JP2009149932A - Electrode for water electrolytic device and water electrolytic device using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrode having excellent electrolysis efficiency and high mechanical strength and used for an alkali water electrolytic device. <P>SOLUTION: An electrolytic unit for the alkali water electrolytic device is composed of an electrolytic bath 1 in which an alkali solution W flows, the electrode 2 for the water electrolytic device and bipolar plates 3, 4, wherein the electrode 2 for the water electrolytic device is formed by interposing both side of an ion permeable diaphragm 5 between electrode bodies E. The electrode body E is composed of a mesh-like electrode member 6 (7) and a mesh-like conductive member 8 (9) joined to the mesh-like electrode member 6 (7) by soldering and having rectangular projecting and recessed surfaces 8A, 8B (9A, 9B). The conductive members 8, 9 are respectively connected to an anode side 3A and a cathode side 4A of the bipolar plates 3, 4. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an electrode for use in an alkaline water electrolysis apparatus, and more particularly, to an electrode for a water electrolysis apparatus having a structure in which an ion-permeable diaphragm is sandwiched between electrode bodies. Moreover, this invention relates to the water electrolysis apparatus provided with such an electrode for water electrolysis apparatuses.

  Reflecting the recent energy situation, hydrogen is attracting attention from various fields as a new energy source to replace oil. Examples of such industrial production methods of hydrogen include coke and petroleum gasification methods, water electrolysis methods, and the like.

  The former method has a problem that the operation is complicated and a very large-scale facility is required, so that the initial cost is considerably increased.

  On the other hand, the latter method uses readily available water as a raw material, and a plurality of electrode pairs are provided in an electrolytic cell, and an alkaline electrolyte such as KOH is circulated between these electrodes and ion permeation is performed. The membrane is divided by a permeable membrane to generate hydrogen on the cathode side and oxygen on the anode side of the ion permeable membrane, but there is an ion permeable membrane and an electrolyte solution between the electrodes. Therefore, there are problems that electric resistance is large and electrolysis efficiency is poor. However, since this water electrolysis method can generate hydrogen even in a relatively small facility and is practical, improvement in electrolysis efficiency is desired.

  As shown in FIG. 5, such an alkaline water electrolysis apparatus includes an electrolytic cell 11 in which an alkaline solution W flows, an electrode 12, and bipolar plates 13 and 14, and the electrode 12 is an ion-permeable diaphragm 15. The conductive member 16A, 17A bent to the mesh electrode 16, 17 is sandwiched between the mesh electrode members 16, 17 so that both sides of the mesh electrode member 16, 17 are in contact with each other. A connection is proposed (see Patent Document 1). In this alkaline water electrolysis apparatus, the conductor members 16A and 17A are connected to the anode side 13A and the cathode side 14A of the bipolar plates 13 and 14, respectively.

  However, in the alkaline water electrolysis apparatus described in the above-mentioned Patent Document 1, the electrode 12 is such that both sides of the ion permeable diaphragm 15 are in contact with the mesh electrode members 16 and 17, respectively, and the ion permeation therebetween. The conductive members 16A and 17A are connected to the mesh-shaped electrodes 16 and 17 with the sex diaphragm 15 interposed therebetween, but it is difficult to ensure sufficient connection strength between the conductor members 16A and 17A. There was a problem. This is partly because spot welding is difficult to join the conductor members 16A and 17A.

  That is, spot welding is a method in which a high current is applied at a time and the wire is heated to a high temperature, so that the wire may be broken when the wire diameter of the mesh plate is thin. The bent conductor members 16A and 17A are preferably about 5 mm in height and about 10 mm in width in terms of electrolysis efficiency and volume occupancy. However, in spot welding, although it is necessary to insert a spot welding jig into the electrode members 16 and 17, the outer dimensions of the jig are much higher than the height and width of the conductor members 16A and 17A. Since it is large, it is difficult to insert a jig inside the conductor members 16A and 17A. Furthermore, since the conductor members 16A and 17A are curved or bent, there is a problem that the mechanical strength is not sufficient.

Therefore, an electrode for an alkaline water electrolysis apparatus, which is not a mesh shape but is spot-welded using Ni—using an electrode member and a conductor member having a metal sheet with a pore of about 1 mm, has also been proposed (non-native). Patent Document 1).
Japanese Examined Patent Publication No. 62-50557 EUR9221EN Comission of the European Communities, 1984

  However, when the metal sheet described in Non-Patent Document 1 has pores, the opening ratio is not sufficient (opening ratio: 34.5%), so the generated gas stays between the electrode member and the diaphragm. In other words, a phenomenon called so-called hot spot occurs, and there is a problem that electrolytic efficiency is lowered. Furthermore, since current concentration is caused, there is a problem that it causes early deterioration of the ion-permeable diaphragm. In addition, when a conductor member having pores is used, there is a problem that the electrolyte is difficult to move in the lateral direction (perpendicular to the flow direction), becomes a fluid close to a laminar flow, and causes a decrease in efficiency. .

  An object of the present invention is to solve the above-described conventional problems and to provide an electrode for use in an alkaline water electrolysis apparatus having good electrolysis efficiency and excellent mechanical strength. Another object of the present invention is to provide a water electrolysis apparatus provided with an electrode having good electrolysis efficiency and excellent mechanical strength.

  In order to solve the above problems, first, the present invention provides an electrode of an alkaline water electrolysis apparatus having a structure in which an ion permeable diaphragm is sandwiched between a pair of electrode bodies, wherein the electrode body exhibits an electrolytic action. And a mesh-shaped conductor member having a rectangular concavo-convex surface with a continuous cross-section joined to the electrode member. Claim 1).

  According to the above invention (invention 1), the mesh electrode member is connected to the mesh electrode member having a rectangular concavo-convex surface having a continuous cross section, so that sufficient water permeability can be secured. Thus, an electrode having good electrolytic efficiency can be obtained. And it is easy to join by joining an electrode member and a conductor member in the contact surface with the uneven surface of a conductor member, and the joining strength and mechanical strength of a conductor member are large.

  In the said invention (invention 1), it is preferable that the said electrode member and the said conductor member are joined by brazing in the contact surface of the uneven surface of the said conductor member (invention 2).

  According to the said invention (invention 2), an electrode member and a conductor member can be joined with big joining strength, and the electrode excellent in mechanical strength can be obtained.

  In the said invention (invention 1 and 2), it is preferable that the said electrode member and the said conductor member consist of a 2-500 mesh net | network board with the conductive wire of the wire diameter of 0.025-2 mm (invention). 3).

  According to the above invention (invention 3), it is possible to obtain an electrode having sufficient water permeability and capable of maintaining mechanical strength.

  Moreover, in the said invention (Invention 1-3), it is preferable that the uneven | corrugated height of the said conductor member is 30 mm or less, and a pitch is 20 mm or less (Invention 4). According to this invention (invention 4), the electrode member and the conductor member can be easily joined by brazing or the like, and the joining strength can be sufficient. Moreover, the water permeability of the electrode obtained can also be made favorable.

  Moreover, in the said invention (invention 2-4), the said electrode member and the said conductor member are comprised with the electroconductive wire which consists of nickel or a nickel alloy, and the said electrode member and the said conductor member are nickel brazing. And are preferably joined by brazing (claim 5).

  According to the above invention (invention 5), since the electrode member and the conductor member are excellent in conductivity and alkali resistance and have good bonding properties between them, the electrode member and the conductor member are excellent in conductivity and alkali resistance, and mechanical. An electrode having excellent strength can be obtained.

  Furthermore, in the said invention (invention 1-5), it is preferable that the said electrode member is modified with sulfur (invention 6).

  According to the above invention (invention 6), the modified sulfur acts as a catalyst for the electrolytic reaction, whereby the hydrogen overvoltage of the electrode can be reduced. This leads to a decrease in electrolysis voltage, and further to further improvement in electrolysis efficiency.

  A second aspect of the present invention is a water electrolysis apparatus including the electrode for a water electrolysis apparatus according to the above inventions (inventions 1 to 6), wherein the electrolysis tank and a plurality of bipolars provided in the electrolysis tank are provided. A plate and a plurality of water electrolysis device electrodes connected to the bipolar plate, wherein the water electrolysis device electrode is connected to the anode side or the cathode side of the bipolar plate via the conductor member, respectively. A water electrolysis apparatus is provided (claim 7).

  According to the said invention (invention 7), since sufficient water permeability can be ensured and an electrode with favorable electrolysis efficiency is used, it can be set as a highly efficient water electrolysis apparatus. In addition, the mechanical strength of the electrode can be increased.

  According to the electrode for a water electrolysis apparatus of the present invention, a mesh-like conductor member having a rectangular uneven surface having a continuous cross section is connected to the mesh-like electrode member, so that sufficient water permeability can be ensured. And an electrode having good electrolysis efficiency can be obtained. Moreover, this electrode can be easily joined by joining the electrode member and the conductor member at the contact surface with the concavo-convex surface of the conductor member, and the joining strength and mechanical strength of the conductor member can be increased. .

Embodiments of the present invention will be described below in detail with reference to the drawings.
FIG. 1 is an enlarged cross-sectional view showing one unit of an electrolysis unit of an alkaline water electrolysis apparatus using an electrode for a water electrolysis apparatus according to an embodiment of the present invention.

  In FIG. 1, an electrolysis unit of an alkaline water electrolysis apparatus includes an electrolysis tank 1 in which an alkaline solution W flows, a water electrolysis apparatus electrode 2, and bipolar plates 3 and 4, and the water electrolysis apparatus electrode 2 is an ion. Both sides of the permeable diaphragm 5 are sandwiched between two electrode bodies E. The electrode body E includes mesh-like electrode members 6 and 7 and mesh-like conductor members 8 and 9 having continuous rectangular uneven surfaces 8A, 8B and 9A, 9B. Concave and convex surfaces 8A and 9A of the conductor members 8 and 9 are joined to the mesh electrode members 6 and 7, respectively. The uneven surfaces 8B and 9B of the conductor members 8 and 9 are connected to the anode side 3A and the cathode side 4A of the bipolar plates 3 and 4, respectively. As the alkaline solution W, a potassium hydroxide (KOH) solution is used.

  In such an alkaline water electrolysis apparatus, as the membrane material for forming the ion permeable diaphragm 5, only ions are allowed to pass through the membrane, there is no gas passage or diffusion, and it is physically and chemically in an alkaline solution. There is no particular limitation as long as it is durable.

  For example, as the membrane material 5A, a stretched organic fiber cloth is contained in a film-forming mixture containing a hydrophilic inorganic material and an organic binding material selected from polysulfone, polypropylene, polyvinylidene fluoride, and the like. It is preferable.

  As the hydrophilic inorganic material, fluoroapatite (FAP) or hydroxyapatite (HAP) is preferably used, and these hydrophilic inorganic materials are preferably used in the form of granules. The particles of the hydrophilic inorganic material preferably have a particle size of 5 μm or less, particularly preferably fine particles having a particle size of 1 μm or less. Therefore, you may grind | pulverize this granular material finely with a mortar beforehand.

Further, as the organic fiber cloth, a mesh made of polypropylene, a mesh made of a pre-halogenated ethylene copolymer such as ethylene and monochlorotrifluoroethylene, or the like can be used. As this organic fiber cloth, a woven fabric or a non-woven fabric can be used. The fiber diameter is preferably 1 mm or less, and particularly preferably the fiber diameter is 0.5 mm or less. The size of the weave of the organic fiber cloth is not particularly limited, but is preferably 4 mm ² or less, and particularly preferably 1 mm ² or less.

  As shown in FIGS. 2 and 3, the electrode body E constituting the electrode 2 for the water electrolysis device is substantially circular and has a mesh-like conductor member 8 having rectangular uneven surfaces 8A and 8B (9A and 9B). (9) is joined to the mesh-like electrode member 6 (7) by the nickel braze 10 on the top surface 8A (9A).

  The conductor members 8 and 9 and the electrode members 6 and 7 are preferably composed of a 2 to 500 mesh screen made of a conductive wire having a wire diameter of 0.025 to 2 mm. If the wire diameter of the conductive wire is less than 0.025 mm, the mechanical strength is not sufficient. On the other hand, if it exceeds 2 mm, the workability is lowered, which is not preferable. Further, if the mesh plate opening is less than 2 mesh, the mechanical strength and the bonding strength between the conductor members 8 and 9 and the electrode members 6 and 7 are not sufficient, while if it exceeds 500 mesh, the water permeability is lowered. Therefore, it is not preferable. As the conductive wire as described above, one made of nickel or a nickel alloy, or a non-nickel material plated with nickel or a nickel compound is preferable. In this embodiment, the electrode members 6 and 7 and the conductor members 8 and 9 are joined to each other by brazing, particularly nickel brazing, on the uneven surfaces 8A and 9A of the conductor member.

  Further, the height of the concave and convex surfaces 8A and 9A of the conductor members 8 and 9 is preferably 30 mm or less, and particularly preferably 5 to 10 mm. If the height of the uneven surfaces 8A and 9A is less than 5 mm, bubbles tend to remain and the efficiency tends to decrease. On the other hand, if the height exceeds 30 mm, the amount of liquid flowing increases, so the output of the circulation pump needs to be increased. Not only does this occur, but when stacked, the electrolysis unit is undesirably enlarged.

  Further, the pitch (width) of the uneven surfaces 8A and 9A of the conductor members 8 and 9 is preferably 20 mm or less, particularly 3 to 10 mm. If the pitch of the concavo-convex surfaces 8A and 9A is less than 3 mm, the bonding strength with the electrode members 6 and 7 is insufficient.

  The electrode 2 for a water electrolysis apparatus comprising the above-described members has a structure in which an ion-permeable diaphragm 5 is sandwiched and fixed between one mesh electrode member 6 and another mesh electrode member 7. However, specifically, it can be produced as follows.

  That is, as shown in FIG. 4, a mesh-like electrode member 6, a conductor member 8, a bipolar plate 3 (4), a conductor member 9, and a mesh-like electrode member 7 are sequentially laminated to form a mesh shape. Between the electrode member 6 and the conductor member 8 (uneven surface 8A), between the conductor member 8 (uneven surface 8B) and bipolar plate 3, between the bipolar plate 3 and conductor member 9 (uneven surface 9B), and conductor member. 9 (uneven surface 9A) and the uneven surfaces 8A, 8B, 9A, 9B that are in contact with each other between the mesh electrode member 7 and the nickel solder 10 are placed and heated to the melting temperature of the nickel solder 10 or higher. The electrode structure U is manufactured. Then, the ion-permeable diaphragm 5 is sandwiched and fixed between the mesh electrode member 6 of the electrode structure U and the mesh electrode member 7 of another electrode structure. By repeating this, a plurality of water electrolysis device electrodes 2 can be configured in parallel.

  It is preferable that the electrode structure U is further subjected to sulfur modification treatment with nickel sulfate, thiourea or the like, thereby reducing the hydrogen overvoltage of the electrode 2 for water electrolysis apparatus and improving the electrolysis efficiency (energy efficiency).

  In the case of the electrode structure U as such a laminated body, in the present embodiment, the conductor members 8 and 9 have a continuous rectangular uneven surface 8A, 8B, 9A, and 9B, and thus are themselves vertical. The mechanical strength in the direction is excellent, and as a result, an improvement in mechanical strength of the entire electrode can be expected.

In the electrolysis unit shown in FIG. 1 using the electrode 2 for a water electrolysis apparatus, when a current is passed through the bipolar plates 3 and 4, the conductor members 8 and 9 are connected between the mesh-like electrode body members 6 and 7. A voltage is generated, and oxygen (O ₂ ) is generated at the interface between the ion permeable diaphragm 5 and the mesh electrode 6 (anode) by electrolysis of the potassium hydroxide solution W.

Then, twice the amount of hydrogen (H ₂ ) is generated at the interface between the ion permeable diaphragm 5 and the mesh electrode 7 (cathode). Since the electrolytic cell 1 in this electrolysis unit is divided into the cathode side and the anode side by the ion permeable diaphragm 5, hydrogen gas can be produced by recovering only hydrogen generated on the cathode side.

  The embodiment described above is described for facilitating understanding of the present invention, and is not described for limiting the present invention. Therefore, each element disclosed in the above embodiment is intended to include all design changes and equivalents belonging to the technical scope of the present invention.

  EXAMPLES Hereinafter, although this invention is demonstrated further in detail based on an Example and a comparative example, this invention is not limited to the following Example at all.

[Example 1]
[Manufacture of electrodes for water electrolysis]
A 50-mesh Ni mesh plate was processed, and a conductor member was manufactured by bending the outer shape to have an irregularity of 6 mm in height and 7 mm in width and having an outer diameter of 400 mm.

  Ni solder (model number: TB-907, manufactured by Tokyo Blaze Co., Ltd.) was applied to the top surface of the concavo-convex portion of this conductor member at a spot interval of 50 mm, and an electrode member (φ400 mm) made of Ni mesh was superimposed. Similarly, Ni brazing was applied to the bottom side and a bipolar plate (φ420 mm) was superposed, and this was repeated to form a laminate of electrode member / conductor member / bipolar plate / conductor member / electrode member. .

  Then, this laminate was put in a hydrogen furnace and baked at 900 ° C. or higher to melt the Ni wax.

Next, the electrode obtained in this manner was made of NiSO ₄ .7H ₂ O (200 g / L), NiCl ₂ .6H ₂ O (40 g / L), boric acid (35 g / L) and thiourea (100 g / L). ) And a counter electrode as a Ni porous plate (product name: Celmet, manufactured by Sumitomo Electric Industries, Ltd.), and a 1.63 A current (current density 1.3 mA / cm ² ) was energized for 2 hours. A modified Ni electrode was obtained.

[Production of ion-permeable membrane]
N-methyl-2-pyrrolidone (NMP) 65 mass% (30 g), calcium fluoride (CaF ₂ , manufactured by Kishida Chemical Co., Ltd.) 26 mass% (12 g) having an average particle size of 5 μm, and polysulfone (PSF, manufactured by Solvay Advanced Polymers) , Trade name: UDEL) 9% by mass (4 g) was mixed and sufficiently stirred to dissolve polysulfone (PSF), and calcium fluoride (CaF ₂ ) was dispersed to prepare a suspension.

This suspension is made of 10 cm × 10 cm glass with a 200 mesh polypropylene fiber cloth (fiber diameter: 87 μm, manufactured by NBC, product name: nip (polypropylene) strong net) installed at a position 400 μm from the bottom. 10 mL was poured onto the frame body to prepare a wet sheet having a surface area of 100 cm ² and a thickness of about 500 μm.

  Immediately after pouring the suspension, the frame was transferred into a water bath and allowed to stand at room temperature for 5 minutes, and N-methyl-2-pyrrolidone (NMP) as a solvent was leached from the wet sheet. Thereafter, the sheet remaining on the frame was peeled off and held for 5 minutes in water to obtain a sheet-like membrane material (ion-permeable membrane). The obtained sheet-like membrane material (ion permeable membrane) had a thickness of about 400 μm.

[Measurement of energy efficiency]
The ion permeable membrane was sandwiched between the electrode members of the pair of electrodes to constitute an electrolysis unit. Using this electrolysis unit, a 25% KOH solution was passed through and water electrolysis was performed at 80 ° C., the electrolysis voltage was measured, and the energy efficiency was calculated.
The results are shown in Table 1.

[Comparative Example 1]
[Manufacture of electrodes for water electrolysis]
A 1 mm through hole is made in a nickel plate having a thickness of 0.2 mm so that the aperture ratio is 32.5%, and as in Example 1, it has a concavo-convex part with a height of 6 mm and a width of 7 mm, and the outer shape is φ400 mm. Was subjected to a bending process to produce a conductor member.

  In addition, a 1 mm through hole was formed in the nickel plate so as to have an opening ratio of 32.5%, and the electrode member was cut into φ400 mm.

  Ni solder was applied to the top surface of the concavo-convex portion of this conductor member at a spot interval of 50 mm, and electrode members made of Ni plate were superposed. Similarly, Ni brazing was applied to the bottom surface and a bipolar plate (φ420 mm) was superposed, and this was repeated to form a laminate of electrode member / conductor member / bipolar plate / conductor member / electrode member. .

  Then, this laminate was put in a hydrogen furnace and baked at 900 ° C. or higher to melt the Ni wax.

Next, the electrode obtained in this manner was made of NiSO ₄ .7H ₂ O (200 g / L), NiCl ₂ .6H ₂ O (40 g / L), boric acid (35 g / L) and thiourea (100 g / L). ) And a counter electrode as a Ni porous plate (product name: Celmet, manufactured by Sumitomo Electric Industries, Ltd.), and a 1.63 A current (current density 1.3 mA / cm ² ) was energized for 2 hours. A modified Ni electrode was obtained.

[Measurement of energy efficiency]
The ion permeable membrane of Example 1 was sandwiched between the electrode members of the pair of electrodes to constitute an electrolysis unit. Using this electrolysis unit, water electrolysis was carried out with a 25% KOH solution at 80 ° C., the electrolysis voltage was measured, and the energy efficiency was calculated.
The results are shown in Table 1.

  As is apparent from Table 1, the electrolysis voltage when water electrolysis is performed using the electrode of Example 1 is lower than that of Comparative Example 1, and the electrode of Example 1 has good energy efficiency. confirmed.

It is an expanded sectional view showing one unit of an electrolysis unit of an alkaline water electrolysis device using an electrode concerning one embodiment of the present invention. It is a top view which shows the conductor member of the electrode which concerns on the same embodiment. It is a longitudinal cross-sectional view which shows the electrode body of the electrode which concerns on the same embodiment. It is a longitudinal cross-sectional view which shows the electrode structure of the electrode which concerns on the same embodiment. It is an expanded sectional view which shows one unit of the electrolysis unit of the alkaline water electrolysis apparatus using the conventional electrode.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Electrolyzer 2 ... Electrode for water electrolysis apparatus 3, 4 ... Bipolar plate 5 ... Ion permeable diaphragm 6, 7 ... Mesh-like electrode member 8, 9 ... Mesh-like conductor member 8A, 8B, 9A, 9B ... Uneven surface 10 ... nickel solder E ... electrode body W ... alkaline solution

Claims (7)

An electrode of an alkaline water electrolysis apparatus having a structure in which an ion-permeable diaphragm is sandwiched between a pair of electrode bodies,
The electrode body includes a mesh-like electrode member that exhibits an electrolytic action, and a mesh-like conductor member that is joined to the electrode member and has a rectangular uneven surface with a continuous cross section. Electrode for water electrolysis device.   The electrode for a water electrolysis apparatus according to claim 1, wherein the electrode member and the conductor member are joined by brazing on a contact surface of the uneven surface of the conductor member.   The electrode for a water electrolysis apparatus according to claim 1 or 2, wherein the electrode member and the conductor member are made of a mesh plate of 2 to 500 mesh made of a conductive wire having a wire diameter of 0.025 to 2 mm. .   The electrode for a water electrolysis apparatus according to any one of claims 1 to 3, wherein the height of the unevenness of the conductor member is 30 mm or less and the pitch is 20 mm or less.   The electrode member and the conductor member are made of a conductive wire made of nickel or a nickel alloy, and the electrode member and the conductor member are brazed with nickel braze and joined. The electrode for water electrolyzers in any one of Claims 2-4.   The electrode for a water electrolysis apparatus according to any one of claims 1 to 5, wherein the electrode member is modified with sulfur. A water electrolysis apparatus comprising the electrode for water electrolysis apparatus according to any one of claims 1 to 6,
An electrolytic cell, a plurality of bipolar plates provided in the electrolytic cell, and a plurality of electrodes for water electrolysis devices connected to the bipolar plate,
The water electrolysis apparatus, wherein the water electrolysis apparatus electrode is connected to each of an anode side or a cathode side of the bipolar plate via the conductor member.

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