JP4124914B2 - Electrolytic cell - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to an electrolytic cell using a solid polymer electrolyte, and particularly to an electrolytic cell suitable for water electrolysis.
[0002]
[Prior art]
Various types of water electrolyzers are known, but electrolyzers using solid polymer electrolytes perform electrolysis utilizing the permeation of protons or oxygen ions etc. of the solid polymer electrolyte membrane. Thus, electrolysis can be performed only by supplying water without using a liquid electrolyte such as acid or alkali.
[0003]
In water electrolyzers using solid polymer electrolytes, catalytic electrodes are bonded to both sides of the cation exchange membrane. For this reason, the distance between the anode and the cathode is small, and the solid polymer electrolyte Since there is no air bubble between them and the electrode, it is possible to energize at a low voltage and a large current density, and since the conductivity by the electrolyte is not utilized, As water, high-purity water having extremely low conductivity can be used, and high-purity hydrogen and oxygen can be obtained.
[0004]
However, joining of the electrode to the solid polymer electrolyte membrane is performed by chemical plating or integration using a fluororesin or the like, but it is necessary to form an electrode with a stable and large area. It was difficult to obtain a large electrolytic cell having a large electrode area.
[0005]
Therefore, in order to easily manufacture an electrolytic cell having a large electrode area, an electrode prepared separately from the solid polymer electrolyte is not bonded to the solid polymer electrolyte membrane without directly joining the anode and the cathode to the solid polymer electrolyte membrane. An electrolytic cell in which both surfaces are in close contact with each other has been proposed.
For example, FIG. 6 shows an electrolytic cell in which electrodes are laminated and adhered to both surfaces of a solid polymer electrolyte. 6A is a front view of the solid polymer electrolytic cell, and FIG. 6B shows a cross-sectional view taken along line AA in FIG. 6A. A large number of solid polymer electrolytes 41, anodes 42, cathodes 43, and bipolar plates 44 are stacked, and end plates 45 and 46 are fastened by a number of fastening bolts 47. However, in such an electrolytic cell, when the electrode area becomes large, it is inevitable that the end plate surface is distorted, and when the number of layers increases, an electrode with non-uniform contact is generated, and the solid polymer electrolyte membrane The poor contact between 41 and the anode 42 and the cathode 43, the non-uniformity of the energization current at the time of electrolysis, and the degradation of the solid polymer electrolyte and the electrode due to the occurrence of the current concentration, or the electrolysis This is not preferable because the voltage rises.
[0006]
In addition, in order to prevent such non-uniform contact between the solid polymer electrolyte membrane and the electrode, a pressing screw member is attached to a part of the end plate, and the laminate is pressed to cause non-uniformity. Although it has been proposed to prevent the occurrence (Japanese Patent Laid-Open No. 6-184873), in an electrolytic cell in which a large number of solid polymer electrolyte membranes and electrodes are laminated, an extremely large screw member for pressing is required, The effect was not satisfactory.
[0007]
[Problems to be solved by the invention]
It is an object of the present invention to provide an electrolytic cell having a large electrolytic area using a solid polymer electrolyte membrane, which forms a uniform contact between the solid polymer electrolyte membrane and an electrode and An object of the present invention is to provide an electrolytic cell that is enhanced and has excellent electrolytic performance.
[0008]
[Means for Solving the Problems]
The present invention relates to an electrolytic cell in which a unit electrolytic cell in which an anode and a cathode are disposed via a solid polymer electrolyte membrane is laminated, and an anode chamber in which the anode and the cathode are disposed via the solid polymer electrolyte membrane and the anode is disposed. A plurality of unit cell tanks each comprising an anode chamber partition wall and a cathode chamber partition wall partitioning a cathode chamber in which a cathode is disposed are electrically conductive elastic bodies in an intermediate frame provided between the anode chamber partition wall and the cathode chamber partition wall. It is the electrolytic cell which laminated | stacked by interposing.
Also, a cathode chamber end plate and a cathode side end plate in which a cathode chamber partition wall, an anode chamber partition wall, and an intermediate frame body, in which conduits are formed, are laminated, and supply conduits and product conduits are provided on both end faces of the laminate. The electrolytic cell is held by holding means that holds the anode-side end plate and the cathode-side end plate in a state where the distance between the anode-side end plate and the cathode-side end plate can be expanded and contracted.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
The present invention will be described below with reference to the drawings.
FIG. 1 is a diagram for explaining an electrolytic cell of the present invention, and shows a state in which two unit electrolytic cells are laminated.
The unit cell 1 has a porous anode 3 and a cathode 4 in close contact with the solid polymer electrolyte membrane 2, and the anode chamber partition 5 and the cathode chamber partition 6 are in contact with the anode 3 and the cathode 4, respectively. ing.
[0010]
Porous anodes and cathodes are porous conductive substrates such as porous metals, nets, expanded metals, metal fiber woven fabrics, non-woven fabrics, metal fiber sintered bodies, and anodes as electrocatalyst materials. Those containing at least one platinum group metal or oxide thereof are preferred, and those having a catalyst layer containing at least one platinum, iridium, iridium oxide, and ruthenium oxide are particularly preferred. On the other hand, it is preferable to use platinum, platinum black, iridium or the like as an electrode catalyst material for the cathode.
[0011]
As the solid polymer electrolyte membrane, a fluororesin-based ion exchange membrane, a hydrocarbon-based resin-based ion exchange membrane, a material in which an ion exchange substance is integrated with a binding resin, or the like can be used.
In addition, these anode electrode catalyst materials can be produced by directly depositing the anode catalyst material on the surface of a conductive substrate such as porous titanium or niobium, using a fluororesin as a binder. can do. Further, the cathode catalyst material may be formed by directly depositing on a porous current collector made of nickel or stainless steel, or by coating the surface of the current collector with a fluororesin as a binder. May be.
[0012]
The electrode catalyst for the anode and the cathode may not be formed on the entire surface of the porous conductive material, and may be present only on the side facing the solid polymer electrolyte membrane. The anode chamber 7 may be formed by laminating the anode 3 and the porous anode current collector 8, and the cathode chamber 9 may be provided with the cathode 4 and the porous cathode current collector 10.
In any case, the anode, the cathode, the anode current collector, and the cathode are supplied so that the water used for electrolysis is supplied to the electrode, and the generated oxygen and hydrogen are quickly taken out from the anode chamber and the cathode chamber. It is preferable to use a highly current collector.
[0013]
The anode chamber 7 is formed by the anode chamber frame 11, the solid polymer electrolyte membrane 2, and the anode chamber partition wall 5, and airtightness is secured by the gasket 12. In the anode chamber frame 11, a passage (not shown) for introducing water into the anode chamber 7, an anode chamber product passage 13 for taking out water containing generated oxygen bubbles, and water containing oxygen bubbles from the anode chamber. It has an anode chamber product conduit 14 that leads to the outside of the electrolytic cell, and water containing oxygen bubbles generated in the anode chamber of each unit electrolytic cell is taken out to the outside.
[0014]
A metal plate having a thickness of about 0.5 to 2 mm can be used for each of the anode chamber partition and the cathode chamber partition, and a material that is stable in an electrolysis environment such as titanium, niobium, zirconium, nickel, and stainless steel is used. Can do.
On the other hand, the cathode chamber 9 is formed by the cathode chamber frame 15, the solid polymer electrolyte membrane 2, and the cathode chamber partition 6, and airtightness is secured by the gasket 12. The cathode chamber frame 15 has no passage for introducing water into the cathode chamber 9.
[0015]
Protons generated by the reaction at the anode and water in the anode chamber migrate to the cathode chamber 9 by electrophoresis, and water containing hydrogen bubbles generated at the cathode is generated. Therefore, water containing hydrogen bubbles is generated in the cathode chamber. Are connected to a cathode chamber product passage 16 and a cathode chamber product conduit 17.
[0016]
The unit cell 1 composed of an anode, a cathode, a solid polymer electrolyte membrane, an anode chamber frame, a cathode chamber frame, an anode chamber partition wall, and a cathode chamber partition wall is laminated via a conductive elastic body 18 and is electrically conductive. The elastic body 18 is disposed and laminated inside an intermediate frame 19 having substantially the same thickness as the conductive elastic body.
[0017]
The conductive elastic body 18 is obtained by dispersing fibers, particles, and plate-like bodies made of copper, conductive carbon material, etc. in elastic rubber, synthetic resin, etc., and having elasticity. This ensures electrical conductivity between the anode chamber partition wall and the cathode chamber partition wall of the unit electrolytic cell in contact with both surfaces. When the unit electrolyzers are stacked with the conductive elastic body 18 disposed, a good conductive connection is formed between the unit electrolyzers even when the number of unit electrolyzers is large, and the solid polymer electrolyte membrane surface is formed. Since the electrodes can be uniformly adhered, the current distribution can be made uniform over the entire energization surface of the unit cell.
[0018]
FIG. 2 is an exploded perspective view illustrating the electrolytic cell.
On one surface of the solid polymer electrolyte membrane 2, an anode 3 is provided in an anode chamber 7 formed by the anode chamber frame 11 and the anode chamber partition wall 5, and on the other surface of the solid polymer electrolyte membrane 2. The cathode 4 is provided in the cathode chamber 9 formed by the cathode chamber frame 15 and the cathode chamber partition 6.
[0019]
Further, an intermediate frame 19 is disposed in contact with the cathode chamber partition 6, and a conductive elastic body 18 is disposed in contact with the cathode chamber partition 6 inside the intermediate frame 19. An anode chamber partition wall 5 of an adjacent unit electrolytic cell is disposed on the other surface of 19.
[0020]
In the solid polymer electrolyte membrane 2, the anode chamber frame 11, the cathode chamber frame 15, the anode chamber partition wall 5 and the cathode chamber partition wall 6, the water supply conduit 20 for supplying water to the anode chamber and the anode chamber 8 are used. An anode chamber product line 14 for taking out oxygen bubble-containing water to be generated and a cathode chamber product line 17 for taking out hydrogen bubble-containing water produced in the cathode chamber are provided. Also, the anode chamber frame 11 has a water supply passage 20a that communicates the anode chamber 7 and the water supply conduit 20, and an anode chamber product passage (not shown) that communicates the anode chamber 7 and the anode chamber product conduit 14. ) For supplying water to the anode chamber and taking out the product. In the cathode chamber frame 15, water containing hydrogen bubbles generated in the cathode chamber is supplied to the cathode chamber product conduit. It has an anode chamber product passage for introduction.
A gasket (not shown) is arranged between the anode chamber partition wall 5, the anode chamber frame 11, the solid polymer electrolyte membrane 2, the cathode chamber frame 15, and the cathode chamber partition wall 6 so as to maintain airtightness.
[0021]
FIG. 3 is a diagram illustrating the flow of fluid and current in the electrolytic cell of the present invention.
The electrolytic cell 21 is obtained by laminating a large number of unit electrolytic cells 1 including an anode chamber 7 and a cathode chamber 9 in series. Water is supplied to each anode chamber from a water supply pipe 20 and a unit is supplied from a DC power source 22. Electrolysis is performed by supplying a current corresponding to the number of electrolytic cells 1.
[0022]
Oxygen is generated in the anode chamber by electrolysis, protons are generated, pass through the solid electrolyte membrane, transfer to the cathode chamber, generate hydrogen, and water moves from the anode chamber to the cathode chamber at the same time by electrophoresis.
As a result, water containing oxygen bubbles is generated from the anode chamber, and water containing hydrogen bubbles is generated from the cathode chamber. They are taken out from the anode chamber product line 14 and the cathode chamber product line 17 respectively.
In the electrolytic cell 21 of the present invention, since the pipe line is formed in the member forming each unit electrolytic cell, water is supplied from either end of the electrolytic cell in which the unit electrolytic cells are stacked, and from either end. The product can be removed.
[0023]
For example, the unit electrolytic cell of the electrolytic effective area 20 dm ² to 75 stacked electrolytic cell is energized at a current density of 100A / dm ^2, the supply water at a flow rate of 3.4 m ³ / h from the anode chamber, the anode chamber Produced 32m ³ / h (0 ° C 1 atm) oxygen and 3.05 m ³ / h water from the cathode chamber, and 63 m ³ / h (0 ° c 1 atm) oxygen and 0.3 m ³ / h from the cathode chamber. Water is produced.
[0024]
FIG. 4 is a diagram illustrating an electrolytic cell in which unit electrolytic cells are stacked.
FIG. 4A is a front view, and FIG. 4B is a view as seen from the right side surface direction. The electrolytic cell 21 is formed by laminating unit electrolytic cells on the surface of the anode side end plate 23 with a conductive elastic body and an intermediate frame interposed therebetween, and after laminating a predetermined number of unit electrolytic cells, the cathode side end plate 24. Are stacked, the fastening rods 25 are arranged evenly on the same circumference, and fastened with nuts 26.
[0025]
Further, between the end plate and the nut, a spring-like member 27 capable of extending and contracting in the axial direction of the fastening rod is provided and fastened. As the spring-like member, a disc spring, a coil spring, or the like is used, and thereby, the distance between the anode side end plate and the cathode side end plate is held in a state where a compressive force capable of expanding and contracting is applied. As a result, deformation of the electrolytic cell due to thermal expansion due to heat generated by electrolysis can be prevented, so that the pressure applied to the electrode surface of the unit electrolytic cell can be prevented from becoming uneven.
The cathode side end plate 24 is provided with two water supply pipes 20 for supplying water to the electrolytic cell 21, and is located symmetrically with a line connecting the centers of the two water supply pipes 20. An anode chamber product line 14 and a cathode chamber product line 17 are arranged.
The anode-side end plate 23 and the cathode-side end plate 24 have an anode-side conductive connection body 28 and a cathode-side conductive connection body 29, respectively. Conductive connection to the electrolytic cell can be performed through these conductive connection bodies. it can.
[0026]
FIG. 5 is a view for explaining a fastening portion of a fastening rod of an electrolytic cell, FIG. 5 (A) is an enlarged side view for explaining one fastening portion, and FIG. 5 (B) is one piece. FIG. 5C shows a cross-sectional view of the disc spring.
The axis of the clamping rod 25 that penetrates the cathode side end plate 24 passes through a plurality of pairs of disc springs 30 that are in contact with each other on the large diameter side, and the cathode side end plate to which the nut 26 is attached via a washer 31. 24 is held by a disc spring and a nut fixed in position, so that the cathode side end plate 24 can be expanded and contracted in the axial direction of the clamping rod, and the electrolytic cell is not affected even if thermal expansion occurs due to a rise in the temperature of the electrolytic cell. Non-uniform deformation is prevented. As a result, non-uniformity does not occur at the contact portion between the solid polymer electrolyte and the electrode, and non-uniform current distribution does not occur.
[0027]
【The invention's effect】
According to the present invention, the contact between the solid polymer electrolyte membrane and the electrode becomes uniform, and the current distribution on the surface of the solid polymer electrolyte membrane can be made uniform. Can be obtained.
[Brief description of the drawings]
FIG. 1 is a diagram for explaining an electrolytic cell of the present invention, in which two unit electrolytic cells are stacked.
FIG. 2 is an exploded perspective view illustrating an electrolytic cell.
FIG. 3 is a diagram for explaining the flow of fluid and current in the electrolytic cell of the present invention.
FIG. 4 is a diagram for explaining an electrolytic cell in which unit electrolytic cells are stacked.
FIG. 5 is a diagram illustrating a tightening portion of a tie rod of an electrolytic cell.
FIG. 6 is an electrolytic cell in which electrodes are laminated and adhered to both surfaces of a solid polymer electrolyte.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Unit electrolytic cell, 2 ... Solid polymer electrolyte membrane, 3 ... Anode, 4 ... Cathode, 5 ... Anode chamber partition, 6 ... Cathode chamber partition, 7 ... Anode chamber, 8 ... Anode collector, 9 ... Cathode chamber DESCRIPTION OF SYMBOLS 10 ... Cathode collector, 11 ... Anode chamber frame, 12 ... Gasket, 13 ... Anode chamber product passage, 14 ... Anode chamber product conduit, 15 ... Cathode chamber frame, 16 ... Cathode chamber product passage, 17 DESCRIPTION OF SYMBOLS ... Cathode chamber product line, 18 ... Conductive elastic body, 19 ... Intermediate frame, 20 ... Water supply line, 20a ... Water supply path, 21 ... Electrolyzer, 22 ... DC power supply, 23 ... Anode-side end plate 24 ... cathode side end plate, 25 ... clamping rod, 26 ... nut, 27 ... spring-like member, 28 ... anode side conductive connector, 29 ... cathode side conductive connector, 30 ... disc spring, 31 ... washer, 41 ... Solid polymer electrolyte, 42 ... anode, 43 ... cathode, 44 ... bipolar plate, 45,46 ... end plate, 47 ... clamping bolt

Claims (2)

In an electrolytic cell in which unit electrolytic cells in which an anode and a cathode are arranged via a solid polymer electrolyte membrane are stacked, an anode chamber in which an anode and a cathode are arranged via a solid polymer electrolyte membrane and an anode chamber in which the anode is arranged is partitioned A plurality of unit electrolytic cells each comprising a cathode chamber partition wall that partitions the cathode chamber in which the partition wall and the cathode are arranged are provided with a conductive elastic body interposed in an intermediate frame provided between the anode chamber partition wall and the cathode chamber partition wall. An electrolyzer characterized by being laminated. A cathode chamber partition wall, an anode chamber partition wall, and an intermediate frame body are laminated, and an anode side end plate and a cathode side end plate provided with supply conduits and product conduits are arranged on both end faces of the laminate. 2. The electrolytic cell according to claim 1, wherein the distance between the anode side end plate and the cathode side end plate is held by holding means which can be expanded and contracted and is held in a state where a compressive force is applied.

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