 12 and the spacers 9 and 9, respectively.
A, 12B and 9A, 9A, 9B are provided respectively,
These holes 11A, 12A, 12B and 9A, 9A, 9
Water from each of the water supply passages 20 and 21 is supplied via B to the gas diffusion electrodes 8 and 18, respectively. That is, water is supplied to the gas diffusion electrode 8 from one of the water supply paths 20 and to the gas diffusion electrode 18 from the other water supply path 21. Others are the same as in the first embodiment.

Therefore, also in the second embodiment, the hydrogen gas can be compressed in the same manner as in the first embodiment. Therefore, only replenishment of water will be described here. In Example 2, each proton conductive film 1, 11,
Water on the anode side of 12 moves to the cathode side. At this time, if the diffusion of water in the proton conductive membranes 1, 11, 12 is not sufficient, the surface of the proton conductive membranes 1, 11, 12 on the anode side tends to be dried. Therefore, when water is replenished from the water replenishment path 20, the replenished water passes through the holes 12A of the proton conductive membrane 12, the holes 9A of the spacer 9 and the holes 11A of the proton conductive membrane 11 as shown by the solid line in FIG. Then, it reaches the groove inside from the hole 9A of the spacer 9 and penetrates into the gas diffusion electrode 8 in this groove. The permeated water moistens the dried anode side surface of the proton conductive membrane 11 through the gas diffusion electrode 8,
The decrease in ionic conductivity of the proton conductive film 11 is prevented. Further, when water is replenished from the water replenishing passage 21, this replenishing water passes through the hole 12B of the proton conductive membrane 12 and the hole 9B of the spacer 9 into the groove inside the spacer 9 as shown by the solid line in FIG. Reaches the gas diffusion electrode 18 in this groove, and also prevents the ionic conductivity of the proton conductive membrane 12 from decreasing, and further improves the electrical characteristics as compared with the electrochemical gas compressor of the first embodiment. However, a large amount of hydrogen gas can be compressed.

In the second embodiment, when replenishing water, a pump may be installed outside to replenish the water. However, the water inlet and the gas outlet 5 on the high pressure side 5
May be connected via a valve to utilize the compressed pressure to replenish the water. This also applies to Example 5 described later.

Example 3. As shown in FIG. 4, the electrochemical gas compressor of this embodiment has the gas diffusion electrodes 8 and 18 of the electrochemical gas compressor of the first or second embodiment.
The external electric circuit 30 is connected to the variable electric circuit to change the voltage applied to each unit cell. The electric circuit 30 includes a lead wire 31 connected to the gas diffusion electrode 2 serving as an anode, a lead wire 32 connected to the gas diffusion electrode 3 serving as a cathode, and the gas diffusion electrodes 2 and 3 via the lead wires 31 and 32. Directly connected DC power source 33, conductive wire 34 connected to gas diffusion electrode 8, and gas diffusion electrodes 2, 8 via conductive wires 31, 34
A DC power source 35 connected to the gas diffusion electrodes 18, and a DC wire 37 connected to the gas diffusion electrode 18, and a DC power source 37 connected to the gas diffusion electrodes 2 and 18 via the wires 31 and 36, respectively.
Is equipped with.

Therefore, also in the third embodiment, the hydrogen gas can be compressed in the same manner as in the first embodiment, and therefore the case where the applied voltage to each unit cell is changed will be described. When hydrogen gas is caused to flow through the gas diffusion electrode 2 and a voltage is applied from the DC power supply 33 between the gas diffusion electrodes 2 and 3, hydrogen gas is generated in the first embodiment.
As described above, the gas flows out in a compressed state on the gas diffusion electrode 3. At this time, the applied voltage between the gas diffusion electrodes 2 and 8 and between the gas diffusion electrodes 8 and 18 depends on the gas pressure at that time. fluctuate. At this time, if the voltage between the gas diffusion electrodes is arbitrarily set, while the current is flowing through the conductors 34 and 36,
The amount of hydrogen gas accumulated in the holes of the gas diffusion electrodes 8 and 18 increases and decreases, the gas pressure fluctuates, and the Nernst voltage between the electrodes changes. When the pressure distribution corresponding to the Nernst voltage corresponding to the set voltage is reached, the lead wire 34,
The current flowing through 36 stops, and the pressure distribution is in accordance with the set voltage. Therefore, according to this embodiment, by appropriately setting the voltage applied between the gas diffusion electrodes, it is possible to maximize the performance of each cell and realize efficient gas compression.

Example 4. In the unit cell constituting the electrochemical gas compressor of this example, as shown in FIG. 5, a reinforcing body 40 was inserted into the inside of the proton conductive membrane 1 in the electrochemical gas compressor to be integrated. It is a thing. The reinforcing body 40 is not particularly limited as long as it is a material that has mechanical strength, can induce water, and does not release metal ions, and its form is mesh, fibrous, porous, or hollow structure. Etc., but is not limited to these. The material of the reinforcing body 40 may be an organic material or an inorganic material. Examples of the organic material include synthetic fibers such as polyester and polyethylene, and natural fibers such as hemp and cotton. Fibers can be mentioned, and the inorganic material may be any of metal and nonmetal as long as it has hydrophilicity, for example,
Inorganic fibers such as carbon fibers can be used. Of course,
The reinforcing member 40 of this embodiment can be applied to each of the above embodiments and the conventional electrochemical gas compressor.

Therefore, according to the fourth embodiment, hydrogen gas can be compressed by the same action as that of the electrochemical gas compressor of the first embodiment, and the proton conductive membrane 1 is reinforced by the reinforcing member 40. Therefore, the mechanical strength of the unit cell can be reinforced in a lightweight and compact form, and its mechanical reliability and electrical characteristics can be further improved.

Example 5. As shown in FIG. 6, the electrochemical gas compressor of this embodiment has a metal collector 7 of the electrochemical gas compressor of Embodiment 5 and a reinforcing member 4 of the proton conductive membrane 1.
A water supply path 41 for supplying water to 0 is provided.

Therefore, only the replenishment of water in Example 5 will be described. As the hydrogen ions move, the water on the anode side of the proton conductive membrane 1 moves to the cathode side. At this time, if the diffusion of water in the proton conductive membrane 1 is not sufficient,
The surface of the proton conductive film 1 on the anode side tends to be dried. Therefore, when water is replenished from the water replenishing passage 41, the replenishing water permeates the reinforcing body 41. The permeated water moistens the dry surface of the proton conductive membrane 1 on the side of the anode, reaches the surface of the gas diffusion electrode 2 which is the anode, and prevents the deterioration of the ionic conductivity, thereby performing the electrochemical gas compression of Example 4. The electric characteristics of the machine can be further improved.

It should be noted that the present invention is not limited to the above embodiments, and the number of stacked proton conductive membranes and gas diffusion electrodes is appropriately changed depending on the capacity of the electrochemical gas compressor. can do.

[0041]

According to the first aspect of the invention, since a plurality of unit cells are integrated, an electrochemical having mechanical reliability and excellent electrical characteristics, and being lightweight and compact and capable of obtaining a large output. A dynamic gas compressor can be provided.

According to the second aspect of the present invention, the gas diffusion electrode of the electrochemical gas compressor according to the first aspect of the present invention is provided with the water supply path for supplying water, so that the electrical characteristics are further improved and a large flow rate of hydrogen gas is obtained. It is possible to provide an electrochemical gas compressor capable of compressing.

According to the third aspect of the invention, since the external electric circuit is connected to the gas diffusion electrodes located between the unit cells and the voltage applied to each unit cell is made variable, the voltage applied between the gas diffusion electrodes is changed. By appropriately setting, it is possible to provide an electrochemical gas compressor capable of realizing efficient gas compression, in which the performance of each unit cell is maximized.

According to the fourth aspect of the invention, since the reinforcing body is integrated with the ion conductive solid electrolyte body, it has mechanical reliability and excellent electrical characteristics, and it is lightweight and compact, and a large output can be obtained. An electrochemical gas compressor capable of being provided can be provided.

According to the fifth aspect of the invention, since the moisture replenishing path for replenishing moisture is provided in the reinforcing body of the electrochemical gas compressor of the fourth aspect of the invention, the electrical characteristics are further improved and a large flow rate of hydrogen gas is provided. It is possible to provide an electrochemical gas compressor capable of compressing.

[Brief description of drawings]

FIG. 1 is a sectional view showing an electrochemical gas compressor according to an embodiment of the first invention.

FIG. 2 is a sectional view showing an electrochemical gas compressor according to an embodiment of the second invention.

3 is an exploded perspective view of the electrochemical gas compressor shown in FIG. 2. FIG.

FIG. 4 is a diagram showing an electric circuit of an electrochemical gas compressor according to an embodiment of the third invention.

FIG. 5 is a sectional view showing a main part of an electrochemical gas compressor according to an embodiment of the fourth invention.

FIG. 6 is a sectional view showing an electrochemical gas compressor according to an embodiment of the fifth invention.

FIG. 7 is a sectional view showing an example of a conventional electrochemical gas compressor.

[Explanation of symbols]

 1 Proton Conductive Membrane (Ionic Conductive Solid Electrolyte) 2 Lower Gas Diffusion Electrode (Anode) 3 Upper Gas Diffusion Electrode (Cathode) 8 Gas Diffusion Electrode 11 Proton Conductive Membrane (Ionic Conductive Solid Electrolyte) 12 Proton Conductive Membrane (Ionic Conductive Solid Electrolyte) 18 Gas Diffusion Electrode 20 Moisture Supply Path 21 Moisture Supply Path 30 Electric Circuit 40 Reinforcement Body 41 Moisture Supply Path

Claims (5)

[Claims] 1. A battery comprising a gas diffusion electrode carrying a catalyst on each side of an ion conductive solid electrolyte body,
By inputting an ionizable gas and applying a predetermined potential to both gas diffusion electrodes, the introduced gas is ionized on one gas diffusion electrode and moves the ion conductive solid electrolyte body as ions, and the other In an electrochemical gas compressor capable of obtaining a compressed gas on the side of the other gas diffusion electrode by returning to the gas on the gas diffusion electrode, an ion conductive solid electrolyte body and a gas are provided between the gas diffusion electrodes. An electrochemical gas compressor comprising a plurality of unit cells integrally formed by alternately stacking a plurality of diffusion electrodes. 2. The electrochemical gas compressor according to claim 1, wherein a moisture replenishment path for replenishing moisture is provided to the gas diffusion electrodes located between the respective unit cells. 3. The electrochemical according to claim 1 or 2, wherein an external electric circuit is connected to the gas diffusion electrodes located between the respective unit cells, and the voltage applied to each unit cell is made variable. Gas compressor. 4. A battery comprising a gas diffusion electrode carrying a catalyst on each side of an ion conductive solid electrolyte body,
By inputting an ionizable gas and applying a predetermined potential to both gas diffusion electrodes, the introduced gas is ionized on one gas diffusion electrode and moves the ion conductive solid electrolyte body as ions, and the other In the electrochemical gas compressor capable of obtaining the compressed gas on the other gas diffusion electrode side by returning to the gas on the gas diffusion electrode, a reinforcing body is integrally provided on the ion conductive solid electrolyte body. An electrochemical gas compressor characterized by the following. 5. The electrochemical gas compressor according to claim 4, wherein a water supply path for supplying water to the reinforcing body is provided.