JP5019926B2 - Gas diffusion layer for fuel cell and manufacturing method thereof - Google Patents

Description

  The present invention relates to a gas diffusion layer for a fuel cell that forms an electrode used in a polymer electrolyte fuel cell and a method for producing the same, and particularly relates to a high humidification operation condition, a high utilization factor operation condition, and a high output of the polymer electrolyte fuel cell. The present invention relates to a gas diffusion layer for a fuel cell capable of improving performance in operation and a method for manufacturing the same.

  In a polymer electrolyte fuel cell, a cathode side electrode and an anode side electrode are formed on both sides of a polymer electrolyte membrane. Usually, the cathode side electrode and the anode side electrode are carbon carrying a catalyst such as platinum. Catalyst layer composed of black and ion exchange resin, carbon black powder for imparting conductivity to carbon base materials such as carbon cloth and carbon paper, and polytetrafluoroethylene (hereinafter referred to as “PTFE”) for imparting water repellency It is also constituted by a gas diffusion layer formed by impregnating or applying a paste kneaded with a dispersion. However, in the gas diffusion layer, in order to increase the drainage capacity and obtain excellent diffusion layer characteristics, it is extremely important to keep the pore structure of the gas diffusion layer uniform.

  Therefore, in the invention disclosed in Patent Document 1, a powder obtained by pulverizing carbon powder is used, and a mixed powder of this carbon powder and a sulfonic acid-treated fluororesin material powder is spread on both surfaces of the polymer electrolyte membrane. A gas diffusion layer is formed by dry coating with a machine. As a result, the gas required for the reaction can be sufficiently diffused while maintaining the strength of the fuel cell electrode.

  Moreover, in the invention disclosed in Patent Document 2, the water permeation pressure in the gas flow path of the separator is controlled by the difference in blending, catalyst basis weight, and the like. As a result, even when the fuel gas has a low flow rate, it is possible to prevent the generated water from collecting in the gas flow path of the fuel gas side separator and to prevent flooding.

Furthermore, in the invention disclosed in Patent Document 3, a glassy carbon fine particle, a water repellent resin, and a viscosity modifier are dispersed in a solvent to prepare a slurry, and this slurry is coated on the surface of the porous conductive substrate. After the coating is formed, the gas diffusion layer for the fuel cell is manufactured by removing the solvent and the viscosity modifier from the coating. As a result, the diameter of the through-holes of the gas diffusion layer is controlled to keep the electrolyte membrane in an appropriate wet state, and a fuel cell gas diffusion layer that is less consumed by the reaction gas is obtained.
JP 2001-243959 A JP 2005-158722 A JP 2006-1000017 A

  However, since the technique described in Patent Document 1 uses a pulverized carbon powder, it is difficult to obtain good battery characteristics because it is not uniform in size and shape. Moreover, since the mixed powder is dry-coated with a spreader, it cannot be produced by conventional wet coating equipment. Moreover, in the technique described in Patent Document 2, the hydraulic pressure is controlled by the difference in blending and catalyst basis weight, but it is difficult to precisely control the hydraulic pressure by this method. Furthermore, in the technique described in Patent Document 3, the through pore diameter of the gas diffusion layer is controlled by using glassy carbon fine particles, but there is a problem that the manufacturing process is complicated and workability is poor. It was.

  Therefore, the present invention can produce a gas diffusion layer for a fuel cell by wet-coating fine particles having a uniform size with a spherical shape, so that the production efficiency can be improved with a conventional wet-coating facility. It is an object of the present invention to provide a gas diffusion layer for a fuel cell and a method for producing the same that can enhance the capability and obtain excellent diffusion layer characteristics.

  The gas diffusion layer for a fuel cell according to the invention of claim 1 is a gas diffusion layer of a solid polymer fuel cell mainly composed of a polymer electrolyte membrane, and comprises carbon black powder and polytetrafluoroethylene (PTFE). The slurry in which the dispersion is mixed is pulverized by spray drying, and is produced using fine particles whose median particle size is in the range of 2 μm to 100 μm.

In particular, the powder obtained by spray drying is heat-treated at 300 ° C. to 390 ° C. and then dispersed in an aqueous solution to form a powder paste. The carbon base material is mixed with carbon black powder and polytetrafluoroethylene dispersion. The powder paste is applied to a base diffusion layer impregnated with the paste and dried, and dried by heating.

A method for producing a gas diffusion layer for a fuel cell according to a second aspect of the present invention is a method for producing a gas diffusion layer of a solid polymer type fuel cell mainly composed of a polymer electrolyte membrane. A step of mixing a tetrafluoroethylene (PTFE) dispersion to obtain a uniform slurry, a step of spray-drying the slurry to obtain a powder having a median particle size in the range of 2 μm to 100 μm, and the powder A powder paste by dispersing in an aqueous solution, a step of impregnating a carbon base material with a paste formed by mixing carbon black powder and polytetrafluoroethylene dispersion, and drying the powder; A step of applying a paste and a step of drying by heating; and spray drying the slurry to reduce the median particle size to 2 After the step of obtaining a powder in the range of μm to 100 μm, a step of heat treating the powder at 300 ° C. to 390 ° C. is added, and the heat treated powder is dispersed in an aqueous solution to obtain a powder paste. Is.

  The gas diffusion layer for a fuel cell according to the invention of claim 1 is a gas diffusion layer of a solid polymer fuel cell mainly composed of a polymer electrolyte membrane, and comprises carbon black powder and polytetrafluoroethylene (PTFE). The slurry mixed with the dispersion is pulverized by spray drying, and the median particle size is prepared using fine particles having a median particle size in the range of 2 μm to 100 μm, more preferably in the range of 10 μm to 50 μm.

  Fine particles obtained by pulverizing the slurry by spray drying are almost spherical and have a uniform particle size. Therefore, a gas diffusion layer for a fuel cell can be prepared by using such fine particles to prepare a slurry by dispersing it in an aqueous solution, for example, and wet-coating it on a carbon substrate. Here, since the median particle diameter is in the range of 2 μm to 100 μm, more preferably in the range of 10 μm to 50 μm, the through-pore diameter of the gas diffusion layer is maintained at an effective size for gas diffusion and drainage of generated water. Excellent air permeability and drainage can be obtained. Therefore, high performance can be achieved even under high humidification operation, high utilization rate, and high output operation conditions of the fuel cell.

The gas diffusion layer for a fuel cell according to the present invention comprises a powder obtained by spray drying, heat-treated at 300 ° C. to 390 ° C., and then dispersed in an aqueous solution to form a powder paste. A powder paste is applied to a base diffusion layer that has been impregnated with a paste formed by mixing a polytetrafluoroethylene dispersion and dried, and then dried by heating.

  Thus, by heat-treating the powder obtained by spray drying at 300 ° C. to 390 ° C., the powder strength can be increased, and ultrasonic dispersion is performed when preparing a slurry by dispersing in an aqueous solution. In addition, since the predetermined particle diameter can be maintained without breaking the spherical powder, it can be more efficiently and uniformly dispersed. The powder paste thus prepared is wet-coated on a base diffusion layer formed by impregnating a carbon base material with carbon black and PTFE, so that the through-pore diameter of the gas diffusion layer is effective for gas diffusion and drainage of generated water. The size is maintained, and excellent air permeability and drainage can be obtained. Therefore, high performance can be achieved even under high humidification operation, high utilization rate, and high output operation conditions of the fuel cell.

Therefore, by producing a gas diffusion layer for a fuel cell by wet-coating fine particles of spherical and uniform size, the production efficiency can be improved with conventional wet coating equipment, and the drainage capacity is increased. It becomes a gas diffusion layer for a fuel cell capable of obtaining excellent diffusion layer characteristics.

A method for producing a gas diffusion layer for a fuel cell according to a second aspect of the invention is a method for producing a gas diffusion layer of a solid polymer fuel cell mainly composed of a polymer electrolyte membrane, comprising carbon black powder and PTFE. A step of mixing a dispersion to obtain a uniform slurry, a step of spray-drying the slurry to obtain a powder having a median particle size in the range of 2 μm to 100 μm, more preferably in the range of 10 μm to 50 μm, A step of dispersing a powder in an aqueous solution to obtain a powder paste, a step of impregnating a carbon base material with a paste formed by mixing carbon black powder and PTFE dispersion and drying, and a powder paste from above It comprises a coating step and a heat drying step.

  Fine particles obtained by pulverizing the slurry by spray drying are almost spherical and have a uniform particle size. Therefore, a fuel cell gas diffusion layer can be prepared by dispersing such fine particles in an aqueous solution to prepare a slurry and wet-coating it on a carbon substrate. Here, since the median particle size of the fine particles is in the range of 2 μm to 100 μm, more preferably in the range of 10 μm to 50 μm, the through-pore diameter of the gas diffusion layer is a size effective for gas diffusion and drainage of generated water. It is possible to obtain excellent air permeability and drainage. Therefore, high performance can be achieved even under high humidification operation, high utilization rate, and high output operation conditions of the fuel cell.

In particular, the method for producing a gas diffusion layer for a fuel cell according to the present invention comprises a step of spray-drying a slurry to obtain a powder having a median particle size in the range of 2 μm to 100 μm. A step of heat treatment at 390 ° C. is added, and the heat treated powder is dispersed in an aqueous solution to obtain a powder paste.

  The powder obtained by spray drying can be heat-treated at 300 ° C. to 390 ° C. to increase the strength of the powder. Even when ultrasonic dispersion is performed when the slurry is dispersed in an aqueous solution, it is spherical. Since the predetermined particle diameter can be maintained without breaking the powder, it can be more efficiently and uniformly dispersed. The powder paste thus prepared is wet-coated on a base diffusion layer formed by impregnating a carbon base material with carbon black and PTFE, so that the through-pore diameter of the gas diffusion layer is effective for gas diffusion and drainage of generated water. The size is maintained, and excellent air permeability and drainage can be obtained. Therefore, high performance can be achieved even under high humidification operation, high utilization rate, and high output operation conditions of the fuel cell.

  In this way, the spherical and uniform fine particles are wet-coated to produce a fuel cell gas diffusion layer, so that the production efficiency is good and the conventional wet-coating equipment can produce the drainage capacity. It becomes the manufacturing method of the gas diffusion layer for fuel cells which can improve the diffusion layer and can obtain the excellent diffusion layer characteristic.

  Hereinafter, a gas diffusion layer for a fuel cell and a method for manufacturing the same according to an embodiment of the present invention will be described with reference to the drawings.

  First, the overall structure of a polymer electrolyte fuel cell having a fuel cell gas diffusion layer according to an embodiment of the present invention will be described with reference to FIG. FIG. 1 is a schematic diagram showing the overall structure of a polymer electrolyte fuel cell using a gas diffusion layer for a fuel cell according to an embodiment of the present invention.

  As shown in FIG. 1, a solid polymer type fuel cell (single cell) 1 having a fuel cell gas diffusion layer according to the present embodiment has platinum on both sides of a solid polymer ion exchange membrane 2 as a center. The catalyst layers 4A and 4B mainly composed of carbon black supporting the catalyst are in close contact with each other, and the fuel cell gas diffusion layers 7A and 7B according to the present embodiment are provided outside the catalyst layers 4A and 4B. 4B and the gas diffusion layers 7A and 7B are integrated to form an anode electrode (fuel electrode) 3A and a cathode electrode (oxidant electrode) 3B.

  Here, the conventional gas diffusion layer is a base diffusion layer 6A produced by applying a paste obtained by mixing carbon black powder and PTFE dispersion to a carbon base material (carbon paper, carbon cloth, etc.). 6B, the fuel cell gas diffusion layers 7A and 7B according to the present embodiment are obtained by coating the base diffusion layers 6A and 6B with the powder diffusion layers 5A and 5B. . Conductive separators 8A and 8B are provided outside the gas diffusion layers 7A and 7B for the fuel cell.

  Next, a method for manufacturing the fuel cell gas diffusion layers 7A and 7B according to the embodiment of the present invention will be described with reference to FIGS. FIG. 2 is a flowchart showing a method of manufacturing a fuel cell gas diffusion layer according to an embodiment of the present invention. FIG. 3 is a graph showing the relationship between the manufacturing conditions and the particle size of the fuel cell gas diffusion layer according to the embodiment of the present invention. FIG. 4 is a graph showing the particle size distribution of four types of pastes used in the manufacture of the fuel cell gas diffusion layer according to the embodiment of the present invention.

  As shown in FIG. 2, first, an aqueous solution in which carbon black (Denka Black manufactured by Denki Kagaku Kogyo Co., Ltd.) and PTFE dispersion (D-1 manufactured by Daikin Co., Ltd.) as a water repellent are dispersed in ion-exchanged water ( The solid content ratio is adjusted to Denka Black / D-1 = 6/4) (Step S10). Next, this aqueous solution was spray-dried with a spray-drying device to obtain a powder having a uniform particle size (step S11), and heat-treated in a baking furnace to obtain a powder with high strength (step S12). This powder was added to ion-exchanged water to which a surfactant was added with stirring until the weight concentration reached 15%, and then ultrasonically dispersed using an ultrasonic disperser (UH-3, manufactured by STM). A body paste was prepared (step S13).

  On the other hand, a carbon paper base material (TGP-060 manufactured by Toray Industries, Inc.) is impregnated with an NV10% paste having a solid content ratio of Denka Black / D-1 = 6/4 (step S14) and dried to form a base diffusion layer. (Step S15), the powder paste obtained in step S13 is applied to the base diffusion layer with a doctor blade having a gap of 150 μm (step S16), and heat treatment is performed at 350 ° C. for 30 minutes (step S17). The fuel cell gas diffusion layers 7A and 7B according to the present embodiment were obtained.

  Here, the type of spray drying apparatus and the spray drying conditions used for the spray drying in step S11 will be described. First, Table 1 shows the types of spray drying apparatus.

  As shown in Table 1, in the present embodiment, two types of spray drying apparatuses, GA32 manufactured by Yamato Robotech Co., Ltd., and CL-8 manufactured by Okawara Chemical Industries Co., Ltd. are used. Thus, by classifying using two types of spray drying apparatuses, powders having a median particle size of 2 μm to 100 μm can be arbitrarily taken out. Then, four types of pastes, paste A, paste B and paste C, which are powder pastes, and paste D, which is a normal paste, are prepared as pastes to be applied to the base diffusion layer with a doctor blade in step S16 of FIG. And tested. Table 2 shows the spray drying conditions for the four types of paste.

  As shown in Table 2, three types of powder A, powder B, and powder C were prepared under three types of powder preparation conditions. Powder A has a median particle size of 8.73 μm, Powder B has a median particle size of 14.85 μm, and Powder C has a median particle size of 30.41 μm. Thus, the particle diameter obtained by powder production conditions (spray drying conditions) can be controlled, and the drainage characteristics, diffusion characteristics, etc. of the finally obtained fuel cell gas diffusion layers 7A, 7B can be adjusted. Can do.

  Next, the powder heat treatment conditions in step S12 of FIG. 2 will be described with reference to FIG. In order to examine the relationship between the heat treatment conditions and the particle size distribution in FIG. 3, among the three types of powder A, powder B, and powder C shown in Table 2, powder C having the largest median particle size was used. The experimental conditions are shown in Table 3.

  As shown in Table 3, as a measurement sample of the particle size distribution of the powder raw material, a dispersion aqueous solution (paste D) of Denka black (carbon black) and D-1 (PTFE dispersion) produced in step S10 of FIG. ) Was used. As the other four kinds of measurement samples, after the powder C was heat-treated at the heat treatment temperature shown in Table 3 for 10 minutes, for the measurement sample without heat treatment, a paste was prepared only by dissolver stirring, and the remaining 3 heat-treated samples were treated. About the kind, the paste obtained by carrying out ultrasonic dispersion | distribution with stirring was used as the measurement sample.

  As a result, as shown in FIG. 3, for the measurement sample heat-treated at 310 ° C. and the measurement sample heat-treated at 320 ° C., a particle size distribution between about 10 μm and 100 μm was obtained. The particle size was also good at 30.3 μm and 30.4 μm, but the measurement sample heat-treated at 250 ° C. has returned to a particle size distribution close to the particle size distribution of the powder raw material, as shown in FIG. .

  This is presumably because the heat treatment temperature was too low, so the strength of the powder did not improve much, and the powder was decomposed by ultrasonic dispersion to return to the original raw material particle size. Further, as shown in FIG. 3, it was not possible to obtain a good particle size distribution for the measurement sample without heat treatment. Therefore, it is necessary to improve the strength of the powder obtained by spray drying so that the powder does not break even if it is subjected to heat treatment at least at 300 ° C. and subjected to ultrasonic dispersion.

  On the other hand, it is considered that the upper limit of the heat treatment temperature needs to be 390 ° C. or less at which PTFE is not decomposed or modified. Thus, the strength of the powder is improved by heat treatment in the temperature range of 300 ° C. to 390 ° C., and the particle size distribution obtained by spray drying is maintained even by stirring and ultrasonic dispersion during paste preparation. Can do.

  And the result of having measured the particle size distribution of four types of paste (Paste A, Paste B, Paste C, and Paste D) shown in Table 2 is shown in FIG. Based on the results shown in FIG. 3 and Table 3, paste A, paste B, and paste C were all heat-treated at 320 ° C. for 10 minutes in step S12 of FIG. As shown in FIG. 4, the paste A, paste B, and paste C, which are powder pastes prepared according to the manufacturing process of FIG. 2, all obtained good particle size distributions. The particle size is large, followed by paste B and paste A.

  Next, the characteristics of the four types of gas diffusion layers obtained by applying these four types of paste onto the base diffusion layer will be described. The gas diffusion layer obtained by applying paste A on the base diffusion layer and heat-treating at 350 ° C. for 30 minutes is defined as diffusion layer A, and the gas diffusion layer obtained by applying paste B is defined as diffusion layer B. The gas diffusion layer obtained by applying paste C was defined as diffusion layer C, and the gas diffusion layer obtained by applying paste D was defined as diffusion layer D. The characteristics of these four types of gas diffusion layers are shown in Table 4, FIG. 5, FIG. 6, and FIG.

  FIG. 5 is a bar graph showing the air permeability in the normal direction of the four types of gas diffusion layers for fuel cells according to the embodiment of the present invention. FIG. 6 is a bar graph showing the volume resistivity of the four types of fuel cell gas diffusion layers according to the embodiment of the present invention. FIG. 7 is a bar graph showing the water permeation start pressures of the four types of fuel cell gas diffusion layers according to the embodiment of the present invention. In Table 4 and FIGS. 5, 6, and 7, the measurement value in the diffusion layer D is 100, and the measurement values in the diffusion layer A, diffusion layer B, and diffusion layer C are relative to the diffusion layer D. Indicated by value.

As shown in Table 4 and FIG. 5, the normal direction air permeability indicating the normal direction gas permeability of the gas diffusion layer is as compared with the diffusion layer D in the diffusion layer A, the diffusion layer B, and the diffusion layer C. Remarkably high, especially the diffusion layer C shows the highest value. Further, as shown in Table 4 and FIG. 6, the volume resistivity (value measured at a load of 20 kg / cm ² ) is one step higher than that of the diffusion layer D in the diffusion layer A, the diffusion layer B, and the diffusion layer C. It is low.

  Furthermore, as shown in Table 4 and FIG. 7, the water permeation start pressure is lower in the diffusion layer D than the diffusion layer A and the diffusion layer B. This is because the diffusion layer D is cracked. And cannot be controlled. On the other hand, since the diffusion layer A, the diffusion layer B, and the diffusion layer C are sequentially lowered, the diffusion layer A has a median particle size of 8.73 μm of the used paste A, and the diffusion layer B is the same as that of the used paste B. The median particle size is 14.85 μm, and the diffusion layer C has a median particle size of the used paste C of 30.41 μm.

  Therefore, in the spray drying process shown in step S11 of FIG. 2, the median particle size of the powder can be controlled by changing the powder production conditions as shown in Table 2, and as shown in FIG. Thus, the water permeation start pressure can be freely controlled so as to be a required value.

  With respect to the output characteristics of the fuel cell (MEA) using the four types of gas diffusion layers thus produced, field tests were conducted on four types of examples and one type of comparative example. In Example 1, a diffusion layer A was used as the cathode diffusion layer and a diffusion layer D was used as the anode diffusion layer. In Example 2, the diffusion layer B was used as the cathode side diffusion layer, and the diffusion layer D was used as the anode side diffusion layer. In Example 3, the diffusion layer C was diffused as the cathode side diffusion layer and diffused as the anode side diffusion layer. What used the layer D was used.

  In Example 4, a diffusion layer B was used as the cathode diffusion layer and a diffusion layer A was used as the anode diffusion layer. And as the comparative example 1, the thing using the diffusion layer D was used for both the cathode side diffusion layer and the anode side diffusion layer. Table 5 summarizes the combinations of these diffusion layers.

  A single cell battery discharge test was performed using the five types of MEAs thus produced, and the performance was compared. The operating conditions of the single cell battery were a cell temperature of 75 ° C., an anode / cathode bubbler temperature: 70 ° C./70° C., and pure hydrogen was used as the fuel gas. The results of the single cell battery discharge test are shown in FIGS. FIG. 8 is a graph showing the relationship between the current density and the output voltage of a single cell battery using four types of fuel cell gas diffusion layers according to an embodiment of the present invention. FIG. 9 is a graph showing the relationship between the cathode utilization rate and the output voltage of a single cell battery using four types of fuel cell gas diffusion layers according to an embodiment of the present invention.

  As shown in FIGS. 8 and 9, Examples 1 to 4 according to the present embodiment show better battery performance than Comparative Example 1 as a conventional example, and in particular, Example 3 In Example 4, the output characteristics are excellent.

  In particular, as shown in FIG. 9, in Examples 1 to 4, even when the cathode utilization rate increases, the output voltage does not drop abruptly as in Comparative Example 1 as a conventional example. An increase in cathode utilization rate corresponds to a decrease in the flow rate of the oxidant gas, and thus shows an output voltage characteristic in a highly humidified operation condition. Thus, in Examples 1 to 4 according to the present embodiment, it has been found that the output voltage can be maintained even under high humidification operation conditions.

  Furthermore, the relationship between the internal water pressure and the amount of drainage in the solid polymer ion exchange membrane 2 of the single cell battery according to the present embodiment will be described with reference to FIG. FIG. 10 compares the relationship between the internal water pressure and the amount of drainage in the solid polymer ion exchange membrane 2 of the single cell battery using the gas diffusion layer for a fuel cell according to Example 1 of the embodiment of the present invention. It is a graph shown.

  In the unit cell 1 according to the present embodiment shown in FIG. 1, ideally, the anode electrode 3A does not give moisture to the anode-side separator 8A in the form of flowing water, and from the cathode electrode 3B to the cathode-side separator. It is preferable to give water in the form of running water to 8B. The reason is that the anode-side separator 8A has a small gas flow rate, so that water is easily clogged. In the unit cell 1 according to the present embodiment, the drainage characteristics of the fuel cell gas diffusion layers 7A and 7B are controlled by controlling the particle diameter as described above.

  Specifically, as shown in FIG. 10, in the single cell battery using Comparative Example 1 which is a conventional gas diffusion layer for a fuel cell, the internal water pressure and the amount of drainage in the solid polymer ion exchange membrane 2 are simple. In the unit cell 1 using the fuel cell gas diffusion layers 7A and 7B according to Example 1 of the present embodiment, the internal water pressure in the solid polymer ion exchange membrane 2 is When it reaches a certain level, a large amount of running water is mainly discharged to the cathode side. In this way, the pressure valve effect can be obtained in the gas diffusion layers for fuel cells 7A and 7B according to the present embodiment.

  In this way, in the fuel cell gas diffusion layer according to the present embodiment, the production efficiency is improved by wet-coating spherical and uniform fine particles to produce the fuel cell gas diffusion layer. It can be manufactured by conventional wet coating equipment, and the drainage capacity can be increased to obtain excellent diffusion layer characteristics.

  In Examples 1 to 3 of the polymer electrolyte fuel cell 1 according to the present embodiment, a fuel cell gas diffusion layer 7B formed by applying a powder paste to the base diffusion layer 6B only on the cathode electrode 3B is provided. However, the present invention is not limited to this, and as shown in Example 4 of the polymer electrolyte fuel cell 1, both the anode electrode 3A and the cathode electrode 3B have a powder paste on the base diffusion layers 6A and 6B. Alternatively, the fuel cell gas diffusion layers 7A and 7B may be used.

  Further, in the method for producing a gas diffusion layer for a fuel cell according to the present embodiment, the powder obtained by spray drying is heat-treated at 300 ° C. to 390 ° C. to increase the strength of the powder, and then the ultrasonic wave Although an example of ultrasonically dispersing in an aqueous solution using a disperser has been described, it is also possible to produce a powder paste without heat-treating powder obtained by spray drying on the assumption that ultrasonic dispersion is not performed.

  In carrying out the present invention, other configurations, components, materials, blending, shapes, sizes, connection relationships, etc. of the fuel cell gas diffusion layer, and other steps of the method for manufacturing the fuel cell gas diffusion layer are also described. Is not limited to the present embodiment.

FIG. 1 is a schematic diagram showing the overall structure of a polymer electrolyte fuel cell using a gas diffusion layer for a fuel cell according to an embodiment of the present invention. FIG. 2 is a flowchart showing a method of manufacturing a fuel cell gas diffusion layer according to an embodiment of the present invention. FIG. 3 is a graph showing the relationship between the manufacturing conditions and the particle size of the fuel cell gas diffusion layer according to the embodiment of the present invention. FIG. 4 is a graph showing the particle size distributions of four types of pastes used in the manufacture of a fuel cell gas diffusion layer according to an embodiment of the present invention. FIG. 5 is a bar graph showing the air permeability in the normal direction of the four types of gas diffusion layers for fuel cells according to the embodiment of the present invention. FIG. 6 is a bar graph showing the volume resistivity of the four types of fuel cell gas diffusion layers according to the embodiment of the present invention. FIG. 7 is a bar graph showing the water permeation start pressures of the four types of fuel cell gas diffusion layers according to the embodiment of the present invention. FIG. 8 is a graph showing the relationship between the current density and the output voltage of a single cell battery using four types of fuel cell gas diffusion layers according to an embodiment of the present invention. FIG. 9 is a graph showing the relationship between the cathode utilization rate and the output voltage of a single cell battery using four types of fuel cell gas diffusion layers according to an embodiment of the present invention. FIG. 10 compares the relationship between the internal water pressure and the amount of drainage in the solid polymer ion exchange membrane 2 of the single cell battery using the gas diffusion layer for a fuel cell according to Example 1 of the embodiment of the present invention. It is a graph shown.

1 Solid polymer fuel cell (single cell)
2 Solid polymer ion exchange membrane 3A Anode electrode 3B Cathode electrode 6A, 6B Base diffusion layer 7A, 7B Gas diffusion layer for fuel cell

Claims (2)

A gas diffusion layer of a polymer electrolyte fuel cell composed mainly of a polymer electrolyte membrane,
The slurry obtained by mixing the carbon black powder and the polytetrafluoroethylene (PTFE) dispersion is pulverized by spray drying so that the median particle size is in the range of 2 μm to 100 μm, and the powder obtained by the spray drying is used. Base diffusion obtained by heat-treating at 300 ° C to 390 ° C and then dispersing in an aqueous solution to form a powder paste, impregnating a carbon substrate with a paste made by mixing carbon black powder and polytetrafluoroethylene dispersion, and drying A gas diffusion layer for a fuel cell , wherein the powder paste is applied to the layer and dried by heating . A method for producing a gas diffusion layer of a polymer electrolyte fuel cell configured with a polymer electrolyte membrane as a center,
Mixing carbon black powder and polytetrafluoroethylene (PTFE) dispersion to obtain a uniform slurry;
Spray drying the slurry to obtain a powder having a median particle size in the range of 2 μm to 100 μm;
Heat treating the powder at 300 ° C. to 390 ° C .;
A step of dispersing the powder in an aqueous solution to obtain a powder paste;
Impregnating and drying a paste formed by mixing carbon black powder and polytetrafluoroethylene dispersion on a carbon substrate;
Coating the powder paste from above,
A method for producing a gas diffusion layer for a fuel cell, comprising the step of heat drying.

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