JP2006004808A - Pressurization method of fuel cell material - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pressurization method of fuel cell material advantageous to improve power generation performance of a fuel cell, where the pressurization method of fuel cell material can keep the porosity of a membrane electrode junction or a gas diffusion layer on an air outlet side relatively higher than a porosity on an air inlet side, and can ensure exhaust performance of water from the air outlet side. <P>SOLUTION: An MEA 30 is sandwiched by a first pressurizing body 300 and a second pressurizing 400 to be pressurized in the thickness direction. In the pressurization process, the amount of pressurization on the air outlet side of the membrane electrode junction 100 or the gas diffusion layer is set to a value less than the amount of pressurization on the air inlet side of the MEA 30. A spacer 60 may exist between the first pressurizing body 300 and the second pressurizing body 400. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a pressurizing method for producing a fuel cell material such as a membrane electrode assembly and a gas diffusion layer.

  A membrane electrode assembly (hereinafter also referred to as MEA (membrane electrode assembly)) is an electrolyte membrane comprising an air electrode (oxidant electrode) into which air as an oxidant-containing gas is introduced and a fuel electrode into which fuel is introduced. It is something that is pinched. The air electrode includes a gas diffusion layer in which air is diffused. The fuel electrode includes a gas diffusion layer in which fuel is diffused.

In a fuel cell, protons that have permeated through an electrolyte membrane during power generation proceed to react with oxygen in a catalyst layer that exists at the interface between the electrolyte membrane and the air electrode. Water is generated on the air electrode side due to the power generation reaction. In particular, in the high current density region of the fuel cell, flooding may occur because water increases on the air electrode side. The flooding phenomenon means that water blocks the gas flow path. When this phenomenon occurs, the reactivity between the oxygen gas diffused in the air electrode and the catalyst is lowered, the output density of the fuel cell is lowered, and the cell performance becomes unstable. In order to suppress this flooding phenomenon, conventionally, a method of decreasing the water repellent concentration from the catalyst layer side in contact with the electrolyte membrane toward the gas diffusion layer side (Patent Document 1), the water repellency of the air electrode catalyst layer. Has been developed (Patent Document 2) that makes it easy to discharge water.
JP 2003-109604 A JP-A-6-52871

  By the way, according to the fuel cell, as described above, since the amount of water increases on the air outlet side of the MEA, a flooding phenomenon is likely to occur. That is, on the air outlet side of the MEA, the catalyst tends to be submerged, and the air flow path of the gas diffusion layer and the air flow path of the catalyst layer tend to be blocked by water. For this reason, there is a limit in improving the power generation performance of the fuel cell.

  The present invention has been made in view of the above circumstances, and the porosity of the membrane electrode assembly (MEA) or gas diffusion layer on the oxidant gas outlet side is set to be relatively higher than that on the oxidant gas inlet side. It is therefore possible to provide a method for pressurizing a fuel cell material, which can ensure the discharge of water on the oxidant gas outlet side and thereby improve the power generation performance of the fuel cell. To do.

  (1) A method for pressurizing a fuel cell material according to the first invention includes a membrane electrode assembly or a gas diffusion layer, and a first pressurizer and a second pressurizer that can pressurize them in the thickness direction. In the method of pressurizing the fuel cell material, the step of pressing the membrane electrode assembly or the gas diffusion layer between the first pressurizing body and the second pressurizing body and pressurizing in the thickness direction. The step is characterized in that the pressurization amount on the oxidant gas outlet side of the membrane electrode assembly or gas diffusion layer is set to be smaller than the pressurization amount on the oxidant gas inlet side of the membrane electrode assembly or gas diffusion layer. To do. Examples of the fuel cell material include a membrane electrode assembly or a gas diffusion layer.

  According to the method for pressurizing the fuel cell material according to the first invention, the amount of pressurization on the oxidant gas outlet side of the membrane electrode assembly or gas diffusion layer is the oxidant gas inlet side of the membrane electrode assembly or gas diffusion layer. Is set to be smaller than the amount of pressurization. Thereby, the porosity of the membrane electrode assembly or the gas diffusion layer on the oxidant gas outlet side is set relatively higher than that on the oxidant gas inlet side. For this reason, the water discharging property on the oxidant gas outlet side in the membrane electrode assembly or the gas diffusion layer is ensured.

  (2) A method for pressurizing a fuel cell material according to the second invention includes a membrane electrode assembly or a gas diffusion layer, and a first pressurizer and a second pressurizer that can pressurize these in the thickness direction. In the method of pressurizing the fuel cell material, the step of pressing the membrane electrode assembly or the gas diffusion layer between the first pressurizing body and the second pressurizing body and pressurizing in the thickness direction. Prior to the step, the spacer is disposed on the oxidant gas outlet side of the membrane electrode assembly or the gas diffusion layer so that the spacer is located between the first pressurizing body and the second pressurizing body. The pressure amount on the oxidant gas outlet side of the membrane electrode assembly or gas diffusion layer is set to be smaller than the pressure amount on the oxidant gas inlet side of the membrane electrode assembly or gas diffusion layer It is.

  According to the method for pressurizing the fuel cell material according to the second invention, prior to pressurization, the spacer is positioned between the first pressurizer and the second pressurizer so that the membrane electrode assembly or gas diffusion is performed. Arranged on the oxidant gas outlet side of the layer. In the pressurizing step, the amount of pressurization on the oxidant gas outlet side of the membrane electrode assembly or gas diffusion layer is less than the pressurization amount on the oxidant gas inlet side of the membrane electrode assembly or gas diffusion layer by the spacer. Is set. Thereby, the porosity of the membrane electrode assembly or the gas diffusion layer on the oxidant gas outlet side is set relatively higher than that on the oxidant gas inlet side. For this reason, the water discharging property on the oxidant gas outlet side in the membrane electrode assembly or the gas diffusion layer is secured.

  The shape, structure, and material of the spacer are not particularly limited, and the amount of pressurization on the oxidant gas outlet side of the membrane electrode assembly or gas diffusion layer is set to the oxidant gas inlet of the membrane electrode assembly or gas diffusion layer. Anything can be used as long as it can be set smaller than the pressurizing amount on the side. The material of the spacer is not particularly limited. Examples of the spacer material include hard materials such as metals (eg, alloys such as stainless steel) and ceramics (eg, silicon nitride, alumina, aluminum nitride, silicon carbide, etc.) and materials having good corrosion resistance. . It is preferable that the position of the spacer can be adjusted in a direction intersecting the pressurizing direction (for example, a direction virtually connecting the oxidant gas outlet side and the oxidant gas inlet side). In this case, it is advantageous to adjust the amount of pressurization on the oxidant gas outlet side.

  (3) A method for pressurizing a fuel cell material according to a third invention includes a membrane electrode assembly or a gas diffusion layer, and a first pressurizer and a second pressurizer that can pressurize these in the thickness direction. In the method for pressurizing a fuel cell material, the first step is a step of pressing the membrane electrode assembly or the gas diffusion layer between the first pressurizer and the second pressurizer in the thickness direction. At least one of the first pressurization surface of the pressurization body and the second pressurization surface of the second pressurization body is configured so that the amount of pressurization on the oxidant gas outlet side of the membrane electrode assembly or gas diffusion layer is determined. Alternatively, the gas diffusion layer is set to have a surface that is set to be smaller than the pressurization amount on the oxidant gas inlet side of the gas diffusion layer.

  According to the method for pressurizing the fuel cell material according to the third invention, the amount of pressurization on the oxidant gas outlet side of the membrane electrode assembly or gas diffusion layer is set to the oxidant gas inlet side of the membrane electrode assembly or gas diffusion layer. At least one of the first pressurizing surface of the first pressurizing body and the second pressurizing surface of the second pressurizing body is set so as to have a surface that is set smaller than the pressurizing amount. Thereby, the porosity of the membrane electrode assembly or the gas diffusion layer on the oxidant gas outlet side is set relatively higher than that on the oxidant gas inlet side. For this reason, the water discharging property on the oxidant gas outlet side in the membrane electrode assembly or the gas diffusion layer is secured.

  According to the present invention, the porosity of the membrane electrode assembly or gas diffusion layer on the oxidant gas outlet side can be maintained relatively higher than that on the oxidant gas inlet side. As a result, water discharge performance can be ensured on the oxidant gas outlet side of the membrane electrode assembly or gas diffusion layer, and the flooding phenomenon can be suppressed. Therefore, it is advantageous for improving the power generation performance of the fuel cell.

  According to each of the present invention, preferably, the first pressurizing body and the second pressurizing body have a structure that can be opened and closed in the vertical direction or a rotating roll structure. Hereinafter, embodiments of the present invention will be specifically described with reference to the drawings.

(Embodiment 1)
FIG. 1 shows the concept of the first embodiment. As shown in FIG. 1, a membrane electrode assembly 100 or a gas diffusion layer 200 having a substantially uniform thickness, and a first pressure body 300A having a first pressure surface 310A that can pressurize these in the thickness direction, A second pressure body 400A having a second pressure surface 410A is prepared. The first pressurizing body 300A can be moved up and down. The second pressurizing body 400A is fixed. The membrane electrode assembly 100 or the gas diffusion layer 200 is sandwiched between the first pressure surface 310A of the first pressure body 300A and the second pressure surface 410A of the second pressure body 400A and applied in the thickness direction (arrow T direction). A pressurizing step for pressing is performed. Prior to pressurization, a spacer 60A that functions as a pressurization amount regulating means for regulating the pressurization amount is positioned between the first pressurization body 300A and the second pressurization body 400A. The spacer 60A is disposed not on the air inlet side (oxidant gas inlet side) of the membrane electrode assembly 100 or the gas diffusion layer 200 but on the air outlet side (oxidant gas outlet side). The upper surface 60u of the spacer 60A protrudes above the upper surface of the membrane electrode assembly 100 or the gas diffusion layer 200.

  In the pressurizing step, the pressurizing amount (compression amount) Pout in the thickness direction on the air outlet side of the membrane electrode assembly 100 or the gas diffusion layer 200 is based on the pressurizing amount regulating effect by the spacer 60A. Alternatively, it is set to be smaller than the pressurization amount (compression amount) Pin in the thickness direction on the air inlet side of the gas diffusion layer 200.

  Thereby, the porosity Vout on the air outlet side of the membrane electrode assembly 100 or the gas diffusion layer 200 is set to be relatively higher than the porosity Vin on the air inlet side. For this reason, the water discharge | release property by the side of the air outlet in the membrane electrode assembly 100 or the gas diffusion layer 200 is ensured. Therefore, the flooding phenomenon on the air outlet side is suppressed. It is preferable that the position of the spacer 60A can be adjusted in a direction (arrow X1, X2 direction) that intersects the pressing direction. Thereby, the pressurization amount on the air outlet side can be adjusted. The arrow X1 direction indicates a direction approaching the center of the membrane electrode assembly 100 or the gas diffusion layer 200. The arrow X2 direction indicates a direction away from the center of the membrane electrode assembly 100 or the gas diffusion layer 200. The material of the spacer 60A is not particularly limited, but a material having a hard material such as metal or ceramics can be exemplified. With respect to the membrane electrode assembly 100 or the gas diffusion layer 200, if the ratio of (porosity of air outlet portion / porosity of air inlet portion) is β, β is 1.02-2, or 1.02-1 .4, or 1.02 to 1.2.

(Embodiment 2)
FIG. 2 shows the concept of the second embodiment. As shown in FIG. 2, the membrane electrode assembly 100 or the gas diffusion layer 200 having a substantially uniform thickness, and a first pressurizing body 300B having a first pressurizing surface 310B capable of pressurizing them in the thickness direction, A second pressure body 400B having a second pressure surface 410B is prepared. The 1st pressurization body 300B and the 2nd pressurization body 400B are made into the roll shape, and are made into the rotation roll system. In general, the second pressure body 400B is rotated in the arrow K2 direction while the first pressure body 300B is rotated in the arrow K1 direction. Then, by inserting the membrane electrode assembly 100 or the gas diffusion layer 200 between the first pressure surface 310B of the first pressure body 300B and the second pressure surface 410B of the second pressure body 400B, the thickness direction A pressurizing step for pressurizing the roll in the direction of arrow T is performed. In the roll pressurization, the spacer 60B is positioned between the first pressurizer 300B and the second pressurizer 400B. The spacer 60 </ b> B is disposed on the air outlet side of the membrane electrode assembly 100 or the gas diffusion layer 200.

  In the pressurizing step, the pressurization amount Pout in the thickness direction on the air outlet side of the membrane electrode assembly 100 or the gas diffusion layer 200 is determined based on the pressurization amount regulation effect by the spacer 60B. It is set to be smaller than the pressurization amount Pin in the thickness direction on the air inlet side of the layer 200. Thereby, the porosity Vout on the air outlet side of the membrane electrode assembly 100 or the gas diffusion layer 200 is set to be relatively higher than the porosity Vin on the air inlet side. For this reason, the water discharge | release property by the side of the air outlet in the membrane electrode assembly 100 or the gas diffusion layer 200 is ensured. Therefore, the flooding phenomenon on the air outlet side is suppressed. It is preferable that the position of the spacer 60B can be adjusted in a direction (arrow Y1, Y2 direction) that intersects the pressing direction. Thereby, the pressurization amount on the air outlet side can be adjusted. The arrow Y1 direction indicates a direction approaching the center of the membrane electrode assembly 100 or the gas diffusion layer 200 along the axial length direction of the first pressurizing body 300B and the second pressurizing body 400B. The arrow Y2 direction indicates a direction away from the center of the membrane electrode assembly 100 or the gas diffusion layer 200 along the axial length direction of the first pressurizing body 300B and the second pressurizing body 400B. The material of the spacer 60B is not particularly limited, but a material having a hard material such as metal or ceramics can be exemplified.

(Embodiment 3)
FIG. 3 shows the concept of the third embodiment. As shown in FIG. 3, a membrane electrode assembly 100 or a gas diffusion layer 200 having a substantially uniform thickness, and a first pressurizing body 300C having a first pressurizing surface 310C capable of pressurizing them in the thickness direction, A second pressure body 400C having a second pressure surface 410C is prepared. The first pressurizing body 300C can be raised and lowered. The second pressurizing body 400C is fixed. Then, a pressurizing step is performed in which the membrane electrode assembly 100 or the gas diffusion layer 200 is sandwiched between the first pressurizing body 300C and the second pressurizing body 400C and pressed in the thickness direction (arrow T direction). The first pressure surface 310C of the first pressure body 300C is inclined at an angle θ1 with respect to the virtual horizontal line P1. As a result, with respect to the first pressure surface 310C, the portion 312C that pressurizes the air outlet side is retracted upward (in the direction of the arrow U) than the portion 313C that pressurizes the air inlet side. The second pressure surface 410C of the second pressure body 400C is along the virtual horizontal line P1.

  Since the angle θ1 is inclined as described above, the pressurization amount Pout in the thickness direction on the air outlet side of the membrane electrode assembly 100 or the gas diffusion layer 200 is set on the air inlet side of the membrane electrode assembly 100 or the gas diffusion layer 200. It is set to be smaller than the pressure amount Pin in the thickness direction. That is, as described above, the first pressure surface 310C of the first pressure body 300C has a surface such that the air outlet side of the membrane electrode assembly 100 or the gas diffusion layer 200 is retracted upward (in the direction of the arrow U). Is set to Thereby, the porosity Vout on the air outlet side of the membrane electrode assembly 100 or the gas diffusion layer 200 is set to be relatively higher than the porosity Vin on the air inlet side. For this reason, the water discharge property on the air outlet side in the membrane electrode assembly 100 or the gas diffusion layer 200 is ensured, and the flooding phenomenon on the air outlet side is suppressed. In FIG. 3, the first pressurizing surface 310C of the first pressurizing body 300C is inclined at an angle θ1 with respect to the virtual horizontal line P1, but not limited thereto, the pressurization amount (compression amount) on the air outlet side is not limited thereto. The second pressure surface 410C of the second pressure body 400C may be inclined at an angle θ1 with respect to the virtual horizontal line P1 so as to be small.

(Embodiment 4)
FIG. 4 shows the concept of the fourth embodiment. As shown in FIG. 4, the membrane electrode assembly 100 or the gas diffusion layer 200 having a substantially uniform thickness, and a first pressurizing body 300D having a first pressurizing surface 310D capable of pressurizing them in the thickness direction, A second pressure member 400D having a second pressure surface 410D is prepared. The first pressurizing body 300D and the second pressurizing body 400D are in the form of a roll and are of a rotating roll type. And the pressurization process of pressing the membrane electrode assembly 100 or the gas diffusion layer 200 in the thickness direction (arrow T direction) with the first pressurizing body 300D and the second pressurizing body 400D interposed therebetween is performed. The axis M1 of the first pressure body 300D and the axis M2 of the second pressure body 400D are relatively inclined by an angle θ2. Accordingly, when the gap between the first pressure surface 310D of the first pressure body 300D and the second pressure surface 410D of the second pressure body 400D is α, the gap α is defined as the membrane electrode assembly 100 or the gas diffusion layer 200. The air outlet side is set to be relatively larger than the air inlet side. As a result, the pressurization amount Pout in the thickness direction on the air outlet side of the membrane electrode assembly 100 or the gas diffusion layer 200 is greater than the pressurization amount Pin in the thickness direction on the air inlet side of the membrane electrode assembly 100 or the gas diffusion layer 200. Is set to less. Thereby, the porosity Vout on the air outlet side of the membrane electrode assembly 100 or the gas diffusion layer 200 is set to be relatively higher than the porosity Vin on the air inlet side. For this reason, the water discharge property on the air outlet side in the membrane electrode assembly 100 or the gas diffusion layer 200 is ensured, and the flooding phenomenon on the air outlet side is suppressed.

(Embodiment 5)
FIG. 5 shows the concept of the fifth embodiment. As shown in FIG. 5, a membrane electrode assembly 100 or a gas diffusion layer 200 having a substantially uniform thickness, and a first pressure body 300E having a first pressure surface 310E that can pressurize these in the thickness direction, A second pressure body 400E having a second pressure surface 410E is prepared. The first pressure body 300E can be moved up and down. The second pressure body 400E is fixed. Regarding the first pressurizing surface 310E of the first pressurizing body 300E, the surface 312E facing the air outlet side is retracted Δγ above the surface 313E facing the air inlet side (in the arrow U direction). The second pressure surface 410E of the second pressure body 400E is along the virtual horizontal line P1.

  And the pressurization process which pressurizes in the thickness direction (arrow T direction) on both sides of the membrane electrode assembly 100 or the gas diffusion layer 200 between the 1st pressurization body 300E and the 2nd pressurization body 400E is implemented. Since Δγ is thus retracted, the pressurization amount Pout in the thickness direction on the air outlet side of the membrane electrode assembly 100 or the gas diffusion layer 200 is the thickness on the air inlet side of the membrane electrode assembly 100 or the gas diffusion layer 200. It is set to be smaller than the pressurizing amount Pin in the direction. Thereby, the porosity Vout on the air outlet side of the membrane electrode assembly 100 or the gas diffusion layer 200 is set to be relatively higher than the porosity Vin on the air inlet side. For this reason, the water discharge | release property by the side of the air outlet in the membrane electrode assembly 100 or the gas diffusion layer 200 is ensured. Therefore, the flooding phenomenon on the air outlet side is suppressed. In FIG. 5, the surface 312E of the first pressure surface 310E of the first pressure body 300E is retracted Δγ upward (in the direction of the arrow U). The second pressure surface 410E of the second pressure body 400E may be retracted Δγ downward (in the direction of arrow D) so as to reduce the size.

Examples of the present invention will be specifically described below. This embodiment is applied to a fixed polymer type fuel cell.
(1) Formation of gas diffusion layer
300 g of carbon black (conductive material) was mixed in 1000 g of water to form a mixed solution. The mixed solution was stirred for 10 minutes with a stirrer. Further, 250 g of a dispersion solution (trade name: POLYFLON Dl grade) having a concentration of 60% by weight containing PTFE (tetrafluoroethylene manufactured by Daikin Industries, Ltd.) capable of functioning as a water repellent was added to the mixed solution. This was further stirred for 10 minutes to form a carbon ink. Then, carbon paper (Toray Industries, Ltd., trading card TGP-060, thickness 180 μm) which is a base material of the gas diffusion layer was put into the carbon ink. Thereby, the carbon paper was sufficiently impregnated with a dispersion stock solution (water repellent) containing PTFE. Next, using a drying furnace maintained at a temperature of 80 ° C., excess water in the carbon paper impregnated with the dispersion stock solution (water repellent) was evaporated in the drying furnace. Thereafter, holding at a sintering temperature of 390 ° C. for 60 minutes to sinter PTFE to produce two water-repellent carbon papers, as shown in FIG. A gas diffusion layer 11 for the agent electrode was obtained.

(2) Formation of catalyst paste Platinum-supporting carbon (TEClOE60E, manufactured by Tanaka Kikinzoku Kogyo Co., Ltd.) having a platinum-supporting concentration of 55 wt% was used. The platinum-carrying carbon is a carbon minute body (conductive minute body) carrying platinum as a catalyst. Then, 12 g of platinum-supporting carbon, 127 g of an ion exchange resin solution having a concentration of 5 wt% (SS-1080, manufactured by Asahi Kasei Kogyo Co., Ltd.), 23 g of water as a solvent, and 23 g of isopropyl alcohol as a molding aid are sufficiently mixed. A catalyst paste for the oxidizer electrode was manufactured. The above-mentioned ion exchange resin solution is mainly composed of a fluorinated electrolyte polymer (glass transition temperature: 120 ° C) having ion conductivity (proton conductivity), which is a mixture of water and ethanol as a liquid medium. It is dissolved or dispersed in a solution. Specifically, according to the present example, the fluorocarbon electrolyte polymer contains perfluorosulfonic acid as a main component.

(3) Formation of Laminate By the doctor blade method, the catalyst paste described above was applied to the fluororesin sheet 13 to form a catalyst layer 14 for the oxidant electrode (see FIG. 6B). In this case, in the catalyst layer 14, the amount of platinum supported per unit area was set to 0.6 mg / cm 2. Thereafter, the catalyst layer 14 was dried to form an oxidant electrode sheet 15 (see FIG. 6B)).

  In addition, platinum ruthenium alloy-supported carbon (manufactured by Tanaka Kikinzoku Kogyo Co., Ltd., TEC61E54) was used as the catalyst metal for the fuel electrode instead of platinum-supported carbon. Then, a catalyst paste for a fuel electrode was formed using platinum ruthenium alloy-supported carbon by the same method as described above. In this case, in the platinum-ruthenium alloy-supported carbon, the platinum support concentration is 30 wt%, and the ruthenium support concentration is 23 wt%. This is a carbon minute body (conductive minute body) carrying platinum and ruthenium. This catalyst paste was applied to a sheet 17 made of fluorinated resin by a doctor blade method to form a fuel electrode catalyst layer 18 (see FIG. 6B). In this case, in the catalyst layer 18, the amount of platinum supported per unit area was set to 0.6 mg / cm 2. Thereafter, the fuel electrode catalyst layer 18 was dried to obtain a fuel electrode sheet 19 (see FIG. 6B). Furthermore, an electrolyte membrane 20 made of an ion exchange membrane having an ion conductivity (thickness: 25 μm, manufactured by DuPont, trade name: Nafion 111) was used. The electrolyte membrane 20 has an end face 20f. Then, as shown in FIG. 6C, the oxidant electrode sheet 15 and the fuel electrode sheet 19 are arranged on both sides of the electrolyte membrane 20 in the thickness direction. Thereby, a sheet-like intermediate laminate 25 was formed. In this case, it laminated | stacked so that the catalyst layers 14 and 18 and the exposed surface of the electrolyte membrane 20 might contact. Then, the intermediate laminate 25 was preliminarily hot-pressed in the thickness direction under the conditions of a temperature of 120 ° C., a pressure of 8 MPa, and a time of 1 minute, and the catalyst layers 14 and 18 were transferred to the electrolyte membrane 20. Thereafter, the fluororesin sheets 13 and 17 were peeled from the intermediate laminate 25 (see FIG. 6D).

(4) Pressurization step As shown in FIG. 6 (E), the gas diffusion layer 10 for the fuel electrode and the gas diffusion layer 11 for the oxidant electrode are disposed on both sides of the intermediate laminate 25 in the thickness direction, respectively. Then, MEA30 was formed. The thickness of the MEA 30 is considered to be substantially equal throughout. Then, under hot press conditions of a temperature of 140 ° C., a pressure of 8 MPa, and a time of 3 minutes, the MEA 30 was heated and pressed in the thickness direction and hot pressed using a hot press mold 50 (see FIG. 7).

  As shown in FIG. 7, the hot press mold 50 includes a first pressure body 300 that functions as an upper mold having a flat first pressure surface 310 and a lower mold that functions as a lower mold having a flat second pressure surface 410. 2 pressure bodies 400. Each of the first pressure body 300 and the second pressure body 400 includes a heater. And in the state where the 2nd pressurization body 400 is being fixed, MEA30 is pressurized in the thickness direction by dropping 1st pressurization body 300 in the direction of arrow D1. This promoted the integration of the MEA 30.

  In performing hot pressing in this way, as shown in FIG. 7, a first intermediate plate 501 made of metal (e.g., an alloy such as stainless steel) is interposed between the first pressure body 300 and the second pressure body 400. And the spacer 60 made of stainless steel was placed between the second intermediate plate 502 and pressed. The spacer 60 is disposed on the air outlet side of the MEA 30, but is not disposed on the air inlet side.

  FIG. 7 shows a state before pressurization. FIG. 7 merely shows the concept and is shown enlarged in the thickness direction. FIG. 7 does not define the size of the details. From the top to the bottom, the first pressure body 300, the first intermediate plate 501, the MEA 30, the second intermediate plate 502, and the second pressure body 400 are arranged in this order. The MEA 30 is arranged in the order of the gas diffusion layer 10, the catalyst layer 14, the electrolyte membrane 20, the catalyst layer 18, and the gas diffusion layer 11 in the thickness direction. The catalyst layers 14 and 18 are porous so as to ensure gas permeability while having a carbon microparticle carrying a catalyst and an electrolyte component having proton conductivity. As shown in FIG. 7, the upper end surface 60u of the spacer 60 protrudes Δh above the upper surface 30u of the MEA 30 before being pressurized. The spacer 60 has a pressurizing amount regulation effect. For this reason, the pressurization amount of the air outlet portion 32 (oxidant gas outlet portion) in the MEA 30 is limited and smaller than the pressurization amount of the air inlet portion (oxidant gas inlet portion) 31. The reason is estimated to be that the first pressurizing body 300 is displaced by the influence of the spacer 60 in the pressurizing step. Therefore, in the thickness direction, the pressurization amount Pout of the air outlet portion 32 of the MEA 30 is set to be smaller than the pressurization amount Pin of the air inlet portion 31 of the MEA 30. Thereby, the porosity Vout of the air outlet portion 32 of the MEA 30 is set relatively higher than the porosity Vin of the air inlet portion 31. For this reason, the water discharge property of the air outlet part 32 in the MEA 30 is ensured, and the flooding phenomenon of the air outlet part 32 is suppressed.

  As described above, according to the present embodiment, the pressurization amount in the thickness direction of the air outlet portion 32 of the MEA 30 is greater than the pressurization amount in the thickness direction of the air inlet portion 31 of the membrane electrode assembly 100 or the gas diffusion layer 200. Set less. Thereby, the porosity of the air outlet portion 32 of the MEA 30 is set to be relatively higher than the porosity of the air inlet portion 31. For this reason, the water discharge property of the air outlet part 32 in the MEA 30 is ensured, and the flooding phenomenon of the air outlet part 32 is suppressed.

  Further, since the spacer 60 is used when the MEA 30 is pressurized, the porosity Vout of the air outlet portion of the gas permeable catalyst layers 14 and 18 bonded to the electrolyte membrane 20 itself is It is considered that it is set relatively higher than the porosity Vin. Accordingly, the flooding phenomenon at the air outlet is also suppressed for the catalyst layers 14 and 18.

  If the position of the spacer 60 is adjusted in the direction crossing the pressurizing direction, that is, in the directions of the arrows X1 and X2, the advantage that the pressurization amount in the thickness direction of the air outlet portion 32 of the MEA 30 can be variably adjusted is obtained. . In this case, the porosity of the air outlet portion 32 of the MEA 30 can be adjusted, and the water discharge performance of the air outlet portion 32 in the MEA 30 is ensured. Since the spacer 60 has a flat upper surface 60u and a flat lower surface 60d, a pressure receiving area during pressurization is secured, which is advantageous in reducing deformation, wear, damage, and the like of the spacer 60. FIG. 7 shows the MEA 30 and the spacer 60 enlarged in the thickness direction. However, since the spacer 60 is plate-shaped, a pressure receiving area at the time of pressurization is secured, and the spacer 60 is deformed, worn, damaged, etc. It is advantageous for reduction of

(5) Test Example As shown in Table 1, the thickness of the spacer 60 was changed in 20 to 100 μm to form a test piece of MEA 30 in which the porosity was changed. Other conditions were the same as above. In this case, FIG. 8 shows a plan view of the pressed state. 8 and 9 also show the size of the test piece used in the test example. In FIG. 8, the dimension L1 of the spacer 60 is 50 millimeters, the dimension L2 of the gas diffusion layer 10 is 170 millimeters, and the dimension L3 of the gas diffusion layer 10 is 130 millimeters. In the present test example, in the MEA 30, as the definition of the air inlet portion 31 and the air outlet portion 32, as shown in FIG. 9, the region defined as the dimension L4 is the air inlet portion 31, and the region defined as the dimension L5 is The air outlet 32 was used. The dimension L4 was 50 millimeters and the dimension L5 was 50 millimeters. The MEA 30 thus formed was measured for porosity, adhesion between the gas diffusion layer and the catalyst layer, and power generation performance. Further, a ratio of (porosity of air outlet portion 32 / porosity of air inlet portion 31) was obtained by calculation, and this was defined as β. β is in the range of about 1.05 to 1.2.

(Evaluation of porosity)
About the porosity of MEA30, it measured about two places of the air inlet part 31 and the air outlet part 32 among MEA30. The porosity measurement device was an AutoPore IV9500 manufactured by Micromeritic, and was measured based on the mercury intrusion method. The measurement results are shown in Table 1.

(Evaluation of adhesion between gas diffusion layer and catalyst layer)
The MEA 30 after hot pressing was manually peeled off, and the degree of adhesion between the gas diffusion layer and the catalyst layer and the surface state of the catalyst layer were observed by visual observation to evaluate the degree of adhesion. The results are shown in Table 1.

（発電性能試験）
図１０は発電性能試験に使用した単セルの断面図を示す。３０はＭＥＡを示す。ＭＥＡ３０は固体高分子電解質膜２０を厚み方向に一対の電極（酸化剤極と燃料極）で挟持接合されて構成されている。このＭＥＡ３０の厚み方向の両側を、カーボン製のセパレータ１５０とセパレータ１８０で挟んで、単セル１００を作製した。一方のセパレータ１５０には酸化剤ガス供給口１５１、酸化剤ガス通流溝１５２、酸化剤ガス排出口１５３が設けられている。他方のセパレータ１８０には燃料ガス供給口１８１、燃料ガス通流溝１８２、燃料ガス排出口１８３が設けられている。酸化剤ガス供給口１５１より酸化剤ガス通流溝１５２を介して酸化剤極に2．5atm（252kPa）の空気を供給した。また、燃料ガス供給口１８１より燃料ガス通流溝１８２を介して燃料極に2．5atm（252kPa）の水素ガスを供給した。水分の加湿はバブリンク法により空気および水素ともに加湿して行った。セパレータ１５０とセパレータ１８０の電気端子から発電した電気を取り出し、外部の可変抵抗１９０で抵抗値を変えて電流密度とセル電圧とを測定した。測定結果を図１１に示す。

(Power generation performance test)
FIG. 10 shows a cross-sectional view of a single cell used in the power generation performance test. Reference numeral 30 denotes an MEA. The MEA 30 is configured by sandwiching and joining the solid polymer electrolyte membrane 20 with a pair of electrodes (oxidant electrode and fuel electrode) in the thickness direction. A single cell 100 was fabricated by sandwiching both sides of the MEA 30 in the thickness direction between a carbon separator 150 and a separator 180. One separator 150 is provided with an oxidant gas supply port 151, an oxidant gas flow groove 152, and an oxidant gas discharge port 153. The other separator 180 is provided with a fuel gas supply port 181, a fuel gas flow groove 182, and a fuel gas discharge port 183. Air at 2.5 atm (252 kPa) was supplied from the oxidant gas supply port 151 to the oxidant electrode through the oxidant gas flow groove 152. Further, 2.5 atm (252 kPa) of hydrogen gas was supplied from the fuel gas supply port 181 to the fuel electrode through the fuel gas flow groove 182. Moisture was humidified by humidifying both air and hydrogen by the bubble link method. Electricity generated from the electric terminals of the separator 150 and the separator 180 was taken out, and the resistance value was changed by an external variable resistor 190 to measure the current density and the cell voltage. The measurement results are shown in FIG.

(Comparative example)
The comparative example is formed under basically the same conditions as in the first embodiment. However, the comparative example is pressed without inserting a stainless steel spacer between the hot press molds 50 at the time of hot pressing. Table 1 shows the porosity of the comparative example and the degree of adhesion between the gas diffusion layer and the catalyst layer. The results of conducting a power generation performance test on the comparative example are shown in FIG.

  As shown in Table 1, when the spacer 60 is interposed between the first pressure body 300 and the second pressure body 400 during hot pressing, the porosity of the air outlet portion 32 in the MEA 30 is the same as that of the air inlet portion 31. It becomes larger than the porosity. This is due to the compression amount regulating effect of the spacer 60, and the air inlet 31 where the spacer 30 is located farther out of the MEA 30 has a larger pressurization amount, and the spacer 30 is closer to the MEA 30. It is considered that the air outlet 32 has a smaller pressurization amount. As the evaluation of the adhesion between the gas diffusion layer and the catalyst layer, Example 1, Example 2, and Example 3 were evaluated as ◎, which was quite good. Moreover, about Example 4 and Example 5, evaluation of the adhesiveness was (circle).

  As shown in FIG. 11, in Examples 1 to 3, the output of the fuel cell is higher than in the comparative example in which the spacer 60 is not used. As shown in Table 1, it is presumed that in Examples 1 to 3, the porosity of the air outlet portion 32 is high, so that the flooding phenomenon is less likely to occur. Example 4 and Example 5 are also presumed to be the same although no power generation performance test was conducted.

(Other)
As in another embodiment shown in FIG. 12, a convex positioning portion 480 for positioning the spacer 60 can be provided on the second intermediate plate 502 on the second pressure member 400 side. In this case, since the position of the spacer 60 in the directions of the arrows X1 and X2 is determined, variation in the pressurization amount Pout in the thickness direction of the air outlet portion 32 of the MEA 30 is suppressed. As a result, the variation in the porosity Vout of the air outlet portion 32 of the MEA 30 is suppressed, which is advantageous for reducing the variation in water discharge performance at the air outlet portion 32 of the MEA 30.

  13A and 13B are schematic projections of gas flow grooves formed in the separator of the MEA 30. FIG. Although the gas flow grooves have various patterns, the pressure amount Pout in the thickness direction of the air outlet portion 32 of the MEA 30 is set to be smaller than the pressure amount Pin in the thickness direction of the air inlet portion 31 of the MEA 30. ing. Thereby, the porosity Vout of the air outlet portion 32 of the MEA 30 is maintained relatively higher than the porosity Vin of the air inlet portion 31. For this reason, the water discharge property of the air outlet part 32 in the MEA 30 is ensured as described above, and the flooding phenomenon of the air outlet part 32 is suppressed. In addition, the present invention is not limited only to the embodiments and examples described above and illustrated in the drawings, and is not limited to hot pressing, and may be pressed in a room temperature range depending on circumstances. The present invention can be implemented with appropriate modifications within a range not departing from the above.

  The present invention can be used for a polymer electrolyte fuel cell.

1 is a cross-sectional view according to Embodiment 1. FIG. 6 is a perspective view according to Embodiment 2. FIG. 10 is a cross-sectional view according to Embodiment 3. FIG. FIG. 6 is a cross-sectional view according to a fourth embodiment. 10 is a cross-sectional view according to Embodiment 5. FIG. (A)-(E) is process drawing which shows a manufacture process in connection with an Example. It is sectional drawing which shows the state which concerns on an Example and presses MEA with the 1st pressurization body and the 2nd pressurization body, using a spacer. It is a top view which shows the state which concerns on an Example and presses MEA with the 1st pressurization body and the 2nd pressurization body, using a spacer. It is a block diagram which shows the air inlet part and air outlet part of MEA. It is sectional drawing of a unit cell. It is a graph which shows the result of a power generation test. It is sectional drawing which concerns on another Example and shows the state which presses MEA with the 1st pressurization body and the 2nd pressurization body, using a spacer. It is a block diagram which shows typically the gas flow in MEA.

Explanation of symbols

  In the figure, 30 is an MEA, 31 is an air inlet portion, 32 is an air outlet portion, 100 is a membrane electrode assembly, 200 is a gas diffusion layer, 300 is a first pressure body, 310 is a first pressure surface, and 400 is a first pressure surface. 2 pressurization bodies and 410 show a 2nd pressurization surface.

Claims (5)

A step of preparing a membrane electrode assembly or a gas diffusion layer, and a first pressurizing body and a second pressurizing body capable of pressurizing them in the thickness direction;
In a method for pressurizing a fuel cell material, a pressurizing step of pressing the membrane electrode assembly or the gas diffusion layer between the first pressurizer and the second pressurizer in the thickness direction is performed.
In the pressurizing step, the pressurization amount on the oxidant gas outlet side of the membrane electrode assembly or the gas diffusion layer is set to be higher than the pressurization amount on the oxidant gas inlet side of the membrane electrode assembly or the gas diffusion layer. A method for pressurizing a fuel cell material, characterized in that it is set to a small amount. A step of preparing a membrane electrode assembly or a gas diffusion layer, and a first pressurizing body and a second pressurizing body capable of pressurizing them in the thickness direction;
In a method for pressurizing a fuel cell material, a pressurizing step of pressing the membrane electrode assembly or the gas diffusion layer between the first pressurizer and the second pressurizer in the thickness direction is performed.
Prior to pressurization, a spacer is disposed on the oxidant gas outlet side of the membrane electrode assembly or the gas diffusion layer so that the spacer is located between the first pressurizer and the second pressurizer,
In the pressurizing step, an amount of pressurization on the oxidant gas outlet side of the membrane electrode assembly or the gas diffusion layer is added by the spacer to an oxidant gas inlet side of the membrane electrode assembly or the gas diffusion layer. A method for pressurizing a fuel cell material, wherein the pressure is set to be less than a pressure amount.   3. The method of pressurizing a fuel cell material according to claim 2, wherein the position of the spacer can be adjusted in a direction crossing the pressurizing direction. A step of preparing a membrane electrode assembly or a gas diffusion layer, and a first pressurizing body and a second pressurizing body capable of pressurizing them in the thickness direction;
In a method for pressurizing a fuel cell material, a pressurizing step of pressing the membrane electrode assembly or the gas diffusion layer between the first pressurizer and the second pressurizer in the thickness direction is performed.
At least one of the first pressure surface of the first pressure body and the second pressure surface of the second pressure body is:
A surface for setting a pressurization amount on the oxidant gas outlet side of the membrane electrode assembly or the gas diffusion layer to be smaller than a pressurization amount on the oxidant gas inlet side of the membrane electrode assembly or the gas diffusion layer; A method for pressurizing a fuel cell material, characterized by being set as follows.   5. The structure according to claim 1, wherein the first pressurizing body and the second pressurizing body have a structure that can be opened and closed in a vertical direction, or a rotating roll structure. A method for pressurizing a fuel cell material.

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