JP2009032688A - Electrode-membrane assembly for fuel cell and fuel cell using it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrode-membrane assembly for a fuel cell capable of stably keeping high output by enhancing efficiency of catalyst reaction and suppressing crossover. <P>SOLUTION: The electrode-membrane assembly is equipped with a fuel electrode having a fuel electrode catalyst layer and a fuel electrode gas diffusion layer formed on one surface of the fuel electrode catalyst layer; an air electrode having an air electrode catalyst layer including a cathode catalyst and an air electrode gas diffusion layer including a cathode catalyst installed on one surface of the air electrode catalyst layer; and an electrolyte-membrane interposed between the fuel electrode catalyst layer of the fuel electrode and the air electrode catalyst layer of the air electrode. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an electrode membrane assembly for a fuel cell, and more particularly to a small liquid fuel direct supply type fuel cell electrode membrane assembly and a fuel cell using the same.

  In recent years, small fuel cells have attracted attention in place of lithium ion secondary batteries. In particular, direct methanol fuel cells (DMFC) using methanol as a fuel are less difficult to handle hydrogen gas than fuel cells using hydrogen gas, and devices that produce hydrogen by reforming organic fuels. Is also excellent for miniaturization.

  The general principle of DMFC is as follows. At the fuel electrode, methanol is oxidatively decomposed to generate carbon dioxide, protons and electrons. In the air electrode, water is generated by oxygen obtained from air, protons supplied from the fuel electrode through the electrolyte membrane, and electrons supplied from the fuel electrode through an external circuit. Electric power is supplied by electrons passing through an external circuit.

  DMFCs that have been developed so far are equipped with a pump for supplying methanol and a blower for supplying air to generate electricity based on the above-described principle, and the overall structure of the system is complicated, and the size is reduced. It was difficult.

  In order to reduce the size of the DMFC, the following technology has been developed. For example, a small pump that does not use a pump to supply methanol, but has a membrane that allows methanol molecules to pass between the methanol storage chamber and the power generation element so that methanol can permeate, and the methanol storage chamber is brought close to the vicinity of the power generation element. DMFC is known. There is also known a small DMFC in which an air intake port is directly attached to a power generation element without using a blower for taking in air.

  Patent Document 1 discloses a technique in which a porous body is installed between a methanol storage chamber and a fuel electrode to control the amount of methanol supplied.

Patent Document 2 discloses a catalyst layer obtained by impregnating a carbon base material having pores with a catalyst, and a method of directly forming a catalyst on an electrolyte membrane.
JP 2004-171844 A US Pat. No. 6,221,523

  However, the conventional fuel cell described above has the following problems in place of the simplified structure. For example, the water produced by the reaction is mixed with the fuel and the fuel concentration decreases, making it difficult to supply a constant concentration of fuel to the power generation element. Since the air is taken into the natural inflow, it is difficult to stably obtain a high power density. The catalytic reaction was insufficient only with the catalyst layer in which the catalyst was impregnated with the carbon substrate having pores. The vaporized fuel supplied on the anode side passes through the electrolyte membrane directly and reacts at the cathode, so-called “crossover” occurs, and it is difficult to obtain a high power density.

  An object of the present invention is to provide an electrode membrane assembly for a fuel cell that can increase the efficiency of a catalytic reaction, suppress crossover, and stably maintain a high output density, and a fuel cell using the same.

  An electrode membrane assembly for a fuel cell according to an embodiment of the present invention comprises a fuel electrode catalyst layer containing an anode catalyst, and a fuel electrode gas diffusion layer provided on one surface of the fuel electrode catalyst layer. An air electrode catalyst layer containing a cathode catalyst, an air electrode having an air electrode gas diffusion layer containing a cathode catalyst provided on one surface of the air electrode catalyst layer, and a fuel electrode catalyst layer of the fuel electrode And an electrolyte membrane sandwiched between the air electrode catalyst layer of the air electrode.

  An electrode membrane assembly for a fuel cell according to another embodiment of the present invention includes a fuel electrode catalyst layer containing an anode catalyst, and a fuel electrode gas containing an anode catalyst provided on one surface of the fuel electrode catalyst layer. A fuel electrode having a diffusion layer, an air electrode catalyst layer containing a cathode catalyst, an air electrode having an air electrode gas diffusion layer provided on one surface of the air electrode catalyst layer, and a fuel electrode catalyst for the fuel electrode And an electrolyte membrane sandwiched between the air electrode and the air electrode catalyst layer of the air electrode.

  A fuel cell according to another embodiment of the present invention is characterized by using any one of the above electrode membrane assemblies for fuel cells.

  An electrode membrane assembly for a fuel cell according to the present invention has an air electrode formed by an air electrode catalyst layer containing a cathode catalyst and an air electrode gas diffusion layer containing a cathode catalyst, or a fuel electrode catalyst layer containing an anode catalyst. By forming the fuel electrode with the fuel electrode gas diffusion layer containing the anode catalyst and the anode catalyst, the efficiency of the catalytic reaction can be increased and the crossover can be suppressed to stably maintain a high output density.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a cross-sectional view of a direct methanol fuel cell electrode membrane assembly according to an embodiment of the present invention. As shown in FIG. 1, a fuel cell electrode membrane assembly (MEA) 1 includes a fuel electrode (anode) 10 having a fuel electrode catalyst layer 11 and a fuel electrode gas diffusion layer 12, an air electrode catalyst layer 21 and an air electrode. Protons (hydrogen ions) sandwiched between an air electrode (cathode) 20 having a gas diffusion layer 22, a fuel electrode catalyst layer 11 of the fuel electrode (anode) 10, and an air electrode catalyst layer 21 of the air electrode (cathode) 20. ) Conductive electrolyte membrane 30.

  In the present invention, the cathode catalyst containing region 23 containing the cathode catalyst is formed in the air electrode gas diffusion layer 22, or the anode catalyst containing region 13 containing the anode catalyst is formed in the fuel electrode gas diffusion layer 12. Has been.

  Examples of the catalyst of the anode electrode catalyst layer 11, the anode catalyst containing region 13 in the anode gas diffusion layer 12, the cathode electrode containing region 23 in the air electrode catalyst layer 21, and the cathode electrode diffusion region 22 are platinum group elements. Examples thereof include simple metals such as Pt, Ru, Rh, Ir, Os, Pd, alloys containing platinum group elements, and the like. The catalyst on the fuel electrode side is preferably Pt—Ru or Pt—Mo having strong resistance to methanol or carbon monoxide, and the catalyst on the air electrode side is preferably platinum or Pt—Ni, but is not limited thereto. The catalyst may be a supported catalyst using a conductive support such as a carbon material or an unsupported catalyst. The catalyst in the anode catalyst containing region 13 in the fuel electrode catalyst layer 11 and the fuel electrode gas diffusion layer 12 may be the same or different. The catalyst in the cathode catalyst containing region 23 in the air electrode catalyst layer 21 and the air electrode gas diffusion layer 22 may be the same or different.

  Examples of proton conductive materials constituting the electrolyte membrane 30 include fluorine resins such as perfluorosulfonic acid polymer having a sulfonic acid group (for example, Nafion (registered trademark) manufactured by DuPont, Flemion (registered trademark) manufactured by Asahi Glass Co., Ltd.). Etc.), hydrocarbon resins having a sulfonic acid group, inorganic substances such as tungstic acid and phosphotungstic acid, and the like, but are not limited thereto.

  A proton conductor may be contained in the fuel electrode gas diffusion layer 12 or the air electrode gas diffusion layer 22. Examples of such proton conductors include fluorine resins such as perfluorosulfonic acid polymers having a sulfonic acid group (such as Nafion (registered trademark) manufactured by DuPont, Flemion (registered trademark) manufactured by Asahi Glass), and sulfonic acid groups. Examples thereof include, but are not limited to, hydrocarbon-based resins and inorganic substances such as tungstic acid and phosphotungstic acid.

  The fuel electrode gas diffusion layer 12 stacked on the fuel electrode catalyst layer 11 serves to uniformly supply fuel to the fuel electrode catalyst layer 11 and also serves as a current collector for the fuel electrode catalyst layer 11. On the other hand, the air electrode gas diffusion layer 22 laminated on the air electrode catalyst layer 21 serves to uniformly supply the oxidant to the air electrode catalyst layer 21 and also serves as a current collector for the air electrode catalyst layer 21.

Next, the operation of the fuel cell electrode membrane assembly 1 according to the present invention will be described.
The vaporized liquid fuel (for example, methanol) diffuses in the anode gas diffusion layer 12 and is supplied to the anode catalyst layer 11. The fuel supplied to the fuel electrode catalyst layer 11 causes an internal reforming reaction of methanol represented by the following formula (1).

CH ₃ OH + H ₂ O → CO ₂ + 6H ⁺ + 6e ⁻ (1)
When pure methanol is used as the liquid fuel, there is no supply of water vapor, so the methanol undergoes an internal reforming reaction of the above formula (1) with water generated in the air electrode catalyst layer 21 or water in the electrolyte membrane 30. The internal reforming reaction occurs through other reaction mechanisms that do not require water other than formula (1).

Protons (H ⁺ ) generated by the internal reforming reaction are conducted through the electrolyte membrane 30 and reach the air electrode catalyst layer 21. The air supplied from the air electrode gas diffusion layer 22 diffuses through the air electrode gas diffusion layer 22 and is supplied to the air electrode catalyst layer 21. The air supplied to the air electrode catalyst layer 21 causes the reaction shown in the following formula (2). By this reaction, water is generated and a power generation reaction occurs.

(3/2) O ₂ + 6H ⁺ + 6e ⁻ → 3H ₂ O (2)
Here, when the cathode catalyst is not contained in the air electrode gas diffusion layer 22, oxygen that has passed through the air intake does not sufficiently reach the air electrode catalyst layer 21, and there is oxygen that is not activated, Does not provide sufficient output. Further, when only the air electrode gas diffusion layer 22 containing the cathode catalyst is provided and the air electrode catalyst layer 21 is not provided, the catalyst amount of the air electrode 20 is not sufficient, so that sufficient protons cannot be supplied. Cannot be obtained.

  On the other hand, when the air electrode catalyst layer 21 is provided and the cathode gas diffusion layer 22 contains a cathode catalyst, oxygen in the air is sufficiently activated and reaction with protons is sufficiently performed. High output can be obtained.

  The average thickness of the cathode catalyst-containing region 23 in the air electrode gas diffusion layer 22 is preferably 10% or more of the average thickness of the air electrode catalyst layer 21. If the thickness of the cathode catalyst-containing region 23 is thin, the above effect cannot be obtained. The cathode catalyst-containing region 23 may be formed over the entire film thickness of the air electrode gas diffusion layer 22.

  When the cathode electrode is contained in the air electrode gas diffusion layer 22 after the proton conductor is previously contained in the air electrode gas diffusion layer 22 and the air electrode catalyst layer 21 is further provided, oxygen in the air is sufficiently activated. Moreover, since the reaction with protons is sufficiently performed, a high output can be obtained.

  The average thickness of the proton conductor-containing region in the air electrode gas diffusion layer 22 is not particularly limited, but is preferably equal to or greater than the average thickness of the cathode catalyst-containing region 23. That is, the average thickness of the proton conductor-containing region is preferably 10% or more of the average thickness of the air electrode catalyst layer 21. The proton conductor containing region may also be formed over the entire film thickness of the air electrode gas diffusion layer 22.

  If the catalyst density in the air electrode gas diffusion layer 22 is too high, the air does not reach the air electrode catalyst layer 21 sufficiently, and a high output cannot be obtained. If the catalyst density in the air electrode gas diffusion layer 22 is lowered to maintain the porosity and air is sufficiently diffused, oxygen and protons sufficiently react in the air electrode catalyst layer 21 to obtain a high output. .

  In addition, when the anode catalyst is not contained in the fuel gas diffusion layer 12, particularly when high concentration methanol is used, the methanol passes through the electrolyte membrane 30 without being activated and reacts on the air electrode 10 side. Increases crossover reaction.

  On the other hand, when an anode catalyst is contained in the anode gas diffusion layer 12, the methanol is activated and the internal reforming reaction proceeds to reduce the excess crossover reaction, resulting in high output. it can.

  The average thickness of the anode catalyst-containing region 13 in the fuel electrode gas diffusion layer 12 is preferably 10% or more of the average thickness of the fuel electrode catalyst layer 11. If the anode catalyst-containing region 13 is thin, the above effect cannot be obtained. The anode catalyst-containing region 13 may be formed over the entire film thickness of the fuel electrode gas diffusion layer 12.

  When the fuel electrode gas diffusion layer 12 contains a proton conductor in advance and then the anode gas diffusion layer 12 contains an anode catalyst, the methanol is activated and the internal reforming reaction proceeds, and an excess crossover reaction occurs. As a result, a high output can be obtained.

  The average thickness of the proton conductor-containing region in the anode gas diffusion layer 12 is not particularly limited, but is preferably equal to or greater than the average thickness of the anode catalyst-containing region 13. That is, the average thickness of the proton conductor-containing region is preferably 10% or more of the average thickness of the fuel electrode catalyst layer 11. The proton conductor containing region may also be formed over the entire film thickness of the fuel electrode gas diffusion layer 12.

  If the catalyst density in the fuel electrode gas diffusion layer 12 is too high, the reformed vaporized fuel does not reach the fuel electrode catalyst layer 11 sufficiently, and a high output cannot be obtained. If the catalyst density in the fuel electrode gas diffusion layer 12 is lowered to maintain the porosity and the vaporized fuel is sufficiently diffused, the fuel reacts sufficiently in the fuel electrode catalyst layer 11 to obtain a high output.

  Therefore, in both the air electrode and the fuel electrode, it is preferable to satisfy the condition of catalyst layer> gas diffusion layer with respect to the density of the catalyst.

  In a direct methanol fuel cell, an aqueous methanol solution or pure methanol is used as the liquid fuel, but the liquid fuel is not limited to these. For example, ethanol fuel such as ethanol aqueous solution or pure ethanol, propanol fuel such as propanol aqueous solution or pure propanol, glycol fuel such as glycol aqueous solution or pure glycol, dimethyl ether, formic acid, or other liquid fuel may be used. In any case, liquid fuel corresponding to the fuel cell is accommodated.

  The present invention can be applied not only to a passive type fuel cell but also to an active type fuel cell, a semi-passive type fuel cell using a pump in part such as a fuel supply, etc. The same effect as the case can be obtained.

  Hereinafter, the present invention will be described based on examples. In addition, the meaning of the abbreviation used in the table | surface of each Example is as follows.

CT: thickness of catalyst layer (or catalyst-containing region),
CD: density of the catalyst,
PT: the thickness of the proton conductor containing region,
ACL: anode catalyst layer,
AGDL: anode gas diffusion layer,
CCL: cathode catalyst layer,
CGDL: cathode gas diffusion layer.

Example 1
Carbon paper having a thickness of 380 μm (TGP-H-120 manufactured by Toray Industries, Inc., porosity by the Archimedes method: 75%) was used for the fuel electrode gas diffusion layer.

  A carbon particle carrying platinum ruthenium alloy fine particles, a Nafion (registered trademark) solution DE2020 (manufactured by DuPont) as a proton conductor, and a solvent were mixed with a homogenizer to prepare a slurry having a solid content of about 15%. This slurry was applied to one surface of the fuel electrode gas diffusion layer made of the carbon paper using a die coater. This was naturally dried at room temperature to form a fuel electrode catalyst layer. Thus, a fuel electrode (anode) was produced.

  Carbon paper having a thickness of 300 μm (TGP-H-090 manufactured by Toray Industries, Inc., porosity by Archimedes method: 75%) was used for the air electrode gas diffusion layer. The platinum-supported graphite particles and the solvent were mixed with a homogenizer to prepare a slurry having about 5% solid content. This slurry was spray-coated on one surface of the air electrode gas diffusion layer made of the carbon paper, and the cathode electrode was impregnated with the air electrode gas diffusion layer. At this time, three types of samples (1a, 1b, 1c) were prepared by adjusting the spray amount so that the thickness of the region impregnated with the cathode catalyst was different. This was naturally dried at room temperature to form an air electrode gas diffusion layer containing a cathode catalyst.

  A platinum-supported graphite particle, Nafion (registered trademark) solution DE2020 (manufactured by DuPont) as a proton conductor, and a solvent were mixed with a homogenizer to prepare a slurry having a solid content of about 15%. This slurry was applied to the air electrode gas diffusion layer containing the cathode catalyst using a die coater. This was naturally dried at room temperature to form an air electrode catalyst layer. Thus, an air electrode (cathode) was produced.

Nafion (registered trademark) 112 (manufactured by DuPont) was prepared as an electrolyte membrane. First, an air electrode was superimposed on one surface of the electrolyte membrane so that the air electrode catalyst layer was on the electrolyte membrane side, and pressed under conditions of a temperature of 135 ° C. and a pressure of 40 kgf / cm ² . Subsequently, the fuel electrode was overlapped so that the fuel electrode catalyst layer was on the side of the electrolyte membrane on the opposite side of the air electrode of the electrolyte membrane, and pressed under conditions of a temperature of 135 ° C. and a pressure of 10 kgf / cm ² . . Thus, a fuel cell electrode membrane assembly (MEA) was produced. The electrode area was 12 cm ² for both the air electrode and the fuel electrode.

  The MEA was sandwiched between two layers of gold foil each having a plurality of openings for taking in air and vaporized methanol, thereby forming an air electrode conductive layer and a fuel electrode conductive layer. A laminate in which the MEA, the fuel electrode conductive layer, and the air electrode conductive layer were stacked was sandwiched between two resin frames. At this time, rubber O-rings were sandwiched between the air electrode side of the MEA and one frame and between the fuel electrode side of the MEA and the other frame, respectively, to provide a seal.

  The fuel electrode side frame was fixed to the liquid fuel storage chamber via a gas-liquid separation membrane by screws. A 0.2 mm thick silicone sheet was used for the gas-liquid separation membrane. On the other hand, a porous plate having a porosity of 28% was placed on the frame on the air electrode side to form a moisture retention layer. On this moisturizing layer, a 2 mm thick stainless steel plate (SUS304) with air inlets (4 mm diameter, 64 holes) for air intake is placed to form a surface cover layer and fixed by screwing did.

5 mL of pure methanol was injected into the liquid fuel storage chamber of the fuel cell formed as described above. Electric power was generated in an environment of a temperature of 25 ° C. and a relative humidity of 50%, current values and voltage values were measured, and the maximum value of the output density was calculated. As a result, the maximum value of the power density was 32.3 to 36.7 mW / cm ² .

  The MEA was taken out of the cell, cut and embedded in the resin so that the cross section was visible. The MEA embedded in the resin was polished so as to have a flat cross section and used as a measurement sample, and then observed with an electron microscope for elemental analysis. Here, with regard to the cutting direction, for example, when the electrode is rectangular, cutting is performed in parallel with the longitudinal direction at the center in the direction orthogonal to the longitudinal direction. Then, a total of three cross-sections are taken out from the central portion and both ends of the cut surface at a position closer to the center of 10% of the longitudinal length. The subsequent results are the average values of these three locations.

  First, SEM photographs of SEI (secondary electron image) and BEI (reflection electron image) of the cross section of the measurement sample were taken, and the average thickness of the fuel electrode and the air electrode was determined from the image seen in the field of view. The average thickness was obtained as an average value by measuring the maximum thickness and the minimum thickness in the image obtained in the visual field.

  Next, EPMA analysis was performed in the same field of view as the SEM photograph, and the average catalyst density of the catalyst layer portion and gas diffusion layer portion was calculated assuming that the intensity at which Pt was detected was the catalyst density. EPMA analysis was performed using an electron beam microanalyzer (EPMA-1610) manufactured by Shimadzu Corporation under the conditions of an acceleration voltage of 15 kV, an irradiation current of 30 nA, a beam size of 1 μm, a data point of 256 × 256 points, and a step size of 0.5 μm.

From the results, the average thickness of the fuel electrode catalyst layer (CT _ACL ), the average thickness of the air electrode catalyst layer (CT _CCL ), the average thickness of the cathode catalyst-containing region in the air electrode gas diffusion layer (CT _CGDL ), _Calculate the ratio of CT _CGDL / CT _CCL (%), the difference between the cathode catalyst density CD _CCL in the air electrode catalyst layer and the cathode catalyst density CD _CGDL in the air electrode gas diffusion layer CD _CCL -CD _CGDL (%) It was. Table 1 shows these results.

(Example 2)
Carbon paper having a thickness of 380 μm (TGP-H-120 manufactured by Toray Industries, Inc., porosity by the Archimedes method: 75%) was used for the fuel electrode gas diffusion layer. Carbon particles carrying platinum ruthenium alloy fine particles and a solvent were mixed with a homogenizer to prepare a slurry having a solid content of about 5%. This slurry was spray-coated on one surface of the fuel electrode gas diffusion layer made of the carbon paper, and the anode gas diffusion layer was impregnated with the anode catalyst. At this time, three types of samples (2a, 2b, 2c) were prepared by adjusting the spray amount so that the thickness of the region impregnated with the anode catalyst was different. This was naturally dried at room temperature to form a fuel electrode gas diffusion layer containing an anode catalyst.

  A carbon particle carrying platinum ruthenium alloy fine particles, Nafion (registered trademark) solution DE2020 (manufactured by DuPont) as a proton conductor, and a solvent were mixed with a homogenizer to prepare a slurry having a solid content of about 15%. This slurry was applied to the anode gas diffusion layer containing the anode catalyst using a die coater. This was naturally dried at room temperature to form a fuel electrode catalyst layer. Thus, a fuel electrode (anode) was produced.

  Carbon paper having a thickness of 300 μm (TGP-H-090 manufactured by Toray Industries, Inc., porosity by Archimedes method: 75%) was used for the air electrode gas diffusion layer. The platinum-supported graphite particles and the solvent were mixed with a homogenizer to prepare a slurry having about 5% solid content. This slurry was spray-coated on one surface of the air electrode gas diffusion layer made of the carbon paper, and the cathode electrode was impregnated with the air electrode gas diffusion layer. At this time, the spray amount was adjusted for each of the three types of samples (2a, 2b, 2c) so that the thickness of the region impregnated with the cathode catalyst was different. This was naturally dried at room temperature to form an air electrode gas diffusion layer containing a cathode catalyst.

  A platinum-supported graphite particle, Nafion (registered trademark) solution DE2020 (manufactured by DuPont) as a proton conductor, and a solvent were mixed with a homogenizer to prepare a slurry having a solid content of about 12%. This slurry was applied to the air electrode gas diffusion layer containing the cathode catalyst using a die coater. This was naturally dried at room temperature to form an air electrode catalyst layer. Thus, an air electrode (cathode) was produced.

Nafion (registered trademark) 112 (manufactured by DuPont) was prepared as an electrolyte membrane. First, an air electrode was superimposed on one surface of the electrolyte membrane so that the air electrode catalyst layer was on the electrolyte membrane side, and pressed under conditions of a temperature of 135 ° C. and a pressure of 40 kgf / cm ² . Subsequently, the fuel electrode was overlapped so that the fuel electrode catalyst layer was on the side of the electrolyte membrane on the opposite side of the air electrode of the electrolyte membrane, and pressed under conditions of a temperature of 135 ° C. and a pressure of 10 kgf / cm ² . . Thus, a fuel cell electrode membrane assembly (MEA) was produced. The electrode area was 12 cm ² for both the air electrode and the fuel electrode.

  The MEA was sandwiched between two layers of gold foil each having a plurality of openings for taking in air and vaporized methanol, thereby forming an air electrode conductive layer and a fuel electrode conductive layer. A laminate in which the MEA, the fuel electrode conductive layer, and the air electrode conductive layer were stacked was sandwiched between two resin frames. At this time, rubber O-rings were sandwiched between the air electrode side of the MEA and one frame and between the fuel electrode side of the MEA and the other frame, respectively, to provide a seal.

  The fuel electrode side frame was fixed to the liquid fuel storage chamber via a gas-liquid separation membrane by screws. A 0.2 mm thick silicone sheet was used for the gas-liquid separation membrane. On the other hand, a porous plate having a porosity of 28% was placed on the frame on the air electrode side to form a moisture retention layer. On this moisturizing layer, a 2 mm thick stainless steel plate (SUS304) with air inlets (4 mm diameter, 64 holes) for air intake is placed to form a surface cover layer and fixed by screwing did.

5 mL of pure methanol was injected into the liquid fuel storage chamber of the fuel cell formed as described above. Electric power was generated in an environment of a temperature of 25 ° C. and a relative humidity of 50%, current values and voltage values were measured, and the maximum value of the output density was calculated. As a result, the maximum value of the power density was 33.4 to 38.8 mW / cm ² .

The MEA was taken out of the cell, cut and embedded in the resin so that the cross section was visible. The MEA embedded in the resin was polished so that its cross section was flat, and then subjected to elemental analysis by observation with an electron microscope. As a result, the average thickness of the anode catalyst layer (CT _ACL ), the average thickness of the anode catalyst-containing region in the anode gas diffusion layer (CT _AGDL ), the ratio of CT _AGDL / CT _ACL (%), the anode Difference between the density CD _ACL of the anode catalyst in the catalyst layer and the density CD _AGDL of the anode catalyst in the anode gas diffusion layer CD _ACL −CD _AGDL (%), average thickness of the cathode catalyst layer (CT _CCL ), air Average thickness of cathode catalyst containing region in electrode gas diffusion layer (CT _CGDL ), ratio of CT _CGDL / CT _CCL (%), density of cathode catalyst in air electrode catalyst layer CD _CCL and in air electrode gas diffusion layer The difference CD _CCL -CD _CGDL (%) from the density CD _{CGDL of the} cathode catalyst was measured. Table 2 shows these results.

(Example 3)
Carbon paper having a thickness of 380 μm (TGP-H-120 manufactured by Toray Industries, Inc., porosity by the Archimedes method: 75%) was used for the fuel electrode gas diffusion layer. Carbon particles carrying platinum ruthenium alloy fine particles and a solvent were mixed with a homogenizer to prepare a slurry having a solid content of about 5%. This slurry was spray-coated on one surface of the fuel electrode gas diffusion layer made of the carbon paper, and the anode gas diffusion layer was impregnated with the anode catalyst. At this time, three types of samples (3a, 3b, 3c) were prepared by adjusting the spray amount so that the thickness of the region impregnated with the anode catalyst was different. This was naturally dried at room temperature to form a fuel electrode gas diffusion layer containing an anode catalyst.

  A carbon particle carrying platinum ruthenium alloy fine particles, a Nafion (registered trademark) solution DE2020 (manufactured by DuPont) as a proton conductor, and a solvent were mixed with a homogenizer to prepare a slurry having a solid content of about 13%. This slurry was applied to the anode gas diffusion layer containing the anode catalyst using a die coater. This was naturally dried at room temperature to form a fuel electrode catalyst layer. Thus, a fuel electrode (anode) was produced.

  Carbon paper having a thickness of 300 μm (TGP-H-090 manufactured by Toray Industries, Inc., porosity by Archimedes method: 75%) was used for the air electrode gas diffusion layer.

  A platinum-supported graphite particle, Nafion (registered trademark) solution DE2020 (manufactured by DuPont) as a proton conductor, and a solvent were mixed with a homogenizer to prepare a slurry having a solid content of about 15%. This slurry was applied to the air electrode gas diffusion layer containing the cathode catalyst using a die coater. This was naturally dried at room temperature to form an air electrode catalyst layer. Thus, an air electrode (cathode) was produced.

Nafion (registered trademark) 112 (manufactured by DuPont) was prepared as an electrolyte membrane. First, an air electrode was superimposed on one surface of the electrolyte membrane so that the air electrode catalyst layer was on the electrolyte membrane side, and pressed under conditions of a temperature of 135 ° C. and a pressure of 40 kgf / cm ² . Subsequently, the fuel electrode was overlapped so that the fuel electrode catalyst layer was on the side of the electrolyte membrane on the opposite side of the air electrode of the electrolyte membrane, and pressed under conditions of a temperature of 135 ° C. and a pressure of 10 kgf / cm ² . . Thus, a fuel cell electrode membrane assembly (MEA) was produced. The electrode area was 12 cm ² for both the air electrode and the fuel electrode.

  The MEA was sandwiched between two layers of gold foil each having a plurality of openings for taking in air and vaporized methanol, thereby forming an air electrode conductive layer and a fuel electrode conductive layer. A laminate in which the MEA, the fuel electrode conductive layer, and the air electrode conductive layer were stacked was sandwiched between two resin frames. At this time, rubber O-rings were sandwiched between the air electrode side of the MEA and one frame and between the fuel electrode side of the MEA and the other frame, respectively, to provide a seal.

  The fuel electrode side frame was fixed to the liquid fuel storage chamber via a gas-liquid separation membrane by screws. A 0.2 mm thick silicone sheet was used for the gas-liquid separation membrane. On the other hand, a porous plate having a porosity of 28% was placed on the frame on the air electrode side to form a moisture retention layer. On this moisturizing layer, a 2 mm thick stainless steel plate (SUS304) with air inlets (4 mm diameter, 64 holes) for air intake is placed to form a surface cover layer and fixed by screwing did.

5 mL of pure methanol was injected into the liquid fuel storage chamber of the fuel cell formed as described above. Electric power was generated in an environment of a temperature of 25 ° C. and a relative humidity of 50%, current values and voltage values were measured, and the maximum value of the output density was calculated. As a result, the maximum value of the power density was 33.6 to 35.7 mW / cm ² .

The MEA was taken out of the cell, cut and embedded in the resin so that the cross section was visible. The MEA embedded in the resin was polished so that its cross section was flat, and then subjected to elemental analysis by observation with an electron microscope. As a result, the average thickness of the anode catalyst layer (CT _ACL ), the average thickness of the anode catalyst-containing region in the anode gas diffusion layer (CT _AGDL ), the ratio of CT _AGDL / CT _ACL (%), the anode The difference between the density CD _ACL of the anode catalyst in the catalyst layer and the density CD _AGDL of the anode catalyst in the anode gas diffusion layer CD _ACL -CD _AGDL (%), the average thickness of the cathode electrode layer (CT _CCL ) did. Table 3 shows these results.

Example 4
Carbon paper having a thickness of 380 μm (TGP-H120 manufactured by Toray Industries, Inc., porosity by the Archimedes method: 75%) was compressed by a flat plate press until the thickness became 1/2. When the porosity of the carbon paper after compression was calculated from the external dimensions and weight, it was 40.5%. This carbon paper was used for the fuel electrode gas diffusion layer.

  A carbon particle carrying platinum ruthenium alloy fine particles, Nafion (registered trademark) solution DE2020 (manufactured by DuPont) as a proton conductor, and a solvent were mixed with a homogenizer to prepare a slurry having a solid content of about 15%. This slurry was applied to one surface of the fuel electrode gas diffusion layer made of the compressed carbon paper using a die coater. This was naturally dried at room temperature to form a fuel electrode catalyst layer. Thus, a fuel electrode (anode) was produced.

  Carbon paper having a thickness of 200 μm (TGP-H-060 manufactured by Toray Industries, Inc., porosity by the Archimedes method: 75%) was used for the air electrode gas diffusion layer. A Nafion (registered trademark) solution DE2020 (manufactured by DuPont) diluted to 5% was prepared as a proton conductor. This solution was spray coated on one surface of the air electrode gas diffusion layer made of the above carbon paper, and the air electrode gas diffusion layer was impregnated with a proton conductor. At this time, two types of samples (4a, 4b) were prepared by adjusting the spray amount so that the thickness of the region impregnated with the proton conductor was different. This was naturally dried at room temperature. The platinum-supported graphite particles and the solvent were mixed with a homogenizer to prepare a slurry having about 5% solid content. This slurry was spray-coated on one surface of the air electrode gas diffusion layer impregnated and dried with the proton conductor, and the cathode gas diffusion layer was impregnated with the cathode catalyst. At this time, the spray amount was adjusted so that the thicknesses of the regions impregnated with the cathode catalyst were different for each of the two types of samples (4a, 4b). This was naturally dried at room temperature to form an air electrode gas diffusion layer containing a cathode catalyst.

  A platinum-supported graphite particle, Nafion (registered trademark) solution DE2020 (manufactured by DuPont) as a proton conductor, and a solvent were mixed with a homogenizer to prepare a slurry having a solid content of about 15%. This slurry was applied to the air electrode gas diffusion layer containing the cathode catalyst using a die coater. This was naturally dried at room temperature to form an air electrode catalyst layer. Thus, an air electrode (cathode) was produced.

Nafion (registered trademark) 112 (manufactured by DuPont) was prepared as an electrolyte membrane. First, an air electrode was superimposed on one surface of the electrolyte membrane so that the air electrode catalyst layer was on the electrolyte membrane side, and pressed under conditions of a temperature of 135 ° C. and a pressure of 40 kgf / cm ² . Subsequently, the fuel electrode was overlapped so that the fuel electrode catalyst layer was on the side of the electrolyte membrane on the opposite side of the air electrode of the electrolyte membrane, and pressed under conditions of a temperature of 135 ° C. and a pressure of 10 kgf / cm ² . . Thus, a fuel cell electrode membrane assembly (MEA) was produced. The electrode area was 12 cm ² for both the air electrode and the fuel electrode.

  The MEA was sandwiched between two layers of gold foil each having a plurality of openings for taking in air and vaporized methanol, thereby forming an air electrode conductive layer and a fuel electrode conductive layer. A laminate in which the MEA, the fuel electrode conductive layer, and the air electrode conductive layer were stacked was sandwiched between two resin frames. At this time, rubber O-rings were sandwiched between the air electrode side of the MEA and one frame and between the fuel electrode side of the MEA and the other frame, respectively, to provide a seal.

  The fuel electrode side frame was fixed to the liquid fuel storage chamber via a gas-liquid separation membrane by screws. A 0.2 mm thick silicone sheet was used for the gas-liquid separation membrane. On the other hand, a porous plate having a porosity of 28% was placed on the frame on the air electrode side to form a moisture retention layer. On this moisturizing layer, a 2 mm thick stainless steel plate (SUS304) with air inlets (4 mm diameter, 64 holes) for air intake is placed to form a surface cover layer and fixed by screwing did.

5 mL of pure methanol was injected into the liquid fuel storage chamber of the fuel cell formed as described above. Electric power was generated in an environment of a temperature of 25 ° C. and a relative humidity of 50%, current values and voltage values were measured, and the maximum value of the output density was calculated. As a result, the maximum value of the power density was 33.3 to 37.4 mW / cm ² .

The MEA was taken out of the cell, cut and embedded in the resin so that the cross section was visible. The MEA embedded in the resin was polished so that its cross section was flat, and then subjected to elemental analysis by observation with an electron microscope. From the results, the average thickness of the fuel electrode catalyst layer (CT _ACL ), the average thickness of the air electrode catalyst layer (CT _CCL ), and the average thickness of the proton conductor-containing region in the air electrode gas diffusion layer (PT _CGDL ) The average thickness of the cathode catalyst-containing region in the air electrode gas diffusion layer (CT _CGDL ), the ratio of CT _CGDL / CT _CCL (%), the density of the cathode catalyst in the air electrode catalyst layer CD _CCL and the air electrode gas diffusion layer The difference CD _CCL -CD _CGDL (%) from the density CD _CGDL of the cathode catalyst was measured. Table 4 shows these results.

(Example 5)
Carbon paper having a thickness of 380 μm (TGP-H-120 manufactured by Toray Industries, Inc., porosity by the Archimedes method: 75%) was used for the fuel electrode gas diffusion layer. A Nafion (registered trademark) solution DE2020 (manufactured by DuPont) diluted to 5% was prepared as a proton conductor. This solution was spray-coated on one surface of the fuel electrode gas diffusion layer made of the carbon paper, and the fuel electrode gas diffusion layer was impregnated with a proton conductor. At this time, two types of samples (5a, 5b) were prepared by adjusting the spray amount so that the thickness of the region impregnated with the proton conductor was different. This was naturally dried at room temperature. A platinum ruthenium alloy-supported graphite particle and a solvent were mixed with a homogenizer to prepare a slurry having a solid content of about 5%. This slurry was spray coated on one surface of the fuel electrode gas diffusion layer impregnated and dried with the proton conductor, and the anode gas diffusion layer was impregnated with the anode catalyst. At this time, for each of the two types of samples (5a, 5b), the spray amount was adjusted so that the thickness of the region impregnated with the anode catalyst was different. This was naturally dried at room temperature to form a fuel electrode gas diffusion layer containing an anode catalyst.

  A carbon particle carrying platinum ruthenium alloy fine particles, Nafion (registered trademark) solution DE2020 (manufactured by DuPont) as a proton conductor, and a solvent were mixed with a homogenizer to prepare a slurry having a solid content of about 15%. This slurry was applied to one surface of the fuel electrode gas diffusion layer using a die coater. This was naturally dried at room temperature to form a fuel electrode catalyst layer. Thus, a fuel electrode (anode) was produced.

  Carbon paper having a thickness of 300 μm (TGP-H-090 manufactured by Toray Industries, Inc., porosity by Archimedes method: 75%) was used for the air electrode gas diffusion layer. A Nafion (registered trademark) solution DE2020 (manufactured by DuPont) diluted to 5% was prepared as a proton conductor. This solution was spray coated on one surface of the air electrode gas diffusion layer made of the above carbon paper, and the air electrode gas diffusion layer was impregnated with a proton conductor. At this time, two types of samples (5a, 5b) were prepared by adjusting the spray amount so that the thickness of the region impregnated with the proton conductor was different. This was naturally dried at room temperature. The platinum-supported graphite particles and the solvent were mixed with a homogenizer to prepare a slurry having about 5% solid content. This slurry was spray-coated on one surface of the air electrode gas diffusion layer impregnated and dried with the proton conductor, and the cathode gas diffusion layer was impregnated with the cathode catalyst. At this time, the spray amount was adjusted so that the thicknesses of the regions impregnated with the cathode catalyst were different for each of the two types of samples (5a, 5b). This was naturally dried at room temperature to form an air electrode gas diffusion layer containing a cathode catalyst.

  A platinum-supported graphite particle, Nafion (registered trademark) solution DE2020 (manufactured by DuPont) as a proton conductor, and a solvent were mixed with a homogenizer to prepare a slurry having a solid content of about 15%. This slurry was applied to the air electrode gas diffusion layer containing the cathode catalyst using a die coater. This was naturally dried at room temperature to form an air electrode catalyst layer. Thus, an air electrode (cathode) was produced.

Nafion (registered trademark) 112 (manufactured by DuPont) was prepared as an electrolyte membrane. First, an air electrode was superimposed on one surface of the electrolyte membrane so that the air electrode catalyst layer was on the electrolyte membrane side, and pressed under conditions of a temperature of 135 ° C. and a pressure of 40 kgf / cm ² . Subsequently, the fuel electrode was overlapped so that the fuel electrode catalyst layer was on the side of the electrolyte membrane on the opposite side of the air electrode of the electrolyte membrane, and pressed under conditions of a temperature of 135 ° C. and a pressure of 10 kgf / cm ² . . Thus, a fuel cell electrode membrane assembly (MEA) was produced. The electrode area was 12 cm ² for both the air electrode and the fuel electrode.

  The MEA was sandwiched between two layers of gold foil each having a plurality of openings for taking in air and vaporized methanol, thereby forming an air electrode conductive layer and a fuel electrode conductive layer. A laminate in which the MEA, the fuel electrode conductive layer, and the air electrode conductive layer were stacked was sandwiched between two resin frames. At this time, rubber O-rings were sandwiched between the air electrode side of the MEA and one frame and between the fuel electrode side of the MEA and the other frame, respectively, to provide a seal.

  The fuel electrode side frame was fixed to the liquid fuel storage chamber via a gas-liquid separation membrane by screws. A 0.2 mm thick silicone sheet was used for the gas-liquid separation membrane. On the other hand, a porous plate having a porosity of 28% was placed on the frame on the air electrode side to form a moisture retention layer. On this moisturizing layer, a 2 mm thick stainless steel plate (SUS304) with air inlets (4 mm diameter, 64 holes) for air intake is placed to form a surface cover layer and fixed by screwing did.

5 mL of pure methanol was injected into the liquid fuel storage chamber of the fuel cell formed as described above. Electric power was generated in an environment of a temperature of 25 ° C. and a relative humidity of 50%, current values and voltage values were measured, and the maximum value of the output density was calculated. As a result, the maximum value of the power density was 35.4 to 39.6 mW / cm ² .

The MEA was taken out of the cell, cut and embedded in the resin so that the cross section was visible. The MEA embedded in the resin was polished so that its cross section was flat, and then subjected to elemental analysis by observation with an electron microscope. As a result, the average thickness of the anode catalyst layer (CT _ACL ), the average thickness of the proton conductor-containing region in the anode gas diffusion layer (PT _AGDL ), the anode catalyst-containing region in the anode gas diffusion layer Average thickness (CT _AGDL ), CT _AGDL / CT _ACL ratio (%), density of anode catalyst in the anode catalyst layer CD _ACL and density of anode catalyst in the anode gas diffusion layer CD _AGDL CD _ACL -CD _AGDL (%), average thickness of air electrode catalyst layer (CT _CCL ), average thickness of proton conductor containing region in air electrode gas diffusion layer (PT _CGDL ), cathode catalyst in air electrode gas diffusion layer The average thickness of the contained region (CT _CGDL ), the ratio of CT _CGDL / CT _CCL (%), the density CD _CCL of the cathode catalyst in the air electrode catalyst layer and the density CD _CGDL of the cathode catalyst in the air electrode gas diffusion layer The difference CD _CCL -CD _CGDL (%) was measured. Table 5 shows these results.

(Example 6)
Carbon paper having a thickness of 380 μm (TGP-H-120 manufactured by Toray Industries, Inc., porosity by the Archimedes method: 75%) was compressed by a flat plate press until the thickness became 1/2. When the porosity of the carbon paper after compression was calculated from the external dimensions and weight, it was 40.5%. This carbon paper was used for the fuel electrode gas diffusion layer. A Nafion (registered trademark) solution DE2020 (manufactured by DuPont) diluted to 5% was prepared as a proton conductor. This solution was spray-coated on one surface of the fuel electrode gas diffusion layer made of the compressed carbon paper, and the fuel electrode gas diffusion layer was impregnated with a proton conductor. This was naturally dried at room temperature. A platinum ruthenium alloy-supported graphite particle, Nafion (registered trademark) solution DE2020 (manufactured by DuPont) as a proton conductor, and a solvent were mixed with a homogenizer to prepare a slurry having a solid content of about 5%. This slurry was spray coated on one surface of the fuel electrode gas diffusion layer impregnated and dried with the proton conductor, and the anode gas diffusion layer was impregnated with the anode catalyst. At this time, two types of samples (6a and 6b) were prepared by adjusting the spray amount so that the thicknesses of the regions impregnated with the proton conductor and the anode catalyst were different. This was naturally dried at room temperature to form a fuel electrode gas diffusion layer containing an anode catalyst.

  A carbon particle carrying platinum ruthenium alloy fine particles, Nafion (registered trademark) solution DE2020 (manufactured by DuPont) as a proton conductor, and a solvent were mixed with a homogenizer to prepare a slurry having a solid content of about 13%. This slurry was applied to one surface of the fuel electrode gas diffusion layer using a die coater. This was naturally dried at room temperature to form a fuel electrode catalyst layer. Thus, a fuel electrode (anode) was produced.

  Carbon paper having a thickness of 380 μm (TGP-H-120 manufactured by Toray Industries, Inc., porosity by the Archimedes method: 75%) was used for the air electrode gas diffusion layer. A platinum-supported graphite particle, Nafion (registered trademark) solution DE2020 (manufactured by DuPont) as a proton conductor, and a solvent were mixed with a homogenizer to prepare a slurry having a solid content of about 15%. This slurry was applied to the air electrode gas diffusion layer containing the cathode catalyst using a die coater. This was naturally dried at room temperature to form an air electrode catalyst layer. Thus, an air electrode (cathode) was produced.

Nafion (registered trademark) 112 (manufactured by DuPont) was prepared as an electrolyte membrane. First, an air electrode was superimposed on one surface of the electrolyte membrane so that the air electrode catalyst layer was on the electrolyte membrane side, and pressed under conditions of a temperature of 135 ° C. and a pressure of 40 kgf / cm ² . Subsequently, the fuel electrode was overlapped so that the fuel electrode catalyst layer was on the side of the electrolyte membrane on the opposite side of the air electrode of the electrolyte membrane, and pressed under conditions of a temperature of 135 ° C. and a pressure of 10 kgf / cm ² . . Thus, a fuel cell electrode membrane assembly (MEA) was produced. The electrode area was 12 cm ² for both the air electrode and the fuel electrode.

  The MEA was sandwiched between two layers of gold foil each having a plurality of openings for taking in air and vaporized methanol, thereby forming an air electrode conductive layer and a fuel electrode conductive layer. A laminate in which the MEA, the fuel electrode conductive layer, and the air electrode conductive layer were stacked was sandwiched between two resin frames. At this time, rubber O-rings were sandwiched between the air electrode side of the MEA and one frame and between the fuel electrode side of the MEA and the other frame, respectively, to provide a seal.

  The fuel electrode side frame was fixed to the liquid fuel storage chamber via a gas-liquid separation membrane by screws. A 0.2 mm thick silicone sheet was used for the gas-liquid separation membrane. On the other hand, a porous plate having a porosity of 28% was placed on the frame on the air electrode side to form a moisture retention layer. On this moisturizing layer, a 2 mm thick stainless steel plate (SUS304) with air inlets (4 mm diameter, 64 holes) for air intake is placed to form a surface cover layer and fixed by screwing did.

5 mL of pure methanol was injected into the liquid fuel storage chamber of the fuel cell formed as described above. Electric power was generated in an environment of a temperature of 25 ° C. and a relative humidity of 50%, current values and voltage values were measured, and the maximum value of the output density was calculated. As a result, the maximum value of the power density was 34.3 to 36.7 mW / cm ² .

The MEA was taken out of the cell, cut and embedded in the resin so that the cross section was visible. The MEA embedded in the resin was polished so that its cross section was flat, and then subjected to elemental analysis by observation with an electron microscope. As a result, the average thickness of the anode catalyst layer (CT _ACL ), the average thickness of the proton conductor-containing region in the anode gas diffusion layer (PT _AGDL ), the anode catalyst-containing region in the anode gas diffusion layer Average thickness (CT _AGDL ), CT _AGDL / CT _ACL ratio (%), density of anode catalyst in the anode catalyst layer CD _ACL and density of anode catalyst in the anode gas diffusion layer CD _AGDL CD _ACL -CD _AGDL (%), the average thickness of the air electrode catalyst layer (CT _CCL ) was measured. Table 6 shows these results.

(Example 7)
Carbon paper having a thickness of 380 μm (TGP-H-030 manufactured by Toray Industries, Inc., porosity by the Archimedes method: 75%) was compressed by a flat plate press until the thickness became 1/2. When the porosity of the carbon paper after compression was calculated from the external dimensions and weight, it was 40.5%. Two sheets of this compressed carbon paper were prepared.

  Carbon particles carrying platinum ruthenium alloy fine particles and a solvent were mixed with a homogenizer to prepare a slurry having a solid content of about 5%. One compressed carbon paper was immersed in this slurry, and then naturally dried at room temperature. At this time, the slurry penetrated over the entire thickness of the compressed carbon paper. A carbon particle carrying platinum ruthenium alloy fine particles, a Nafion (registered trademark) solution DE2020 (manufactured by DuPont) as a proton conductor, and a solvent were mixed with a homogenizer to prepare a slurry having a solid content of about 15%. The slurry was applied to one surface of the compressed carbon paper using a die coater and then naturally dried at room temperature. Thus, an anode catalyst layer with an anode gas diffusion layer was formed.

  The platinum-supported graphite particles and the solvent were mixed with a homogenizer to prepare a slurry having about 5% solid content. Another sheet of compressed carbon paper was immersed in this slurry, and then naturally dried at room temperature. At this time, the slurry penetrated over the entire thickness of the compressed carbon paper. A platinum-supported graphite particle, Nafion (registered trademark) solution DE2020 (manufactured by DuPont) as a proton conductor, and a solvent were mixed with a homogenizer to prepare a slurry having a solid content of about 15%. The slurry was applied to one surface of the compressed carbon paper using a die coater and then naturally dried at room temperature. Thus, an air electrode catalyst layer with an air electrode gas diffusion layer was formed.

  Carbon paper having a thickness of 300 μm (TGP-H-090 manufactured by Toray Industries, Inc., porosity by Archimedes method: 75%) was compressed by a flat plate press until the thickness became 1/2. When the porosity of the carbon paper after compression was calculated from the external dimensions and weight, it was 40.5%. Two sheets of this compressed carbon paper were prepared and used for the fuel electrode gas diffusion layer and the air electrode gas diffusion layer, respectively.

Nafion (registered trademark) 112 (manufactured by DuPont) was prepared as an electrolyte membrane. First, on one surface of the electrolyte membrane, an air electrode catalyst layer with an air electrode gas diffusion layer is overlaid so that the air electrode catalyst layer is on the electrolyte membrane side, and an air electrode gas diffusion layer is overlaid thereon, Pressing was performed under conditions of a temperature of 135 ° C. and a pressure of 40 kgf / cm ² . Subsequently, a fuel electrode catalyst layer with a fuel electrode gas diffusion layer is overlaid on the opposite side of the air electrode of the electrolyte membrane so that the fuel electrode catalyst layer is on the electrolyte membrane side. The diffusion layers were overlaid and pressed under conditions of a temperature of 135 ° C. and a pressure of 10 kgf / cm ² . Thus, a fuel cell electrode membrane assembly (MEA) was produced. The electrode area was 12 cm ² for both the air electrode and the fuel electrode.

  The MEA was sandwiched between two layers of gold foil each having a plurality of openings for taking in air and vaporized methanol, thereby forming an air electrode conductive layer and a fuel electrode conductive layer. A laminate in which the MEA, the fuel electrode conductive layer, and the air electrode conductive layer were stacked was sandwiched between two resin frames. At this time, rubber O-rings were sandwiched between the air electrode side of the MEA and one frame and between the fuel electrode side of the MEA and the other frame, respectively, to provide a seal.

  The fuel electrode side frame was fixed to the liquid fuel storage chamber via a gas-liquid separation membrane by screws. A 0.2 mm thick silicone sheet was used for the gas-liquid separation membrane. On the other hand, a porous plate having a porosity of 28% was placed on the frame on the air electrode side to form a moisture retention layer. On this moisturizing layer, a 2 mm thick stainless steel plate (SUS304) with air inlets (4 mm diameter, 64 holes) for air intake is placed to form a surface cover layer and fixed by screwing did.

5 mL of pure methanol was injected into the liquid fuel storage chamber of the fuel cell formed as described above. Electric power was generated in an environment of a temperature of 25 ° C. and a relative humidity of 50%, current values and voltage values were measured, and the maximum value of the output density was calculated. As a result, the maximum value of the power density was 39.8 mW / cm ² .

The MEA was taken out of the cell, cut and embedded in the resin so that the cross section was visible. The MEA embedded in the resin was polished so that its cross section was flat, and then subjected to elemental analysis by observation with an electron microscope. As a result, the average thickness of the anode catalyst layer (CT _ACL ), the average thickness of the anode catalyst-containing region in the anode gas diffusion layer (CT _AGDL ), the ratio of CT _AGDL / CT _ACL (%), the anode Difference between the density CD _ACL of the anode catalyst in the catalyst layer and the density CD _AGDL of the anode catalyst in the anode gas diffusion layer CD _ACL −CD _AGDL (%), average thickness of the cathode catalyst layer (CT _CCL ), air Average thickness of cathode catalyst containing region in electrode gas diffusion layer (CT _CGDL ), ratio of CT _CGDL / CT _CCL (%), density of cathode catalyst in air electrode catalyst layer CD _CCL and in air electrode gas diffusion layer The difference CD _CCL -CD _CGDL (%) from the density CD _{CGDL of the} cathode catalyst was measured. Table 7 shows these results.

(Example 8)
Two sheets of carbon paper having a thickness of 100 μm (TGP-H-030 manufactured by Toray Industries, Inc., porosity by the Archimedes method: 75%) were prepared. A Nafion (registered trademark) solution DE2020 (manufactured by DuPont) diluted to 5% was prepared as a proton conductor. Each carbon paper was immersed in this solution and then naturally dried at room temperature. At this time, the solution penetrated over the entire thickness of the carbon paper.

  Carbon particles carrying platinum ruthenium alloy fine particles and a solvent were mixed with a homogenizer to prepare a slurry having a solid content of about 5%. One carbon paper subjected to the above proton conductor immersion treatment was immersed in this slurry, and then naturally dried at room temperature. At this time, the slurry penetrated over the entire film thickness of the carbon paper. A carbon particle carrying platinum ruthenium alloy fine particles, a Nafion (registered trademark) solution DE2020 (manufactured by DuPont) as a proton conductor, and a solvent were mixed with a homogenizer to prepare a slurry having a solid content of about 15%. The slurry was applied to one side of the carbon paper using a die coater, and then naturally dried at room temperature. Thus, an anode catalyst layer with an anode gas diffusion layer was formed.

  The platinum-supported graphite particles and the solvent were mixed with a homogenizer to prepare a slurry having about 5% solid content. One carbon paper subjected to the above proton conductor immersion treatment was immersed in this slurry, and then naturally dried at room temperature. At this time, the slurry penetrated over the entire film thickness of the carbon paper. A platinum-supported graphite particle, Nafion (registered trademark) solution DE2020 (manufactured by DuPont) as a proton conductor, and a solvent were mixed with a homogenizer to prepare a slurry having a solid content of about 15%. The slurry was applied to one side of the carbon paper using a die coater, and then naturally dried at room temperature. Thus, an air electrode catalyst layer with an air electrode gas diffusion layer was formed.

  Carbon paper having a thickness of 300 μm (TGP-H-090 manufactured by Toray Industries, Inc., porosity by Archimedes method: 75%) was compressed by a flat plate press until the thickness became 1/2. When the porosity of the carbon paper after compression was calculated from the external dimensions and weight, it was 40.5%. Two sheets of this compressed carbon paper were prepared and used for the fuel electrode gas diffusion layer and the air electrode gas diffusion layer, respectively.

Nafion (registered trademark) 112 (manufactured by DuPont) was prepared as an electrolyte membrane. First, on one surface of the electrolyte membrane, an air electrode catalyst layer with an air electrode gas diffusion layer is overlaid so that the air electrode catalyst layer is on the electrolyte membrane side, and an air electrode gas diffusion layer is overlaid thereon, Pressing was performed under conditions of a temperature of 135 ° C. and a pressure of 40 kgf / cm ² . Subsequently, a fuel electrode catalyst layer with a fuel electrode gas diffusion layer is overlaid on the opposite side of the air electrode of the electrolyte membrane so that the fuel electrode catalyst layer is on the electrolyte membrane side. The diffusion layers were overlaid and pressed under conditions of a temperature of 135 ° C. and a pressure of 10 kgf / cm ² . Thus, a fuel cell electrode membrane assembly (MEA) was produced. The electrode area was 12 cm ² for both the air electrode and the fuel electrode.

  The MEA was sandwiched between two layers of gold foil each having a plurality of openings for taking in air and vaporized methanol, thereby forming an air electrode conductive layer and a fuel electrode conductive layer. A laminate in which the MEA, the fuel electrode conductive layer, and the air electrode conductive layer were stacked was sandwiched between two resin frames. At this time, rubber O-rings were sandwiched between the air electrode side of the MEA and one frame and between the fuel electrode side of the MEA and the other frame, respectively, to provide a seal.

  The fuel electrode side frame was fixed to the liquid fuel storage chamber via a gas-liquid separation membrane by screws. A 0.2 mm thick silicone sheet was used for the gas-liquid separation membrane. On the other hand, a porous plate having a porosity of 28% was placed on the frame on the air electrode side to form a moisture retention layer. On this moisturizing layer, a 2 mm thick stainless steel plate (SUS304) with air inlets (4 mm diameter, 64 holes) for air intake is placed to form a surface cover layer and fixed by screwing did.

5 mL of pure methanol was injected into the liquid fuel storage chamber of the fuel cell formed as described above. Electric power was generated in an environment of a temperature of 25 ° C. and a relative humidity of 50%, current values and voltage values were measured, and the maximum value of the output density was calculated. As a result, the maximum value of the power density was 40.0 mW / cm ² .

The MEA was taken out of the cell, cut and embedded in the resin so that the cross section was visible. The MEA embedded in the resin was polished so that its cross section was flat, and then subjected to elemental analysis by observation with an electron microscope. As a result, the average thickness of the anode catalyst layer (CT _ACL ), the average thickness of the proton conductor-containing region in the anode gas diffusion layer (PT _AGDL ), the anode catalyst-containing region in the anode gas diffusion layer Average thickness (CT _AGDL ), CT _AGDL / CT _ACL ratio (%), density of anode catalyst in the anode catalyst layer CD _ACL and density of anode catalyst in the anode gas diffusion layer CD _AGDL CD _ACL -CD _AGDL (%), average thickness of air electrode catalyst layer (CT _CCL ), average thickness of proton conductor containing region in air electrode gas diffusion layer (PT _CGDL ), cathode catalyst in air electrode gas diffusion layer The average thickness of the contained region (CT _CGDL ), the ratio of CT _CGDL / CT _CCL (%), the density CD _CCL of the cathode catalyst in the air electrode catalyst layer and the density CD _CGDL of the cathode catalyst in the air electrode gas diffusion layer The difference CD _CCL -CD _CGDL (%) was measured. Table 8 shows these results.

(Comparative Example 1)
Carbon paper having a thickness of 380 μm (TGP-H-120 manufactured by Toray Industries, Inc., porosity by the Archimedes method: 75%) was compressed by a flat plate press until the thickness became 1/2. When the porosity of the carbon paper after compression was calculated from the external dimensions and weight, it was 40.5%. This carbon paper was used for the fuel electrode gas diffusion layer.

  A carbon particle carrying platinum ruthenium alloy fine particles, Nafion (registered trademark) solution DE2020 (manufactured by DuPont) as a proton conductor, and a solvent were mixed with a homogenizer to prepare a slurry having a solid content of about 15%. This slurry was applied to one surface of the fuel electrode gas diffusion layer made of the compressed carbon paper using a die coater. This was naturally dried at room temperature to form a fuel electrode catalyst layer. Thus, a fuel electrode (anode) was produced.

  Carbon paper having a thickness of 380 μm (TGP-H-120 manufactured by Toray Industries, Inc., porosity by the Archimedes method: 75%) was used for the air electrode gas diffusion layer. A platinum-supported graphite particle, Nafion (registered trademark) solution DE2020 (manufactured by DuPont) as a proton conductor, and a solvent were mixed with a homogenizer to prepare a slurry having a solid content of about 15%. This slurry was applied to the air electrode gas diffusion layer made of the carbon paper using a die coater. This was naturally dried at room temperature to form an air electrode catalyst layer. Thus, an air electrode (cathode) was produced.

Nafion (registered trademark) 112 (manufactured by DuPont) was prepared as an electrolyte membrane. First, an air electrode was superimposed on one surface of the electrolyte membrane so that the air electrode catalyst layer was on the electrolyte membrane side, and pressed under conditions of a temperature of 135 ° C. and a pressure of 40 kgf / cm ² . Subsequently, the fuel electrode was overlapped so that the fuel electrode catalyst layer was on the side of the electrolyte membrane on the opposite side of the air electrode of the electrolyte membrane, and pressed under conditions of a temperature of 135 ° C. and a pressure of 10 kgf / cm ² . . Thus, a fuel cell electrode membrane assembly (MEA) was produced. The electrode area was 12 cm ² for both the air electrode and the fuel electrode.

  The MEA was sandwiched between two layers of gold foil each having a plurality of openings for taking in air and vaporized methanol, thereby forming an air electrode conductive layer and a fuel electrode conductive layer. A laminate in which the MEA, the fuel electrode conductive layer, and the air electrode conductive layer were stacked was sandwiched between two resin frames. At this time, rubber O-rings were sandwiched between the air electrode side of the MEA and one frame and between the fuel electrode side of the MEA and the other frame, respectively, to provide a seal.

  The fuel electrode side frame was fixed to the liquid fuel storage chamber via a gas-liquid separation membrane by screws. A 0.2 mm thick silicone sheet was used for the gas-liquid separation membrane. On the other hand, a porous plate having a porosity of 28% was placed on the frame on the air electrode side to form a moisture retention layer. On this moisturizing layer, a 2 mm thick stainless steel plate (SUS304) with air inlets (4 mm diameter, 64 holes) for air intake is placed to form a surface cover layer and fixed by screwing did.

5 mL of pure methanol was injected into the liquid fuel storage chamber of the fuel cell formed as described above. Electric power was generated in an environment of a temperature of 25 ° C. and a relative humidity of 50%, current values and voltage values were measured, and the maximum value of the output density was calculated. As a result, the maximum value of the power density was 29.8 mW / cm ² .

The MEA was taken out of the cell, cut and embedded in the resin so that the cross section was visible. The MEA embedded in the resin was polished so that its cross section was flat, and then subjected to elemental analysis by observation with an electron microscope. From the results, when the average thickness (CT _ACL ) of the fuel electrode catalyst layer and the average thickness (CT _CCL ) of the air electrode catalyst layer were measured, CT _ACL was 48 μm and CT _CCL was 50 μm.

(Comparative Example 2)
Carbon paper having a thickness of 380 μm (TGP-H-120 manufactured by Toray Industries, Inc., porosity by the Archimedes method: 75%) was compressed by a flat plate press until the thickness became 1/2. When the porosity of the carbon paper after compression was calculated from the external dimensions and weight, it was 40.5%. This carbon paper was used for the fuel electrode gas diffusion layer.

  A carbon particle carrying platinum ruthenium alloy fine particles, a Nafion (registered trademark) solution DE2020 (manufactured by DuPont) as a proton conductor, and a solvent were mixed with a homogenizer to prepare a slurry having a solid content of about 5%. This slurry was spray-coated on one surface of the anode gas diffusion layer made of the compressed carbon paper, and impregnated in the anode gas diffusion layer. This was naturally dried at room temperature to form a fuel electrode gas diffusion layer without a fuel electrode catalyst layer.

  Carbon paper having a thickness of 380 μm (TGP-H-120 manufactured by Toray Industries, Inc., porosity by the Archimedes method: 75%) was used for the air electrode gas diffusion layer. A platinum-supported graphite particle, Nafion (registered trademark) solution DE2020 (manufactured by DuPont) as a proton conductor, and a solvent were mixed with a homogenizer to prepare a slurry having a solid content of about 5%. This slurry was spray-coated on one surface of the air electrode gas diffusion layer made of the above carbon paper to form an air electrode gas diffusion layer without an air electrode catalyst layer.

Nafion (registered trademark) 112 (manufactured by DuPont) was prepared as an electrolyte membrane. First, an air electrode gas diffusion layer is superimposed on one surface of the electrolyte membrane so that the surface impregnated with the cathode catalyst layer is on the electrolyte membrane side, and pressed under conditions of a temperature of 135 ° C. and a pressure of 40 kgf / cm ^2. did. Subsequently, the fuel electrode gas diffusion layer is overlaid on the opposite side of the electrolyte membrane air electrode gas diffusion layer so that the surface impregnated with the anode catalyst is on the electrolyte membrane side. Pressing was performed under the condition of 10 kgf / cm ² . Thus, a fuel cell electrode membrane assembly (MEA) was produced. The electrode area was 12 cm ² for both the air electrode and the fuel electrode.

  The MEA was sandwiched between two layers of gold foil each having a plurality of openings for taking in air and vaporized methanol, thereby forming an air electrode conductive layer and a fuel electrode conductive layer. A laminate in which the MEA, the fuel electrode conductive layer, and the air electrode conductive layer were stacked was sandwiched between two resin frames. At this time, rubber O-rings were sandwiched between the air electrode side of the MEA and one frame and between the fuel electrode side of the MEA and the other frame, respectively, to provide a seal.

  The fuel electrode side frame was fixed to the liquid fuel storage chamber via a gas-liquid separation membrane by screws. A 0.2 mm thick silicone sheet was used for the gas-liquid separation membrane. On the other hand, a porous plate having a porosity of 28% was placed on the frame on the air electrode side to form a moisture retention layer. On this moisturizing layer, a 2 mm thick stainless steel plate (SUS304) with air inlets (4 mm diameter, 64 holes) for air intake is placed to form a surface cover layer and fixed by screwing did.

5 mL of pure methanol was injected into the liquid fuel storage chamber of the fuel cell formed as described above. Electric power was generated in an environment of a temperature of 25 ° C. and a relative humidity of 50%, current values and voltage values were measured, and the maximum value of the output density was calculated. As a result, the maximum value of the power density was 12.0 mW / cm ² .

The MEA was taken out of the cell, cut and embedded in the resin so that the cross section was visible. The MEA embedded in the resin was polished so that its cross section was flat, and then subjected to elemental analysis by observation with an electron microscope. From the results, where the average thickness of the anode catalyst containing region of the fuel electrode gas diffusion layer (CT _AGDL) and the average thickness of the cathode catalyst-containing region of the air electrode gas diffusion layer in (CT _CGDL) was measured, CT _AGDL Was 10 μm and CT _CGDL was 8 μm.

  When Examples 1-8 and Comparative Examples 1 and 2 are compared, it can be seen that the power density of the example is higher than that of the comparative example.

  In addition, the method of making a proton conductor osmose | permeate carbon paper is not specifically limited. Further, the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. In addition, various inventions can be formed by appropriately combining a plurality of components disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, constituent elements over different embodiments may be appropriately combined.

  Further, the configuration of the fuel cell body is not limited to a passive type fuel cell, but also to an active type fuel cell, and also to a fuel cell of a type called a semi-passive that uses a pump or the like for part of a fuel supply. The present invention can be applied. In the semi-passive type fuel cell, the fuel supplied from the liquid fuel container to the membrane electrode assembly is used for the power generation reaction, and is not circulated and returned to the liquid fuel container. The semi-passive type fuel cell is different from the conventional active method because it does not circulate the fuel, and does not impair the downsizing of the device. In addition, the fuel cell uses a pump for supplying fuel, and is different from a pure passive system such as a conventional internal vaporization type. For this reason, the fuel cell is referred to as a semi-passive method as described above. In this semi-passive type fuel cell, a fuel cutoff valve may be arranged in place of the pump as long as fuel is supplied from the fuel storage portion to the membrane electrode assembly. In this case, the fuel cutoff valve is provided to control the supply of liquid fuel through the flow path.

  Also, the liquid fuel supplied to the membrane electrode assembly may be supplied with all the vapor of the liquid fuel, but the present invention can be applied even when a part of the liquid fuel is supplied in a liquid state. .

Sectional drawing of the electrode membrane assembly for direct methanol type fuel cells which concerns on one Embodiment of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Fuel cell electrode membrane assembly (MEA), 10 ... Fuel electrode (anode), 11 ... Fuel electrode catalyst layer, 12 ... Fuel electrode gas diffusion layer, 20 ... Air electrode (cathode), 21 ... Air electrode catalyst layer , 22 ... air electrode gas diffusion layer, 30 ... electrolyte membrane.

Claims (12)

A fuel electrode having an anode catalyst layer containing an anode catalyst, and a fuel electrode gas diffusion layer provided on one surface of the fuel electrode catalyst layer;
An air electrode having an air electrode catalyst layer containing a cathode catalyst, and an air electrode gas diffusion layer containing a cathode catalyst provided on one surface of the air electrode catalyst layer;
A fuel cell electrode membrane assembly comprising an electrolyte membrane sandwiched between a fuel electrode catalyst layer of the fuel electrode and an air electrode catalyst layer of the air electrode.   2. The fuel cell according to claim 1, wherein an average thickness of a region containing the cathode catalyst of the air electrode gas diffusion layer is 10% or more of an average thickness of the air electrode catalyst layer. Electrode membrane assembly.   The electrode membrane assembly for a fuel cell according to claim 1 or 2, wherein the air electrode gas diffusion layer contains a proton conductor.   4. The electrode membrane assembly for a fuel cell according to claim 1, wherein the anode gas diffusion layer contains an anode catalyst. 5.   5. The average thickness of the region containing the anode catalyst in the anode gas diffusion layer is 10% or more of the average thickness of the anode electrode catalyst layer. 6. The electrode membrane assembly for a fuel cell according to Item.   The electrode membrane assembly for a fuel cell according to any one of claims 1 to 5, wherein the anode gas diffusion layer contains a proton conductor.   The fuel cell electrode according to any one of claims 1 to 6, wherein the density of the cathode catalyst in the air electrode catalyst layer is larger than the density of the cathode catalyst in the air electrode gas diffusion layer. Membrane assembly. A fuel electrode having a fuel electrode catalyst layer containing an anode catalyst and a fuel electrode gas diffusion layer containing an anode catalyst provided on one surface of the fuel electrode catalyst layer;
An air electrode catalyst layer containing a cathode catalyst, and an air electrode having an air electrode gas diffusion layer provided on one surface of the air electrode catalyst layer;
A fuel cell electrode membrane assembly comprising an electrolyte membrane sandwiched between a fuel electrode catalyst layer of the fuel electrode and an air electrode catalyst layer of the air electrode.   9. The fuel cell according to claim 8, wherein an average thickness of a region containing the anode catalyst in the anode gas diffusion layer is 10% or more of an average thickness of the anode electrode catalyst layer. Electrode membrane assembly.   10. The fuel cell electrode membrane assembly according to claim 8, wherein the fuel electrode gas diffusion layer contains a proton conductor.   11. The fuel cell electrode according to claim 8, wherein a density of the anode catalyst in the anode catalyst layer is higher than an anode catalyst in the anode gas diffusion layer. 11. Membrane assembly.   A fuel cell using the electrode membrane assembly for a fuel cell according to any one of claims 1 to 11.

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