JP2010053401A - Separator for electrolyzer and method for manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enhance the porosity satisfactorily while sustaining high strength and to inexpensively obtain a separator for an electrolyzer by reducing the number of components. <P>SOLUTION: An anode side separator 34 is unified with an anode side power feed body 54. The anode side power feed body 54 includes: a flow passage layer 54a forming a first flow passage 56; an intermediate layer 54b which is provided on the flow passage layer 54a and formed to have pores finer than those of the flow passage layer 54a; and a membrane support layer 54c which is provided on the intermediate layer 54b, formed to have pores finer than those of the intermediate layer 54b, and brought into contact with a solid polymer electrolyte membrane 38. The flow passage layer 54a, the intermediate layer 54b and the membrane support layer 54c are successively formed in the anode side separator 34 by low pressure plasma spraying. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a separator for an electrolysis apparatus in which a porous conductor used as a power feeding body for electrolysis is integrated, and a manufacturing method thereof.

  For example, an electrolyte membrane / electrode structure in which an anode electrode and a cathode electrode each having an electrode catalyst layer and a gas diffusion layer are disposed on both sides of an electrolyte membrane made of a polymer ion exchange membrane is sandwiched by separators. Solid polymer fuel cells are known.

  In this type of fuel cell, a fuel gas (a gas mainly containing hydrogen, for example, hydrogen gas) is supplied to the anode side electrode, while an oxidant gas (a gas mainly containing oxygen, for example, a hydrogen gas) is supplied to the cathode side electrode. , Air) is supplied to obtain direct current electric energy.

  In general, a water electrolysis apparatus is employed to produce hydrogen gas that is a fuel gas. This water electrolysis apparatus uses a solid polymer electrolyte membrane in order to decompose water and generate hydrogen (and oxygen). Electrode catalyst layers are provided on both sides of the solid polymer electrolyte membrane to form an electrolyte membrane / electrode structure, and a power feeder is provided on both sides of the electrolyte membrane / electrode structure. It is configured. That is, the unit is configured substantially in the same manner as the above fuel cell.

  Therefore, in a state where a plurality of units are stacked, a voltage is applied to both ends in the stacking direction, and water is supplied to the anode-side power feeding body. For this reason, water is decomposed and hydrogen ions (protons) are generated on the anode side of the electrolyte membrane / electrode structure, and the hydrogen ions permeate the solid polymer electrolyte membrane and move to the cathode side to bond with electrons. Thus, hydrogen is produced. On the other hand, on the anode side, oxygen produced together with hydrogen is discharged from the unit with excess water.

  As said electric power feeder, as disclosed by patent document 1, for example, it is the electric power feeder for water electrolysis cells used by arranging on both sides of a membrane electrode assembly, and titanium is used in an inert gas atmosphere. There has been known one made of a titanium fiber sintered plate in which the surface in contact with the membrane electrode assembly is smoothed by plasma spraying.

Japanese Patent Application Laid-Open No. 11-302891

  By the way, the anode-side separator has a flow path and a power supply body installation portion, and the membrane contact surface of the separator is smooth with the power supply body (membrane electrode assembly) laminated on the power supply body installation portion. It is configured to be.

  However, since the process of laminating the power feeding body on the separator is necessary, there is a problem that the entire laminating process of the unit is complicated and the working efficiency is lowered. In addition, it is necessary to prevent a step and a gap from being generated on the film contact surface of the separator in a state where the power feeder is laminated on the separator. As a result, the processing accuracy of the power supply installation portion of the separator and the processing accuracy of the power supply must be kept high, resulting in a problem that the manufacturing cost increases.

  The present invention solves this type of problem, and it is possible to optimally control the porosity while maintaining high strength, and to reduce the number of parts and obtain it economically, and its separator An object is to provide a manufacturing method.

  The present invention relates to a separator for an electrolytic device in which a porous conductor used as a power feeding body for electrolysis is integrated, and a manufacturing method thereof.

  The porous conductor is formed on the first porous layer communicating with the liquid manifold through which the electrolyzing liquid is circulated, and is formed on the first porous layer so as to be more porous than the first porous layer. The first porous layer and the second porous layer are integrally formed on the separator by thermal spraying, and at least two layers including a second porous layer in contact with the electrolyte membrane are set. .

  The porous conductor is molded by thermal spraying between the first porous layer and the second porous layer, and has a pore smaller than the first porous layer and the second porous layer. It is preferable to include a third porous layer that is set to have larger pores than the porous layer.

  Furthermore, the first porous layer is molded using a spherical titanium powder as a thermal spray material, while the second porous layer is molded using a spherical titanium powder finer than the spherical titanium powder as a thermal spray material. Is preferred.

  Furthermore, the thermal spraying is preferably low-pressure plasma spraying.

  The second porous layer is preferably subjected to a plating process.

  Furthermore, the method for manufacturing a separator includes a step of spraying the separator with a first porous layer communicating with a liquid manifold through which an electrolysis liquid is circulated, and the first porous layer on the first porous layer. And a step of forming the second porous layer in contact with the electrolyte membrane by thermal spraying, which is set to be more pores than the one porous layer.

  According to the present invention, the porous conductor includes at least the first and second porous layers, and the first and second porous layers are formed on the separator by thermal spraying. A conductor) is integrated with the separator. Therefore, the number of parts is reduced as compared with the case where a power feeding body is separately manufactured, and it is not necessary to maintain the processing accuracy of the power feeding body installation portion of the separator and the processing accuracy of the power feeding body high.

  Moreover, since the first and second porous layers are formed on the separator by thermal spraying, a large amount of heat is not applied to the separator as compared with, for example, sintering. For this reason, it can prevent reliably that a separator heat-deforms.

  Thereby, while maintaining high strength, the porosity can be optimally controlled, and the number of parts can be reduced and an economical power supply integrated separator can be obtained easily and reliably.

  FIG. 1 is a perspective explanatory view of a water electrolysis device 10 to which a separator for an electrolysis device manufactured by a manufacturing method according to an embodiment of the present invention is applied, and FIG. 2 is a partial cross-sectional side view of the water electrolysis device 10 FIG.

  The water electrolysis apparatus 10 includes a stacked body 14 in which a plurality of unit cells 12 are stacked in the horizontal direction (arrow A direction). At one end in the stacking direction of the stacked body 14, a terminal plate 16a, an insulating plate 18a, and an end plate 20a are sequentially disposed outward. Similarly, a terminal plate 16b, an insulating plate 18b, and an end plate 20b are sequentially disposed on the other end in the stacking direction of the stacked body 14 toward the outside.

  The water electrolysis apparatus 10 integrally clamps and holds between the end plates 20a and 20b via a plurality of tie rods 22 extending in the direction of arrow A, for example. The water electrolysis apparatus 10 may employ a configuration in which the water electrolysis apparatus 10 is integrally held by a box-like casing (not shown) including end plates 20a and 20b configured as squares as end plates. Moreover, the water electrolysis apparatus 10 can be set to various shapes such as a cylindrical shape in addition to a cubic shape.

  As shown in FIG. 1, terminal portions 24a and 24b are provided on the side portions of the terminal plates 16a and 16b so as to protrude outward. The terminal portions 24a and 24b are electrically connected to the power source 28 via the wirings 26a and 26b. The terminal part 24 a on the anode (anode) side is connected to the positive pole of the power supply 28, while the terminal part 24 b on the cathode (cathode) side is connected to the negative pole of the power supply 28.

  As shown in FIGS. 2 and 3, the unit cell 12 includes an electrolyte membrane / electrode structure 32, and an anode separator 34 and a cathode separator 36 that sandwich the electrolyte membrane / electrode structure 32. The anode side separator 34 and the cathode side separator 36 are made of, for example, a carbon member or the like, or a steel plate, a stainless steel plate, a titanium plate, an aluminum plate, a plated steel plate, or a metal surface thereof is subjected to a surface treatment for corrosion prevention. The metal plate is formed by press-forming or cutting and then performing anticorrosion surface treatment.

  The electrolyte membrane / electrode structure 32 includes, for example, a solid polymer electrolyte membrane 38 in which a perfluorosulfonic acid thin film is impregnated with water, and one surface of the solid polymer electrolyte membrane 38 (a surface facing the cathode separator 36). ) Provided on the cathode side.

  An anode electrode catalyst layer 44 a and a cathode electrode catalyst layer 44 b are formed on both surfaces of the solid polymer electrolyte membrane 38. The anode electrode catalyst layer 44a uses, for example, a Ru (ruthenium) -based catalyst, while the cathode electrode catalyst layer 44b uses, for example, a platinum catalyst.

  One end edge of the unit cell 12 in the arrow B direction (horizontal direction in FIG. 3) communicates with each other in the arrow A direction, which is the stacking direction, to supply water (pure water) (liquid) Manifold) 46 is provided. The other end edge of the unit cell 12 in the direction of arrow B communicates with each other in the direction of arrow A, and a discharge communication hole (liquid manifold) 48 for discharging oxygen generated by the reaction and used water, Hydrogen flow communication holes 50 for flowing hydrogen generated by the reaction are arranged in the direction of arrow C.

  As shown in FIGS. 3 to 5, a supply passage 52 a communicating with the supply communication hole 46 and a discharge passage communicating with the discharge communication hole 48 are provided on the surface 34 a of the anode separator 34 facing the electrolyte membrane / electrode structure 32. 52b. The anode side power feeding body 54 laminated on the solid polymer electrolyte membrane 38 is integrated with the surface 34a.

  As shown in FIG. 5, the anode-side power feeder 54 includes a flow path layer (first porous layer) 54a that forms a first flow path 56 that communicates with the supply passage 52a and the discharge passage 52b, and the flow path layer. An intermediate layer 54b provided on the intermediate layer 54b and provided on the intermediate layer 54b, and provided on the intermediate layer 54b. The solid polymer is provided on the intermediate layer 54b. And a membrane support layer (second porous layer) 54c in contact with the electrolyte membrane 38.

  As will be described later, the flow path layer 54a, the intermediate layer 54b, and the membrane support layer 54c are sequentially formed on the surface 34a of the anode-side separator 34 by, for example, low-pressure plasma spraying using pure titanium particles as a spraying material. The porosity of each layer is set within a range of 10% to 50%. The intermediate layer 54b may be provided as necessary, and preferably has at least first and second porous layers.

  As shown in FIG. 3, for example, a second flow path 58 extending in the direction of arrow B is formed on the surface 36 a of the cathode separator 36 facing the electrolyte membrane / electrode structure 32. The second flow path 58 is provided within a range corresponding to the surface area of the cathode power supply body 42 and communicates with the hydrogen flow communication hole 50. The other surface 36b of the cathode side separator 36 is configured to be flat.

  The seal members 60a and 60b are integrated with each other around the outer peripheral ends of the anode side separator 34 and the cathode side separator 36. The seal members 60a and 60b include, for example, EPDM, NBR, fluorine rubber, silicone rubber, fluorosilicone rubber, butyl rubber, natural rubber, styrene rubber, chloroprene, acrylic rubber, or other seal materials, cushion materials, or packing materials. Used.

  As shown in FIG. 1, pipes 62 a, 62 b and 62 c communicating with the supply communication hole 46, the discharge communication hole 48, and the hydrogen flow communication hole 50 are connected to the end plate 20 a.

  Next, an operation of integrally manufacturing the anode-side power feeding body 40 on the surface 34a of the anode-side separator 34 will be described along the flowchart shown in FIG. The cathode side power supply 42 may be manufactured in the same manner as the anode side power supply 54.

  First, as shown in FIG. 7, a pure titanium or titanium alloy plate 64 that serves as a base of the anode-side separator 34 is manufactured by cutting or casting (step S1). A supply communication hole 46, a discharge communication hole 48, and a hydrogen flow communication hole 50 are formed through the plate 64, and a supply passage 52 a that communicates with the supply communication hole 46 and a discharge that communicates with the discharge communication hole 48. A passage 52b is provided. Further, the plate 64 is formed with a thermal spray recess 66 in communication with the supply passage 52a and the discharge passage 52b.

  Next, as shown in FIG. 8, the channel layer 54a, the intermediate layer 54b, and the membrane support layer 54c are sprayed in this order in the recess 66 of the plate 64. This thermal spraying process is a low-pressure plasma spraying process. Specifically, as shown in FIG. 9, a plate 64 is disposed in the vacuum chamber 70, and in this vacuum chamber 70, the thermal spray gun 72 is applied to the plate 64. opposite. The spray gun 72 is provided with a powder material inlet 74, a working gas inlet 76, a cooling water inlet 78a and a cooling water outlet 78b.

  Therefore, in the vacuum chamber 70, spherical titanium powder (pure titanium particles) 80 is supplied from the powder material inlet 74 of the spray gun 72, and an inert gas such as argon or helium is supplied from the working gas inlet 76. In this state, a plasma jet is generated, and the spherical titanium powder 80 is charged therein, whereby the molten particles of the spherical titanium powder 80 are sprayed onto the concave portions 66 of the plate 64.

  At this time, since plasma spraying is performed in a vacuum or in an inert gas, an oxide film is not formed on the surface of the titanium particles. Therefore, film formation is performed in a low melting state, and the porous flow path layer 54a having a porosity set within a range of 10% to 50% is reliably formed. The flow path layer 54a is set to a particle size of 150 μm or more, for example.

  Furthermore, on the flow path layer 54a, the intermediate layer 54b set to have a pore (for example, a particle diameter of 45 μm to 150 μm) is sprayed more than the flow path layer 54a in the same manner as described above. On the intermediate layer 54b, a membrane support layer 54c set to have a pore (particle diameter of 45 μm or less) than the intermediate layer 54b is sprayed.

  When the thermal spraying process ends, the process proceeds to step S3, and the surface of the film support layer 54c is subjected to a smoothing process by grinding or cutting (see FIG. 10). In this smoothing process, clogging occurs due to grinding or the like, and an etching process is performed after the smoothing process (step S4).

  Specifically, a mixed solution of 10 ml of nitric acid, 10 ml of 10% hydrofluoric acid and 180 ml of pure water is used as an etching solution, and etching is performed at room temperature with an etching time of 90 seconds. Note that the smoothing process and the etching process may be performed as necessary, and may be deleted.

  Next, after the cleaning and activation processes are performed, the process proceeds to step S5, and the membrane support layer 54c is subjected to, for example, a plating process using platinum (Pt). Thereby, the anode side separator 34 with which the anode side electric power feeding body 54 was integrated is manufactured.

  The operation of the water electrolysis apparatus 10 configured as described above will be described below.

  As shown in FIG. 1, water is supplied from a pipe 62a to the supply communication hole 46 of the water electrolysis apparatus 10, and via a power supply 28 electrically connected to the terminal portions 24a and 24b of the terminal plates 16a and 16b. Voltage is applied. Therefore, as shown in FIG. 5, in each unit cell 12, water is supplied from the supply communication hole 46 to the first flow path 56 formed in the flow path layer 54 a of the anode power feeding body 54 of the anode separator 34. The water moves along the anode-side power feeding body 54.

  Accordingly, water is decomposed by electricity in the anode electrode catalyst layer 44a, and hydrogen ions, electrons, and oxygen are generated. Hydrogen ions generated by this anodic reaction permeate the solid polymer electrolyte membrane 38 and move to the cathode electrode catalyst layer 44b side, and combine with electrons to obtain hydrogen (see FIG. 3).

  For this reason, hydrogen flows along the second flow path 58 formed between the cathode side separator 36 and the cathode side power supply body 42. This hydrogen is maintained at a high pressure and can flow out of the water electrolysis apparatus 10 through the hydrogen flow communication hole 50. On the other hand, oxygen generated by the reaction and used water flow in the first flow path 56, and these are discharged to the outside of the water electrolysis apparatus 10 along the discharge communication hole 48.

  In this case, in this embodiment, as shown in FIG. 5, the anode-side power feeding body 54 is integrated with the anode-side separator 34 by a low-pressure plasma spraying process. Specifically, the anode side having the flow path layer 54a, the intermediate layer 54b, and the membrane support layer 54c is sprayed on the plate 64 while inclining a spherical titanium powder having a small particle diameter from a spherical titanium powder having a large particle diameter. The anode separator 34 in which the power feeding body 54 is integrated is produced.

  At that time, the flow path layer 54a having a large particle diameter functions to form the first flow path 56 and diffuse water to the electrolysis surface, and collect generated oxygen and unreacted water to be discharged out of the system. Can have.

  In addition, the membrane support layer 54 c having a small particle diameter has a dense opening and can have a function of supporting the solid polymer electrolyte membrane 38 against the high-pressure hydrogen gas in the second flow path 58. For example, the tensile stress acting on the solid polymer electrolyte membrane 38 is satisfactorily reduced by setting the particle size of the membrane support layer 54c to a particle size of 1/2 or less of the solid polymer electrolyte membrane 38.

  Furthermore, the intermediate layer 54b having an intermediate particle size can have a function of preventing an increase in the pressure loss of the flow path layer 54a due to small particles entering the gaps between the large particles. Note that the intermediate layer 54b may not be required depending on the combination of the large diameter particles and the small diameter particles.

  The particle size of each titanium particle used in the flow path layer 54a, the intermediate layer 54b, and the membrane support layer 54c is appropriately determined according to the required flow rate of water, the amount of oxygen generated, the pressure on the second flow path 58 side, and the like. Selected.

  As described above, in the present embodiment, the anode-side power feeder 54 is integrally formed with the anode-side separator 34 by thermal spraying. For this reason, compared with the case where the anode side power feeding body 54 is separately manufactured, the number of parts is reduced, and it is not necessary to maintain the processing accuracy of the power feeding body installation portion of the anode separator 34 and the processing accuracy of the power feeding body high. .

  Moreover, since the flow path layer 54a, the intermediate layer 54b, and the membrane support layer 54c are formed on the anode separator 34 by thermal spraying, for example, a larger amount of heat is applied to the anode separator 34 than in the case of sintering. There is no. Therefore, it is possible to prevent the anode-side separator 34 from being thermally deformed as much as possible, and there is an advantage that water electrolysis can be performed satisfactorily.

  As a result, the feeder-integrated anode-side separator 34 can maintain the high strength and optimally control the porosity, and can reduce the number of components and can be obtained economically.

  In addition, although this embodiment demonstrated using the water electrolysis apparatus 10, it is not limited to this, It can apply to various electrolysis apparatuses.

It is a perspective explanatory view of a water electrolysis device to which a separator for electrolysis devices manufactured by a manufacturing method concerning an embodiment of the present invention is applied. It is a partial cross section side view of the water electrolysis device. It is a disassembled perspective explanatory drawing of the unit cell which comprises the said water electrolysis apparatus. It is front explanatory drawing of the anode side separator which comprises the said unit cell. FIG. 5 is a cross-sectional view of the anode separator taken along line VV in FIG. 4. It is a flowchart explaining the said manufacturing method. It is explanatory drawing of the plate used as a base. It is explanatory drawing at the time of spraying to the said plate. It is explanatory drawing of a thermal spraying process. It is explanatory drawing of a smoothing process.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Water electrolysis apparatus 12 ... Unit cell 14 ... Laminated body 16a, 16b ... Terminal plate 18a, 18a ... Insulation plate 20a, 20b ... End plate 24a, 24b ... Terminal part 28 ... Power supply 32 ... Electrolyte membrane and electrode structure 34 ... Anode-side separator 36 ... Cathode-side separator 38 ... Solid polymer electrolyte membrane 40 ... Anode feeder 42 ... Cathode-side feeder 44a ... Anode electrode catalyst layer 44b ... Cathode electrode catalyst layer 46 ... Supply communication hole 48 ... Discharge communication hole 50 ... Hydrogen flow communication hole 54... Anode-side power supply 54 a... Channel layer 54 b .. intermediate layer 54 c .. membrane support layer 56, 58.

Claims (10)

A separator for an electrolysis device that is in contact with an electrolyte membrane and is integrated with a porous conductor used as a power supply for electrolysis,
The porous conductor includes a first porous layer that communicates with a fluid manifold through which electrolysis liquid is circulated;
A second porous layer that is molded on the first porous layer, is set to be more pores than the first porous layer, and is in contact with the electrolyte membrane;
Comprising at least two layers
The separator for an electrolytic device, wherein the first porous layer and the second porous layer are integrally formed with the separator by thermal spraying.   2. The separator according to claim 1, wherein the porous conductor is formed by thermal spraying between the first porous layer and the second porous layer, and moreover than the first porous layer. A separator for an electrolysis apparatus, comprising a third porous layer that is also pores and has a larger pore than the second porous layer. The separator according to claim 1 or 2, wherein the first porous layer is formed using a spherical titanium powder as a thermal spray material,
The separator for an electrolysis apparatus, wherein the second porous layer is formed by using a spherical titanium powder having a particle diameter smaller than that of the spherical titanium powder as a thermal spray material.   The separator according to any one of claims 1 to 3, wherein the thermal spraying is low-pressure plasma spraying.   5. The separator according to claim 1, wherein the second porous layer is subjected to a plating treatment. 6. A manufacturing method of a separator for an electrolysis device in which a porous conductor used as a power feeding body for electrolysis is integrated with an electrolyte membrane,
Forming a first porous layer communicating with a liquid manifold through which electrolysis liquid is circulated in the separator by thermal spraying;
On the first porous layer, the step of forming a second porous layer that is set to be smaller than the first porous layer and is in contact with the electrolyte membrane by thermal spraying;
The manufacturing method of the separator for electrolyzers characterized by having.   The manufacturing method according to claim 6, wherein the first porous layer and the second porous layer are more porous than the first porous layer and more than the second porous layer between the first porous layer and the second porous layer. A method for manufacturing a separator for an electrolysis device, comprising: forming a third porous layer having a large pore size by thermal spraying. The manufacturing method according to claim 6 or 7, wherein the first porous layer is formed using a spherical titanium powder as a thermal spray material,
The method for manufacturing a separator for an electrolysis device, wherein the second porous layer is formed by using a spherical titanium powder finer than the spherical titanium powder as a thermal spray material.   The manufacturing method according to any one of claims 6 to 8, wherein the thermal spraying is low pressure plasma spraying.   10. The manufacturing method according to claim 6, wherein the second porous layer is plated. 10.

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