JP5493544B2 - GAS DIFFUSION LAYER FOR FUEL CELL, METHOD FOR PRODUCING GAS DIFFUSION LAYER FOR FUEL CELL, FUEL CELL, AND FUEL CELL CAR - Google Patents

Description

  The present invention relates to a fuel cell gas diffusion layer, a method for producing a fuel cell gas diffusion layer, a fuel cell, and a fuel cell automobile.

  A polymer electrolyte fuel cell (PEFC) generally has a configuration in which a plurality of single cells that exhibit a power generation function are stacked. Each single cell has a polymer electrolyte membrane, a catalyst layer provided on both sides of the polymer electrolyte membrane, and a gas diffusion layer provided so as to face the catalyst layer. Various researches and developments are currently being conducted on solid polymer fuel cells. For example, Patent Document 1 proposes a gas diffusion layer in which a winding body is arranged on a plate-like separator.

JP 2008-243572 A

  However, when a gas diffusion layer is formed by stacking a plurality of base materials, an oxide film is formed at the interface between the base materials, resulting in contact resistance, which may cause a decrease in power generation performance.

  The present invention has been made in order to solve such problems, and it is easy to set a flow path pitch and can suppress contact resistance, and a fuel cell gas diffusion layer. It aims at providing the manufacturing method of. Another object of the present invention is to provide a fuel cell and a fuel cell vehicle capable of suppressing a decrease in power generation performance.

In order to achieve the above object, a gas diffusion layer for a fuel cell according to the present invention is a gas diffusion layer for a fuel cell including a porous and conductive current collecting layer, and a flow path is formed on one surface of the current collecting layer. Are disposed. A joining portion is provided between the current collecting layer and the wire to join and electrically connect them , and the microporous layer is disposed on the other surface of the current collector .

In order to achieve the above object, a method for producing a gas diffusion layer for a fuel cell according to the present invention includes a porous and conductive current collecting layer on one surface opposite to a surface on which a microporous layer is disposed. It has the arrangement | sequence process which arranges a some electroconductive wire and comprises a flow path. Method for manufacturing a fuel cell gas diffusion layer of the present invention may also, after the aligning step, with the bonding step that forms the shape of the joint portion for connecting them joined vital electrically between the collector layer and the wire.

  In order to achieve the above object, a fuel cell of the present invention has the above fuel cell gas diffusion layer. The wire of the fuel cell gas diffusion layer faces the separator, and the current collecting layer of the fuel cell gas diffusion layer faces the catalyst layer.

  Since the gas diffusion layer for a fuel cell of the present invention has a plurality of wires arranged on the surface of the current collecting layer, a flow path can be formed between the wires and the flow path can be changed by changing the interval between the wires. You can change the pitch. For this reason, compared with the case where the flow path is formed by carving or punching the base material, for example, there are less restrictions on forming the flow path such as breakage of the base material, and the gas diffusion for the fuel cell of the present invention The layer is easy to set the channel pitch. Moreover, since the gas diffusion layer for fuel cells of this invention has a junction part, a wire and a current collection layer are electrically connected, and it can aim at suppression of contact resistance.

  In the method for producing a gas diffusion layer for a fuel cell of the present invention, since the arranging step arranges a plurality of wires on the surface of the current collecting layer, a flow path can be formed between the wires and the wires. The channel pitch can be changed by changing the interval. For this reason, compared with the case where the flow path is formed by carving or punching the base material, for example, there are less restrictions on forming the flow path such as breakage of the base material, and the gas diffusion for the fuel cell of the present invention The layer manufacturing method is easy to set the channel pitch. Further, in the method for producing a gas diffusion layer for a fuel cell according to the present invention, since the current collecting layer and the wire are joined in the joining step, the wire and the current collecting layer can be electrically connected to suppress contact resistance. .

  Since the fuel cell of the present invention has the fuel cell gas diffusion layer and can suppress the contact resistance, it can suppress the decrease in power generation performance.

  Since the fuel cell vehicle of the present invention includes the fuel cell, similarly, the reduction in power generation performance can be suppressed.

(A) is a schematic sectional view of a gas diffusion layer for a fuel cell according to the first embodiment, (B) is a schematic plan view of the gas diffusion layer for a fuel cell according to the first embodiment, and (C) is a fuel according to the first embodiment. It is a partial expansion schematic sectional drawing of the gas diffusion layer for batteries. FIG. 2 is a partially enlarged schematic cross-sectional view taken along line 2-2 of FIG. It is a schematic sectional drawing of a fuel cell. It is a schematic perspective view which shows a fuel cell partially disassembled. FIG. 5 is a partially enlarged schematic cross-sectional view of the fuel cell viewed from the direction of an arrow 5 in FIG. 4. FIG. 5 is a partially enlarged schematic cross-sectional view of the fuel cell viewed from the direction of an arrow 6 in FIG. 4. 1 is a schematic view of a fuel cell vehicle. It is a flowchart for demonstrating the manufacturing method of the gas diffusion layer for fuel cells. It is a schematic perspective view for demonstrating an arrangement | sequence process. It is a schematic perspective view for demonstrating a joining process. It is a schematic block diagram for demonstrating the outline | summary of resistance measurement. It is the schematic which compares and shows the example of electric power generation performance. It is a schematic plan view for demonstrating 2nd Embodiment. FIG. 10 is a schematic plan view for explaining a first modification. FIG. 10 is a schematic plan view for explaining a modification example 2; It is a schematic plan view which shows the example of a wire different from embodiment, and another wire.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that, in the embodiments described below, members having functions common to the embodiments are denoted by similar reference numerals, and redundant description is omitted.

<First Embodiment>
As shown in FIG. 1, the fuel cell gas diffusion layer 100 of the first embodiment includes a porous and conductive current collecting layer 120 and a plurality of conductive wires 110 arranged on the surface of the current collecting layer 120. Have. The fuel cell gas diffusion layer 100 also includes a joint 114 that electrically connects the current collecting layer 120 and the wire 110. The fuel cell gas diffusion layer 100 has a wire 110 on one surface of a current collecting layer 120. The other surface of the current collecting layer 120 is covered with a metal 122. The fuel cell gas diffusion layer 100 also includes a wire 112 (another wire) that intersects the plurality of wires 110. The fuel cell gas diffusion layer 100 includes a plurality of wires 112. The interval between the wires 112 is equal to or greater than the interval between the wires 110.

  The current collecting layer 120 is, for example, an unemployed cloth, a woven cloth, a knitted cloth, or a net. An unemployed cloth, a woven cloth, a knitted cloth, or a net | network is comprised by the electroconductive fine wire, for example. A well-known material can be used as a material for forming the fine wire, and the material for forming the fine wire is, for example, stainless steel, aluminum, copper, or titanium.

  The plurality of wire rods 110 are substantially linear and are arranged substantially in parallel. The plurality of wires 110 are arranged at equal intervals, preferably at least at an interval equal to or larger than the diameter of the wires 110. Known materials can be used for forming the wire 110. The material for forming the wire 110 is, for example, stainless steel, aluminum, copper, or titanium.

  The joining portion 114 is formed by melting the wire 110 and integrally joining the wire 110 and the current collecting layer 120. In consideration of the bonding between the wire 110 and the current collecting layer 120, the material forming the wire 110 and the material forming the current collecting layer 120 are preferably an alloy mainly composed of the same metal, more preferably the same metal. is there.

  As shown in FIG. 2, the wire 112 intersects with the plurality of wires 110 so as to float up and down alternately. The wire 112 is melted and joined to the wire 110 integrally. Although not shown, the wire 112 is melted and integrally joined with the current collecting layer 120.

  The fuel cell 130 will be described with reference to FIG. The fuel cell 130 is a polymer electrolyte fuel cell. The fuel cell 130 includes a single cell 135 that exhibits a power generation function, and has a configuration in which a plurality of these are stacked. The number of single cells 135 to be stacked can be set as appropriate.

  The single cell 135 includes an electrolyte membrane 131 made of a polymer electrolyte, a catalyst layer 132 disposed on both surfaces of the electrolyte membrane 131, and a microporous layer 133 disposed on the surface of the catalyst layer 132. The single cell 135 also includes a fuel cell gas diffusion layer 100 that sandwiches the electrolyte membrane 131, the catalyst layer 132, and the microporous layer 133 from the stacking direction. The current collecting layer 120 faces the catalyst layer 133 with the microporous layer 133 interposed therebetween.

  The single cell 135 also has a flat separator 134. The separator 134 sandwiches the electrolyte membrane 131, the catalyst layer 132, the microporous layer 133, and the fuel cell gas diffusion layer 100 from the stacking direction. The separator 134 faces the wire 110. As the electrolyte membrane 131, the catalyst layer 132, the microporous layer 133, and the separator 134, known ones can be used.

  Generally, the polymer electrolyte constituting the electrolyte membrane 131 is roughly classified into a fluorine-based electrolyte containing fluorine atoms in the whole or a part of the polymer skeleton and a hydrocarbon-based electrolyte not containing fluorine atoms in the polymer skeleton.

  The catalyst layer 132 is a layer containing a catalyst. The catalyst is, for example, platinum. Moreover, the catalyst layer 132 contains an ionomer. One of the catalyst layers 132 disposed on both surfaces of the electrolyte membrane 131 has a function of promoting a reaction (oxygen reduction reaction) that generates water from protons, electrons, and oxygen. The other of the catalyst layers 132 has a function of promoting a reaction (hydrogen oxidation reaction) for dissociating hydrogen into protons and electrons.

  The microporous layer 133 is a film containing a resin and a conductive material as main components. Here, the resin is a water-repellent resin, such as polytetrafluoroethylene (PTFE). The conductive material is, for example, carbon black. The microporous layer 133 plays a role of retaining the moisture of the electrolyte membrane 131 and a role of discharging excess moisture. Since the current collection layer 120 collects electrons generated by the reaction from the microporous layer 133, it is preferable to secure a contact area with the microporous layer 133 while ensuring diffusion and discharge of gas and water.

  The separator 134 has conductivity. The material forming the separator 134 is, for example, metal or carbon. The metal forming the separator 134 is, for example, stainless steel, aluminum, or titanium.

  A plurality of conductive wires 116 are positioned between the adjacent single cells 135, that is, between the separator 134 and the separator 134. The wires 116 are substantially straight and are arranged in parallel. The plurality of wires 116 are arranged at equal intervals, and preferably the wires 116 are arranged at least at an interval equal to or larger than the diameter of the wires 116. A known material can be used as the material for forming the wire 116, and the material forming the wire 116 is, for example, stainless steel, aluminum, or titanium.

  As shown in FIG. 4, the separator 134 has a manifold hole 137 penetrating in the thickness direction. Gas or cooling water flows through the manifold hole 137. The gas is, for example, a fuel gas containing hydrogen or an oxidant gas containing oxygen.

  The separator 134 also has a diffuser 136 for flowing gas or cooling water in the surface direction of the separator 134. The diffuser 136 surrounds the surface between the manifold holes 137 that form a pair separated from each other in the surface direction of the separator 134, through which the same kind of gas or cooling water flows, and the pair of manifold holes 137. The diffuser 136 surrounds the plurality of wires 110. The surface of the separator 134 is flat.

  The wire 110 is melted and joined to the separator 134 integrally. In order to enhance the electrical conductivity between the separator 134 and the wire 110 and to further strengthen the bonding between them, it is preferable that a joint (not shown) that joins the wire 110 and the separator 134 extends along the wire 110. Further, from the viewpoint of enhancing conductivity and further strengthening the bonding, the material forming the wire 110 and the material forming the separator 134 are preferably an alloy containing the same metal as a main component, more preferably The same metal. The same applies to the wire 116 and the separator 134.

  Gas or cooling water flows in from one of the paired manifold holes 137, flows through the surface of the separator 134, and then flows out from the other manifold hole 137. The gas flows between the wire 110 and the wire 110. The cooling water flows between the wire 116 and the wire 116. That is, the gas flow path 118 is between the wire 110 and the wire 110, and the cooling water flow path 119 is between the wire 116 and the wire 116. The channel 118 also plays a role of discharging generated water.

  By increasing the diameter of the wire 110 or the wire 116 and increasing the equivalent diameter of the flow path, that is, by widening the flow path, pressure loss when flowing through the flow path 118 or the flow path 119 is suppressed, and the flow is made smooth. it can. Here, the equivalent diameter is a representative length indicating how much a diameter of a flow path having a certain cross-sectional shape is equivalent to a set of circular pipes in terms of flow. On the other hand, when the diameter of the wire 110 or the wire 116 is increased, the thickness of the fuel cell gas diffusion layer 100 may be increased and the fuel cell 130 may be enlarged.

  Therefore, from the viewpoint of suppressing the pressure loss and the thickness of the entire fuel cell, the diameters of the wire 110 and the wire 116 are preferably 10 μm or more and 300 μm or less, and more preferably 20 μm or more and 200 μm or less. The diameters of commercially available thin wire rod 110 and wire rod 116 that are currently practical are about 20 μm, and the diameter of wire rod 110 and wire rod 116 is larger than 20 μm due to work hardening by thinning. Mechanical properties do not deteriorate and sufficient strength can be obtained. If the diameters of the wire 110 and the wire 116 are smaller than 200 μm, the wire height (wire diameter) itself can reduce the thickness per unit unit of the battery. The thickness of carbon paper, which is a commercially available gas diffusion layer, is about 200 μm. When the thickness of the wire is 200 μm or more, the unit unit thickness of the battery is conversely increased. Therefore, the wire used in the present invention is most preferably a thin and solid solid material.

  Moreover, although arrangement | positioning of the wire 110 and the wire 116 can be set suitably, it is preferable to arrange | position the wire 110 and the wire 116 so that gas or water may flow smoothly. For example, the wire 110 and the wire 116 are parallel to the separation direction of the manifold hole 137 on the gas and cooling water inflow side and the manifold hole 137 on the gas and cooling water outflow side.

  As shown in FIG. 5, the gas flows along the wire 110 and, at this time, diffuses in the current collecting layer 120 toward the microporous layer 133 and the catalyst layer 132. As shown in FIG. 6, if the diameters of the fine wires constituting the current collecting layer 120 and the intervals between the fine wires are different from those of the wire 110, the gas moves between the adjacent flow channels 118 and 118. easy. Such gas movement is preferable because it leads to uniform gas diffusion in the entire surface direction.

  The metal 122 coated on the current collecting layer 120 is preferably one that can withstand even in an environment where the electrolyte membrane 131 is strongly acidic containing a sulfone group or the like and the catalyst layer 132 is at a high potential of about 1V. Further, depending on the type of the metal 122, there is a possibility that ions may be dissolved and the electrolyte membrane 131 may be deteriorated, so that it is preferable to select the type of the metal 122 in consideration of this. The metal 122 to be coated is preferably gold.

  Next, the fuel cell vehicle 150 will be described.

  As shown in FIG. 7, the fuel cell vehicle 150 is equipped with a fuel cell 130 as a driving power source. A motor (not shown) is driven by electric power generated by the fuel cell 130, and the fuel cell automobile 150 travels.

  A method for manufacturing the fuel cell gas diffusion layer 100 will be described.

  Referring to FIG. 8, the method for manufacturing the fuel cell gas diffusion layer 100 includes an oxide film removal step S110 for removing the oxide film on the surface of the wire 110. The manufacturing method of the fuel cell gas diffusion layer 100 also includes an arrangement step S120 in which the wires 110 are arranged side by side on the surface of the current collection layer 120 after the oxide film removal step S110, and a current collection layer 120 after the arrangement step S120. Joining process S130 which joins wire 110. Moreover, the manufacturing method of the gas diffusion layer 100 for fuel cells has the coating | coating process S140 which coat | covers the metal 122 on the surface of the current collection layer 120 after joining process S130.

  A known technique can be used as the oxide film removal step S110, and the oxide film removal step S110 is, for example, acid cleaning.

  As shown in FIG. 9, in the arranging step S <b> 120, a plurality of wire rods 110 are arranged in parallel, and the wire rods 110 are arranged on the surface of the current collecting layer 120 with the current collecting layer 120 and the separator 134 sandwiched therebetween. At this time, the plurality of wires 110 are accommodated in the diffuser 136 of the separator 134. Further, the wire 112 is crossed with the plurality of wires 110.

Referring to FIG. 10, the bonding step S <b> 130 heats the wire 110 and presses it against the current collecting layer 120. In the joining step S130, the wire 110 is melted and joined to the current collecting layer 120. More specifically, in the bonding step S130, a load is applied in a state where the wire 110 is sandwiched between the current collecting layer 120 and the separator 134, and these are heated as they are in a non-oxidizing gas atmosphere. In this case, the temperature and time are, for example, 1000 ° C. and 10 minutes. In addition, by appropriately filling the furnace with N ₂ , mixing of oxygen and the like can be prevented. A small amount of H ₂ may be added to prevent oxidation of the member surface.

  The coating step S140 can use a known technique and includes plating using a liquid, vacuum deposition, sputtering, and the like. In the coating step S140, various metals 122 can be coated, but gold is preferably coated on the surface of the current collecting layer 120 from the viewpoint of corrosion resistance and conductivity.

  Further, the covering step S140 may be performed before the joining step S130. However, when the covering step S140 is performed before the joining step S130, between the separator 134 and the wire 110, or between the wire 110 and the current collecting layer 120, There is a possibility that a metal intervenes between them and the joining of the members is hindered. In addition, migration due to the coated metal may occur. Therefore, the covering step S140 is preferably performed after the joining step S130.

  The effect of the first embodiment will be described.

  Since the fuel cell gas diffusion layer 100 has a plurality of wires 110 arranged on the surface of the current collecting layer 120, a flow path 118 can be formed between the wires 110 and the wires 110, and an interval between the wires 110 is changed. As a result, the pitch P between adjacent flow paths (see FIG. 3; hereinafter referred to as flow path pitch P) can be changed. For this reason, for example, compared with the case where the flow path is formed by carving or punching a base material made of a carbon porous body, there are less restrictions on forming the flow path, such as breakage of the base material. The working gas diffusion layer 100 is easy to set the channel pitch P. In addition, since the fuel cell gas diffusion layer 100 has the joint 114, the wire 110 and the current collecting layer 120 are electrically connected, and the wire 110 and the current collecting layer 120 are simply in contact with each other. The contact resistance can be suppressed.

  Without the joint 114, the wire 110 contacts the porous current collecting layer 120 at a plurality of contacts. That is, the wire 110 and the porous current collecting layer 120 are in contact with each other at a point. On the other hand, since the gas diffusion layer 100 for fuel cells has a joint 114 formed by melting the wire 110, the wire 110 and the current collecting layer are compared with the case where, for example, the wire 110 and the current collecting layer 120 are simply in contact. The contact area with the electric layer 120 is large. Therefore, the fuel cell gas diffusion layer 100 can suppress contact resistance.

  Further, as a factor for increasing the contact resistance, an oxide film at the interface between the wire 110 and the current collecting layer 120 can be cited. On the other hand, in the present embodiment, the wire 110 and the current collecting layer 120 are integrally joined by the joint 114 formed by melting the wire 110, so that the fuel cell gas diffusion layer 100 is oxidized. It is possible to suppress the contact resistance by suppressing the influence of the film.

  Since the fuel cell gas diffusion layer 100 includes the wire rod 112, a plurality of wire rods 110 can be connected to prevent variations in the wire rod 110.

  Moreover, since the space | interval of the wire 112 and the wire 112 is more than the space | interval of the wire 110 and the wire 110, the frictional resistance when gas flows can be suppressed and a pressure loss can be suppressed.

  Since the current collecting layer 120 includes a conductive non-woven fabric, woven fabric, knitted fabric, or net, it is possible to ensure the diffusion and discharge properties of gas and water and cushioning properties as well as conductivity.

  Since the surface of the current collecting layer 120 is coated with the metal 122, the corrosion resistance and conductivity are excellent.

  In the method of manufacturing the fuel cell gas diffusion layer 100, since the arranging step S120 arranges the plurality of wires 110 on the surface of the current collecting layer 120, the flow path 118 can be formed between the wires 110 and 110, and The flow path pitch P can be changed by changing the interval between the wires. For this reason, compared with the case where the flow path is formed by carving or punching the base material, for example, there are less restrictions on forming the flow path, such as breakage of the base material. The manufacturing method is easy to set the channel pitch P. Further, in the method of manufacturing the fuel cell gas diffusion layer 100, the joining step S130 joins the wire 110 and the current collecting layer 120, so that the wire 110 and the current collecting layer 120 are electrically connected, and simply the wire 110 and the current collecting layer. The contact resistance can be suppressed as compared with the case where the electric layer 120 is merely brought into contact.

  In the joining step S130, the wire 110 is melted and joined to the current collecting layer 120, so that the contact area between the wire 110 and the current collecting layer 120 is smaller than when the wire 110 and the current collecting layer 120 are merely brought into contact, for example. It is possible to increase the contact resistance.

  Moreover, since joining process S130 melts the wire 110, the wire 110 and the current collection layer 120 are joined integrally. For this reason, the manufacturing method of the gas diffusion layer 100 for fuel cells can suppress the influence of the oxide film of the interface of the wire 110 and the current collection layer 120, and can suppress contact resistance.

  In the joining step S130, the wire 110 is heated and pressed against the current collecting layer 120. For this reason, the junction part 114 of the wire 110 and the current collection layer 120 increases, and suppression of contact resistance can be aimed at. Since the manufacturing method of the fuel cell gas diffusion layer 100 includes the oxide film removal step S110, the oxide film on the surface of the wire is removed, and the contact resistance between the wire 110 and the current collecting layer 120 can be suppressed. Moreover, since the manufacturing method of the gas diffusion layer 100 for fuel cells has the oxide film removal process S110, when the oxide film on the surface of the wire is removed and overlapped with the separator 134, the contact resistance between the wire 110 and the separator 134 is reduced. Suppression can be achieved.

  Since the manufacturing method of the fuel cell gas diffusion layer 100 includes the coating step S140 and the surface of the current collecting layer 120 is coated with the metal 122, the corrosion resistance and conductivity can be improved.

  Since the fuel cell 130 includes the fuel cell gas diffusion layer 100 and can suppress contact resistance, it is possible to suppress reduction in power generation performance.

  Further, in the fuel cell 130, since the wire 110 is melted and integrally joined to the separator 134, the contact resistance between the wire 110 and the separator 134 can be suppressed.

  Since the fuel cell vehicle 150 includes the fuel cell 130, the power generation performance can be suppressed from being lowered similarly to this.

  Next, examples and comparative examples will be described.

<Example>
As shown in Table 1, in Example 1, a 300 mesh SUS316 wire mesh was used as the current collecting layer 120. The wire 110 is made of SUS316. In Example 1, the diameter of the wire 110 was 100 μm, and the distance between the wire 110 and the wire 110 was 200 μm. The separator 134 is made of SUS316.

  And the gas diffusion layer for fuel cells was produced by oxide film removal process S110, arrangement | sequence process S120, and joining process S130. The joining step S130 was heated in a non-oxidizing gas atmosphere, and the temperature and time in this case were set to 1000 ° C. and 10 minutes. In Example 1, the coating step S140 is not performed. That is, the surface of the current collecting layer 120 is not covered with the metal 122.

  Example 2 is substantially the same as Example 1, but the surface of the current collecting layer 120 was coated with gold as the metal 122 in the coating step S140. A coating step S140 was performed after the joining step S130. The thickness of the coated gold is 100 nm. In Example 2, unlike Example 1, the wire 110 having a diameter of 30 μm was used, and the distance between the wire 110 and the wire 110 was set to 30 μm.

  Example 3 is substantially the same as Example 2, but the diameter of the wire 110 and the spacing between the wires are different from those of Example 2. In Example 3, the diameter of the wire 110 was 100 μm, and the distance between the wire 110 and the wire 110 was 200 μm.

<Comparative example>
Unlike the embodiment, Comparative Example 1 has a configuration in which two base materials made of carbon paper are stacked on the fuel cell gas diffusion layer. As the carbon paper, TGP-H-60 manufactured by Toray Industries, Inc. was used. In Comparative Example 1, a gas diffusion layer for a fuel cell was produced by superposing two carbon papers without performing the oxide film removing step S110, the arranging step S120, the joining step S130, and the covering step S140. Therefore, the overlapping carbon papers are not joined to each other, and the surface of the carbon paper is not covered with the metal 122.

  In Comparative Example 2, the same carbon paper as in Comparative Example 1 was used as the current collecting layer 120. The wire 110 is made of SUS316. The diameter of the wire 110 was 100 μm, and the distance between the wire 110 and the wire 110 was 200 μm. In Comparative Example 2, the joining step S130 and the covering step S140 are not performed. Therefore, the gas diffusion layer for fuel cell of Comparative Example 2 has a configuration in which the separator 134, the wire 110, and the current collecting layer 120 overlap in this order, but these members are not joined to each other, The surface of the current collecting layer 120 is not covered with the metal 122. A separator made of SUS316L was used.

  Comparative Example 3 is substantially the same as Comparative Example 2, but differs from Comparative Example 2 in that a 300 mesh SUS316L wire mesh is used as the current collecting layer 120.

  About the Example and comparative example which were demonstrated above, the resistance value and the power generation performance were compared.

As shown in FIG. 11, the catalyst layer 132, the microporous layer 133, the current collecting layer 120, the wire 110 (or carbon paper), and the separator 134 are stacked, and these are sandwiched by two electrodes 160. The resistance value was calculated from the voltage drop between the separator 134 and the current collecting layer 120 when flowing. By changing the compression load of the electrode 160, it is possible to confirm a change in the resistance value with respect to the compression load. Here, the resistance value shown in Table 1 is obtained by multiplying the calculated resistance value by the area S of the electrode 160, and the unit is mΩcm ² .

  For example, when Comparative Example 3 and Example 1 are compared, the members are joined (here, referring to FIG. 11, the joining of the separator 134 and the wire 110 and the joining of the wire 110 and the current collecting layer 120). .) Can confirm that the contact resistance can be suppressed.

As a factor for increasing the contact resistance, there is formation of an oxide film formed on the surface of the member. By joining the members as in the embodiment, in particular, by melting and integrally joining the members, the oxide film does not exist at the contact points between the members, and the contact resistance at the interface can be reduced. Further, it can be confirmed from the comparison between Example 1 and Example 3 that the contact resistance can be suppressed by coating the surface of the current collecting layer 120 with the metal 122, here, gold. The resistance value is preferably 0.01 mΩcm ² or more and 100 mΩcm ² or less.

  Next, the power generation performance will be described. For comparison of power generation performance, a single cell 135 was prepared for Comparative Example 1 and Examples 2 and 3, and current / voltage curves were measured.

  As shown in FIG. 12, it was confirmed that the power generation performance was lower in Comparative Example 1 than in Examples 2 and 3. In Comparative Example 1, it is considered that flooding occurred due to lower drainage on the high current density side than in the example, and power generation performance was reduced.

  In addition, it was confirmed that the power generation performance of Example 2 was lower than that of Example 3. This is probably because the pressure loss in Example 2 is larger than that in Example 3 and the occurrence of flooding.

Second Embodiment
Referring to FIG. 13, the second embodiment is substantially the same as the first embodiment, but the second embodiment has a plurality of wires 210 arranged at different intervals rather than being arranged at equal intervals. Is different from the first embodiment.

  In the second embodiment, three wire rods 210 are arranged at equal intervals, and the interval L2 between the three wire rods 210 arranged at equal intervals and the three wire rods 210 arranged at equal intervals is arranged at equal intervals. Is larger than the interval L1 (L2> L1). For this reason, the flow path 218 at the interval L2 has a lower pressure loss than the flow path 218 at the interval L1, and gas or water flows easily.

  Since the present embodiment has a plurality of wires 210 arranged at different intervals, the flow rate of the flowing gas or water changes according to the width of the flow path, and in addition to the effect of the first embodiment, the flow rate of the gas or water can be adjusted. There is an effect.

  For example, if the intervals between the wires are all equal as in the first embodiment, gas or water flows more easily in the flow path near the manifold hole than in the flow path away from the manifold hole, and flows uniformly in the entire flow path. May be difficult. On the other hand, the spacing between the wires is different as in this embodiment. For example, by setting the width of the flow path away from the manifold hole wider than the width of the flow path near the manifold hole, gas or water The flow rate can be made substantially uniform throughout the flow path.

  Moreover, since it has not only the wire 210 arranged in a different space | interval but the wire 210 lined up at equal intervals, the flow volume of gas or water can be adjusted more appropriately.

<Modification 1>
Referring to FIG. 14, Modification 1 is substantially the same as Embodiment 1, but the arrangement of the wire 310 and the wire 312 is different from that of the wire 110 and the wire 112. The gas diffusion layer for a fuel cell according to the modified example 1 includes the wire 310 that is arranged so that the intervals are closer toward the downstream where the gas partial pressure is lower. The distance between the wire 310 and the wire 310 is narrowed from the manifold hole 337 into which the fuel gas or the oxidant gas flows into the manifold hole 337 into which the fuel gas or the oxidant gas flows out.

  Moreover, in the modification 1, the other wire 312 which cross | intersects the wire 310 is arrange | positioned so that a space | interval may become denser as the downstream where gas partial pressure becomes low, and the space | interval of the wire 312 and the wire 312 is fuel gas or The closer to the manifold hole 337 through which the oxidant gas flows out, the narrower it is.

  Further, the distance between the manifold hole 337 through which the fuel gas or the oxidizing gas flows out and the wire 312 is shorter than the distance between the manifold hole 337 into which the fuel gas or the oxidizing gas flows and the wire 312. That is, the wire 312 is disposed on the downstream side where the gas partial pressure is low. The wire 312 is preferably thinner than the wire 310.

  The effect of the first modification will be described.

  Since the modification 1 has the wire 310 arranged so that the intervals become denser toward the downstream where the gas partial pressure becomes lower, in addition to the effect of the first embodiment, the reduction in the gas partial pressure upstream is suppressed, There is an effect that the electrochemical reaction can proceed smoothly.

  In addition, since the other wire 312 is disposed so that the intervals become denser as the gas partial pressure becomes lower, the decrease in the gas partial pressure in the upstream can be suppressed and the electrochemical reaction can proceed smoothly. .

  Moreover, since the wire 312 is arrange | positioned in the downstream, the fall of the gas partial pressure in an upstream can be suppressed and an electrochemical reaction can advance smoothly.

  Further, by making the wire 312 thinner than the wire 310, gas pressure loss can be suppressed.

<Modification 2>
Referring to FIG. 15, Modification 2 is substantially the same as in Embodiment 1, except that another wire 412 intersecting the wire 410 is outside the reaction region (the region shown by the oblique lines in FIG. 15) facing the catalyst layer. It differs in that it is provided. Specifically, the wire 412 is provided between the reaction region and the manifold 437.

  Since the other wire 412 is provided outside the reaction region, in addition to the effect of the first embodiment, the effect of suppressing the pressure loss of the gas in the reaction region and facilitating the electrochemical reaction can be achieved in Modification 2. Will play.

  The present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the claims.

  For example, a wire is not limited to what is formed from a metal. As an example, the wire may be formed by mixing metal and ceramics in order to improve the corrosion resistance, or may be a resin core coated with a conductive material.

  Moreover, a junction part is not limited to what fuse | melted the wire, For example, an electroconductive adhesive agent containing silver may be sufficient.

  The arranging step is not limited to the embodiment, and the wire and the current collecting layer may be arranged on both sides of the separator, and the wire may be sandwiched between the separator and the current collecting layer. At this time, a joining process presses what has arrange | positioned a wire and a current collection layer on both surfaces of a separator from these lamination directions.

  Moreover, a joining process is not limited to embodiment, You may weld a wire to a current collection layer.

  Moreover, the metal which coat | covers the surface of a current collection layer is not limited to gold | metal | money. The metal to coat | cover should just be able to improve corrosion resistance and electroconductivity, for example, the alloy which has gold as a main component, silver, or the alloy which has silver as a main component may be sufficient.

  Moreover, the number of the other wire which cross | intersects a wire may be one. Moreover, as shown in FIG. 16, a some wire and some other wire may cross | intersect so that a textile fabric or a mesh | network may be formed, for example. In this case, the junction between the current collecting layer and the wire and the junction between the separator and the wire are increased, which is preferable for improving the conductivity. On the other hand, since the pressure loss of flowing gas and water may increase, the distance between the wire and the wire and the diameter of each wire are set in consideration of this.

  The fuel cell may have the fuel cell gas diffusion layer of the second embodiment instead of the fuel cell gas diffusion of the first embodiment.

100 Gas diffusion layer for fuel cells,
110, 210, 310, 410, 510 wire,
112, 212, 312, 412, 512 wire (other wire),
114 joints,
118, 119 flow path,
120 current collecting layer,
122 metal,
130 fuel cell,
131 electrolyte membrane,
132 catalyst layer,
133 microporous layer,
134 separator,
135 single cells,
136 diffuser,
137 Manifold hole,
150 Fuel cell vehicle.

Claims (15)

A gas diffusion layer for a fuel cell including a porous and conductive current collecting layer,
A plurality of conductive wires constituting a flow path are disposed on one surface of the current collecting layer, and a joining portion that joins and electrically connects the current collecting layer and the wire. A gas diffusion layer for a fuel cell , wherein a microporous layer is disposed on the other surface of the current collecting layer.   The gas diffusion layer for a fuel cell according to claim 1, wherein the joining portion is formed by melting the wire. The wire for a fuel cell gas diffusion layer according to claim 1 or claim 2 intervals toward the downstream to be lower in the gas partial pressure is arranged to be dense. The gas diffusion layer for a fuel cell according to any one of claims 1 to 3, wherein another wire that intersects the plurality of wires is provided . Provided with a plurality other wire pre SL intersect, other wire rod the crossing for a fuel cell gas diffusion layer according to claim 4 which is arranged such that the distance toward the downstream to be lower in the gas partial pressure becomes dense .   6. The gas diffusion layer for a fuel cell according to claim 4, wherein the intersecting other wire is provided outside a reaction region facing the catalyst layer.   The said current collection layer is a gas diffusion layer for fuel cells as described in any one of Claims 1-6 containing an electroconductive nonwoven fabric, a woven fabric, a knitted fabric, or a net | network. Fuel cell gas diffusion layer according to any one of claims 1 to 7 in which the metal is coated on the other surface of the front Symbol collector layer. In the porous and conductive current collecting layer , an arrangement step of arranging a plurality of conductive wires on one surface opposite to the surface on which the microporous layer is arranged to constitute a flow path;
After the aligning step, the manufacturing method for a fuel cell gas diffusion layer having a bonding step that forms the shape of the joint portion for connecting them joined vital electrically between said wire and said collector layer.   The method for producing a gas diffusion layer for a fuel cell according to claim 9, wherein in the joining step, the wire is melted and joined to the current collecting layer.   The method of manufacturing a gas diffusion layer for a fuel cell according to claim 10, wherein the joining step heats the wire and presses the wire against the current collecting layer or welds the wire to the current collecting layer.   The method for producing a gas diffusion layer for a fuel cell according to any one of claims 9 to 11, further comprising an oxide film removing step of removing an oxide film on a surface of the wire before the arranging step. The sequence step, the wire is arranged on the one surface of the collector layer, before or after the aligning step and the joining step, in terms of side where the microporous layer in the collector layer is disposed The manufacturing method of the gas diffusion layer for fuel cells as described in any one of Claims 9-12 which has a coating process which coat | covers a metal on a certain other surface. A gas diffusion layer for a fuel cell according to any one of claims 1 to 8,
A separator facing the wire,
And a catalyst layer facing the microporous layer .   The fuel cell according to claim 14, wherein the wire is melted and joined to the separator.

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