JP2011127215A - Feed conductor for electrolytic cell and electrolytic cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent the damage of an electrolyte membrane by diffusing current enough to prevent the heating due to the increase of current density. <P>SOLUTION: The feed conductor 1 for an electrolytic cell is provided with a plurality of metal made plate materials 2a-2g formed net-like and mutually laminated and the adjacent metal made plate materials 2a-2g are individually spot-welded and the minimum space distance between nuggets due to the spot welding is defined by numerical expression 1. In numerical expression 1, (r) expresses the minimum space distance between the nuggets, R<SB>12</SB>expresses contact resistance value between the metal made plate materials and R<SB>p</SB>expresses in-plane resistance value of the metal made plate material. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an electrolytic cell power supply and an electrolytic cell applied to a water electrolysis apparatus that electrolyzes water to generate oxygen and hydrogen.

  As an electrolytic cell constituting an electrolytic stack applied to a water electrolysis apparatus that electrolyzes water to generate oxygen and hydrogen, a pair of separators and an electrolyte having electrodes formed on both surfaces provided between the pair of separators A device including a membrane and a power feeding body interposed between the separator and the electrolyte membrane is known. As a power supply body for such an electrolytic cell, Patent Document 1 (Japanese Patent No. 3555353) discloses a powder sintered portion sintered after press-molding titanium powder and an expanded metal made of titanium. It is provided with a laminated elastic part, in which a powder sintered part and an elastic part are joined by spot welding.

Japanese Patent No. 3555353

  However, as described above, when an electrolysis cell having a power supply body for an electrolysis cell in which a powder sintered portion and an elastic portion are joined by spot welding is applied to a water electrolysis apparatus, DC power is supplied from one separator. When applied to the other separator, the current concentrates on the nugget by spot welding. If the concentrated current passes through the power supply body without sufficiently diffusing in the powder sintered portion or the elastic portion, the current density in the portion becomes locally high, and heat may be generated. In particular, when the distance between nuggets by spot welding is close, the current concentrated on one nugget reaches an adjacent nugget without diffusing, so that the current density of the nugget increases and heat may be generated. Becomes more problematic. And if heat is generated and the local high temperature reaches the electrolyte membrane, the electrolyte membrane may be damaged.

  The present invention has been made in order to solve the above-mentioned problem, and it is possible to prevent damage to the electrolyte membrane due to sufficient diffusion of current and prevention of heat generation due to increase in current density. It aims at providing the electric power feeder for electrolysis cells, and an electrolysis cell.

In order to solve the above problems, the present invention employs the following means.
The present invention includes a plurality of metal plate members that are formed in a net shape and are stacked on each other, and each of the adjacent metal plate members is spot-welded individually, and the minimum separation distance between the nuggets by the spot welding is expressed by the following formula 1. A power supply for an electrolytic cell defined by the formula is provided.

Here, r is the minimum distance between the nugget, R ₁₂ is the contact resistance between the metal plate, the R _P is a plane resistance value of the metal plate.

  According to the present invention, when adjacent metal plate materials are spot-welded, the separation distance between the nuggets is determined by the contact resistance value between the metal plate materials and the in-plane resistance value of the metal plate material. Therefore, even if the current concentrates on any nugget when the current flows in the metal plate material, the current does not reach other nuggets and the in-plane of the metal plate material Since the current is dispersed, the heat generation due to the local concentration of current and the increase in current density can be prevented. Therefore, when the electrolytic cell power supply of the present invention is applied to an electrolytic cell, the metal plate material, that is, the electrolyte film caused by the high temperature does not reach the electrolyte membrane from the electrolytic cell power supply. Can be prevented from being damaged.

Moreover, in the above-described electrolytic cell power supply body, it is preferable that the minimum separation distance between the nuggets of the different metal plates is defined by the equation (1).
According to the present invention, since the minimum separation distance between the nuggets between different metal plate materials is the above-described formula 1, when a current flows through the metal plate material, any of the metal plate materials Even when the current is concentrated on an arbitrary nugget, the current does not reach the nuggets of different metal plate materials. That is, even in such a case, current does not reach different metal plate materials, and the current is dispersed in the plane of the metal plate material having the nugget where the current is concentrated. Heat generation due to an increase in current density can be prevented.

Furthermore, in the above-described electrolytic cell power supply body, it is preferable that the minimum separation distance between the nuggets of the same metal plate is defined by Equation (1).
According to the present invention, since the minimum separation distance between the nuggets of the same metal plate material is the above formula 1, when the current flows through the metal plate material, any of the metal plate materials Even when the current is concentrated on the nugget, the current does not reach other nuggets of the same metal plate. That is, even in such a case, since current does not reach different metal plate materials and current is dispersed within the same metal plate material, current is locally concentrated and current density is increased. It is possible to prevent heat generation.

  Further, the present invention provides a pair of separators, an electrolyte membrane provided between the pair of separators and having electrodes formed on both surfaces, and provided between the separator and the electrolyte membrane, and formed in a net-like shape. Provided is an electrolysis cell comprising a plurality of laminated metal plates, each of the adjacent metal plates is spot welded individually, and the minimum separation distance between nuggets by the spot welding is defined by the following equation (2) .

Here, r is the minimum distance between the nugget, R ₁₂ is the contact resistance between the metal plate, the R _P is a plane resistance value of the metal plate.

  According to the present invention, when adjacent metal plate materials are spot-welded, the above-mentioned number determined by the contact resistance value between the metal plate materials and the in-plane resistance value of the metal plate material as the minimum separation distance between the nuggets. Because it is set to 2 types, even if the current is concentrated on an arbitrary nugget when the current flows in the metal plate, the current does not reach other nuggets and the plane of the metal plate Since the current is dispersed, the heat generation due to the local concentration of current and the increase in current density can be prevented. Therefore, local high temperature does not reach from the metal plate material to the electrolyte membrane, and damage to the electrolyte membrane due to the high temperature can be prevented.

In the above-described electrolytic cell, it is preferable that a current diffusing means having an in-plane resistance value smaller than the in-plane resistance value of the metal plate material is disposed between the electrolyte membrane and the metal plate material.
According to the present invention, by applying a current diffusion means having a smaller in-plane resistance value than the in-plane resistance value of the metal plate material, the current is sufficiently diffused in the plane of the current diffusion means, The current spreading means functions as a buffer material, and prevents current from concentrating and flowing from the metal plate material to the electrolyte membrane. That is, by disposing the current diffusion means between the electrolyte membrane and the metal plate material, it is possible to prevent the local high temperature from being applied to the electrolyte membrane, thereby preventing the electrolyte membrane from being damaged due to the high temperature. . In addition, as for a current spreading | diffusion means, it is more preferable that the in-plane resistance value is sufficiently small compared with the contact resistance with a feeder.

In the above-described electrolysis cell, it is preferable that spot welding is not performed at the central portion where the water electrolysis reaction of the current diffusion means is performed.
According to the present invention, current is sufficiently diffused in the plane of the current spreading means, particularly in the region other than the center part, by not performing spot welding on the portion of the current spreading means where the water electrolysis reaction important in the electrolysis cell is performed. To do.

  As described above, according to the present invention, the current is sufficiently diffused and the heat generation due to the increase in the current density is prevented, thereby preventing the electrolyte membrane from being damaged.

It is sectional drawing which shows schematic structure of the electric power feeding body of this invention. It is explanatory drawing which shows the positional relationship between the nuggets by the spot welding of the electric power feeding body of this invention. It is sectional drawing which shows schematic structure of the electrolytic cell of this invention. It is sectional drawing which shows schematic structure of the other example of the electrolytic cell of this invention.

  Below, one Embodiment of the electric power feeder for electrolytic cells which concerns on this invention is described with reference to drawings.

  FIG. 1 is a cross-sectional view showing a schematic configuration of an electrolytic cell power supply body (hereinafter simply referred to as “power supply body”) according to the present embodiment. As shown in FIG. 1, the feeder 1 is made of titanium as a metal plate formed in a net shape so that water can be supplied to the solid polymer electrolyte membrane when the feeder 1 is applied to an electrolytic cell. A plurality of expanded meshes 2a to 2g made from each other are laminated. In this embodiment, expanded meshes 2a to 2g having a mesh thickness of 0.4 mm, a mesh opening opened in a rhombus, a long direction distance (LW) of 5.0 mm, and a short direction distance (SW) of 2.5 mm. However, the present invention is not limited to this. For example, as a metal plate formed in a net shape, a wire mesh in which thin wires are knitted, or a punching metal in which holes are formed in a plate Etc. can also be applied. In addition, the number of laminated metal plate materials formed in a net shape can be determined as appropriate.

  The expanded meshes 2a to 2g are joined together by spot welding the adjacent expanded meshes 2a to 2g individually in a state where they are stacked on each other. That is, in each expanded mesh, all the expanded meshes 2a to 2g are joined by joining adjacent expanded meshes by spot welding with each other. For example, when the power feeding body 1 is applied to an electrolysis cell, a first expanded mesh is disposed on the separator of the electrolysis cell, and a predetermined location is spot-welded. At this time, one electrode used for spot welding is connected to the separator and the other electrode is pressed against the expanded mesh to pass current. As a result, the separator and the first expanded mesh are welded and joined. Subsequently, the second expanded mesh is disposed on the first expanded mesh, and a predetermined portion is similarly spot welded. One electrode of spot welding is connected to the separator in the same manner as the first expanded mesh, and the other electrode is pressed against the second expanded mesh to pass current. At this time, only the first and second expanded meshes are welded and joined by applying current so that the separator and the first expanded mesh are not welded and joined. Thereafter, the same procedure is sequentially repeated to weld-join a desired number of expanded meshes. In this way, by supplying a current that can spot weld only adjacent expanded meshes, adjacent expanded meshes are spot welded to each other, and all the expanded meshes 2a to 2g are joined. The power feeder 1 can be obtained.

  When a direct current is applied to the feeder 1, the in-plane current vector, in-plane voltage distribution, electrode voltage, in-plane resistance, and contact resistance of each of the expanded meshes 2a to 2g should be defined as shown in Table 1 below. Can do. Here, when a direct current is applied to the power supply body 1, if each of the expanded meshes 2 a to 2 g is regarded as a resistor, this is equivalent to a state in which the resistors are connected in series. Accordingly, the electrode voltage is intended to mean a voltage on the anode side and a voltage on the cathode side with respect to any of the expanded meshes 2a to 2g.

また、各エキスパンドメッシュ２ａ〜２ｇの面内電流ベクトルは以下の数３式で定義できる。

The in-plane current vectors of the expanded meshes 2a to 2g can be defined by the following equation (3).

  Furthermore, the outflow of the in-plane current vector of each of the expanded meshes 2a to 2g can be defined by the following equation (4) from the balance of current inflow and outflow from the electrode voltage.

  From the above formulas 3 and 4, the voltage governing equation can be obtained as shown in the following formula 5.

  Furthermore, the above equation (5) can be expressed as equation (7) using a cylindrical coordinate system represented by the following equation (6).

R ₁₂ is a combined resistance of R ₁ and R ₂ and is defined by the following equation (8).

  Here, when the dimensionless distance X is defined as in the following Expression 9, the Expression 7 can be made dimensionless with respect to the distance as shown in the following Expression 10.

  Furthermore, by defining the second term on the right side of Equation (10) as Equation (11) below, Equation (10) can be simplified as Equation (12).

It is known that the special solution of the differential equation of Formula 12 is a 0th-order Bessel function (I ₀ , K ₀ ), and writing the general solution of Formula 12 using these, C ₁ , C Assuming ₂ is an arbitrary constant, the following formula is obtained.

  In addition, the same-diameter distribution of the in-plane current can be expressed as Equation 15 using Equation 14 which is a recurrence equation regarding the differentiation of the modified Bessel function.

From the above formulas, it has been found that when X = 1, the value of the current applied to the nuggets of the expanded meshes 2a to 2g is approximately halved.
That is, from Equation 9, Equation 16 can be defined as the minimum separation distance r between the nuggets.

  Therefore, the power feeder 1 is defined by the following equation (16) between nuggets between different expanded meshes, that is, between nuggets of adjacent expanded meshes in the stacked expanded mesh and between nuggets in the expanded mesh plane. The minimum separation distance r is maintained.

  FIG. 2 shows, as an example, the positional relationship of each nugget formed by spot welding the expanded meshes 2a to 2g. In the example of FIG. 2, first, the electrolysis range (a range in which a direct current is applied) of the power supply body 1, that is, the expanded meshes 2 a to 2 g in a stacked state, is approximately three times the minimum separation distance r on each side. It is roughly divided into 9 squares. The first expanded mesh 2a indicates that spot welding is performed at the position (1) in each square. Further, the second expanded mesh 2b indicates that spot welding is performed at the position (2) in each square. Similarly, the third and subsequent expanded meshes 2c to 2g are spot welded at the positions (3) to (7), respectively. The nuggets (1) to (7) are separated from each other by the minimum separation distance r in each square. In addition, the minimum separation distance r is maintained between the nuggets in the adjacent squares, and the distance between all the nuggets as a whole maintains the minimum separation distance r.

Next, an electrolysis cell to which the power feeder 1 is applied will be described with reference to FIG. FIG. 3 is a cross-sectional view illustrating a schematic configuration of the electrolytic cell 10.
As shown in FIG. 3, an electrolytic cell 10 according to this embodiment includes a pair of separators 11a and 11b and a solid polymer electrolyte membrane provided between the pair of separators 11a and 11b and having an anode and a cathode formed on both sides. 12, current supply members 1a and 1b provided between the solid polymer electrolyte membrane 12 and the separators 11a and 11b, and current diffusion members 13a provided between the power supply members 1a and 1b and the solid polymer electrolyte membrane 12. 13b and a photoetching mesh 14 are provided.

  The current spreading members 13a and 13b have in-plane resistance values smaller than the in-plane resistance values of the expanded meshes 2a to 2g of the power feeding bodies 1a and 1b, and the current spreading members 13a and 13b and the power feeding bodies 1a and 1b Are joined by spot welding only in the vicinity of the periphery without spot welding. As the current spreading members 13a and 13b, for example, the mesh is finer than the expanded meshes 2a to 2g of the power feeders 1a and 1b, such as a titanium expanded mesh having a thickness of 0.1 mm, a wire mesh, a punching metal, and the like. Thin ones can be applied. More preferably, the in-plane resistance values of the current diffusion members 13a and 13b are preferably sufficiently smaller than the contact resistances of the power feeders 1a and 1b with the expanded meshes 2a to 2g. Also, a plurality of current spreading members 13a and 13b can be provided.

  The photoetching mesh 14 is provided to protect the electrolyte membrane because the expanded meshes 2a to 2g of the power feeding bodies 1a and 1b may damage the electrolyte membrane when directly in contact with the electrolyte membrane. A material having a thickness of 0.1 mm and a diameter of about 0.1 mm to 0.2 mm processed by an etching method is applied.

Hereinafter, a case where water electrolysis is performed in a water electrolysis apparatus using the power feeder 1 or the electrolysis cell 10 configured as described above will be described.
When a direct current is applied from one separator to the other separator, water passes through the electrolytic cell 10, and a current flows through the separator to the power feeder 1 and the solid polymer electrolyte membrane 12. Water is electrolyzed at the electrode portion of the membrane 12 to generate hydrogen and oxygen. At this time, in one of the expanded meshes of the power feeder 1, it is assumed that the current concentrates on an arbitrary nugget. Even in this case, the nuggets are provided with a minimum separation distance r. Therefore, this current does not reach other nuggets of different expanded meshes as well as the expanded mesh, and the currents are distributed in the plane of the expanded mesh. Further, the current is sufficiently diffused in the plane of the current diffusion members 13 a and 13 b by the current diffusion members 13 a and 13 b provided between the solid polymer electrolyte membrane 12 and the power feeder 1. Therefore, it is possible to prevent heat generation due to local concentration of current and increase in current density, and local high temperature does not reach from the power supply 1 to the solid polymer electrolyte membrane 12, and the electrolyte caused by the high temperature. Breakage of the membrane can be prevented.

  As described above, according to the power supply body and the electrolysis cell described above, the separation distance between the nuggets is determined by the contact resistance value between the expanded meshes 2a to 2g and the in-plane resistance value of each of the expanded meshes 2a to 2g. Therefore, even if the current flows in the expanded meshes 2a to 2g and the current concentrates on any nugget, the current does not reach the other nuggets, and the expanded meshes 2a to 2g The current is distributed in the plane. Further, between the solid polymer electrolyte membrane 12 and the power feeder 1, that is, the expanded meshes 2a to 2g, current diffusion members 13a and 13b having in-plane resistance values smaller than the in-plane resistance values of the expanded meshes 2a to 2g are provided. By disposing, the current spreading members 13a and 13b function as a buffer material, and the current is sufficiently diffused in the plane of the current spreading members 13a and 13b. Therefore, heat can be prevented from flowing due to the current flowing from the power supply 1 to the solid polymer electrolyte membrane 12 and the current being locally concentrated to increase the current density. That is, since the local high temperature is prevented from reaching the solid polymer electrolyte membrane 12, it is possible to prevent the solid polymer electrolyte membrane 12 from being damaged due to the high temperature.

  In the above-described embodiment, the configuration in which the power feeding body is provided on both the anode side and the cathode side of the electrolytic cell has been described. However, the present invention is not limited to this, and the power feeding body for electrolysis cell according to the present embodiment is used as the anode side or the cathode. It is good also as a structure provided in either one of the sides. In this case, for example, a carbon fiber sintered body 15 can be provided in place of the cathode-side power feeder as in the example shown in FIG. In the example of FIG. 4, a 0.1 mm photoetching mesh 16 for height adjustment is provided between the carbon fiber sintered body 15 and the separator 11b, and carbon is interposed between the carbon fiber sintered body 15 and the electrolyte membrane. The paper 17 is provided.

DESCRIPTION OF SYMBOLS 1 Electric power feeder 2a-2g for electrolytic cells Expanded mesh 10 Electrolytic cells 11a, 11b Separator 12 Solid polymer electrolyte membrane 13a, 13b Current diffusion member 14 Photoetching mesh 15 Carbon fiber sintered body 16 Photoetching mesh 17 Carbon paper

Claims (6)

Provided with a plurality of metal plates formed in a net shape and stacked on each other,
The power feeding body for an electrolytic cell, wherein each of the adjacent metal plate materials is spot-welded individually, and the minimum separation distance between the nuggets by the spot welding is defined by the following equation (1).

Here, r is the minimum distance between the nugget, R ₁₂ is the contact resistance between the metal plate, the R _P is a plane resistance value of the metal plate.   The power feeding body for electrolytic cells according to claim 1, wherein a minimum separation distance between nuggets of the different metal plates is defined by Formula 1.   The power supply body for electrolytic cells according to claim 1 or 2, wherein a minimum separation distance between nuggets of the same metal plate is defined by Formula 1. A pair of separators;
An electrolyte membrane provided between the pair of separators and having electrodes formed on both sides;
Provided between the separator and the electrolyte membrane, comprising a plurality of metal plate members that are formed in a net shape and stacked on each other,
An electrolytic cell in which each of the adjacent metal plate materials is spot-welded individually, and the minimum separation distance between the nuggets by the spot welding is defined by the following equation (2).

Here, r is the minimum distance between the nugget, R ₁₂ is the contact resistance between the metal plate, the R _P is a plane resistance value of the metal plate.   The electrolytic cell according to claim 4, wherein current spreading means having an in-plane resistance value smaller than an in-plane resistance value of the metal plate material is disposed between the electrolyte membrane and the metal plate material. 6. The electrolytic cell according to claim 5, wherein spot welding is not performed at a central portion where water electrolysis reaction of the current spreading means is performed.

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