JP2009043690A - Fuel cell porous member, fuel cell using the same, and fuel cell porous member manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel cell porous member for compatibly attaining improved gas permeability (less pressure loss) and improved collecting efficiency, resulting that a solid polymeric fuel cell has improved generating efficiency and output, and to provide its manufacturing method and the fuel cell using the fuel cell porous member. <P>SOLUTION: The fuel cell porous member comprises a pore layer arranged on the surface of a metal porous body and including a conductive particle part formed of conductive particles accumulated on the surface of the metal porous body. The existence of the conductive particle part reduces the electronic resistance of the pore layer and suitably smoothes the surface. As a result, the fuel cell porous member simultaneously attains both improved gas permeability (less pressure loss) and improved collecting efficiency. Thus, the fuel cell adopting the fuel cell porous member has improved generating efficiency and output density. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a porous member that can be used in a polymer electrolyte fuel cell, and more particularly to a porous member that can improve power generation efficiency and output density of a polymer electrolyte fuel cell. The present invention also relates to a solid polymer fuel cell using such a porous member, and a method for producing the porous member.

  A unit cell of a polymer electrolyte fuel cell has a configuration in which a solid polymer electrolyte membrane is sandwiched between an anode electrode (fuel electrode) and a cathode electrode (oxidant electrode), and fuel gas supplied to the anode electrode Power generation is performed by electrochemically reacting (for example, hydrogen) and an oxidant gas (for example, air) supplied to the cathode electrode.

  Specifically, as a result of the following electrode reactions that occur at the anode electrode and the cathode electrode, the unit cell of the polymer electrolyte fuel cell, as a whole, undergoes water generation reaction with hydrogen and oxygen to generate electromotive force. appear.

Anode electrode: H ₂ → 2H ⁺ + 2e ⁻
Cathode electrode: (1/2) O ₂ + 2H ⁺ + 2e ⁻ → H ₂ O

  An electrode (anode electrode, cathode electrode) in such a polymer electrolyte fuel cell is generally a catalyst layer serving as a reaction field for electrode reaction, and a gas (fuel gas, Gas diffusion layers that diffuse (oxidant gas) into each catalyst layer (for example, Patent Documents 1 to 3).

  Here, Patent Documents 2 and 3 describe electrodes using a porous metal body as a gas diffusion layer. For example, Patent Document 2 is formed by laminating a metal porous body having a three-dimensional network structure and an organic porous film having water repellency as a porous member usable as a gas diffusion layer. The porous member in which the metal porous body is exposed on a part of the surface is described. Patent Document 3 describes a metal porous body in which a layer having a lower porosity than the central porosity is provided on the side in contact with the catalyst layer as a metal porous body that can be used as a gas diffusion layer. .

The electrode in which the gas diffusion layer is composed of a metal porous body is superior in gas permeability (gas supply property) and current collection compared to the case where the carbon porous body is a gas diffusion layer, and the output density of the fuel cell is improved. Can be improved.
JP-A-3-295176 JP 2003-272638 A JP2003-282068A

  However, in the porous member described in Patent Document 2, the current collection resistance depends on the inter-fiber distance (pitch) of the metal porous body. The increase in the porosity of the metal porous body is effective in improving gas permeability (suppressing gas pressure loss), but on the other hand, the distance between fibers is increased, and the current collecting resistance is reduced. Increase to lower current collection efficiency. Therefore, the porous member described in Patent Document 2 has a problem that it is difficult to achieve both improvement in gas permeability and improvement in current collection efficiency.

  Moreover, since the metal porous body described in patent document 3 is comprised by the low porosity in the layer which contacts the catalyst layer, current collection resistance can be reduced. However, on the other hand, since the whole metal porous body made of metal has hydrophilicity, naturally, the low porosity layer in contact with the catalyst layer also has hydrophilicity. For this reason, such a metal porous body is inferior in discharging of water generated in the catalyst layer, and there is a problem that a water film is easily formed in the pores of the metal porous body. When a water film is formed in the pores of the metal porous body, water stays in the pores, so that the gas permeability is deteriorated and the power generation performance of the fuel cell is lowered.

  On the other hand, unlike the metal porous body described in Patent Document 3, the metal porous body having a water-repellent pore layer formed on the surface discharges water generated in the catalyst layer to the metal porous body side. It is easy to suppress deterioration of gas permeability due to the formation of a water film. However, as the porosity of the metal porous body increases, the surface of the metal porous body becomes rougher. In general, the surface roughness is absorbed by increasing the thickness of the pore layer, and the surface of the pore layer (the surface on the side in contact with the catalyst layer) is smoothed.

  The water-repellent pore layer is caused by the hydrophobic resin (for example, polytetrafluoroethylene) as a component, and the electronic resistance increases as the thickness increases, thereby increasing the porosity of the metal porous body. In contrast, the electronic resistance increases and the current collection efficiency decreases. Therefore, although a metal porous body having a water-repellent pore layer formed on the surface has excellent water discharging properties, there is a problem that it is difficult to achieve both improved gas permeability and improved current collection efficiency. It was.

  The present invention has been made to solve the above-described problems, and can achieve both improvement in gas permeability (inhibition of pressure loss) and improvement in current collection efficiency. As a result, solid polymer fuel It aims at providing the porous member for fuel cells which can improve the power generation efficiency and output density of a battery. Another object of the present invention is to provide a polymer electrolyte fuel cell using the fuel cell porous member and a method for producing the fuel cell porous member.

  In order to achieve this object, the porous member for a fuel cell according to claim 1 is composed of a plate-like metal porous body made of conductive fibers and having a plurality of pores formed by a three-dimensional network structure; A porous layer having a large number of pores that are in contact with the surface side in the surface direction of the porous metal body, have conductivity and water repellency, and communicate with each other, and the porous layer is a surface of the porous metal body A conductive particle portion formed from conductive particles deposited on the surface side in the direction, and a plurality of pores formed from a material press-bonded to the metal porous body via the conductive particle portion and interconnected to each other And at least an organic porous part having water repellency.

  The porous member for a fuel cell according to claim 2 is the porous member for a fuel cell according to claim 1, wherein the conductive particle portion is deposited on a surface side in a surface direction of the metal porous body. A base composed of first conductive particles having a particle size larger than the pore size of the body, and further deposited in the height direction of deposition of the first conductive particles at the base, and having a particle size smaller than the pore size of the metal porous body And a surface portion composed of second conductive particles.

  The porous member for a fuel cell according to claim 3 is the porous member for a fuel cell according to claim 1 or 2, wherein the organic porous portion has water repellency and conductivity. It penetrates from the surface in the surface direction of the porous metal body to the depth corresponding to the diameter of the conductive fiber through the gap between the conductive particles constituting the particle part.

  5. The fuel cell according to claim 4, comprising a solid polymer electrolyte membrane, an anode catalyst layer containing a catalyst in contact with one of the solid polymer electrolyte membranes, and a catalyst in contact with the other of the solid polymer electrolyte membranes. A cathode catalyst layer, a surface of the cathode catalyst layer opposite to the surface in contact with the solid polymer electrolyte membrane, and a surface in contact with the solid polymer electrolyte membrane in the anode catalyst layer Is provided with the porous member for a fuel cell according to any one of claims 1 to 3, which is disposed on the opposite surface in contact with the pore layer.

  The manufacturing method according to claim 5 is a plate-like metal porous body made of conductive fibers having a hydrophilic surface and having a plurality of pores formed by a three-dimensional network structure, and a plane direction in the metal porous body A porous member for a fuel cell comprising a plurality of pore layers having electrical conductivity and water repellency and communicating with each other. Conductive particle deposition step of spreading and depositing conductive particles on the surface in the surface direction of the porous body, and the conductive particle portion formed by the deposition of the conductive particles by the conductive particle deposition step and at least water repellency A material capable of forming an organic porous part having a plurality of pores communicating with each other, and the pore layer configured to include the conductive particle part and the organic porous part and the metal Join the porous body And a bonding step that.

  According to a sixth aspect of the present invention, in the method for manufacturing a porous member for a fuel cell according to the fifth aspect, the conductive particle depositing step has a particle size that can be deposited on a surface in a surface direction of the metal porous body. A first deposition step of depositing one conductive particle to a predetermined thickness to form a base, and a second conductive particle having a particle size smaller than the pore diameter of the metal porous body after the formation of the base by the first deposition step Is further deposited to form a surface portion.

  The manufacturing method according to claim 7 is the method for manufacturing the porous member for a fuel cell according to claim 5 or 6, wherein the material has a plurality of pores communicating with each other and has water repellency and conductivity. A material capable of forming a porous portion, and in the joining step, a pressure height for controlling a penetration depth of the material that penetrates into the metal porous body through a gap between the conductive particles constituting the conductive particle portion. Use control means.

  According to the porous member for a fuel cell of the first aspect, the metal porous body is formed in a three-dimensional network structure from conductive fibers and has a large number of pores communicating with each other. Therefore, when the fuel cell porous member having such a metal porous body is adopted as a part of the fuel cell, that is, the fuel cell porous member having the metal porous body has a catalyst layer and a gas barrier property as a reaction field. When disposed between the conductive plate and the conductive plate, a large number of pores existing inside the porous metal body can function as gas (oxidant gas, fuel gas) flow paths.

  According to the porous member for a fuel cell according to claim 1, a pore layer having a large number of pores communicating with each other is formed on the surface side in the surface direction of the metal porous body. Here, such a pore layer was pressure-bonded to the metal porous body through the conductive particle portion formed from the conductive particles deposited on the surface side in the surface direction of the metal porous body. It includes a plurality of pores formed of a material and communicating with each other, and at least an organic porous portion having water repellency.

  When a porous member for a fuel cell having such a pore layer is adopted as a part of the fuel cell, electron transfer between the catalyst layer serving as a reaction field of the electrode reaction and the metal porous body is possible due to its conductivity. And In addition, due to the water repellency of the organic porous portion, water generated in the catalyst layer serving as a reaction field for the electrode reaction is easily moved (discharged) to the metal porous body side. Therefore, it is excellent in current collecting property and gas permeability (gas supply property), and when the porous member for a fuel cell having such a pore layer is adopted as a part of the fuel cell, the power generation efficiency of the fuel cell and The power density can be improved.

  Therefore, even if the porosity is increased to improve the gas permeability (reduction of pressure loss), the deterioration of the current collection efficiency that occurs contrary to the increase in the porosity is suppressed, so that the gas permeability can be improved. There is an effect that it is possible to simultaneously improve the current collection efficiency.

  According to the porous member for a fuel cell according to claim 2, in addition to the effect exhibited by the porous member for fuel cell according to claim 1, the following effect is exhibited. The conductive particle portion in the pore layer is deposited on the surface side in the surface direction of the metal porous body, and is composed of a first conductive particle having a particle diameter larger than the pore diameter of the metal porous body, and a first portion in the base portion. And a surface portion composed of second conductive particles deposited further in the height direction of the conductive particles. The second conductive particles are conductive particles having a particle size smaller than the pore size of the metal porous body.

  First, the 1st electroconductive particle which comprises a base absorbs the surface roughness of a metal porous body, and improves the electroconductivity of the thickness direction in a pore layer. And since the 2nd electroconductive particle which comprises a surface part is an electroconductive particle of a particle size smaller than the hole diameter of a metal porous body, the electrical connection of the surface direction of the electroconductive particle which comprises a base is reinforced, As a result, the conductivity in the surface direction in the pore layer is increased (resistance in the surface direction is reduced). Thus, according to the porous member for a fuel cell according to claim 2, the conductivity in the height direction and the surface direction in the pore layer can be improved.

  Moreover, since the surface part in the electroconductive particle part is comprised from the 2nd electroconductive particle of a particle size smaller than the hole diameter of a metal porous body, the electroconductive particle (mainly surface is mainly located in the surface of an electroconductive particle part. The pitch between the tops of the second conductive particles constituting the part is shorter than the distance between the fibers of the metal porous body. Therefore, the current collecting resistance is improved. Furthermore, since the second conductive particles having a small diameter constituting the surface portion are mainly arranged on the surface of the conductive particle portion, unevenness is hardly generated and the surface of the pore layer is preferably smoothed.

  Therefore, according to the porous member for a fuel cell according to claim 2, there is an effect that it is excellent in current collection efficiency and can increase the working area with the catalyst layer. By adopting such a porous member for a fuel cell as a part of the fuel cell, the power generation efficiency and output density of the fuel cell can be improved, which is useful for application to a fuel cell.

  In addition, since the first conductive particles constituting the base portion have a particle size larger than the pore size of the metal porous body, the conductive particles constituting the conductive particle portion (the first conductive particles and the first conductive particles). 2nd electroconductive particle deposited on the metal can be prevented from dropping through the pores of the metal porous body.

  According to the porous member for a fuel cell according to claim 3, in addition to the effect exhibited by the porous member for fuel cell according to claim 1 or 2, the following effect is exhibited. The organic porous part, which is part of the pore layer and has water repellency and conductivity, passes through the gap between the conductive particles constituting the conductive particle part, and the diameter of the conductive fiber from the surface in the plane of the metal porous body Since it penetrates to a considerable depth, sufficient contact can be ensured between the pore layer and the porous metal body.

  In addition, since the organic porous portion penetrates from the surface in the plane direction of the metal porous body to a depth corresponding to the diameter of the conductive fiber, the organic porous portion becomes a water path (water path) in the pore layer. Since the probability of contact between the pores and the surface of the conductive fiber that becomes the water path of the metal porous body can be increased, the communication of the water path between the pore layer and the metal porous body is increased, and the pore layer is liquid. It is possible to suitably prevent clogging with water.

  Therefore, according to the porous member for a fuel cell according to claim 3, the pore layer can suitably relay the electron transfer between the catalyst layer and the metal porous body, and the liquid water can be suitably transferred to the metal porous body side. Since it can discharge | emit, there exists an effect that the electric power generation efficiency and output efficiency of a fuel cell can be improved by employ | adopting this porous member for fuel cells as a part of fuel cell.

  Since the fuel cell according to claim 4 uses the porous member for fuel cell according to any one of claims 1 to 3, the porous member for fuel cell according to any one of claims 1 to 3 is used. Has the same effect as In particular, since the surface of the pore layer in the fuel cell porous member is suitably smoothed by the presence of the conductive particle layer, the area of action with the catalyst layer is increased and the catalyst utilization rate is improved. There is an effect that power generation efficiency and output density can be improved.

  According to the manufacturing method of claim 5 (a manufacturing method of a porous member for a fuel cell), a plurality of pores are formed by a three-dimensional network structure composed of conductive fibers having a hydrophilic surface by a conductive particle deposition step. It is formed by depositing conductive particles after spreading conductive particles on the surface in the planar direction of the plate-like metal porous body and depositing the conductive particles on the surface in the planar direction of the metal porous body. The conductive particle part and the material that can form an organic porous part having a plurality of pores having at least water repellency and communicating with each other are pressure-bonded by a joining process, and the conductive particle part and the organic porous part To obtain a joined body of a porous layer and a porous metal body.

  Here, conductive particles (for example, metal particles, particles provided with conductivity by metal coating, particles made of a conductive material, etc.) are deposited in advance on the surface in the surface direction of the metal porous body. The surface roughness of the metal porous body can be absorbed by the conductive particles, and as a result, the pore layer surface can be suitably smoothed. Therefore, even when the porosity of the metal porous body is increased, the surface of the pore layer can be smoothed without depending on the increase in the thickness of the organic porous portion that becomes the electronic resistance.

  Therefore, even if the porosity is increased to improve the gas permeability (reduction of pressure loss), the deterioration of the current collection efficiency that occurs contrary to the increase in the porosity is suppressed, so that the gas permeability can be improved. There is an effect that it is possible to simultaneously improve the current collection efficiency.

  In addition, since the conductive particles are deposited on the surface side of the metal porous body in the surface direction, there is an effect that the resistance in the thickness direction of the pore layer is reduced and the conductivity is increased.

  Therefore, since the porous member for a fuel cell manufactured by the manufacturing method according to claim 5 is excellent in current collection efficiency and gas permeability (gas supply property), the porous member for a fuel cell is used as a fuel cell. By adopting as a part, the power generation efficiency and output density of the fuel cell can be improved. Further, since the surface of the pore layer is smoothed, the working area (contact area) with the catalyst layer is increased, so that the catalyst utilization rate is improved. Also in this respect, the power generation efficiency and output density of the fuel cell are reduced. Can be improved. Therefore, it is useful for application to a fuel cell.

  According to the manufacturing method of claim 6 (manufacturing method of the porous member for a fuel cell), in addition to the effect of the manufacturing method of claim 5, the following effect is obtained. In the case where conductive particles are deposited on the surface in the surface direction of the metal porous body by the conductive particle deposition step, first, the first particle size of the first particle size that can be deposited on the surface of the metal porous body in the surface direction is deposited. After the conductive particles are deposited to a predetermined thickness to form the base, the second deposition step further deposits second conductive particles having a particle size smaller than the pore size of the metal porous body to form the surface portion. Do.

  Here, the first conductive particles, which are first dispersed by the first deposition step and form the base formed on the surface side in the surface direction of the metal porous body, absorb the surface roughness of the metal porous body and The conductivity in the thickness direction in the pore layer is increased. On the other hand, since the surface portion formed by the second deposition step performed after the first deposition step is composed of the second conductive particles having a particle size smaller than the pore size of the metal porous body, the conductive portion constituting the base portion is formed. The electrical connection in the surface direction of the conductive particles is reinforced, and as a result, the surface conductivity in the pore layer is increased (resistance in the surface direction is reduced). Therefore, according to the porous member for a fuel cell manufactured by the manufacturing method according to the sixth aspect, the conductivity in the height direction and the surface direction in the pore layer is excellent.

  In addition, since the second conductive particles constituting the surface portion are conductive particles having a particle size smaller than the pore diameter of the porous metal body, the conductive particles located on the surface of the conductive particle portion (mainly the surface portion The pitch between the tops of the second conductive particles) can be made shorter than the distance between the fibers of the metal porous body, and the current collection resistance can be improved. Furthermore, since the second conductive particles having a small diameter constituting the surface portion are mainly arranged on the surface of the conductive particle portion, unevenness is hardly generated and the surface of the pore layer is preferably smoothed.

  Therefore, by dividing the conductive particle deposition step into two steps (first deposition step and second deposition step) according to the particle size of the conductive particles, the current collection efficiency can be improved and the catalyst can be improved. There is an effect that the active area with the layer can be increased. By adopting such a porous member for a fuel cell as a part of the fuel cell, the power generation efficiency and output density of the fuel cell can be improved, which is useful for application to a fuel cell.

  Further, the particle diameter of the first conductive particles dispersed in the first deposition step is the particle diameter that can be deposited on the surface side in the surface direction of the metal porous body, that is, the distance between fibers of the metal porous body (or the metal porous body). The diameter of the particle is approximately equal to or larger than the diameter of the pores of the body), or larger, the conductive particles constituting the conductive particle portion (the first conductive particles and the first conductive particles deposited on the first conductive particles). (2 conductive particles) can be prevented from dropping through the pores of the metal porous body.

  According to the manufacturing method (manufacturing method of the porous member for a fuel cell) according to claim 7, in addition to the effect exhibited by the manufacturing method according to claim 5 or 6, the following effect is achieved. In the joining process, when a metal porous body and a material that has a large number of interconnecting pores and can form an organic porous part having water repellency and conductivity are used, pressure bonding height control means is used. Then, the penetration depth of the material that penetrates into the porous metal body through the gap between the conductive particle layers is controlled.

  Therefore, the depth of penetration of the organic porous part, which is a part of the pore layer, from the surface of the metal porous body through the gap between the conductive particles constituting the conductive particle part is optimal. Therefore, the contact resistance between the pore layer and the metal porous body and the movement of water from the pore layer to the metal porous layer can be optimally controlled. As a result, the power generation efficiency and the output efficiency of the fuel cell can be improved by employing the porous member for a fuel cell manufactured by such a manufacturing method as a part of the fuel cell.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a schematic diagram showing a fuel cell system 1 including a fuel cell stack 50 including a single fuel cell 10 (hereinafter referred to as “fuel cell 10”) according to an embodiment of the present invention.

  The fuel cell system 1 is connected to a predetermined location (for example, the lower portion) of the fuel cell stack 50 via a fuel cell stack 50, a hydrogen tank 33, an air fan 34, and a circulation pump 36, which will be described later with reference to FIG. The radiator 37 is mainly composed.

  In this fuel cell system 1, the hydrogen tank 33 is a tank that stores fuel gas (hydrogen in this embodiment), and a fuel gas supply port 50 c in the fuel cell stack 50 (see FIG. 2) via the valve 32. It is connected to the. By opening the valve 32, the hydrogen stored in the hydrogen tank 33 can be supplied into the fuel cell stack 50.

  The air fan 34 takes in the oxidant gas (air in the present embodiment) from the outside and blows it to the oxidant supply port 50a (see FIG. 2), thereby supplying the oxidant gas into the fuel cell stack 50. Is.

  As will be described in detail later, the air fan 34 is operated to supply the oxidant gas to the oxidant supply port 50a. On the other hand, when the valve 32 is opened, the fuel gas is supplied from the hydrogen tank 33 to the fuel gas supply port 50c. Then, each fuel cell 10 (see FIG. 2) constituting the fuel cell stack 50 generates power.

  The fuel cell stack 50 collects electricity generated by each fuel cell 10 and can extract a direct current from current collecting terminals 50e and 50f (both of which are shown in FIG. 2) as current extraction units. The direct current extracted from the fuel cell stack 50 is supplied to a load 35 (for example, a motor of an automobile) electrically connected to the fuel cell stack 50, and as a result, the load 35 can be driven.

  FIG. 2 is a perspective view schematically showing a fuel cell stack 50 including the fuel cell 10 in the present embodiment. As shown in FIG. 2, the fuel cell stack 50 is a stacked body in which a plurality of fuel cells 10 to be described later are stacked in the direction of arrows XX.

  In the fuel cell stack 50, adjacent fuel cells 10 are composed of a conductive cathode-side separator 11 (see FIG. 3) in one fuel cell 10 and a conductive anode-side separator 12 (see FIG. 3) in the other fuel cell 10. Are electrically connected in series.

  In the fuel cell stack 50, an oxidant gas communicating with an oxidant gas flow path (not shown) formed in the fuel cell stack 50 is formed on the exposed surface of the fuel cell 10 located on the foremost side in FIG. 2. The supply port 50a is opened.

  The oxidant gas (air) taken from the outside by the operation of the air fan 34 (see FIG. 1) is supplied into the fuel cell stack 50 through the oxidant gas supply port 50a, and an oxidant gas flow path (not shown). To the upstream side of the cathode electrode 13 (see FIG. 3) of each fuel cell 10.

  Although not shown, the downstream end of the cathode electrode 13 (see FIG. 3) in the fuel cell stack 50 is exposed, and the oxidant gas supplied to the upstream side of the cathode electrode 13 is exposed. Is configured to be discharged from the exposed end to the outside.

  Further, a fuel gas communicating with a fuel gas flow path (not shown) formed inside the fuel cell stack 50 is formed on the exposed surface of the fuel cell 10 located on the most front side in the fuel cell stack 50 shown in FIG. A supply port 50b is formed. When the valve 32 (see FIG. 1) is opened, fuel gas is supplied from the hydrogen tank 33 (see FIG. 1) to the inside of the fuel cell stack 50 through the fuel gas supply port 50b, and passes through a fuel gas flow path (not shown). Then, it is supplied to the anode electrode 14 (see FIG. 3) of each fuel cell 10.

  On the other hand, the fuel communicated with a fuel gas flow path (not shown) formed inside the fuel cell stack 50 on the exposed surface of the fuel cell 10 located on the innermost side in the fuel cell stack 50 shown in FIG. A gas supply port 50c (shown by a hidden line on the front side because it is the back side of the fuel cell stack 50 in FIG. 2) is formed. The fuel gas supplied from the fuel gas supply port 50b to the inside of the fuel cell stack 50 is finally discharged from the fuel gas discharge port 50c.

  Therefore, each fuel cell 10 can generate electric power by supplying the oxidant gas and the fuel gas from the oxidant gas supply port 50a and the fuel gas supply port 50b to the inside of the fuel cell stack 50, respectively. As a result, a direct current can be taken out from the fuel cell stack 50. The fuel cell stack 50 is provided with current collecting terminals 50d and 50e at the top, and the current generated as a result of the power generation of each fuel cell 10 can be taken out as a direct current from these current collecting terminals 50d and 50e. .

  Next, the fuel cell 10 of the present embodiment will be described with reference to FIGS. 3 and 4. FIG. 3 is a schematic partial cross-sectional view showing the main part of the fuel cell 10.

  As shown in FIG. 3, the fuel cell 10 includes a solid polymer electrolyte membrane 15, a cathode electrode 13 and an anode electrode 14 disposed on both surfaces of the solid polymer electrolyte 15, and a pair of these electrodes 13 and 14. It is the laminated body comprised from the electroconductive cathode side separator 11 and the anode side separator 12 which were each distribute | arranged to the outer surface side.

  Examples of the solid polymer electrolyte membrane 15 include solid polymer electrolyte membranes applicable to solid polymer fuel cells such as Nafion (registered trademark: manufactured by DuPont) and Aciplex (registered trademark: manufactured by Asahi Kasei Corporation). Can be used.

  As shown in FIG. 3, the cathode electrode 13 is a porous electrode composed of a first porous body 23 that contacts the cathode-side separator 11 and a catalyst layer 33 that contacts the solid polymer electrolyte 15.

  The catalyst layer 33 is a layer that is brought into contact with the solid polymer electrolyte membrane 15 to promote an electrode reaction in the cathode electrode 13, and the catalyst layer of the anode electrode 14 that is in contact with the other surface of the solid polymer electrolyte membrane 15. Together with 14c, promotes the electrochemical reaction between oxygen and hydrogen. As the catalyst layer 33, for example, a catalyst layer configured to include a catalyst-supported carbon in which a catalyst such as platinum is supported on carbon particles and an electrolyte can be employed.

  As shown in FIG. 3, the first porous body 23 is formed on the first mesh member 23a that is in contact with the cathode-side separator 11 and on one surface (the left surface in FIG. 3) of the first mesh member 23a. And a plate-like member composed of a microporous layer (MPL) 23b in contact with the catalyst layer 33. Details of the first porous body 23 will be described later with reference to FIG.

  The anode electrode 14 is also a porous electrode similar to the cathode electrode 13 and includes a second porous body 24 that contacts the anode separator 12 and a catalyst layer 34 that contacts the solid polymer electrolyte 15. The catalyst layer 34 is a layer that is brought into contact with the solid polymer electrolyte membrane 15 and promotes an electrode reaction in the anode electrode 14. The catalyst layer 34 is configured similarly to the catalyst layer 33 of the cathode electrode 13.

  As shown in FIG. 3, the second porous body 24 is formed on the second mesh member 24 a that is in contact with the anode-side separator 12 and on one surface (the right-hand surface in FIG. 3) of the second mesh member 24 a. It is a plate-like member composed of the pore layer 24b in contact with the catalyst layer 34. The second porous body 24 is configured in the same manner as the first porous body 23 described later with reference to FIG.

  Here, with reference to FIG. 4A and FIG. 4B, the first porous body 23 will be described in more detail. 4A is a cross-sectional view schematically showing the first porous body 23 of the present embodiment, and FIG. 4B is an enlarged view schematically showing the structure of the E portion in FIG. 4A. It is.

  The first net member 23a is a plate-like member that is formed in a three-dimensional network structure from conductive fibers (conductive fibers) and has pores that communicate with each other. As this 1st net | network material 23a, the net | network material of thickness about 500-1500 micrometers comprised by the distance (pitch) between about 90 micrometers-130 micrometers is employable, for example. In addition, as a conductive fiber which comprises the 1st net | network material 23a, metal fibers which have corrosivity and electroconductivity, such as SUS, a tantalum, or hastelloy other than titanium fiber, and electroconductivity, such as nickel or carbon Fiber can be employed.

  By employing the first net member 23a having many holes communicating with each other as the cathode electrode 13, the holes function as a part of the flow path of the oxidizing gas (for example, air). That is, the cathode electrode 13 of this embodiment has both a function as a cathode electrode and a function as a gas flow path (oxidant gas flow path).

  Moreover, it is preferable that the 1st net | network material 23a has hydrophilic property on the surface of an electroconductive fiber. By configuring the first net member 23a from conductive fibers having a hydrophilic surface, water generated by the reaction is easily diffused in the thickness direction of the first net member 23a, and the pores of the first porous body 23 are formed. It is possible to prevent clogging with liquid water.

  The pore layer 23b is a layer having many pores communicating with each other as well as having conductivity and water repellency. As shown in FIG. 4B, the pore layer 23b in the present embodiment includes a metal particle portion 23b1 deposited on the surface of the first mesh material 23a, and the first mesh material 23a via the metal particle portion 23b1. The organic porous portion 23b2 is pressure-bonded to the organic porous portion 23b2.

  The metal particle portion 23b1 is formed on the base layer 23b11 formed by depositing the metal particles M1 on the surface of the first net member 23a and on the base layer 23b11 (that is, on the side opposite to the first net member 23a in the base layer 23b11). And a surface layer 23b12 formed by deposition. The metal particles M2 constituting the surface layer 23b12 are smaller than the metal particles M1 constituting the base layer 23b11 and smaller than the inter-fiber distance of the conductive fibers constituting the first net member 23a (or the pore diameter of the first net member 23a). It is a metal particle of a particle size.

  As described above, by forming the metal particle portion 23b1 on the surface of the first net member 23a, the resistance in at least the thickness direction (the deposition height direction of the metal particles M1 and M2) in the pore layer 23b is reduced and the conductive property is reduced. Increases nature.

  In particular, in the pore layer 23b in the present embodiment, the conductivity in the thickness direction of the pore layer 23b is improved by the large-diameter metal particles M1 (base layer 23b11) deposited on the surface of the first netting material 23a. In addition, the small-diameter metal particles M2 (surface layer 23b12) further deposited in the height direction of the metal particles M1 improve the surface conductivity in the pore layer 23b. Therefore, the pore layer 23b in the present embodiment has superior conductivity as compared with a conventional pore layer that does not include a metal particle portion.

  Further, since the metal particles located on the surface side of the pore layer 23b are mainly small-diameter metal particles M2 constituting the surface layer 23b12, the pitch of the metal particles located on the surface side of the pore layer 23b is set to The current collection resistance can be reduced and improved as compared with the inter-fiber distance (average distance between fibers) of the conductive fibers constituting one mesh material 23a.

  Furthermore, by forming the metal particle portion 23b1 on the surface of the first mesh material 23a, the surface roughness of the first mesh material 23a is absorbed, and the smoothness of the surface of the pore layer 23b is improved (improved). Can do. Therefore, even if the surface is roughened by increasing the porosity of the first mesh member 23a, the thickness of the pore layer 23b, in particular, the water-repellent organic porous portion 23b2 that provides electronic resistance. The surface of the pore layer 23b can be smoothed without depending on the increase in thickness.

  In general, the electronic resistance of the pore layer 23b increases as the thickness thereof increases. Therefore, by forming the metal particle portion 23b1 on the surface of the first net member 23a, the porosity of the first net member 23a is increased (that is, the gas permeability is improved) while suppressing an increase in electronic resistance. be able to. That is, it is possible to achieve both improvement in gas permeability and improvement in current collection efficiency.

  Further, since the smoothness of the surface of the pore layer 23b is improved by the presence of the metal particle portion 23b1, the contact area (working area) of the catalyst layer 33 is increased, so that the catalyst utilization rate can be improved. In particular, since the particle size of the metal particles M2 constituting the surface layer 23b12 is smaller than the particle size of the metal particles M1 constituting the base layer 23b11, the surface of the pore layer 23b is less likely to be uneven, and the pore layer 23b The surface is preferably smoothed.

  In addition, the particle size of the metal particles M1 constituting the base layer 23b11 is a particle size that can be deposited on the surface of the first mesh member 23a, that is, a particle size (pitch) between the fibers of the first mesh member 23a or more ( Alternatively, it is preferable to mainly use a hole diameter of the first net member 23a or larger. Alternatively, it is preferable that the particle diameter is approximately equal to or larger than the diameter of the pores of the first net member 23a.

  By setting the particle size of the metal particles M1 to a particle size greater than or equal to the inter-fiber distance of the first mesh member 23a, or a particle size approximately equal to or greater than the diameter of the pores of the first mesh member 23a, the metal particles M1. Functions as a seal for the pores of the first mesh member 23a, and the metal particles (metal particles M1, M2) constituting the metal particle layer 23a pass through the pores of the first mesh member 23a and drop off. Can be suppressed.

  Here, when the particle size of the metal particles M1 constituting the base layer 23b11 is about the distance between the fibers of the first mesh member 23a or the diameter of the pores, about half of one particle becomes the pores of the first mesh member 23a. Since the metal particles M1 can be fitted, the surface roughness of the first mesh member 23a is easily absorbed, and as a result, the surface of the first mesh member 23a can be suitably smoothed. Therefore, the particle size of the metal particles M1 is set to about the distance between fibers of the first mesh member 23a (average distance between fibers) or the diameter of the holes of the first mesh member 23a (average diameter of the holes). It is more preferable.

  As the metal particles M1 and M2 constituting the metal particle portion 23b1 (base layer 23b11, surface layer 23b12), particles made of various metals can be adopted, but when the first mesh member 23a is a mesh material made of metal fibers. The particles are preferably made of the same metal as the metal fiber. By making the metal particles M1 and M2 into particles made of the same type of metal as the metal fibers constituting the first netting material 23a, corrosion of the metal due to the oxidation-reduction potential difference between the metals can be prevented.

  The metal particles M1 and the metal particles M2 may be the same type of metal particles or different types of metal particles, but are preferably the same type of metal particles so that no redox potential difference occurs between the metals. .

  The organic porous part 23b2 is a porous body having many pores communicating with each other. In the present embodiment, for example, a porous body including carbon particles and PTFE (Polytetrafluoroethylene) is used as the organic porous portion 23b2. Therefore, the organic porous part 23b2 of the present embodiment has conductivity due to the carbon particles and water repellency due to PTFE. The pores in the organic porous portion 23b2 are pores smaller than the pores of the first net member 23a described above (for example, pores having a minimum inner diameter of about 0.01 μm to several μm).

  Therefore, the pore layer 23b moves the water in the catalyst layer 33 to the pore layer 23b by the water repellency of the organic porous portion 23b2 and the many pores that the organic porous portion 23b2 communicates with each other. In addition, while maintaining the catalyst layer 33 appropriately, the excess water is discharged out of the system, and the function of suppressing the electrochemical reaction in the catalyst layer 33 by water is suppressed.

  In addition, the pore layer 23b is formed from the catalyst layer 33 (see FIG. 3) serving as a reaction field of an electrochemical reaction (electrode reaction) from the metal particle portion 23b1 and the organic porous portion 23b2 to the first net member 23a. Takes the function of making it easy to move electrons. In particular, as described above, the pore layer 23b in the first porous body 23 of the present embodiment includes the metal particle portion 23b1, so that the conductivity in the height direction and the surface direction is improved, and excellent conductivity is achieved. Can be provided.

  Further, as shown in FIG. 4B, in the pore layer 23b, the organic porous portion 23b2 is disposed in a state where it penetrates the first netting material 23a by the penetration depth D through the gap between the metal particle portions 23b1. ing. Therefore, sufficient contact can be ensured between the organic porous portion 23b2 and the first net member 23a.

  Further, since the organic porous portion 23b2 has penetrated into the first netting material 23a by the penetration depth D, the pores of the organic porous portion 23b2 serving as the water path (water path) of the pore layer 23b, The contact probability of the surface of the conductive fiber that becomes the water path of the first net member 23a can be increased. Therefore, the water path communication between the pore layer 23b and the first net member 23a is enhanced, and as a result, the pore layer 23b (particularly, the organic porous portion 23b2) is blocked by the liquid water. It can suppress suitably.

  The penetration depth D of the organic porous portion 23b2 with respect to the first net member 23a is preferably about the fiber diameter of the conductive fibers constituting the first net member 23a (corresponding to the diameter of the conductive fibers) or more. By setting the penetration depth D to be at least about the fiber diameter of the conductive fibers constituting the first mesh member 23a (corresponding to the diameter of the conductive fibers), the organic porous portion 23b2 can conduct the first mesh member 23a. The surroundings of the conductive fiber can be covered, and sufficient contact can be ensured with the first netting material 23a (the conductive fiber). Further, sufficient water path communication and gas permeability are ensured between the pore layer 23b and the first net member 23a.

  On the other hand, as the penetration depth D of the organic porous portion 23b2 into the first net member 23a is shallower, the required thickness of the pore layer 23b is reduced, and the gas permeability of the pore layer 23b is improved. Therefore, the penetration depth D is particularly preferably about the fiber diameter of the conductive fibers constituting the first net member 23a.

  The pore layer 23b has a total thickness of about 50 to 300 μm including the thickness of the portion that has penetrated into (intruded into) the first netting material 23a, that is, the penetration depth D described above. Is preferred.

  In the first porous body 23, metal particles of the metal particle portion 23b1 (mainly metal particles M2 constituting the surface layer 23b11) are formed from the organic porous portion 23b2 on the surface on the catalyst layer 33 side of the pore layer 23b. Although it is preferable that it is exposed, the metal particle part 23b1 may be buried in the organic porous part 23b at a predetermined depth as necessary. By exposing the metal particles to the surface of the pore layer 23b, the contact resistance with the catalyst layer 33 can be reduced.

  Although the first porous body 23 has been described above, the second porous body 24 of the anode electrode 14 is also configured similarly to the first porous body 23. That is, in the description of the first porous body 23 described above, (1) “first porous body 23” is read as “second porous body 24”, and (2) “first net member 23a” is replaced with “second net”. (3) “pore layer 23b” as “pore layer 24b”, (4) “catalyst layer 33” as “catalyst layer 34”, (5) “cathode electrode” 13 ”is replaced with“ anode electrode 14 ”, and (6)“ oxidant gas ”is replaced with“ fuel gas ”.

  Further, the metal particle portion 23b1 (base layer 23b11, surface layer 12b12) and the organic porous portion 23b2 constituting the pore layer 23 of the cathode electrode 13 can be applied to the pore layer 24 of the anode electrode 14 as they are. That is, the pore layer 24 of the anode electrode 14 also has the same metal particle part (base layer and surface layer) and organic porous part as the pore layer 23 of the cathode electrode 13, and is the same as the pore layer 23. Furthermore, it is excellent in surface smoothness and conductivity.

  Next, a method for manufacturing the first porous body 23 and the second porous body 24 described above will be described with reference to FIGS. In the following, the manufacturing method of the first porous body 23 will be described, but the same applies to the manufacturing method of the second porous body 24.

  FIG. 5 is a process diagram showing a manufacturing flow of the first porous body 23. As shown in FIG. 5, when manufacturing the 1st porous body 23, the organic porous part preparation process which prepares the organic porous part 23b2 first is performed (S1).

  This organic porous part preparation process (S1) is comprised from a raw material mixing process (S1a), an organic porous part formation process (S1b), and a drying process (S1c). In the raw material mixing step (S1a), PTFE fine powder as a raw material for the organic porous portion 23b2 and carbon powder are charged at a predetermined ratio (for example, PTEF is about 20 to 60 parts by weight with respect to carbon). Then, the mixture (a material capable of forming the organic porous portion 23b2) is obtained by stirring with a stirrer such as a hybrid mixer for a predetermined time (for example, about 4 to 8 minutes).

  In the organic porous part forming step (S1b) performed next to the raw material mixing step (S1a), the mixture obtained in the raw material mixing step (S1a) is made of a SUS plate having a release sheet such as a polyimide sheet disposed on one side. Screen printing is performed thereon to form a sheet of the organic porous portion 23b2.

  In the drying step (S1c) performed after the organic porous portion forming step (S1b), the formed sheet of the organic porous portion 23b2 is subjected to hot air drying. Thus, since the fluidity | liquidity of the organic porous part 23b2 falls by drying the sheet | seat of the organic porous part 23b2 formed on the SUS board, the outflow of the organic porous part 23b2 can be prevented.

  After performing the organic porous part preparation process (S1) as described above, a metal particle spraying process is performed (S2). Here, with reference to FIG. 6, this metal particle dispersion | distribution process (S2) is demonstrated. Fig.6 (a) is a schematic diagram for demonstrating the 1st dispersion | distribution process (S2a) first performed in a metal particle dispersion | distribution process (S2), FIG.6 (b) is a 1st dispersion | distribution process (S2a). It is a mimetic diagram for explaining the 2nd spreading process (S2b) performed subsequently.

  As shown in FIG. 6A, in the first spraying step (S2a), the surface of the first net member 23a has a thickness of, for example, about one layer (that is, an extent that covers the surface of the first net member 23a). Thus, the metal particles M1 are sprayed to form the base layer 23b11.

  Here, the amount of metal particles M1 applied in the first application step (S2a) is preferably an amount in which the metal particles M1 deposited on the first netting material 23a are deposited in a thickness of about one layer or more. . By setting the thickness of the metal particles M1 deposited on the first mesh member 23a to about one layer or more, the metal particles M1 can sufficiently function as a seal against the pores of the first mesh member 23a, and the first Absorbing the surface roughness of one mesh material 23a contributes to smoothing the surface of the pore layer 23b.

  As shown in FIG. 6B, in the second spraying step (S2b), the surface of the base layer 23b11 formed in the first spraying step (S2a) is smoothed with metal particles M2 having a particle diameter smaller than that of the metal particles M1. The surface layer 23b12 is formed by spraying to such an extent that the surface metal particle layer 23b1 is obtained. In this second spraying step (S2b), the surface of the pore layer 23b can be suitably smoothed by spraying the metal particles M2 to such an extent that the metal particle layer 23b1 having a smooth surface can be obtained. .

  In addition, in this metal particle dispersion | distribution process (S2) and the process of handling the metal particle M1 and the metal particle M2, in order to suppress that an oxide film is formed on the surface of the metal particle M1 and the metal particle M2, atmospheric temperature Is kept at 150 ° C. or lower, or under an inert gas atmosphere such as nitrogen gas, if necessary. By handling the metal particles M1 and the metal particles M2 in an atmosphere in which the formation of an oxide film on the particle surface is suppressed, the growth of the oxide film can be suppressed and the increase in contact resistance due to the oxide film can be suppressed. be able to.

  Returning again to FIG. After performing a metal particle dispersion | distribution process (S2), a joining process is performed (S3). In this joining step (S3), the sheet of the organic porous portion 23b2 formed on the SUS plate in the organic porous portion preparation step (S1) and the metal particle portion 23b1 on the surface in the metal particle spraying step (S2). This is a step of crimping the first net member 23a.

  FIG. 7 is a schematic diagram for explaining the joining step (S3). In FIG. 7, the pore layer 23b is illustrated in a simplified manner. As shown in FIG. 7, in the joining step (S3), the first net member 23a having the metal particle portion 23b1 disposed on the surface (upper surface) is disposed and formed on the SUS plate from above the metal particle portion 23b1. The organic porous portions 23b2 are combined and subjected to pressure bonding (cold bonding) by applying a load from above the SUS plate to obtain a bonded body of the first netting material 23a and the pore layer 23b.

  As shown in FIG. 7, in this joining step (S3), a member whose height can be specified, such as a sizing guide 80, is used to control the overall height of the joined body. In this way, by controlling the height of the entire joined body using a member whose height can be specified, it is possible to prevent the first net member 23a from being excessively crushed by a load during crimping (joining). The penetration depth D (see FIG. 4) of the organic porous portion 23b2 into the one net member 23a and the entire thickness of the pore layer 23b can be reliably controlled.

  Returning again to FIG. After performing the joining step (S3), a PTFE melting and fixing step is performed (S4). In this PTFE melt-fixing step (S4), the joined body of the first netting material 23a and the pore layer 23b obtained in the joining step (S3) is subjected to heat treatment, and the pore layer 23b (organic porous portion 23b2). PTFE contained in is melted to fix the pore layer 23b. As a result of fixing the pore layer 23b, the first porous body 23 is obtained.

  In the PTFE melting and fixing step (S4), heat treatment is performed in a low oxygen atmosphere in order to suppress the formation and growth of oxide films on the surfaces of the metal particles M1 and the metal particles M2. For example, the joined body of the first net member 23a and the pore layer 23b is subjected to heat treatment at 345 ° C. for 2 hours in a nitrogen atmosphere of 10 Torr.

  When the first porous body 23 is produced according to the manufacturing flow shown in FIG. 5, next, catalyst-carrying carbon (for example, platinum-carrying carbon) and solid polymer are formed on the surface of the first porous body 23 on the pore layer 23b side. The catalyst layer 33 is formed by applying and drying a catalyst paste containing an electrolyte (for example, Nafion (registered trademark)) by screen printing. Thereby, the cathode electrode 13 which is a porous body electrode is obtained.

  The anode electrode 14 is produced in the same manner as the cathode electrode 13, the catalyst layers 33 and 34 are made to face each other, the solid polymer electrolyte membrane 15 is interposed between the catalyst layers 33 and 34, and pressure bonding is performed by hot pressing. A joined body of a pair of porous electrodes (cathode electrode 13 and anode electrode 14) and the solid polymer electrolyte membrane 15 is obtained.

  Then, the fuel cell 10 is obtained by sandwiching the joined body of the pair of porous electrodes (cathode electrode 13 and anode electrode 14) and the solid polymer electrolyte membrane 15 between the cathode side separator 11 and the anode side separator 12. It is done.

  Hereinafter, the present invention will be described in detail based on examples, but the present invention is not limited to the following examples.

  A titanium fiber sintered plate (distance between fibers: about 100 μm, thickness: about 1000 μm) formed from hydrophilic titanium fibers (fiber diameter: about 100 μm) is used as the first network material 23a and the second network material 24a. And the pore layer (in the case of the 1st porous body 23, the pore layer 23b) was formed in each one side, and the 1st porous body 23 and the 2nd porous body were obtained.

  As the metal particles M1 constituting the metal particle part of the pore layer (the metal particle part 23b1 in the case of the first porous body 23), titanium particles (Ti particles having a particle diameter of about 100 μm which is substantially equal to the interfiber distance) ) And titanium particles having a particle size of about ½ of the particle size of the metal particles M1 were used as the metal particles M2.

  Further, as a carbon powder constituting the organic porous part of the pore layer (organic porous part 23b2 in the case of the first porous body 23), the primary particle diameter of carbon is 30 μm, and the secondary particle diameter is the primary particle. What was about 30-50 times the diameter was used. The fine powder of PTFE was mixed at 35% by weight with respect to the carbon powder.

  The penetration depth D of the organic porous portion 23b2 with respect to the first net member 23a was set to about the fiber diameter (that is, about 100 μm) of the titanium fiber constituting the first net member 23a. The penetration depth D of the organic porous portion with respect to the second netting material was also the same. The total thickness of the pore layer (pore layer 23b in the case of the first porous body 23) was about 150 μm.

Here, with reference to FIG. 8, the IV performance of the fuel cell 10 employing the first porous body 23 and the second porous body 24 of the example is evaluated. FIG. 8 is a graph showing IV characteristics. In the graph of FIG. 8, the horizontal axis represents current I (unit: A / cm ² ) per unit area, and the vertical axis represents voltage (unit: V).

  In the graph of FIG. 8, the IV characteristic of the fuel cell 10 employing the first porous body 23 and the second porous body 24 of the example is represented by the symbol “■”. On the other hand, as a comparative example, the IV characteristic of a conventional fuel cell having a pore layer not including a metal particle portion is represented by the symbol “シ ン ボ ル”.

  As is apparent from the graph of FIG. 8, the voltage drop in the high current region is smaller in the fuel cell 10 employing the first porous body 23 and the second porous body 24 of the present embodiment than in the conventional fuel cell. Excellent IV characteristics are shown.

  In the fuel cell 10 of this embodiment, this is because (1) the pore layers 23b and 24b are caused by the metal particle portions (the metal particle portions 23b1 in the first porous body 23) included in the pore layers 23b and 24b. Smoothing the surface, and (2) improving the conductivity of the pore layers 23b and 24b. As a result, the current collection efficiency of the first porous body 23 and the second porous body 24 is improved. This is thought to be because power generation efficiency and power density are improved. In addition, since the surface of the pore layer 23b of the first porous body 23 and the surface of the pore layer 24b of the second porous body 24 are smoothed, the working area with the catalyst layers 33 and 34 increases, and as a result, This is probably because the power generation efficiency and output density of the fuel cell 10 are improved.

  As described above, since the pore layer 23b of the first porous body 23 includes the metal particle portion 23b1, the metal particle portion 23b1 has a porosity without relying on the increase in the thickness of the organic porous portion serving as electronic resistance. It is possible to absorb the surface roughness of the first net member 23a due to the increase of. As a result, the surface of the pore layer 23b can be smoothed.

  Therefore, the first porous body 23 increases the porosity of the first netting material 23a to improve the gas permeability (reduction in pressure loss), and on the other hand, is a collection that occurs contrary to the increase in the porosity. The deterioration of the electric efficiency is suppressed, and it is possible to achieve both improvement in gas permeability and improvement in current collection efficiency. The second porous body 24 is the same as the first porous body 23.

  Further, the metal particle portion 23b1 is formed by further depositing the base layer 23b11 formed by depositing the metal particles M1 on the first netting material 23a and the metal particles M2 having a smaller particle size than the metal particles M1 on the base layer 23b11. Therefore, the conductivity in the thickness direction (deposition height direction) is improved by the large-diameter metal particles M1, and the conductivity in the surface direction is improved by the small-diameter metal particles M2. . Therefore, the conductivity of the pore layer 23b can be preferably improved.

  Accordingly, in the fuel cell 10 configured using the first porous body 23 and the second porous body 24, the active area of the catalyst layers 33 and 34 is increased by the smoothed pore layers 23b and 24b. The catalyst utilization rate is improved, and excellent power generation efficiency and output density are exhibited. Furthermore, since the pore layers 23b and 24b are suitably smoothed, the bonding strength with the catalyst layers 33 and 34 can be improved.

  Further, since the surface of the pore layer 23b is smoothed by providing the metal particle portion 23b1, fluffing does not occur on the surface of the pore layer as in the case of smoothing using conductive fibers. Therefore, in the fuel cell 10 configured using the first porous body 23 including the pore layer 23b having no fluff, the catalyst layer 23 adjacent to the pore layer 23b or the solid polymer electrolyte membrane adjacent to the catalyst layer 23 15 is hardly damaged by the surface state (fluffing etc.) of the pore layer 23b.

  Thus, since the 1st porous body 23 and the 2nd porous body 24 of this embodiment are excellent in current collection efficiency and gas permeability (gas supply property), this 1st porous body 23 and 2nd porous body By adopting 24 as a part of the fuel cell 10, the power generation efficiency and output density of the fuel cell 10 can be improved. In addition, since the surface of the pore layer (pore layer 23b) is smoothed, the active area (contact area) with the catalyst layer (catalyst layer 23) increases, so that the catalyst utilization rate is improved. In this case, the power generation efficiency and output density of the fuel cell 10 can be improved. Therefore, the first porous body 23 and the second porous body 24 of the present embodiment are useful for application to a fuel cell.

  As described above, the present invention has been described based on the embodiments, but the present invention is not limited to the above-described embodiments, and various improvements and modifications can be easily made without departing from the spirit of the present invention. It can be guessed.

  For example, in the above embodiment, the metal particles M1 and M2 are deposited on the first netting material 23a to form the metal particle portion 23b1, but instead of the metal particles, conductive particles (for example, metal Particles imparted with conductivity by coating, particles made of a conductive material, or the like) may be deposited on the first netting material 23a.

  Moreover, in the said embodiment, although the metal particle part 23b1 was comprised from metal particle M1, M2 of a different particle size, you may comprise a metal particle part only with the metal particle M1 which can be deposited on the 1st net | network material 23a. . Further, one or more layers composed of metal particles smaller than the metal particles M1 and larger than the metal particles M2 may be interposed between the base layer 23b11 and the surface layer 23b12 constituting the metal particle portion 23b1.

  Moreover, in the said embodiment, although the organic porous part 23b2 comprised including a carbon particle and PTFE was used, you may use the organic porous part comprised only from PTFE without a carbon particle. That is, instead of the organic porous part 23b2 having water repellency and conductivity, a water repellent organic porous part having many pores communicating with each other may be employed. In this case, the metal particle part 23b1 bears the conductivity of the pore layer 23b.

  Moreover, in the said embodiment, although it was set as the structure which forms the pore layers 23b and 24b in each one side of the 1st net | network material 23a and the 2nd net | network material 24a, these pore layers 23b and 24b are made into the 1st net | network material 23a and It is good also as a structure formed in both surfaces of the 2nd net | network material 24a.

  The fuel cell of the present invention exemplified as the above embodiment and the fuel cell stack composed of the fuel cell of the present invention include a power source for movement of an electric vehicle, an outdoor stationary power source, a portable power source, a portable electronic device power source, etc. It can be used as various power sources.

It is a mimetic diagram showing a fuel cell system constituted from a fuel cell stack in one embodiment of the present invention. It is a perspective view which shows a fuel cell stack typically. It is a typical fragmentary sectional view which shows the principal part of a fuel cell. (A) is sectional drawing which shows typically the 1st porous body of this embodiment, (b) is an enlarged view which shows typically the structure of the E section in (a). It is process drawing which shows the manufacturing flow of a 1st porous body. (A) is a schematic diagram for demonstrating a 1st spraying process, (b) is a schematic diagram for demonstrating a 2nd spraying process. It is a schematic diagram for demonstrating a joining process. It is a graph which shows an IV characteristic.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Fuel cell 15 Solid polymer electrolyte membrane 23 1st porous body (porous member for fuel cells)
23a First mesh material (metal porous body)
23b Pore layer 23b1 Metal particle part 23b11 Base layer (base part)
23b12 surface layer (surface part)
23b2 Organic porous part 24 2nd porous body (porous member for fuel cell)
24a Second mesh material (metal porous body)
24b Pore layer 33 Catalyst layer 34 Catalyst layer 80 Fixed size guide (crimp height control means)
M1 metal particles (conductive particles, first conductive particles)
M2 metal particles (conductive particles, second conductive particles)
S2 Metal particle deposition step S2a First spraying step (first deposition step)
S2b Second spraying step (second deposition step)
S3 Joining process

Claims (7)

A plate-like metal porous body composed of conductive fibers and having a plurality of pores formed by a three-dimensional network structure;
A porous layer having a large number of pores that are in contact with the surface side in the surface direction of the porous metal body and have electrical conductivity and water repellency and communicate with each other;
The pore layer is made of conductive particles formed from conductive particles deposited on the surface side in the surface direction of the metal porous body, and a material pressure-bonded to the metal porous body via the conductive particle parts. A porous member for a fuel cell, comprising a plurality of pores formed from the above and communicating with each other and at least an organic porous portion having water repellency. The conductive particle part is
A base composed of first conductive particles deposited on the surface side in the surface direction of the porous metal body and having a particle diameter larger than the pore diameter of the porous metal body;
And a surface portion composed of second conductive particles having a particle diameter smaller than the pore diameter of the metal porous body, further deposited in the height direction of deposition of the first conductive particles at the base portion. The porous member for a fuel cell according to claim 1.   The organic porous part has conductivity as well as water repellency, and the diameter of the conductive fiber from the surface in the planar direction of the metal porous body through the gap between the conductive particles constituting the conductive particle part. The porous member for a fuel cell according to claim 1 or 2, wherein the porous member penetrates to a considerable depth. A solid polymer electrolyte membrane;
An anode catalyst layer containing a catalyst in contact with one of the solid polymer electrolyte membranes;
A cathode catalyst layer containing a catalyst in contact with the other side of the solid polymer electrolyte membrane;
The surface of the cathode catalyst layer opposite to the surface in contact with the solid polymer electrolyte membrane, and the surface of the anode catalyst layer opposite to the surface in contact with the solid polymer electrolyte membrane A fuel cell comprising the fuel cell porous member according to any one of claims 1 to 3, wherein the fuel cell porous member is disposed in contact with the pore layer. A plate-like metal porous body composed of conductive fibers having a hydrophilic surface and having a large number of pores formed by a three-dimensional network structure, and contacted with the surface side in the surface direction of the metal porous body to be electrically conductive And a porous member for a fuel cell comprising a pore layer having a plurality of pores having water repellency and communicating with each other,
Conductive particle deposition step of spreading and depositing conductive particles on the surface in the planar direction of the metal porous body,
The conductive particle portion formed by depositing the conductive particles by the conductive particle deposition step and the material capable of forming an organic porous portion having at least water repellency and having many pores communicating with each other are pressure-bonded. A porous structure for a fuel cell, comprising: a bonding step of obtaining a bonded body of the porous layer including the conductive particle portion and the organic porous portion and the porous metal body. Manufacturing method of member. The conductive particle deposition step includes:
A first deposition step of depositing first conductive particles having a particle diameter that can be deposited on a surface in a planar direction of the porous metal body to a predetermined thickness to form a base;
A second deposition step of forming a surface portion by further depositing second conductive particles having a particle size smaller than the pore size of the porous metal body after the formation of the base portion by the first deposition step. The manufacturing method of the porous member for fuel cells of Claim 5. The material is a material capable of forming an organic porous part having a plurality of pores communicating with each other and having water repellency and conductivity,
The pressure bonding height control means for controlling a penetration depth of the material that penetrates into the metal porous body through a gap between conductive particles constituting the conductive particle portion is used in the joining step. Item 7. A method for producing a porous member for a fuel cell according to Item 5 or 6.

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