JPH08167416A - Cell for solid high polymer electrolyte fuel cell - Google Patents

Abstract

PURPOSE: To provide a cell for a solid high polymer electrolyte fuel cell by which excessive generating water does not stay in an oxidating agent electrode film. CONSTITUTION: A cell 1 of a fuel cell uses a fuel electrode film 11 and an oxidating agent electrode film 12. The fuel electrode film 11 uses carbon paper having a thickness of 0.4mm and has an electrode film base material 112 divided into two parts in the flowing direction of fuel gas 5a and a porous catalyst layer 111 which has a thickness of 0.02mm on an upstream side electrode film base material and a thickness of 0.03mm on a downstream side electrode film base material and is composed of a platinum catalyst and a fluororesin. The oxidating agent electrode film 12 uses carbon paper having a thickness of 0.4mm and has an electrode film base material 122 divided into two parts in the flowing direction of oxidating agent gas 5b and a porous catalyst layer 121 which has a thickness of 0.02mm on an upstream side electrode film base material and a thickness of 0.03mm on a downstream side electrode film base material and is composed of a platinum catalyst and a fluororesin.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel cell used in a solid polymer electrolyte fuel cell, and has been improved so as to prevent excessive retention of produced water in an oxidizer electrode membrane. Regarding its composition.

[0002]

2. Description of the Related Art A fuel cell is a kind of power generator that generates direct current power by using hydrogen and oxygen, and as is well known, it is converted into electric energy as compared with other energy engines. High efficiency and low emission of carbon dioxide, nitrogen oxides and other air pollutants,
It is expected as a so-called clean energy source. As the fuel cell, depending on the type of electrolyte used, a solid polymer electrolyte type, phosphoric acid type, molten carbonate type,
Various fuel cells such as solid oxide type are known.

In recent years, compared to internal combustion engines, fuel cells have
Since it has major characteristics such as low air pollution due to exhaust gas and low noise generated during operation, it is possible to use fuel cells as an on-vehicle power source for drive motors used to drive vehicles such as automobiles. It is coming to be considered. When using a fuel cell as an in-vehicle power source, it is desirable that the power source system be as small as possible. From this point of view, solid polymer electrolyte fuel cells are receiving attention among various fuel cells. Is becoming.

When a polymer resin membrane having a proton (hydrogen ion) exchange group in the molecule is saturated with water, the solid polymer electrolyte fuel cell shows a low resistivity and functions as a proton conductive electrolyte. It is the fuel cell used. As the polymer resin membrane having a proton exchange group in the molecule (hereinafter, may be simply referred to as a solid polymer electrolyte membrane or simply PE membrane), a perfluorosulfonic acid resin membrane (for example, DuPont Co., USA) is used. Fluorine-based ion exchange resin membranes represented by Nafion Membrane (trade name, manufactured by Nippon Chemical Industry Co., Ltd.) are well known at the present time, but in addition to these, hydrocarbon-based ion exchange resin membranes, composite membranes and the like are used. These solid polymer electrolyte membranes (PE membranes) show a resistivity of 20 [Ω · cm] or less at room temperature by being saturated with water, and all of them have
It is a membrane that functions as a proton conductive electrolyte.

This solid polymer electrolyte fuel cell system is generally constructed with a cell body 8 whose concept is shown in FIG. 4 as the core. The battery body 8 is a sheet-shaped P
A fuel cell comprising an E film 7, a sheet-shaped fuel electrode (anode) film 61 and a sheet-shaped oxidant electrode (cathode) film 62 bonded to both main surfaces of the PE film 7, Usually, a plurality of layers are laminated. Each of the fuel electrode film 61 and the oxidant electrode film 62 carries catalyst layers 61a and 62a and catalyst layers 61a and 62a, and a fuel gas (hydrogen or a gas containing hydrogen at a high concentration).
Alternatively, an oxidant gas (oxygen or a gas containing oxygen at a high concentration such as air) is supplied to and discharged from the catalyst layers 61a and 62a, and at the same time, a porous electrode film base material having a function as a current collector ( The material used is, for example, carbon paper.) 61b and 62b, and the catalyst layers 61a and 62a are in close contact with both main surfaces of the PE film 7.

In the battery main body 8 using the fuel cell having the above structure, the fuel gas is supplied to the fuel electrode film 61.
Further, the oxidant gas is supplied to the oxidant electrode film 62, and the reaction gases (these may be said in the generic name of the fuel gas and the oxidant gas) of these gases.
It is supplied after being humidified and containing water vapor. The reason is that, as described above, the PE membrane 7 is a membrane that functions as a proton conductive electrolyte by being saturated with water, but conversely speaking, the PE membrane 7 is dried and its moisture content is increased. This is because, if the value is reduced, the proton conductivity is lowered and the resistivity thereof is increased. Fuel electrode membrane 6
1, when a reaction gas is supplied to the oxidant electrode film 62, the catalyst layers 61a and 6 provided on the electrode films 61 and 62, respectively.
Gas phase (fuel gas or oxidant gas), liquid phase (liquid H ₂ 0), solid phase (fuel electrode,
A three-phase interface of (catalyst possessed by the oxidant electrode) is formed, and direct-current power is generated by causing an electrochemical reaction.
In many cases, the catalyst layers 61a and 62a are made of fine particulate platinum catalyst and a fluororesin having water repellency, and moreover, many pores are formed in the layers. By doing so, the efficient diffusion of the reaction gas to the three-phase interface is maintained, and the three-phase interface having a sufficiently large area is formed.

At the three-phase interface, the following electrochemical reaction occurs. First, on the fuel electrode film 61 side, the reaction according to the equation (1) occurs.

[0008]

[Image Omitted] H ₂ → 2H ⁺ + 2e ⁻ (1) Further, on the oxidant electrode film 62 side, the reaction according to the equation (2) occurs.

[0009]

Embedded image (1/2) O ₂ + 2H ⁺ + 2e ⁻ H ₂ O (2) That is, as a result of this reaction, H ⁺ ions (protons) generated in the fuel electrode film 61 are in the PE film 7. To the oxidant electrode film 62, and electrons (e ⁻ ) move to the oxidant electrode film 62 through the load device 9. On the other hand, in the oxidant electrode film 62, oxygen contained in the oxidant gas,
The H ⁺ ions that have moved from the fuel electrode film 61 in the PE film 7 react with the electrons that have moved through the load device 9, and H ₂ O (water vapor) is generated. Thus, the battery main body 8 obtains hydrogen and oxygen to generate DC power, and thus H ₂ O (steam) as a byproduct.

By the way, in the fuel cell, the PE film 7, the fuel electrode film 61, and the oxidizer electrode film 62, which are separately prepared, and the catalyst layers 61a and 62a are provided on different main surfaces of the PE film 7. They are laminated so that they face each other, and heating and pressing are performed to join them. The fuel cell thus obtained has the structure and shape shown in FIG. 5 and FIG. Here, FIG. 5 is a side sectional view of a main part schematically showing the fuel cell of the conventional example used in the battery main body shown in FIG. 4 in a developed state. That is, the fuel cell 6 has a rectangular shape with a thin thickness, and the PE film 7 used for this is larger than the outer dimension of the fuel electrode film 61 and the oxidant electrode film 62 in the surface direction. Since it has an outer dimension in the plane direction, therefore, as shown in FIGS. 5 and 6, PE is formed in the periphery of the fuel electrode film 61 and the oxidizer electrode film 62 between the end of the PE film 7. The exposed surface of the membrane 7 is present. In many cases, the thickness of the fuel cell 6 is about 1 [mm] or less, and the PE film 7 constituting the fuel cell 6 in that case is 7 mm or less.
Has a thickness of about 0.1 [mm] to 0.2 [mm].

This fuel battery cell 6 is incorporated into a unit fuel cell device 5 having the structure shown in FIG. 6, and a required number of the unit fuel cell device 5 is stacked to form a battery body 8. Of. Here, FIG. 6 is a side cross-sectional view of a main part schematically showing a unit fuel cell device of a general example configured by using the fuel battery cell shown in FIG. Note that FIG.
Among the reference numerals given in FIG. 5, only representative reference numerals are shown. In FIG. 6, the unit fuel cell device 5 includes a fuel cell 6, a separator 51 having a plurality of grooves 51a arranged on one side surface of the fuel cell 6 for allowing the fuel gas 5a to flow therethrough, and a fuel cell 6, a separator 52 having a plurality of grooves 52a for allowing the oxidant gas 5b to flow therethrough, and a seal body 53 such as an O-ring.
And are provided. Each separator 51, 52
Are arranged in the exposed peripheral portion of the PE film 7 so as to sandwich the fuel cell 6 with a seal body 53 interposed therebetween. The seal body 53 has a function of preventing the reaction gas flowing in the grooves 51a, 52a of the separators 51, 52 from leaking out of the flow passages. A groove 51b formed in the peripheral portion,
It is fitted and mounted in 52b.

The reaction gas supplied to the fuel cell 6 is
Generally, the supply side is arranged above the gravity direction and the discharge side is arranged below the gravity direction. As described above, in the fuel cell 6, steam is generated as a by-product at the time of power generation, but due to this steam, a larger amount of steam is contained in the reaction gas on the downstream side, As a result, in the reaction gas near the discharge end, water vapor corresponding to supersaturation may be condensed and exist as water in a liquid state.
By arranging the supply side of the reaction gas on the upper side with respect to the gravity direction and the discharge side of the reaction gas on the lower side with respect to the gravity direction, the condensed water is allowed to flow into the reaction gas flow grooves 51a, 5a.
Since it can flow down in 2a by gravity, it is easy to remove condensed water from each unit fuel cell device 5.

By the way, the electrochemical reaction described in the above equations (1) and (2) performed in the fuel cell 6 is an exothermic reaction. Therefore, in the fuel cell 6, the formula (1),
When power is generated by the electrochemical reaction according to the equation (2), it is unavoidable that heat having a value almost equal to the value of the generated DC power is generated. For this reason, when the cell main body 8 is configured using the unit fuel cell device 5, a cooling means (not shown) for removing heat from the fuel cell 6 is incorporated. As a result, the fuel cell 6
Generally, it is operated under a temperature condition of about 70 [° C] to 80 [° C].

A specific example of the conventional fuel cell 6 is shown. As the PE film 7, a Nafion film having a thickness of 0.17 mm is used. The thickness of the electrode film base materials 61b and 62b is 0.4.
[Mm] carbon paper is used. Also,
A dispersion mixture of carbon powder supporting 20% of platinum black and polytetraethylene was adhered to the electrode film base materials 61b and 62b to a uniform thickness of 0.025 mm, and the vacuum dryer was used. After being dried for 24 [h] by, it is baked at 365 [° C] for 15 [min].
As a result, the catalyst layer 61 is formed on the electrode film base materials 61b and 62b.
The fuel electrode film 61 and the oxidizer electrode film 62 having a and 62a are obtained. The fuel electrode film 61 and the oxidant electrode film 62 are formed on the side of the catalyst layer 61a and the catalyst layer 62a by P
The sandwiching body sandwiching the E film 7 between the two is 120 [° C], 3.5
Under the condition of [MPa], the fuel cell 6 is obtained by heating and pressurizing for 15 [min] to join both membranes.

[0015]

A solid polymer electrolyte fuel cell having desired power generation performance can be obtained by using the above-described fuel cell for a solid polymer electrolyte fuel cell according to the prior art. However, the following problems remain. That is, as described above, the electrochemical reaction occurring in the fuel cell is a reaction in which water vapor is by-produced in the oxidant electrode film, and this water vapor is mainly discharged from the oxidant electrode film into the oxidant gas. To be done. Therefore, the amount of water vapor in the oxidant gas is the smallest at the inlet of the fuel cell, and gradually increases as it passes through the fuel cell. At that time, in order to easily discharge the generated water from the oxidant electrode film into the oxidant gas, it is desirable that the water vapor pressure value in the oxidant electrode film be higher than the water vapor pressure value in the oxidant gas. Is.

If the temperature of the oxidant electrode film is uniform, for the above reason, the amount of water vapor in the oxidant gas increases in the vicinity of the outlet from the fuel cell unit. The value will be higher. For this reason, it becomes difficult to discharge the generated water from the oxidizer electrode film near the outlet. Furthermore, when the water vapor pressure value in the oxidant gas reaches the saturated water vapor pressure (for the above reason, the probability of occurrence in the vicinity of the outlet is high), the water generated from the oxidant electrode film is generated. Since the discharge is stopped, the water produced by the reaction is condensed and liquefied, and a large amount of the produced water is retained in the oxidant electrode film. When a large amount of generated water is retained in the oxidant electrode film, the pores in the catalyst layer are filled with the generated water, or at least a part of the voids formed in the electrode membrane substrate is generated by the generated water. It will be filled up. In this case, the diffusion of the oxidant gas in the oxidant electrode film is hindered, the reaction in the fuel battery cell is reduced, and the power generation performance of the fuel battery cell is reduced.

As a measure for preventing a large amount of generated water from accumulating in the oxidant electrode film, it is conceivable to reduce the amount of water vapor contained in the oxidant gas supplied to the fuel cell, but in this case, , If the PE film is dried by reducing the amount of water vapor contained too much, the resistivity of the PE film may increase, which may lead to deterioration of the output characteristics of the fuel cell. There is a new problem that coordination and management become very difficult.

The present invention has been made in view of the above-mentioned problems of the prior art, and an object thereof is a solid polymer electrolyte type which does not cause excessive retention of generated water in the oxidizer electrode film. It is to provide a fuel cell for a fuel cell.

[0019]

Means for Solving the Problems The above-mentioned objects of the present invention are as follows: 1) A fuel cell for receiving a supply of a fuel gas and an oxidant gas to generate DC power, which is a sheet-like solid polymer electrolyte membrane And a sheet-shaped fuel electrode film and a sheet-shaped oxidant electrode film, which are joined to both main surfaces of the solid polymer electrolyte membrane, respectively. Alternatively, a porous sheet-like electrode film base material that provides a path for supplying an oxidant gas to the catalyst layer and also has a function as a current collector, and a planar surface on almost one side surface of the electrode film base material. And a catalyst layer supported on the catalyst layer, the catalyst layer side being in close contact with both main surfaces of the solid polymer electrolyte membrane, and the other side surface that is the side opposite to the catalyst layer is fuel gas and oxidant gas. Is the one that flows through each In a fuel cell for a polymer electrolyte fuel cell, at least the catalyst layer of the oxidizer electrode film, the amount of the catalyst carried by the catalyst layer, the structure is different depending on the location of the catalyst layer in the horizontal direction, or, 2) In the means described in the above item 1, the amount of catalyst carried by the catalyst layer is such that, in the catalyst layer near the outlet of the flowing oxidant gas, the catalyst layer near the inlet of the oxidant gas. It is achieved by using more configurations.

[0020]

Since the electrochemical reaction represented by the above equations (1) and (2) is a reaction that is performed by the catalyst as described above, the amount of heat generated during this electrochemical reaction is It is generated in correspondence with the amount of the catalyst carried in the fuel cell unit. The present invention has been made with this point in mind.

That is, according to the present invention, in the fuel cell for a solid polymer electrolyte fuel cell, at least the catalyst layer of the oxidizer electrode film is passed through by the amount of the catalyst carried by the catalyst layer. The catalyst layer in the vicinity of the outlet of the oxidant gas has a larger amount of catalyst supported than the catalyst layer in the vicinity of the inlet of the oxidant gas. By adopting a different structure depending on the location, at least in the oxidizer electrode film, the amount of heat generated in the vicinity of the reaction gas outlet is increased compared to the vicinity of the reaction gas inlet in relation to the amount of catalyst supported. .

Thus, the operating temperature of the oxidant electrode film near the outlet of the oxidant gas is compared with the operating temperature of the oxidizer electrode film near the inlet of the oxidant gas, and the oxidant near the outlet is oxidized. Since the generated water from the agent electrode film can be easily discharged to a high level, the ability to discharge the generated water from the oxidant electrode film near the oxidant gas outlet side to the oxidant gas is improved. Become.

Further, since the reaction gas, for example, oxygen in the oxidant gas is consumed by the electrochemical reaction in the fuel cell, the oxygen concentration in the oxidant gas is different from that of the oxidant gas near the inlet. The oxidant gas in the vicinity of the outlet decreases. In at least the oxidant electrode film of the fuel cell of the present invention having the above-described structure, since the reactivity of the electrochemical reaction in the vicinity of the outlet of the reaction gas is increased, for example, in the vicinity of the outlet where the oxygen concentration is lowered Even with the reaction gas, it is possible to maintain an electrochemical reactivity similar to that in the vicinity of the inlet portion, and it is possible to make the electrochemical reactivity in the reaction gas flow direction of the fuel cell cell surface substantially uniform. .

[0024]

Embodiments of the present invention will be described in detail below with reference to the drawings. FIG. 2 is a side cross-sectional view of a main part schematically showing a developed state of a fuel cell for a solid polymer electrolyte fuel cell according to an embodiment of the present invention. (In some cases, it is referred to as an embodiment when distinguished from the different embodiments described later.) In FIG. 2, the same portion as the fuel cell for the solid polymer electrolyte fuel cell according to the conventional example shown in FIG. Are denoted by the same reference numerals, and description thereof will be omitted.

In FIG. 2, reference numeral 2 denotes a fuel cell in which the oxidant electrode (cathode) film 12 is used in place of the oxidant electrode film 62 in the conventional fuel cell 6 shown in FIG. It is a cell. The oxidant electrode film 12 is the oxidant electrode film 62 included in the fuel cell 6 of the conventional example shown in FIG.
On the other hand, the catalyst layer 121 is used in place of the catalyst layer 62a, and the electrode film base material 122 is used in place of the electrode film base material 62b.

The electrode film base material 122 is a porous electrode film base material having a thickness of 0.4 as in the electrode film base material 62b.
Although the carbon paper of [mm] is used, FIG.
As shown therein, the electrode film base materials 122a and 122b are each divided into two along the direction in which the oxidant gas 5b flows. Then, the dispersion liquid mixture having the same content as in the conventional example is attached to the electrode film base material 122a on the upstream side of the reaction gas in a uniform thickness of 0.02 mm, and the vacuum dryer is used. After 24 [h] drying by
The catalyst layer 1 was calcined at 365 [° C] for 15 [min],
21a is formed.

Further, the electrode film substrate 12 on the downstream side of the reaction gas
On 2b, a dispersion liquid mixture having the same content as that of the conventional example is attached to a uniform thickness of 0.03 [mm],
After performing 24 [h] drying with a vacuum dryer, 365
The catalyst layer 121b is baked at [° C] for 15 [min].
Is formed. Then, the catalyst layer 121a and the catalyst layer 1
21b and the catalyst layer 121.

These fuel electrode film 61 and oxidant electrode film 12 are P-sided on the side of the catalyst layer 61a and the catalyst layer 121.
The sandwiching body sandwiching the E film 7 between the two is 120 [° C], 3.5
Under the condition of [MPa], heating and pressurization are performed for 15 [min] to bond the both membranes to obtain the fuel cell unit 2. In the embodiment shown in FIG. 2, the oxidant electrode film 12 has the above-mentioned structure.
Then, due to the amount of the catalyst carried, the amount of heat generated in the vicinity of the outlet of the oxidant gas 5b is increased with respect to the vicinity of the inlet of the oxidant gas 5b. Therefore, the oxidizing gas 5
The operating temperature of the oxidant electrode film 12 in the vicinity of the outlet of b is compared with the operating temperature of the oxidant electrode film 12 in the vicinity of the inlet of the oxidant gas 5b, and the oxidant electrode film 12 in the vicinity of the outlet is compared.
It can be actively raised to a level that facilitates the discharge of the produced water from. As a result, the ability to discharge the generated water from the oxidant electrode film 12 near the outlet of the oxidant gas 5b to the oxidant gas 5b is improved. Further, since the reactivity of the electrochemical reaction near the outlet of the oxidizing gas 5b is increased, the oxidizing gas 5b near the outlet where the oxygen concentration is lowered
Even in this case, it is possible to maintain an electrochemical reactivity similar to that in the vicinity of the inlet. Therefore, the uniformity of the electrochemical reactivity in the flowing direction of the oxidant gas 5b on the surface of the fuel cell 2 can be improved.

FIG. 1 is a side sectional view of the essential part schematically showing a fuel cell for a solid polymer electrolyte fuel cell according to another embodiment of the present invention in a developed state. (It may be referred to as an embodiment when distinguished from other embodiments.) In FIG. 1, a fuel cell for a solid polymer electrolyte fuel cell according to one embodiment of the present invention shown in FIG. 2,
The same parts as those of the fuel cell for a solid polymer electrolyte fuel cell according to the conventional example shown in FIG. 5 are designated by the same reference numerals, and the description thereof will be omitted.

In FIG. 1, reference numeral 1 denotes a fuel electrode (anode) film 11 in place of the fuel electrode film 61 in the fuel cell 2 according to the embodiment of the present invention shown in FIG. It is a fuel cell. The fuel electrode film 11 is different from the fuel electrode film 61 shown in FIGS.
The catalyst layer 111 is used in place of 1a, and the electrode film base 112 is used in place of the electrode film base 61b.

The electrode film base material 112 has a thickness of 0.4 as a porous electrode film base material, like the electrode film base material 61b.
Although carbon paper of [mm] is used, FIG.
As shown therein, the electrode film base materials 112a and 112b are divided into two along the direction in which the fuel gas 5a flows. Then, the electrode film substrate 112a on the upstream side of the reaction gas
The dispersion mixture having the same content as in the case of the conventional example is attached to a uniform thickness of 0.02 [mm], dried by a vacuum dryer for 24 [h], and then subjected to 365
The catalyst layer 111a is fired at [° C.] for 15 [min].
Is formed.

Further, the electrode film substrate 1 on the downstream side of the reaction gas
On 12b, a dispersion liquid mixture having the same content as in the case of the conventional example is attached to a uniform thickness of 0.03 [mm], and dried for 24 [h] by a vacuum dryer, and then 3
The catalyst layer 11 is calcined at 65 [° C.] for 15 [min].
1b is formed. Thus, the catalyst layer 111a and the catalyst layer 111b form the catalyst layer 111.

These fuel electrode film 11 and oxidant electrode film 12 are P-sided on the catalyst layer 111 and catalyst layer 121 side.
The sandwiching body sandwiching the E film 7 between the two is 120 [° C], 3.5
Under the condition of [MPa], the fuel cell 1 is obtained by heating and pressurizing for 15 [min] to bond both membranes. Since the embodiment shown in FIG. 1 has the above-mentioned configuration, in addition to the configuration in the embodiment shown in FIG. 2, the fuel electrode film 11 is also different from the vicinity of the inlet of the fuel gas 5a due to the amount of catalyst supported. hand,
The calorific value near the outlet of the fuel gas 5a is increased. In both the fuel electrode film 11 and the oxidant electrode film 12, the amount of heat generated near the outlet of the reaction gas is larger than the amount of heat generated near the inlet of the reaction gas. The temperature difference between the operating temperature of the oxidant electrode film 12 and the operating temperature of the oxidant electrode film in the vicinity of the inlet of the oxidant gas 5b can be made higher than in the embodiment shown in FIG. Becomes As a result, the ability to discharge the generated water from the oxidant electrode film 12 near the outlet to the oxidant gas 5b is further improved.
Further, in addition to the case of the oxidant gas 5b, the reactivity of the electrochemical reaction in the vicinity of the outlet of the fuel gas 5a is also increased, so that even the fuel gas 5a near the outlet side where the hydrogen concentration has decreased, It is possible to maintain an electrochemical reactivity that is almost the same as the electrochemical reactivity near the inlet side. For this reason,
The electrochemical reactivity in both directions of the reaction gas flow on both surfaces of the fuel cell 2 can be made substantially uniform.

FIG. 3 is a side sectional view of the essential part schematically showing the fuel cell for a solid polymer electrolyte fuel cell according to another embodiment of the present invention in a developed state.
(In the case of distinguishing from other embodiments, it may be referred to as an embodiment.) In FIG. 3, the same parts as those of the fuel cell according to the conventional example shown in FIG. To do.

In FIG. 3, 3 is a fuel electrode (anode) film 31 and an oxidizer electrode film 62 in place of the fuel cell 6 according to the conventional example shown in FIG. 5, respectively. This is a fuel cell in which an oxidant electrode (cathode) film 32 is used. Fuel electrode film 31
In contrast to the fuel electrode film 61 of the fuel cell 6 of the conventional example shown in FIG. 5, the catalyst layer 31a is used instead of the catalyst layer 61a.
1 is replaced with the electrode film base material 61b, and the electrode film base material 312 is used. The oxidant electrode film 32 is shown in FIG.
With respect to the oxidant electrode film 62 of the fuel cell 6 of the conventional example shown therein, a catalyst layer 321 is used instead of the catalyst layer 62a.
The electrode film base material 322 is used instead of the electrode film base material 62b.

The respective electrode film base materials 312 and 322 are
Similar to the electrode film base materials 61b and 62b, carbon paper having a thickness of 0.4 [mm] is used as the porous electrode film base material. As shown in FIG. 5a and the oxidant gas 5b flow along the direction,
3 for the electrode film base materials 312a, 312b, 312c and 3 for the electrode film base materials 322a, 322b, 322c, respectively.
Has been split. Then, a dispersion mixed solution having the same content as that in the case of the conventional example is applied to each of the electrode film base materials 312a and 322a on the upstream side of the reaction gas by 0.02 [m].
m] to a uniform thickness, and a vacuum dryer 24
[H] After drying, at 365 [° C.], 15 [min]
During this period, the catalyst layers 311a and 321a are formed by firing.

Further, a dispersion mixed solution having the same content as that of the conventional example is adhered to each of the electrode film base materials 312b and 322b in the midstream region of the reaction gas in a uniform thickness of 0.025 [mm]. And 24 [h] with a vacuum dryer.
After drying, it is baked at 365 [° C.] for 15 [min] to form catalyst layers 311b and 321b. Further, each electrode film substrate 312 on the downstream side of the reaction gas
Dispersion mixed solution having the same content as in the conventional example is applied to c and 322c to a uniform thickness of 0.03 [mm], and dried for 24 [h] by a vacuum dryer, and then subjected to 365 The catalyst layers 311c and 321c are formed by firing at [° C.] for 15 [min]. Then, the catalyst layer 311 is formed by the catalyst layer 311a, the catalyst layer 311b, and the catalyst layer 311c, and the catalyst layer 321a, the catalyst layer 321b,
The catalyst layer 321c is formed with the catalyst layer 321c.

These fuel electrode film 31 and oxidant electrode film 32 are PE on the side of the catalyst layer 311 and the catalyst layer 321.
The sandwiching body sandwiching the membrane 7 between the two is 120 [° C], 3.5 [M
Under the condition of [Pa], the both membranes are joined by heating and pressurizing for 15 [min] to obtain the fuel cell 3. Since the embodiment shown in FIG. 3 has the above-mentioned configuration, compared with the case of the configuration in the embodiment shown in FIG. 1, both electrode films (fuel electrode film 3
The term "1" and the like, and the oxidant electrode film 32, etc. may be collectively referred to as this. In view of the amount of the catalyst supported in (1), the degree of increase in the amount of heat generated from the vicinity of the reaction gas inlet to the vicinity of the reaction gas outlet is equalized. Therefore, the oxidant gas 5b at the operating temperature of the oxidant electrode film 32 is
It is possible to gradually increase the change from the vicinity of the inlet portion of the above to the vicinity of the outlet portion of the oxidant gas 5b. As a result, the oxidant gas 5b is discharged from the oxidant electrode film 12
It is possible to improve the discharge capability of the generated water to almost the entire surface of the oxidizer electrode film 32 including the vicinity of the outlet. Further, it becomes possible to further homogenize the electrochemical reactivity on both surfaces of the fuel cell 2 in the reaction gas flow direction.

The fuel electrode film and the oxidant electrode film of each of the unit fuel cell devices using the fuel cells according to the examples to those described above in the section of this example and the fuel cells of the conventional example have An example of the measured temperature distribution is summarized in "Table 1". In addition, in "Table 1",
For the stability evaluation, each unit fuel cell device was operated continuously for 24 hours, and the degree of decrease in the voltage value output by each unit fuel cell device was less than 2 [%], the result was ○. Those that were more than [%] are marked as △.

[0040]

[Table 1]

In Table 1, the temperature difference between the temperature at the inlet of the reaction gas (a and b in Table 1) and the temperature at the outlet of the reaction gas (a and b in Table 1). Focusing on, the temperature difference in the conventional example is only about 3 [° C.], while in the cases of the examples according to the present invention,
A temperature difference of about [° C] is obtained. This also allows
The fact that a large amount of generated water is retained in the oxidizer electrode films 12 and 32 including the vicinity of the outlet of the reaction gas is eliminated, and the main reason is that a large amount of generated water is retained. It can be confirmed that the degree of decrease in the generated output voltage value is reduced.

In the above description of the examples, the electrode film base materials 112, 122, 31 included in the fuel cells 1 to 3 are provided.
2, 322 are said to be divided into a plurality in the direction in which the reaction gas flows, but the present invention is not limited to this, and for example, for fuel electrode films and oxidant electrode films provided in the fuel cells 1 to 3. The electrode film base material may be integrated, and the catalyst layer formed on the electrode film base material is formed by changing the thickness in the direction in which the reaction gas flows through the integrated electrode film base material. It may be done.

[0043]

According to the present invention, when the fuel cell for a solid polymer electrolyte fuel cell is constructed as described above, the temperature difference between the inlet and outlet of the reaction gas is As shown in No. 1, it is possible to obtain a temperature difference that is more than double that of the conventional example. As a result, a large amount of generated water is retained in at least the oxidant electrode film and the diffusion of the oxidant gas in the oxidant electrode film is prevented from being hindered, so that the output voltage value of the fuel cell unit is reduced. The effect is that the degree is reduced.

[Brief description of drawings]

FIG. 1 is a side sectional view of a main part schematically showing a fuel cell for a solid polymer electrolyte fuel cell according to a different embodiment of the present invention in a developed state.

FIG. 2 is a side sectional view of a main part schematically showing a fuel cell for a solid polymer electrolyte fuel cell according to an embodiment of the present invention in a developed state.

FIG. 3 is a side sectional view of a main part schematically showing a fuel cell for a solid polymer electrolyte fuel cell according to another embodiment of the present invention in a developed state.

FIG. 4 is a conceptual diagram showing a solid polymer electrolyte fuel cell of a general example.

FIG. 5 is a side sectional view of a main part schematically showing a fuel cell for a solid polymer electrolyte fuel cell of a conventional example in a developed state.

6 is a side cross-sectional view of a main part schematically showing a unit fuel cell device of a general example configured by using the fuel battery cell shown in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Fuel cell 11 Fuel electrode film 111 Catalyst layer 112 Electrode film base material 12 Oxidizing electrode film 121 Catalyst layer 122 Electrode film base material 5a Fuel gas 5b Oxidizing gas

Claims (2)

[Claims] 1. A fuel cell for receiving a supply of a fuel gas and an oxidant gas to generate DC power, comprising a sheet-like solid polymer electrolyte membrane and both main surfaces of the solid polymer electrolyte membrane. A sheet-shaped fuel electrode film and a sheet-shaped oxidant electrode film that are bonded to each other, and each of the fuel electrode film and the oxidant electrode film provides a path for supplying fuel gas or oxidant gas to the catalyst layer. Together with a porous sheet-shaped electrode film base material having a function as a current collector, and a catalyst layer planarly supported on substantially the entire one side surface of the electrode film base material. A solid polymer electrolyte fuel, which is in close contact with each of the two main surfaces of the solid polymer electrolyte membrane on the layer side, and has a fuel gas and an oxidant gas flowing to the other side surface, which is the side opposite to the catalyst layer. Fuel cell for batteries , The catalyst layer having at least an oxidant electrode film, the amount of supported catalyst having a catalyst layer, a fuel cell for a solid polymer electrolyte fuel cell which being different from the surface direction of the location of the catalyst layer. 2. The fuel cell for a solid polymer electrolyte fuel cell according to claim 1, wherein the catalyst layer has a catalyst loading amount in the vicinity of the outlet of the flowing oxidant gas. 2. A fuel cell for a solid polymer electrolyte fuel cell, characterized in that there are more catalyst layers than in the vicinity of the oxidant gas inlet.