JP2001196067A - Solid high-polymer fuel cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a solid high-polymer fuel cell for unifying the amount of reaction in an electrode and improving the stability of generation. SOLUTION: The solid high-polymer fuel cell has an oxygen pole, where the ion exchange capacity of an ion exchanging resin in a catalyst in the close area where oxygen is supplied is lower than the ion exchange capacity of the ion exchange resin in the close area where oxygen is exhausted.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a polymer electrolyte fuel cell.

[0002]

2. Description of the Related Art A hydrogen-oxygen fuel cell electrochemically oxidizes a hydrogen fuel using oxygen or air to extract the chemical energy of the fuel as electric energy. Therefore, it is attracting attention as a low-pollution power generation system that has almost no adverse effect on the global environment. Fuel cells are classified into alkaline aqueous solution type, phosphoric acid type, molten carbonate type, solid electrolyte type, etc., depending on the type of electrolyte used. Among them, solid polymer type fuel cells using an ion exchange membrane as a solid electrolyte Was developed by GE in the late 1950's and was first commercialized among fuel cells, such as a 1kW fuel cell mounted on Gemini-5 in 1965. It has various features as compared with the conventional fuel cell.

[0003] That is, since it operates at low temperature, the power density is increased by the rapid progress of research in recent years, it is possible to reduce the size and weight, and it has low temperature operability, high power density, and CO ₂ resistance. Unlike the alkaline aqueous solution type, fuel gas and air containing CO ₂ can be used, and therefore, practical use as a power source for transportation of spacecraft and vehicles is greatly expected.

In particular, (1) a proton (hydrogen ion) highly conductive membrane has been developed as a solid polymer electrolyte, and (2) a catalyst used for an electrode layer is supported on carbon.
Further, it is considered that the polymer electrolyte fuel cell has attracted attention in recent years due to the fact that by coating it with an ion exchange resin, an extremely high activity has been obtained.

[0005] The polymer electrolyte fuel cell is characterized in that it can be started at a low temperature and has a short start-up time because its operating temperature is as low as room temperature to 120 ° C. There is a drawback that it is difficult to effectively use it for mobility and the like. In order to compensate for this, the polymer electrolyte fuel cell is required to have a particularly high output density, and many studies have been made to improve the output density.

As one of the problems for this purpose, there is a problem that the chemical reaction amount becomes non-uniform depending on the position inside the electrode. That is, for example, at the oxygen electrode, a chemical reaction of generating water from oxygen and protons is performed.In the vicinity of the oxygen supply port, oxygen, which is an oxidizing agent, is supplied abundantly. On the other hand, near the oxygen outlet,
Since a considerable portion of the supplied oxygen has already been consumed by the above reaction, the oxygen partial pressure (oxygen concentration) has dropped, and the amount of reaction here must of course be considerably reduced. Absent. In order to perform stable power generation, it is necessary to keep a basic reaction amount uniform inside the electrode. The non-uniformity of the reaction inside the electrode leads to the non-uniformity of the power generation efficiency and, consequently, the instability of the power generation output characteristics.

[0007]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a polymer electrolyte fuel cell capable of equalizing the amount of reaction inside an electrode and improving power generation stability.

[0008]

According to the present invention, there is provided a fuel electrode comprising a gas diffusion electrode containing an electrode catalyst and an ion exchange resin, and an oxygen electrode. In a polymer electrolyte fuel cell in which the electrode is arranged on the other surface, the oxygen electrode is provided in parallel with the surface of the oxygen electrode on the surface opposite to the surface in contact with the membrane-shaped polymer electrolyte. The gas is flowing, and at the oxygen electrode, the ion exchange capacity of the ion exchange resin in the portion that contacts the upstream of the flow is configured to be lower than the ion exchange capacity of the ion exchange resin in the portion that contacts the downstream of the flow. A polymer electrolyte fuel cell is provided.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.

In the polymer electrolyte fuel cell of the present invention, basically, a gas diffusion electrode containing an electrode catalyst and an ion exchange resin is used as a fuel electrode and an oxygen electrode.

The electrode catalyst may be any catalyst which has a catalytic action on an oxidation reaction of a fuel such as hydrogen or a reduction reaction of oxygen as an oxidizing agent. Examples thereof include platinum, palladium, rhodium, ruthenium, vanadium, palladium, osmium, and the like. It can be selected from iridium or alloys thereof, preferably platinum or platinum and gold, ruthenium, rhenium, chromium, cobalt, nickel, aluminum,
An alloy with one or more elements selected from gallium, silicon, germanium, tin, lead, phosphorus, antimony, bismuth, selenium, tellurium and the like is used.

These electrode catalysts may be used as they are in the form of fine particles, but are preferably supported on a suitable carrier in order to ensure a high specific surface area and stability. Preferably, the carrier has both conductivity and corrosion resistance,
Particularly, carbon black such as acetylene black and furnace black, graphite and the like are desirable. The specific surface area of these carriers is preferably about 30 to 1600 (m ² / g).

The gas diffusion electrode of the present invention comprises an electrode catalyst supported on these carriers and an ion exchange resin which is a solid polymer electrolyte.

The method of forming the electrodes is not particularly limited. However, since the fuel electrode and the oxygen electrode are arranged on both sides of the ion exchange membrane which is a membrane-shaped solid polymer electrolyte, these electrodes and the membrane are not used. Are preferably joined together, for example, the following method can be adopted.

That is, methanol, ethanol, 2
-Dispersing the electrode catalyst fine particles in a solution in which an ion exchange resin is dissolved in a solvent such as alcohols such as propanol, fluorocarbons, hydrofluorocarbons, hydrochlorofluorocarbons, and water (hereinafter, this dispersion is referred to as a catalyst dispersion). ), Carbon paper, carbon cloth, or a conductive porous body formed by filling one side of carbon cloth with carbon particles, etc., as a gas diffusion layer, and then applying or spraying a catalyst dispersion liquid thereon. After forming the electrode by pressing, the method of bonding / heat-pressing the ion-exchange membrane, or applying the catalyst dispersion liquid as a coating liquid, applying the screen directly to the ion-exchange membrane by screen printing, etc. And pressure bonding. In the above, a sheet in which a carbon layer made of carbon and a fluororesin is formed on a carbon fiber woven fabric may be used instead of carbon paper or the like. Alternatively, it may be formed on a separately prepared flat plate and transferred to an ion exchange membrane.

As the apparatus for hot pressing, a heating press machine, a roll press machine, or the like is used. The pressing temperature may be at least the glass transition temperature of the ion exchange resin used, and is usually 120 to 250 ° C. The pressing pressure is about 0.5 to 10 MPa.

The preferred range of the viscosity of the catalyst dispersion varies depending on the method of forming the electrode, and a wide range of viscosity from a dispersion of about several tens cP to a paste of about 20,000 cP can be used. In order to adjust the viscosity, the liquid for forming an electrode may contain a thickener or a diluting solvent. Ethyl cellulose, methyl cellulose or cellosolve-based thickeners can be used.

If necessary, the catalyst dispersion may contain:
Polytetrafluoroethylene, tetrafluoroethylene-perfluoro (alkyl vinyl ether) copolymer, tetrafluoroethylene- which also functions as a binder and a water repellent
A hexafluoropropylene copolymer or the like can be added for use. These are preferably contained in the electrode in an amount of 0.01 to 30% by mass. The water repellent has an effect of suppressing flooding.

As the ion exchange resin in the present invention,
A fluorine-based ion exchange resin, a hydrocarbon-based ion-exchange resin, or the like can be used, and may be a single ion-exchange resin or a mixture of two or more ion-exchange resins. Further, the ion exchange resin may be the same or different on the fuel electrode side and the oxygen electrode side.

The present invention relates to a polymer electrolyte fuel cell having a membrane-like solid polymer electrolyte having a fuel electrode on one surface and an oxygen electrode on the other surface. The ion exchange capacity of the ion exchange resin in the vicinity where oxygen is supplied (milli-equivalent / g dry resin) is configured to be lower than the ion exchange capacity of the ion exchange resin in the vicinity where oxygen is discharged, and flows in parallel to the oxygen electrode surface. It is characterized in that the ion exchange capacity of the ion exchange resin in the portion contacting upstream of the oxygen flow is lower than the ion exchange capacity of the ion exchange resin in contact with the downstream portion of the oxygen flow. Incidentally, hydrogen is usually used as fuel, and oxygen is supplied as a gas containing oxygen, for example, air.

Hereinafter, specific embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 1 is an explanatory diagram schematically showing a relationship between an electrode and a separator arranged adjacent to the electrode.

As shown in FIG. 1A, a fuel electrode 10 and an oxygen electrode 13 arranged on both sides of a membrane solid polymer electrolyte 1 respectively have a surface opposite to a surface in contact with the membrane solid polymer electrolyte 1. The separators 20 and 23 are arranged adjacent to each other, and continuous grooves 20a and 20 are formed on the electrode facing surface of the separator.
0a ′, 20a ″,... And 23a, 23a ′, 2
3a '', is ... are formed, as shown in FIG. 1 (b), the fuel gas to the fuel electrode, supplying oxygen to the oxygen electrode gas flow path L _20, L ₂₃ are formed . Note that a cooling water flow passage groove is usually formed on the back surface of the separator, but is not shown in FIG. 1 (a).

[0023] Incidentally, for example, the top and bottom of the separator 23 facing the anode 13, the oxygen supply port 23 _i and the oxygen discharge port 23 _o are respectively provided, and both ends of the gas flow path L ₂₃ is It is connected to the oxygen supply port and the oxygen discharge port. Here, the separator is formed of a dense carbon material or metal material having conductivity and gas impermeability.

FIGS. 2 (1) to 2 (4) are explanatory views showing an example of the form of the oxygen flow passage formed in the separator 23 adjacent to the oxygen electrode. FIG. 4 is an explanatory diagram showing a surface region of an oxygen electrode corresponding to the oxygen flow passage.

In the present invention, basically, the ion exchange capacity of the ion exchange resin at the portion of the oxygen electrode that is in contact with the upstream of the oxygen flow (in the vicinity of the oxygen supply port) is reduced by the portion that is in contact with the oxygen flow downstream (the oxygen flow). (In the vicinity of the discharge port), specifically, as shown in FIG. 2 (1 ′) and the like, the oxygen electrode is divided into at least two regions of an upstream portion A and a downstream portion B of the flow passage. Then, an ion exchange resin having a lower ion exchange capacity is arranged in the upstream section A, and an ion exchange resin having a higher ion exchange capacity is arranged in the downstream section B.

[0026] In the present invention, as a form of oxygen flow passage L ₂₃ connecting the oxygen supply port and the oxygen outlet is not particularly limited, as the most common form is 2
(1) as shown, the oxygen supply port, the upper portion of the inlet manifold m, the oxygen outlet is connected to a lower portion of the outlet manifold m ', the two manifold, a plurality of parallel flow paths extending downward respectively l ₁ , L ₂ , l ₃ ,... The oxygen gas supplied from the oxygen supply port is dispersed while flowing through the inlet manifold, and flows down in each of the parallel flow paths l ₁ , l ₂ , l ₃ ,.
It reacts with protons while diffusing in the oxygen electrode along this flow path to produce water.

FIG. 2 (2) shows that the manifolds m and m 'are perpendicular to the bottom surface and are parallel to the parallel flow passages l ₁ and l
₂ , ₃ and so on.

As another form of the oxygen flow passage, FIG.
As shown in (3) and (4), the oxygen supply port and the oxygen discharge port can be connected by a single flow passage. in this case,
The supplied oxygen can be dispersed and supplied to each part of the oxygen electrode by bending the flow passage zigzag in the horizontal direction as shown in (3) or zigzag in the vertical direction as shown in (4). Done.

With respect to the basic configuration of the oxygen flow passage as described above, the oxygen electrode is connected to the upstream part A and the downstream part B as shown in FIG. When divided into 25, the upstream portion A is a portion having a higher oxygen concentration, and the downstream portion B is a portion having a low oxygen concentration. Therefore, FIG.
For the configuration of the oxygen flow passage of (1), it is sufficient to dispose an ion exchange resin having a low ion exchange capacity in part A and dispose a resin having a high ion exchange capacity in part B. The arrow in the figure indicates the direction of the overall change from a high oxygen concentration to a low oxygen concentration. As described above, the difference in oxygen concentration between the region A and the region B can be compensated for by changing the ion exchange capacity, and the reaction amount can be made uniform in both regions.

On the other hand, in the case of FIG.
As shown in (2) ′, the upstream portion A and the downstream portion B having a high oxygen concentration are divided by the line 25 perpendicular to the floor surface. Therefore, the lower ion exchange capacity resin is A
The resin having a higher ion exchange capacity will be placed in the portion B.

The above description is basically valid even when one flow passage is bent in a zigzag manner. The positional relationship between the upstream side A and the downstream side B is shown in FIG.
(4) '.

In the above description, the area is divided into the upstream area A and the downstream area B. However, the area is further divided into the upstream area A, the middle stream area B, and the downstream area C, and A → B → Arranging a resin having a larger ion exchange capacity in the order of C is also a more preferable embodiment. By doing so, the reaction amount in each region can be made more uniform.

More generally, the uppermost stream section A, the middle stream section B,..., The downstream section F, the most downstream section G are divided into a larger number of areas, and similarly, A → B →,. , → F → G, and the resin may be arranged in this order. As will be easily understood,
By increasing the number of divisions, the reaction amount in each part within the electrode surface can be made more uniform as a whole.

For regions A and B as shown in FIG.
The arrangement of ion exchange resins having different ion exchange capacities is performed as follows. That is, as described above, when the catalyst dispersion is applied as a coating liquid on an ion exchange membrane or a gas diffusion layer to form an electrode layer, two types of ion exchange resins having different ion exchange capacities are dissolved. Are prepared (provided that the ion exchange capacity of the resin is a <b), and the coating liquid a is applied to the region A.
Then, the coating liquid b may be applied to the region B. Similarly, when the regions are A, B, and C, three types of coating liquids a, b, and c are used as the coating liquid.

In the type in which the oxygen supply port and the oxygen discharge port are connected by a single flow passage, the flow passage is bent in a zigzag manner in the horizontal or vertical direction, for example, as described in JP-A-10-284094. As described above, it can be formed in a spiral shape having a folded portion at the center of the electrode surface. In this case, the definition of the upstream portion A and the downstream portion B is as follows.
This is performed along the spiral flow path, and the area along the flow path from the oxygen supply port to the center turning portion is the upstream portion A, the portion along the flow path from the turning portion to the oxygen discharge port. Becomes the downstream part B. Therefore, both the upstream part and the downstream part have a convoluted spiral shape. An ion exchange resin having a low ion exchange capacity is provided in the spiral upstream portion A.
A resin having a low exchange capacity is arranged in the spiral downstream portion.

Also, in the case of other complicated flow passages, an upstream portion and a downstream portion are defined along the flow passage, and the defined region (that is, a region along the flow passage or a region including the flow passage) is defined. What is necessary is just to arrange ion exchange resins having different ion exchange capacities. It should be understood that the upstream portion includes an oxygen supply port and the downstream portion includes an oxygen discharge port.

In addition, even in the case of such a flow passage, it goes without saying that it can be divided into three parts, that is, an upstream part, a middle part, and a downstream part, or even more.

In the case of dividing into two parts, the upstream part A and the downstream part B, in the model shown in FIG. 2, the area areas of A and B are treated as being substantially equal, but the area is not necessarily divided equally. However, the area areas of A and B may be different as A> B. In this case, the area of the portion having a small area (B in this case) is preferably 5% or more, particularly 10% or more, more preferably 20% of the whole (A + B).
% Or more. If it is less than 5%, the effect of making the reaction uniform in the present invention is not sufficiently exhibited.

Generally speaking, it is preferable that the surface area of the upstream portion and the surface area of the downstream portion of the gas flow passage are each 5% or more of the total surface area of the oxygen electrode.

In the present invention, the difference between the ion exchange capacity of the ion exchange resin in the vicinity where oxygen is supplied and the vicinity where oxygen is discharged in the oxygen electrode is preferably 0.05 meq / g dry resin or more. More preferably, it is 0.1 meq / g dry resin or more. If the amount is less than 0.05 meq / g dry resin, the effect of making the reaction uniform cannot be sufficiently obtained. In addition, a preferable specific ion exchange capacity value is as follows: 1. near the inlet (or upstream).
0 meq / g dry resin or less, near the outlet (or downstream)
In this case, the amount is preferably 1.0 meq / g dry resin or more, and more preferably 1.1 meq / g dry resin or more.

The reaction of the oxygen introduced from the oxygen supply port starts from the supplied portion. Oxygen flows from the upstream to the downstream in the oxygen flow path formed by the groove of the separator while being consumed by this reaction, and unreacted oxygen is finally discharged from the oxygen outlet. For this reason, compared to the vicinity of the oxygen supply port where the oxygen concentration is the highest, the oxygen concentration is considered to be the lowest because the oxygen is consumed in the middle of the reaction near the oxygen discharge port.
That is, since the oxygen concentration, which is the driving force of the reaction, is reduced, the amount of reaction in the vicinity of the outlet is considerably lower than in the vicinity of the supply port. The amount of power generation is remarkably reduced, resulting in large non-uniformity of power generation inside the electrode. Particularly, in a cell having a large power generation area, specifically, in a cell of 20 cm ² or more, the difference becomes large, and there is a problem that power generation stability is reduced.

On the other hand, in the present invention, regarding the ion exchange capacity of the ion exchange resin in the gas diffusion electrode, the higher the exchange capacity of the resin, the higher the moisture content, so that the conductivity and the gas permeability are higher. Focusing attention, the reaction amount is adjusted so as to compensate for the decrease in oxygen concentration. That is, by using a resin having a low ion exchange capacity in the vicinity of the supply of oxygen, the amount of reaction in this portion is suppressed, while a resin having a high ion exchange capacity is used in the vicinity of the outlet from which oxygen is discharged, Promote the reaction here. Thus, the reaction amount inside the electrode can be made more uniform.

In the present invention, as described above, as the ion exchange resin contained in the oxygen electrode (and the fuel electrode), a fluorine ion exchange resin, a hydrocarbon ion exchange resin and the like can be used.

As the fluorine-based ion exchange resin, a perfluorocarbon polymer is preferable, and a polymer containing a polymer unit represented by the formula (1) and a polymer unit represented by the formula (2) is particularly preferable. In the present specification, the term "perfluorocarbon polymer" includes not only a polymer in which all the hydrogen atoms of a hydrocarbon polymer are replaced with fluorine atoms, but also a polymer containing ether-bonding oxygen atoms and the like. .

[0045]

Embedded image

In the equation (1), X¹ Is a fluorine atom or
Is a trifluoromethyl group, and X ^Two Is a fluorine atom or
Is a perfluoroalkyl group having 1 to 6 carbon atoms.

In the formula (2), A ¹ is SO ₃
M, COOM or a group converted to these groups by hydrolysis (here, M represents a hydrogen atom or an alkali metal atom), and X ³ represents a fluorine atom or a carbon atom having 1 to 6 carbon atoms.
Is a perfluoroalkyl group.

Y is expressed by the following equations (3) (P), (4) (Q),
It is composed of fluorine-containing units represented by the formulas (5) (R) and (6) (S), and-(PQRS)
-Or -O- (PQRSS)-, wherein (P
Q.R.S) indicates that at least one or more of P, Q, R and S are arranged in an arbitrary order, and a, b, c,
d, e and f are 0 or an integer of 1 to 6. Also,
x is 0 or 1.

[0049]

Embedded image

In the formulas (3) to (6), X ⁴ , X ⁶ ,
X ⁸ and X ¹⁰ are a fluorine atom or a trifluoromethyl group, and X ⁵ , X ⁷ , X ⁹ , and X ¹¹ are a fluorine atom or a C 1-6 perfluoroalkyl group.
a, b and c are each independently an integer of 0 to 6,
Not all of a = b = c = 0 at the same time, d, e
And f are integers of 1 to 6.

It should be noted that-(PQRS)-or-
Preferred specific examples of O- (PQRSS)-
Formulas (7) to (11) are given.

[0052]

Embedded image

In the above equation, f, g, h, i, j, k,
r and s are each independently an integer of 1 to 6, and Z ¹ ,
Z ² , Z ³ , Z ⁴ and Z ⁵ are each independently a fluorine atom or a C 1-6 perfluoroalkyl group.

On the other hand, preferred examples of the hydrocarbon ion exchange resin include a polymerized unit represented by the formula (12) and a polymerized unit represented by the formula (1).
And a polymer containing the polymerized unit represented by 3).

[0055]

Embedded image

In the above formula, P ¹ is a phenyltolyl group,
Biphenyl tolyl group, naphthalene reel group, phenanthrene reel group, anthracent reel group,
P ² is a phenylene group, a biphenylene group, a naphthylene group, a phenanthrylene group, an anthracylene group;
^2, (here M, hydrogen atom, or an alkali metal atom or less the same.) -SO ₃ M, - by COOM or hydrolysis is a group convertible into these groups, B ^1, B ²
Is independently an oxygen atom, a sulfur atom, a sulfonyl group or an isopropylidene group. Note that P ¹ and P ²
Is not particularly limited.

Further, those in which one or more of the hydrogen atoms of P ¹ and P ² are substituted with a fluorine atom, a chlorine atom, a bromine atom or an alkyl group having 1 to 3 carbon atoms can also be preferably used.

In the present invention, the electrode catalyst contained in the oxygen electrode and the fuel electrode and the ion-exchange resin are in a mass ratio of the catalyst:
Ion exchange resin = 0.40: 0.60-0.95: 0.
05 is preferable from the viewpoint of electrode conductivity.
In addition, in the case of a supported catalyst supported on a carrier such as carbon, the mass of the catalyst herein includes the mass of the carrier.

It is preferable that the membrane solid polymer electrolyte of the present invention also comprises the above-mentioned ion exchange resin. The film-like solid polymer electrolyte can be obtained by, for example, extruding and forming these resins. Membrane solid polymer electrolyte (hereinafter, referred to as
Also called an ion exchange membrane. ) Is 30-300μ
m, preferably 50 to 200 μm.

[0060]

EXAMPLES The present invention will be described below with reference to Examples (Examples 1 to 4) and Comparative Examples (Examples 5 to 7), which are merely examples, and the technical scope of the present invention is limited by these. Not something.

(Formation of Gas Diffusion Electrode-Ion Exchange Membrane Assembly) [Example 1] As an ion exchange resin, polymerized units based on CF ₂ = CF ₂ and CF ₂ = CFOCF ₂ CF (CF ₃ ) O
Perfluorocarbon polymer (ion exchange capacity: 1.1 meq / g resin) consisting of a copolymer consisting of polymerized units based on CF ₂ CF ₂ SO ₃ H, and 40% by mass of platinum
An electrode catalyst in which platinum was supported on carbon black powder so as to be contained was dispersed and dissolved in ethanol at a mass ratio of 1: 3 to prepare a catalyst dispersion.

Using this catalyst dispersion as a coating liquid, a screen printing machine was used to apply a carbon layer made of carbon and polytetrafluoroethylene on a sheet formed on a carbon fiber woven fabric, and then ethanol was dried. A diffusion electrode was obtained. This is used as an electrode sheet for the fuel electrode.

Similarly, the same perfluorocarbon polymer as described above (provided that the ion exchange capacity is 1.0 meq / g)
Using a dry resin and 0.91 meq / g dry resin), a coating liquid comprising a catalyst dispersion was prepared in the same manner as described above, and applied as shown in the pattern of FIG. 2 (3) ′ ( That is, a coating liquid using an ion exchange capacity of 0.91 meq / g dry resin was added to Part A, and 1.0 meq / g was also used.
A dry resin coating solution is applied to part B. ), FIG. 2 (3) ′
Was produced. The ratio (A / B) of each electrode area is 50% / 50%. This gas diffusion electrode is used as an electrode sheet for the oxygen electrode. The coating liquid is
It was applied so that the amount of platinum contained in the electrode sheet was 0.5 mg / cm ² . The electrode sheet was cut out to have an effective electrode area of 25 cm ^{2 for} both the fuel electrode and the oxygen electrode.

A perfluorosulfonic acid type ion exchange membrane (trade name: Flemion HR,
Asahi Glass Co., Ltd., ion exchange capacity: 1.1 meq / g dry resin, film thickness: 50 μm) was used. The oxygen electrode and fuel electrode
A gas diffusion electrode / ion exchange membrane assembly is formed by bonding the electrode and membrane by hot pressing with the ion exchange membrane sandwiched between the surfaces with the catalyst paste applied on the electrode sheet facing inward. Was prepared.

[Examples 2 to 3] As the ion exchange resin used for the oxygen electrode, the same perfluorocarbon polymer containing a sulfonic acid group as in Example 1 (however, the ion exchange capacity of the ion exchange resin contained in Part B is 1. The electrode shown in the pattern of FIG. 2 (3) ′ was prepared in the same manner as in Example 1, except that the dry resin was replaced by 1 meq / g dry resin (Example 2) and 1.33 meq / g dry resin (Example 3). The fuel electrode used was an ion exchange resin having the same ion exchange capacity of 1.1 meq / g dry resin as in Example 1. A gas diffusion electrode / ion exchange membrane assembly was prepared in the same manner as in Example 1. did.

Example 4 An oxygen electrode was prepared in the same manner as in Example 3, except that the ratio of the electrode area of the portion A to that of the portion B in the oxygen electrode was 95/5. A gas diffusion electrode / ion exchange membrane assembly was prepared in the same manner as in Example 1 except that this oxygen electrode was used.

[Examples 5 to 7] The ion exchange capacity was 0.91 meq / g dry resin (Example 5), 1.1 meq / g dry resin in the same manner as the method for preparing the fuel electrode in Example 1. An oxygen electrode was prepared using the ion exchange resin (Example 6) and 1.33 meq / g dry resin (Example 7), and the same fuel electrode as in Example 1 was used for the ion exchange membrane / electrode assembly. Obtained.

Tables 1 and 2 show the ion exchange capacity values of the ion exchange resins used for the fuel electrode and the oxygen electrode and their area ratios.

(Battery Performance Test) The above-mentioned gas diffusion electrode / ion exchange membrane assembly was placed in a cell for measuring battery performance, and hydrogen was passed through the fuel electrode and air was passed through the oxygen electrode under normal pressure (0.1 MPa). A power generation test was performed at a cell temperature of 80 ° C. The groove shapes of the fuel electrode and oxygen electrode separators used here are as shown in FIG. 2 (3). 0.1 A / c
Operation was performed for 24 hours at a constant current of m ² , and the terminal voltage value and the amplitude of the voltage at that time were measured. The results are shown in Table 3.

[0070]

[Table 1]

[0071]

[Table 2]

[0072]

[Table 3]

[0073]

According to the present invention, in the oxygen electrode, the ion exchange capacity of the ion exchange resin existing basically near the inlet to which oxygen is supplied is made lower than that of the ion exchange resin near the outlet. Can be made uniform regardless of the position, and the output of the battery can be stabilized.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram schematically showing a relationship between an electrode and a separator adjacent to the electrode.

FIG. 2 is an explanatory view showing a form of an oxygen flow passage formed in a separator adjacent to an oxygen electrode and a surface region of the oxygen electrode corresponding to the oxygen flow passage.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Membrane solid polymer electrolyte 10 Fuel electrode 13 Oxygen electrode 20 Separator adjacent to fuel electrode 23 Separator adjacent to oxygen electrode 20a, 20a ', 20a''Groove of separator 23a, 23a', 23a 'adjacent to fuel electrode 'Groove of separator adjacent to oxygen electrode 23 _i oxygen supply port 23 _o oxygen outlet 25 line dividing oxygen electrode L ₂₀ gas flow path at fuel electrode L ₂₃ gas flow path at oxygen electrode m inlet manifold m at oxygen electrode m' Outlet manifold at the oxygen electrode l ₁ , l ₂ , l ₃ , l ₄ Parallel flow path A, B Each divided region of the oxygen electrode

Claims (5)

[Claims] 1. A fuel electrode comprising a gas diffusion electrode containing an electrode catalyst and an ion exchange resin, and an oxygen electrode, wherein the fuel electrode is provided on one surface of the membrane solid polymer electrolyte, and the oxygen electrode is provided on the other surface. In the polymer electrolyte fuel cell in which is disposed, a gas containing oxygen flows in parallel to the surface of the oxygen electrode opposite to the surface in contact with the membrane-shaped solid polymer electrolyte, and the oxygen electrode Wherein the ion exchange capacity of the ion exchange resin in the portion contacting upstream of the flow is configured to be lower than the ion exchange capacity of the ion exchange resin in the portion contacting downstream of the flow. . 2. The ion exchange capacity difference of the ion exchange resin between the portion of the oxygen electrode contacting upstream of the flow and the portion contacting downstream of the flow is not less than 0.05 meq / g dry resin. 2. The polymer electrolyte fuel cell according to 1. 3. A separator is disposed on the opposite surface of the oxygen electrode, and a continuous groove is formed on a surface of the separator in contact with the oxygen electrode, and a gas containing oxygen is supplied to the oxygen electrode. A gas flow passage to be supplied is formed, and both ends of the gas flow passage are connected to an oxygen supply port leading to the upstream of the flow and an oxygen outlet leading to the downstream of the flow, respectively. Is divided into at least two regions of an upstream portion and a downstream portion of the gas flow passage, wherein an ion exchange resin having a low ion exchange capacity is disposed in the upstream portion, and an ion exchange resin having a high ion exchange capacity is provided in the downstream portion. The resin according to claim 1, wherein the resin is disposed.
9. The polymer electrolyte fuel cell according to item 1. 4. An oxygen electrode is divided into at least three regions of an upstream portion, a middle portion, and a downstream portion of the gas flow passage, and each region contains an ion exchange resin having a different ion exchange capacity. 4. The polymer electrolyte fuel cell according to claim 3, wherein an ion exchange resin having a lower ion exchange capacity is included as the distance increases. 5. The solid polymer type according to claim 3, wherein the area of the surface of the upstream part and the area of the surface of the downstream part of the gas flow passage are each 5% or more of the total surface area of the oxygen electrode. Fuel cell.