JP2013069551A - Solid polymer fuel cell and manufacturing method of gas diffusion electrode - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polymer electrolyte fuel cell excellent in ion conductivity and excellent in crossover prevention effect and a method for producing a gas diffusion electrode.
An electrolyte membrane that permeates cations or anions, and a pair of catalyst layers formed with a supported or unsupported metal catalyst with a cation exchange resin or anion exchange resin as a binder, sandwiched between the electrolyte membranes; A pair of gas diffusion layers for diffusing gas disposed between the pair of catalyst layers, and a pair of separators disposed between the pair of gas diffusion layers and having gas flow paths formed therebetween. A solid polymer fuel cell in which at least one of the pair of catalyst layers contains a hydrophilic oxide.
[Selection] Figure 1

Description

  The present invention relates to a polymer electrolyte fuel cell and a method for producing a gas diffusion electrode, and more particularly to a polymer electrolyte fuel cell having a hydrophilized catalyst layer and a method for producing a gas diffusion electrode.

  In the polymer electrolyte fuel cell, a polymer electrolyte membrane having high ion conductivity has been developed, and catalyst-supported carbon fine particles coated with an ion exchange resin of the same type or different from the polymer electrolyte membrane are used as an electrode catalyst. The battery characteristics were dramatically improved by using it as a constituent material of the layer and making the reaction sites in the catalyst layer three-dimensional.

  In addition to being able to obtain such high battery characteristics, it is easy to reduce the size and weight, so solid polymer fuel cells are used for mobile vehicles such as electric vehicles, power sources for small cogeneration systems, etc. Promotion of practical application as

  However, solid polymer fuel cells generally have a low operating temperature range due to restrictions such as heat resistance and ion conductivity of the polymer electrolyte membrane, and it is difficult to use the exhaust heat. Therefore, for practical application of polymer electrolyte fuel cells, high power generation efficiency and high power density are obtained, especially under operating conditions with high utilization rates of anode reaction gas such as pure hydrogen and cathode reaction gas such as air. Performance that can be done is also required.

  Here, when the electrolyte composition constituting the electrolyte membrane is dried, the ion conductivity and the electrode performance are remarkably deteriorated. On the other hand, the higher the wetness of the electrolyte composition, the higher the ionic conductivity. Therefore, when a current flows through the electrolyte composition and the energy loss in the electrode reaction is reduced, a high-performance solid polymer fuel cell Can be obtained. A sufficiently wetted electrolyte composition can also prevent a so-called crossover in which, for example, hydrogen gas supplied to the anode and oxygen gas supplied to the cathode pass through the electrolyte composition and leak. .

  Thus, it is intended to prevent the electrolyte composition from drying and to prevent crossover, thereby improving the ionic conductivity of the electrolyte composition and improving the electrode reaction rate. Solid electrolyte compositions have been proposed. In the polymer solid electrolyte composition of Patent Document 1, at least one metal catalyst selected from platinum, gold, palladium, rhodium, iridium and ruthenium is added to the polymer solid electrolyte made of a cation exchange resin. 0.01 to 80% by weight with respect to the weight of the molecular solid electrolyte, and at least one metal oxide fine particle and / or fiber selected from silica and titania with respect to the weight of the polymer solid electrolyte 0.01 to 50% by weight is included.

  Thereby, it is said that the polymer solid electrolyte composition excellent in the ion conductivity and the crossover prevention effect can be provided.

Japanese Patent No. 3375200

  However, the polymer solid electrolyte composition described in Patent Document 1 constitutes an electrolyte membrane, and it is complicated to place fine metal oxide “particles” or “fibers” such as silica in the electrolyte membrane. There is a problem that a process is required and it is difficult to uniformly enter the film.

  Further, the electrolyte membrane has an upper limit on the amount of silica added, and there is a problem that the influence of the amount added is not so great.

  In view of such circumstances, the present invention intends to provide a polymer electrolyte fuel cell and a gas diffusion electrode manufacturing method that do not require a complicated process, have excellent ion conductivity, and have excellent low-humidity starting performance. It is.

  Each problem of the present invention can be solved by the following invention.

  That is, the polymer electrolyte fuel cell according to the present invention comprises an electrolyte membrane that allows permeation of cations or anions, and a supported or unsupported metal catalyst that is disposed with the electrolyte membrane sandwiched between the cation exchange resin or the anion exchange resin. A pair of formed catalyst layers, a pair of gas diffusion layers for diffusing gas disposed between the pair of catalyst layers, and a gas flow disposed between the pair of gas diffusion layers. And a pair of separators formed with channels, and at least one of the pair of catalyst layers includes a hydrophilic oxide.

  As a result, the hydrophilic oxide in the catalyst layer traps the water generated by the reaction of the fuel cell and humidifies the electrolyte membrane with the trapped water, so that the catalyst layer and the electrolyte membrane can be removed without any external humidification. Humidification can be performed, whereby ion conductivity can be improved, and start-up performance at low humidity can be improved.

  In addition, when a highly humidified gas is supplied from the outside, the hydrophilic oxide traps moisture and adjusts the humidified state, so that the catalyst layer can be prevented from being excessively humidified.

  The main feature of the solid polymer fuel cell of the present invention is that the hydrophilic oxide is prepared from an oxide sol.

  Furthermore, the method for producing a gas diffusion electrode of the present invention includes a preparation step of preparing a mixed solution of alcohol, a metal oxide precursor sol, and an inorganic acid, and a gel dispersion solution of a hydrophilic oxide by stirring the mixed solution. Preparing a gel dispersion solution, preparing a Pt / C catalyst, water and alcohol, mixing these to prepare a catalyst mixture, preparing the catalyst mixture, the catalyst mixture, and the gel dispersion And a catalyst paste preparation step for preparing a catalyst paste in which a hydrophilic oxide gel is dispersed by mixing an ion exchange resin, and applying the catalyst paste on the gas diffusion layer or the electrolyte membrane A gas diffusion layer having a paste, and a gas diffusion layer having a hydrophilic oxide, which is prepared in the application step and dried. And a step of producing a diffusion electrode.

  As a result, the hydrophilic oxide uniformly dispersed in the catalyst layer traps the water generated by the reaction of the fuel cell, and further humidifies the electrolyte membrane with the trapped water, so there is no need for external humidification. The catalyst layer and the electrolyte membrane can be humidified, whereby a gas diffusion electrode that can improve the ionic conductivity and adjust the moisture of the catalyst layer can be manufactured.

  In addition, when a highly humidified gas is supplied from the outside, the hydrophilic oxide traps moisture and adjusts the humidified state, thereby preventing the catalyst layer from being excessively humidified and inhibiting oxygen diffusion. It is possible to manufacture a gas diffusion electrode that can be used.

  Furthermore, the method for producing an electrode-integrated electrolyte membrane of the present invention includes a preparation step of preparing a mixed solution of alcohol, a metal oxide precursor sol, and an inorganic acid, and stirring the mixed solution to form a hydrophilic oxide. Preparing a gel dispersion solution, preparing a gel dispersion solution, preparing a Pt / C catalyst, water and alcohol, mixing these to prepare a catalyst mixture, preparing the catalyst mixture, the catalyst mixture, and A catalyst paste preparation step for preparing a catalyst paste in which a hydrophilic oxide gel is dispersed by mixing a gel dispersion solution and an ion exchange resin, and an electrolyte with a catalyst paste by applying the catalyst paste on the electrolyte membrane An application step for producing a membrane, and an electrode-integrated electrolyte membrane containing a hydrophilic oxide by drying the electrolyte membrane with catalyst paste produced in the application step The main feature is that it comprises a step of manufacturing.

  As a result, the hydrophilic oxide uniformly dispersed in the catalyst layer traps the water generated by the reaction of the fuel cell, and further humidifies the electrolyte membrane with the trapped water, so there is no need for external humidification. The catalyst layer and the electrolyte membrane can be humidified, whereby an electrode-integrated electrolyte membrane that can improve ionic conductivity and adjust the moisture of the catalyst layer can be produced.

  In addition, when a highly humidified gas is supplied from the outside, the hydrophilic oxide traps moisture and adjusts the humidified state, thereby preventing the catalyst layer from being excessively humidified and inhibiting oxygen diffusion. An electrode-integrated electrolyte membrane that can be manufactured can be manufactured.

  The main feature of the method for producing a gas diffusion electrode of the present invention is that the catalyst paste is applied by a pulse swirl spray method.

  Furthermore, the method for producing an electrode-integrated electrolyte membrane of the present invention is characterized in that a catalyst paste is applied onto the electrolyte membrane by a pulse swirl spray method.

  It is possible to provide a method for producing a solid polymer fuel cell and a gas diffusion electrode that are excellent in ion conductivity and excellent in the moisture control function of the catalyst layer.

It is the schematic which showed the structure of the polymer electrolyte fuel cell which concerns on this invention. It is a flowchart which shows an example of the manufacturing process of a gas diffusion electrode. It is explanatory drawing for demonstrating a pulse swirl spray (PSS) method. It is a figure which shows the polarization curve and ohmic resistance in 80 degreeC and 30% RH. 80 ° C., shows a cyclic voltammogram of SiO _2-MEA and normal-MEA in 30% RH and 20 mV / sec.

  Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the accompanying drawings. In the present specification, when the numerical range is expressed using “˜”, the upper and lower numerical values indicated by “˜” are also included in the numerical range.

<Configuration of fuel cell>
The structure of the polymer electrolyte fuel cell according to the present invention will be described with reference to FIG. FIG. 1 is a schematic view showing a configuration of a solid polymer fuel cell using a hydrogen ion conductive electrolyte membrane according to the present invention. As shown in FIG. 1, the polymer electrolyte fuel cell of the present invention comprises a pair of separators 10 and 20, an anode 30 as a fuel electrode, a cathode 40 as an air electrode, and an electrolyte membrane 50. Is done.

The electrolyte membrane 50 is disposed so as to be sandwiched between the anode 30 and the cathode 40, and is formed of an ion exchange resin such as Nafion (registered trademark) that transmits hydrogen ions (proton: H ⁺ ). MEA (Membrane Electrode Assembly) is configured by the electrolyte membrane 50, the anode 30, and the cathode 40 arranged in this manner. The pair of separators 10 and 20 are arranged with the MEA interposed therebetween.

  The separators 10 and 20 are made of, for example, metal, graphite, or the like, and have grooves that serve as fuel or air flow paths. The anode 30 includes a gas diffusion layer 60 formed of a porous material such as graphite fiber and a catalyst layer 70 formed on the surface of the gas diffusion layer 60. The catalyst layer 70 comprises, for example, a metal catalyst such as platinum, gold, palladium, rhodium, iridium, ruthenium (generally supported on carbon or other conductive carrier), a precursor of a hydrophilic oxide, and a binder. It can be formed by mixing.

  Here, a cation exchange resin that passes hydrogen ions or an anion exchange resin that passes hydroxide ions or the like is used as a binder contained in the catalyst layer 70. When the binder is included, in addition to assuming the conductivity of ions related to the battery reaction in the catalyst layer, the strength of the catalyst layer can be increased and a hydrophilic layer can be efficiently formed on the surface of the electrolyte membrane 50. It is particularly preferable that the binder is a resin similar to the resin constituting the electrolyte membrane 50 because adhesion between the binder, the catalyst, and the electrolyte membrane 50 can be improved.

  As an ion exchange resin used as a binder, for example, Nafion (registered trademark) manufactured by DuPont can be used. As a raw material for the hydrophilic oxide, a sol of a metal compound such as Si, Ti or Sn (metal alkoxide in sol) is preferably used.

  Similarly to the anode 30, the cathode 40 includes a gas diffusion layer 80 formed of a porous material such as graphite fiber and a catalyst layer 90 formed on the surface of the gas diffusion layer 80. The catalyst layer 90 can be formed, for example, by mixing a supported or unsupported metal catalyst such as platinum, gold, palladium, rhodium, iridium, and ruthenium, a hydrophilic oxide, and a binder.

  Here, similarly to the catalyst layer 70, the catalyst layer 90 includes a binder made of an ion exchange resin. When the binder is included, in addition to assuming ion conductivity related to the battery reaction, the strength of the catalyst layer is increased, and a hydrophilic layer can be efficiently formed on the surface of the electrolyte membrane 50. It is particularly preferable that the binder is a resin similar to the resin constituting the electrolyte membrane 50 because adhesion between the binder, the catalyst, and the electrolyte membrane 50 can be improved.

  As an ion exchange resin used as a binder, for example, Nafion (registered trademark) manufactured by DuPont can be used. As the precursor of the hydrophilic oxide, a sol (metal alkoxide or the like) of a metal compound such as Si, Ti, or Sn is preferably used.

  The polymer electrolyte fuel cell according to the present invention is characterized in that a hydrophilic oxide is contained in at least one of the catalyst layer 70 of the anode 30 and the catalyst layer 90 of the cathode 40. As a result, since the hydrophilic oxide has a high water retention capability, the water generated by the oxygen reduction reaction at the cathode is back-diffused to prevent deterioration of characteristics due to drying of the ion exchange resin in the catalyst layers 70 and 90. I can do it. Moreover, high performance can be maintained by keeping the substantial oxygen partial pressure in the catalyst layer high by the reverse diffusion of water.

  As described above, the polymer electrolyte fuel cell according to the present invention has excellent startability at low humidity and also has excellent startability at low temperature.

  Next, for the fuel cell according to the present invention, an acid electrolyte fuel cell in which hydrogen ions are responsible for conductivity in the cell, and an alkaline electrolyte membrane fuel cell in which negative ions such as hydroxide ions are responsible for conductivity in the cell; Further explanation will be given separately.

(1) Acid electrolyte fuel cell A polymer electrolyte fuel cell according to the present invention includes an electrolyte membrane that allows hydrogen ions to permeate, and a pair of catalyst layers that are formed of a metal catalyst and sandwiched between the electrolyte membranes. A pair of gas diffusion layers for diffusing gas disposed between the pair of catalyst layers, and a pair of separators disposed between the pair of gas diffusion layers and having gas flow paths formed therebetween And at least one of the pair of catalyst layers, preferably a catalyst layer that generates water during power generation, includes a hydrophilic oxide.

  As a result, the hydrophilic oxide in the catalyst layer traps the water generated by the reaction of the fuel cell and humidifies the electrolyte membrane with the trapped water, so that the catalyst layer and the electrolyte membrane can be removed without any external humidification. It can be humidified, thereby improving the ionic conductivity and promoting the water movement from the water-generating electrode (here cathode) to the electrolyte membrane and further to the counter electrode (here anode). The substantial oxygen partial pressure in the layer can be increased.

  In addition, when a highly humidified gas is supplied from the outside, the hydrophilic oxide traps moisture and adjusts the humidified state, so that the catalyst layer can be prevented from being excessively humidified.

(2) Alkaline electrolyte membrane fuel cell On the other hand, in an alkaline electrolyte membrane fuel cell in which negative ions such as hydroxide ions are responsible for conduction in the cell, an electrolyte membrane that allows hydroxide ions to pass therethrough and the electrolyte membrane A pair of catalyst layers formed of a metal catalyst disposed between, a pair of gas diffusion layers for diffusing gas disposed between the pair of catalyst layers, and the pair of gas diffusion layers. And a pair of separators formed with gas flow paths interposed therebetween, and at least one of the pair of catalyst layers, preferably a catalyst layer (anode) that generates water during power generation, is hydrophilic. The main feature is the inclusion of oxides.

  As a result, the hydrophilic oxide in the catalyst layer traps the water generated by the reaction of the fuel cell and humidifies the electrolyte membrane with the trapped water, so that the catalyst layer and the electrolyte membrane can be removed without any external humidification. The anode catalyst can be humidified, thereby improving the ionic conductivity and promoting moisture movement from the water-generating electrode (here, the anode) to the electrolyte membrane and further to the counter electrode (here, the cathode). The substantial hydrogen partial pressure in the layer can be increased and the ionic conductivity can be increased by humidifying the electrolyte in the cathode catalyst layer, thereby accelerating the cell reaction.

  Further, even when highly humidified gas is supplied from the outside, the hydrophilic oxide traps moisture and adjusts the humidified state, thereby preventing the catalyst layer from being excessively humidified and inhibiting hydrogen diffusion. be able to.

The main feature of the polymer electrolyte fuel cell of the present invention is that the hydrophilic oxide is SiO ₂ , TiO ₂ , SnO ₂ or the like.

  Furthermore, the method for producing a catalyst layer for a gas diffusion electrode according to the present invention comprises a step of preparing a sol mixed solution of alcohol, an oxide precursor such as TEOS (tetraethoxysilane) and an inorganic acid (nitric acid, hydrochloric acid, etc.), and the sol mixing Prepare the gel dispersion solution step to prepare the dispersion solution of hydrophilic oxide gel by stirring the solution, and prepare the catalyst mixture solution by preparing Pt / C catalyst, water and alcohol, and mixing them to prepare the catalyst mixture solution A catalyst paste preparing step of preparing a catalyst paste by stirring and mixing the catalyst mixed solution, the gel dispersion solution, and an ion exchange resin with a ball mill or the like, and applying the catalyst paste onto the gas diffusion layer The coating step and the gas diffusion layer with the catalyst paste prepared in the coating step is dried under vacuum, etc., and promotes dehydration condensation of the gel to make the catalyst layer hydrophilic Further comprising a step of preparing a gas diffusion electrode product is uniformly dispersed is the main feature.

  Thus, the hydrophilic oxide uniformly dispersed in the catalyst layer traps the water generated by the reaction of the fuel cell, and further humidifies the electrolyte membrane with the trapped water, so that the catalyst can be obtained without any external humidification. The layer and the electrolyte membrane can be humidified, whereby a gas diffusion electrode that can improve the ionic conductivity and adjust the moisture of the catalyst layer can be manufactured.

  In addition, when a highly humidified gas is supplied from the outside, the hydrophilic oxide traps moisture and adjusts the humidified state, thereby preventing the catalyst layer from being excessively humidified and inhibiting oxygen diffusion. It is possible to manufacture a gas diffusion electrode that can be used.

<Operation>
Next, an example of using an acid electrolyte membrane for the operation of the polymer electrolyte fuel cell according to the present invention will be described with reference to FIG. When hydrogen gas is supplied to the anode 30, the hydrogen diffuses in the gas diffusion layer 60 and is ionized in the catalyst layer 70 to become hydrogen ions H ⁺ . At this time, electrons separated from the hydrogen pass through an external circuit. Move to the cathode.

  The hydrogen ions move to the catalyst layer 90 of the cathode 40 through the electrolyte membrane 50. At the cathode 40, the supplied oxygen diffuses in the gas diffusion layer 80 and moves to the catalyst layer 90. In the catalyst layer 90, hydrogen ions, oxygen, and electrons that have moved through the external circuit react with each other by the action of the catalyst of the catalyst layer 90 to generate water.

  At this time, the generated water is retained by the hydrophilic oxide contained in the catalyst layer 90, and the retained water humidifies the ion exchange resin as a binder contained in the catalyst layer 90 and the electrolyte membrane 50.

  Here, in the present invention, at least one of the catalyst layer 70 of the anode 30 and the catalyst layer 90 of the cathode 40 contains a hydrophilic oxide. When a hydrophilic oxide is contained in the catalyst layer 70 of the anode 30, the water generated at the cathode 40 moves to the catalyst layer 70 of the anode 30 by back diffusion, and the hydrophilic oxide contained in the catalyst layer 70 The water retained and the retained water humidifies the ion exchange resin as a binder contained in the catalyst layer 70 and the electrolyte membrane 50.

  Further, when both the catalyst layer 70 and the catalyst layer 90 include a hydrophilic oxide, the above-described effect when the catalyst layer 70 includes a hydrophilic oxide and the catalyst layer 90 are hydrophilic. Both of the effects when the conductive oxide is contained are exhibited.

  Thereby, it is possible to effectively use the reaction site in the catalyst layer by preventing the characteristic deterioration due to drying of the ion exchange resin in the catalyst layer during the operation of the fuel cell. In particular, even when the gas supplied to the cathode is low-humidified or non-humidified, the output voltage is unlikely to decrease, and a high battery output can be stably obtained over a long period from the start.

  Further, by including a hydrophilic oxide in the catalyst layer, the amount of humidification from the outside can be reduced, and a non-humidifying operation can be performed. Conversely, even when a large amount of moisture is externally humidified, the hydrophilic oxide traps moisture from the outside due to the water retention capacity of the hydrophilic oxide. Battery characteristic deterioration can be suppressed.

  In a fuel cell using an alkaline electrolyte membrane, water is generated at the anode in the cell reaction. Even in this case, the effects of the present invention can be obtained in the same manner.

<Method for producing gas diffusion electrode>
Next, an example of a method for producing a gas diffusion electrode of a polymer electrolyte fuel cell according to the present invention will be described with reference to the drawings. Here, the gas diffusion electrodes refer to the anode and the cathode in FIG.

FIG. 2 is a flowchart showing an example of a manufacturing process of the gas diffusion electrode. As shown in FIG. 2, first, a mixed solution of ethanol, TEOS (tetraethoxysilane) and nitric acid is prepared (S1), and then this mixed solution is stirred to prepare a sol solution of SiO ₂ which is a hydrophilic oxide. Prepare (S2).

A Pt / C catalyst, water, and ethanol are prepared, and these are mixed in a ball mill to prepare a mixed solution (S3). Next, the mixed solution prepared in S3, the sol solution prepared in S2 and the Nafion (registered trademark) solution are mixed (S4) and ball mill mixed to prepare a SiO ₂ gel-containing catalyst paste (S5). .

  The catalyst paste prepared in S5 is applied on the gas diffusion layer (GDL) (S6). The application in S6 is preferably performed by a pulse swirl spray method (PSS method). The PSS method will be described with reference to FIG. FIG. 3 is an explanatory diagram for explaining the PSS method. As shown in FIG. 3, the PSS method refers to a suspension containing a mixed solution to be applied, an electrocatalyst, a binder, a hydrophilic oxide sol, a solvent, and the like, and is sprayed in a pulsed manner with high-pressure air. On the other hand, it is a method of flowing the sprayed droplets in a tornado type (swirl), and when the suspension reaches the substrate to be coated, the suspension becomes almost dry. This tornado-type spray prevents scattering out of the substrate, increases the yield, and reduces the cost. Moreover, clogging of the spray gun can be prevented by making it pulsed.

Next, the gas diffusion electrode with the catalyst paste prepared in S6 is vacuum-dried to form a catalyst layer from the catalyst paste, thereby manufacturing a gas diffusion electrode (S7, S8). In this process, the dehydration condensation of the SiO ₂ gel uniformly dispersed in the catalyst is promoted, and an insoluble hydrophilic silica network is formed.

  The gas diffusion electrode produced in this production method can be used not only for a solid polymer fuel cell using an acid electrolyte membrane but also for other fuel cells. In particular, the catalyst layer produced by this production method Is applicable to a wide range of uses as an electrode catalyst for any battery.

  As described above, instead of directly applying the catalyst layer on the gas diffusion layer, the catalyst layer may be applied on the electrolyte membrane and then integrated with the gas diffusion layer to form a gas diffusion electrode. The application method is not limited to the above-described pulse swirl spray method, and a normal spray method, printing method, transfer method, filtration method, and the like can also be applied.

<Evaluation>
(1) IV characteristics evaluation In order to keep the coating of the binder on the platinum catalyst uniform, the volume ratio of Nafion (registered trademark) to the total volume of the carbon support and SiO ₂ V _Nafion / (V _c + V _{SiO 2} ) to, changing the volume ratio V _SiO2 / V _c of SiO ₂ to carbon constant (0.77). As a result, under high humidification conditions, the cell characteristics hardly depended on the composition of V _SiO2 / V _c , but the characteristics at low humidification were V _SiO2 / V _c = 0.39 for both gas diffusion electrodes (GDE). It was the highest for the composition electrode.

When the polarization curve and ohmic resistance of the SiO ₂ -MEA using GDE and the normal-MEA not containing SiO ₂ at a cell temperature of 80 ° C. and 30% RH of both electrodes were examined, it was as shown in FIG. FIG. 4 is a diagram showing a polarization curve and ohmic resistance at 80 ° C. and 30% RH. As shown in FIG. 4, it can be seen that SiO ₂ -MEA has significantly improved IV characteristics as compared with normal-MEA.

(2) Evaluation of utilization rate of platinum catalyst In order to examine the utilization rate of the platinum catalyst, the cyclic voltammogram (CV) of the cathode at the same cell temperature and relative humidity (RH) was measured, and the result shown in FIG. 5 was obtained. FIG. 5 is a view showing cyclic voltammograms of SiO ₂ -MEA and normal-MEA at 80 ° C., 30% RH and 20 mV / sec.

From FIG. 5, it can be seen that SiO ₂ -MEA has a larger amount of hydrogen adsorption / desorption electricity than normal-MEA and the catalyst utilization rate is improved. This is presumably because the moisture content in the catalyst layer is kept high by SiO ₂ . In SiO ₂ -MEA, the oxidation-reduction wave of platinum is remarkably large, and under low humidification conditions, the anion species [sulfonic acid in Nafion (registered trademark)] is unique with the decrease of water molecules on the platinum surface. It was found that adsorption occurs and oxygen reduction activity decreases. It is considered that the water adsorbed by SiO ₂ has an effect of suppressing such specific adsorption. From these, it can be seen that the addition of SiO ₂ to the catalyst layer can significantly improve the low humidification operation characteristics of the polymer electrolyte fuel cell.

DESCRIPTION OF SYMBOLS 10 ... Separator, 20 ... Separator, 30 ... Anode, 40 ... Cathode, 50 ... Electrolyte membrane, 60 ... Gas diffusion layer, 70 ... Catalyst layer, 80 ... Gas diffusion layer, 90 ... Catalyst layer, 300 ... Spray gun, 310 ... Plate, 320 ... GDL

Claims (6)

An electrolyte membrane that is permeable to cations or anions;
A pair of catalyst layers formed of a supported or unsupported metal catalyst with a cation exchange resin or anion exchange resin as a binder disposed between the electrolyte membranes;
A pair of gas diffusion layers arranged to sandwich the pair of catalyst layers for diffusing gas;
A pair of separators disposed between the pair of gas diffusion layers and having gas flow paths formed thereon,
At least one of the pair of catalyst layers is a solid polymer fuel cell containing a hydrophilic oxide.   2. The polymer electrolyte fuel cell according to claim 1, wherein the hydrophilic oxide is prepared from an oxide sol. A method for producing a gas diffusion electrode comprising a gas diffusion layer and a catalyst layer,
Preparing a mixture of alcohol, metal oxide precursor sol, and inorganic acid;
A gel dispersion solution preparation step of stirring the mixed solution to prepare a gel dispersion solution of a hydrophilic oxide;
A catalyst mixture preparation step of preparing a Pt / C catalyst, water and alcohol, and mixing them to prepare a catalyst mixture;
A catalyst paste preparation step of preparing a catalyst paste in which a hydrophilic oxide gel is dispersed by mixing the catalyst mixture, the gel dispersion solution, and an ion exchange resin;
An application step of producing a gas diffusion layer with a catalyst paste by applying the catalyst paste onto the gas diffusion layer or the electrolyte membrane;
Producing a hydrophilic oxide-containing gas diffusion electrode by drying the gas diffusion layer with catalyst paste produced in the coating step;
A method of manufacturing a gas diffusion electrode comprising: A method for producing an electrode-integrated electrolyte membrane used in a fuel cell,
Preparing a mixture of alcohol, metal oxide precursor sol, and inorganic acid;
A gel dispersion solution preparation step of stirring the mixed solution to prepare a gel dispersion solution of a hydrophilic oxide;
A catalyst mixture preparation step of preparing a Pt / C catalyst, water and alcohol, and mixing them to prepare a catalyst mixture;
A catalyst paste preparation step of preparing a catalyst paste in which a hydrophilic oxide gel is dispersed by mixing the catalyst mixture, the gel dispersion solution, and an ion exchange resin;
An application step of producing an electrolyte membrane with a catalyst paste by applying the catalyst paste onto the electrolyte membrane;
Drying the electrolyte membrane with the catalyst paste produced in the application step to produce an electrode-integrated electrolyte membrane containing a hydrophilic oxide; and
A method for producing an electrode-integrated electrolyte membrane comprising:   The method of manufacturing a gas diffusion electrode according to claim 3, wherein in the applying step, the catalyst paste is applied by a pulse swirl spray method.   The method for producing an electrode-integrated electrolyte membrane according to claim 4, wherein in the applying step, the catalyst paste is applied onto the electrolyte membrane by a pulse swirl spray method.

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