JP2000348741A - Solid high-polymer type fuel cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a solid high-polymer type fuel cell capable of preventing the damage of an ion exchange film. SOLUTION: This solid high-polymer type fuel cell 1 is composed by catching an ion exchange film 3 with a pair of separators 2 and by arranging electrodes 4A, 4B between the separators 2 and the ion exchange film 3. The separators 2 is formed out of a resin molded body containing carbon powder and a thermoset resin as main constituents. The thermal expansion coefficient of the resin molded body is 1/5-1 as much as that of the ion exchange film 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polymer electrolyte fuel cell.

[0002]

2. Description of the Related Art In recent years, there has been a demand for a next-generation power generation device that is clean and has a high power generation efficiency, and a fuel cell (Fu) that directly converts the chemical energy of oxygen and hydrogen into electric energy.
The expectations for el Cell) are increasing. At present, types of fuel cells include a phosphoric acid type, an alkaline type, a molten carbonate type, a solid electrolyte type, a solid polymer type (also referred to as an ion exchange membrane type), and the like. In particular, polymer electrolyte fuel cells (PEFC: Polymer Electrolyte
Fuel Cell) is considered to be suitable for use as a small and portable power source (for example, a power source for an electric vehicle). Therefore, development is currently being vigorously pursued for practical use.

[0003] This type of fuel cell has a membrane / electrode laminate in which electrodes are arranged on both sides of an ion exchange membrane. This ion exchange membrane is made of resin and can selectively pass hydrogen ions (H ⁺ ). These electrodes carry a metal catalyst such as platinum. One of the pair of electrodes is called a hydrogen electrode (cathode), and the other is called an oxygen electrode (anode). A pair of separators is arranged on both sides of the membrane / electrode laminate, and the outer periphery of the ion-exchange membrane protruding from both electrodes is sandwiched between the separators. As a material for a separator, conventionally, a resin molded body mainly containing carbon powder and a thermosetting resin has been proposed.

The hydrogen gas (H ₂ ) supplied through the separator on the hydrogen electrode side becomes hydrogen ions (H ⁺ ) by a catalytic reaction at the hydrogen electrode. The hydrogen ions move toward the oxygen electrode while passing through the ion exchange membrane. Oxygen gas (O ₂ ) is supplied to the oxygen electrode side. Therefore, hydrogen ions and oxygen gas react with each other by a catalytic reaction at the oxygen electrode, and water (H ₂ O) is generated. In the course of such a reaction, electrons (e ⁻ ) move from the hydrogen electrode to the oxygen electrode, and current flows from the oxygen electrode to the hydrogen electrode. In other words, using oxygen gas and hydrogen gas as fuel,
An electromotive force is obtained by a reverse reaction of the electrolysis reaction. An advantage of this type of fuel cell is that it operates at a relatively low temperature (about 100 ° C.).

[0005]

Although the fuel cell of the prior art operates at a relatively low temperature, a temperature difference of at least several tens of degrees Celsius occurs between use and non-use. Therefore, when the apparatus encounters such a heat cycle, there is a possibility that the separator may pull and break the ion exchange membrane due to the difference in the coefficient of thermal expansion between the constituent members.

[0006] The present invention has been made in view of the above problems, and an object of the present invention is to provide a polymer electrolyte fuel cell capable of preventing breakage of an ion exchange membrane.

[0007]

According to a first aspect of the present invention, there is provided a membrane / electrode laminate in which electrodes are disposed on both sides of an ion exchange membrane; In a polymer electrolyte fuel cell including a pair of separators sandwiching the outer peripheral portion of the ion exchange membrane that is protruding, the separator is formed of a resin molded body mainly containing carbon powder and a thermosetting resin, The gist of the present invention is a polymer electrolyte fuel cell whose coefficient of thermal expansion is 1/50 to 1 times the coefficient of thermal expansion of the ion exchange membrane.

[0008] In the invention according to the second aspect, a membrane / electrode laminate in which electrodes are arranged on both sides of the ion exchange membrane, and a pair of a pair sandwiching an outer peripheral portion of the ion exchange membrane protruding from both the electrodes. In a polymer electrolyte fuel cell provided with a separator, the separator is formed of a resin molded body containing carbon powder and a thermosetting resin as main components, and has a coefficient of thermal expansion of a coefficient of thermal expansion of the ion exchange membrane. 1/10 times ~
The gist of the present invention is a polymer electrolyte fuel cell which is one-time.

According to a third aspect of the present invention, in the second aspect, the thermal expansion coefficient of the ion exchange membrane is 4 × 10 ^-5 to 1
× 10 ^-4 ° C ^-1 and the coefficient of thermal expansion of the separator is 1
It was assumed to be from × 10 ^-5 to 1 × 10 ^-4 ° C ^-1 .

Hereinafter, the "action" of the present invention will be described. According to the first aspect of the present invention, since the thermal expansion coefficient of the separator is 1/50 to 1 times the thermal expansion coefficient of the ion exchange membrane, the difference between the two is smaller than that of the conventional one. Has become. Therefore, even when the apparatus encounters a heat cycle, a large tensile force that may damage the ion exchange membrane does not act on the ion exchange membrane via the separator. Therefore, damage to the ion exchange membrane is reduced, and as a result, damage to the ion exchange membrane is prevented.

According to the second and third aspects of the present invention, the thermal expansion coefficient of the separator is 1/1 / the thermal expansion coefficient of the ion exchange membrane.
Since it is 10 times to 1 time, the difference between the two coefficients of thermal expansion is extremely small. Therefore, breakage of the ion exchange membrane is more reliably prevented.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a polymer electrolyte fuel cell 1 according to an embodiment of the present invention will be described in detail with reference to FIGS.

The fuel cell 1 shown in FIGS. 1 and 2 is a so-called single cell type. The fuel cell 1 of the present embodiment includes one unit of a membrane / electrode laminate and two separators 2.

The membrane / electrode laminate has a structure in which electrodes 4A and 4B are arranged on both sides of the ion exchange membrane 3. One is a hydrogen electrode 4A and the other is an oxygen electrode 4B. However, the ion exchange membrane 3 and the electrodes 4A and 4B are not necessarily joined. The ion exchange membrane 3 can selectively pass hydrogen ions. In the present embodiment, a membrane made of a fluororesin-based material such as Teflon is used as the ion exchange membrane 3. In this embodiment, the coefficient of thermal expansion (CTE) of the ion exchange membrane 3 is 4
The temperature is set to about × 10 ^-5 to 1 × 10 ^-4 ° C ^-1 . In the embodiment, the term "coefficient of thermal expansion" specifically refers to the value of the coefficient of thermal expansion when measurement is performed in accordance with "ASTM D-696" which is a normal measurement method.

The hydrogen electrode 4A and the oxygen electrode 4B are air-permeable mats containing carbon fiber as a main component, and are processed in a rectangular shape here. Platinum and palladium are supported as catalysts on the mat-like material. Note that a fluorine resin or the like may be added to the mat-like material.

A pair of separators 2 are arranged on both sides of the membrane / electrode laminate. The separator 2 of the present embodiment is a rectangular and plate-like solid body, and is formed to be slightly larger than the hydrogen electrode 4A and the oxygen electrode 4B. On the inner surface side of the separator 2, a concave portion 2b having a shape and a depth capable of accommodating the hydrogen electrode 4A and the oxygen electrode 4B is provided. Similarly, a plurality of parallel grooves 2 a are formed on the inner surface side of the separator 2. The outer peripheral portion of the ion exchange membrane 3 protruding from both electrodes 4A and 4B is sandwiched by the inner peripheral portions of both separators 2 in a sealed state. As a result, the membrane / electrode laminate is fixed between the separators 2 so as not to be displaced. A flange (not shown) may be provided on the outer periphery of the ion exchange membrane 3, and a sealing member (not shown) such as packing may be arranged between the flange and the outer periphery of the inner surface of the separator 2.

A plurality of gas supply / discharge holes 5 are formed in two of the four side surfaces of the separator 2.
These gas supply / exhaust holes 5 extend in parallel along the surface direction of the separator 2, and are connected to the outer region of the separator 2 and the recess 2.
b. Therefore, the gas or the like flowing into the concave portion 2b through the gas supply / discharge hole group 5 on one side surface is in the groove 2b.
After flowing along the line a, it flows out again to the external region through the group of gas supply / discharge holes 5 on the other side surface. The separator 2 is also provided with a gas vent hole 6 communicating with the concave portion 2b. The gas vent hole 6 extends along the thickness direction of the separator 2.

In the case of the fuel cell 1, as a material for the separator 2, a resin molded product containing carbon powder and a thermosetting resin as its components is used. The role of the carbon powder in the resin molded body is to reduce the electrical resistivity and improve the conductivity of the separator 2. Usable carbon powders include natural graphite powders, as well as artificial graphite powders, glassy carbon, mesocarbon, carbon black, and the like. Of course, a mixture of these can also be used. In this case, it is desirable to use a high-purity carbon powder with as small an impurity content as possible. Specifically, in the present embodiment, flaky artificial graphite powder having an impurity concentration of about 200 ppm to 300 ppm is used as the carbon powder.

The role of the thermosetting resin in the resin molding is to give the separator 2 a property that does not allow gas to permeate, and to give suitable moldability. Examples of usable thermosetting resins include an epoxy resin, a polyimide resin, and a phenol resin. Among these, it is particularly preferable to select a phenol resin. This is because the phenolic resin is excellent not only in moldability and gas impermeability but also in acid resistance, heat resistance and cost. The phenol resin includes a novolak resin and a resol resin. Of course, a mixture of a novolak phenol resin and a resol phenol resin may be used.

The mixing ratio of the carbon powder (A for convenience) and the thermosetting resin (B for convenience) is as follows: A: B = 90 w
t% to 50% by weight: preferably 10% to 50% by weight. However, A: B = 80wt% -60wt%: 20wt
% To 40 wt% is even more preferred. If the mixing ratio of the thermosetting resin is too large, the electrical resistivity may be excessively increased. On the other hand, if the mixing ratio of the thermosetting resin is too small, suitable moldability, gas impermeability, and mechanical strength may not be obtained.

The electrical resistivity of the separator 2 is 50
It is preferably about 00 μΩ · cm to 200000 μΩ · cm, and more preferably about 5000 μΩ · cm to 50,000 μΩ · cm. If this value is too large, separator 2
This is because the internal resistance of the fuel cell 1 increases due to the increase in the electric resistivity. Conversely, if this value is excessively reduced, it may be difficult to select raw materials.

In the case of the separator 2 of the present embodiment, the concentration of impurities contained in the resin molded product is extremely lower than that of the conventional product. More specifically, the concentration of a base metal impurity having a higher ionization tendency than mercury is
The total is less than 100 ppm. "Base metal impurities" refers to those excluding noble metal impurities such as gold, silver, mercury, and platinum group, and specifically, potassium, sodium, barium, calcium, magnesium, aluminum, iron, nickel, tin, and lead. , Copper, silicon, phosphorus and the like. Most of these metal species have the property of relatively easily ionizing in the presence of hydrogen ions. That is, the impurity metal ions generated in this manner adhere or adsorb to the inside and the surface of the ion exchange membrane 3, and are a main factor for poisoning the ion exchange membrane 3.

The concentration of the base metal impurity having a large ionization tendency is preferably 20 ppm or less in total, more preferably 10 ppm or less, and even more preferably about 0.01 ppm to 5 ppm. Is good. This is because the lower the value of the concentration of such metal impurities, the lower the risk of poisoning the ion exchange membrane 3.

In the present embodiment, it is necessary that the thermal expansion coefficient of the separator 2 made of a resin molded body is set to be equal to or slightly smaller than the thermal expansion coefficient of the ion exchange membrane 3. Specifically, the separator 2
Is 1/5 of the thermal expansion coefficient of the ion exchange membrane 3.
It is required to be 0 to 1 times, preferably 1/2.
It is good to be 0 to 1 times, most preferably 1/10 to 1 time.

The coefficient of thermal expansion of the ion exchange membrane 3 is 4 ×
10^-Five~ 1 × 10^-Four° C^-1In the case of this embodiment set to
The thermal expansion coefficient of the separator 2 is 1 × 10^-Five~ 1 × 10
^-Four° C ^-1It is preferable to adopt the range of.

Next, a procedure for manufacturing the separator 2 of the present embodiment will be described. First, it is desirable to treat a carbon powder as a starting material with a halogen compound under heating. Specifically, here, the treatment using chlorine gas as the halogen compound is performed. As a result, the concentration of impurities in the carbon powder can be reduced. Note that the heating temperature is preferably 2000 ° C to 2300 ° C.

Next, the carbon powder subjected to the heat treatment and the thermosetting resin are blended in the above-described preferred range to obtain a mixture. The mixture is adjusted to an appropriate viscosity by adding a solvent such as methanol, and well kneaded using a kneader. Instead of methanol, for example, acetone, higher viscosity higher alcohols, or the like may be used as the solvent. The obtained flaky mixture is pulverized by a mixer or the like to obtain a raw material for molding.

Next, using the obtained molding raw material, a separator 2 having a predetermined shape is formed by a resin molding method (for example, a press molding method, a transfer molding method, an injection molding method, an extrusion molding method, etc.). At this time, not only the outer shape of the separator 2 but also the groove 2a, the concave portion 2b, the gas supply / discharge hole 5, and the gas discharge hole 6 are preferably formed at the same time. In other words, such a method eliminates the need for cutting or the like, which is convenient for cost reduction. At the time of such resin molding, for example, a hot press molding machine is used. At this time, the molding raw material is molded at 150 ° C. to 200 ° C. using a mold,
Further, at 200 ° C. to 250 ° C., the curing of the thermosetting resin contained in the raw material is promoted.

Then, the separator 2 manufactured in this manner is divided into an ion exchange membrane 3, a hydrogen electrode 4A and an oxygen electrode 4B.
When assembled together, the desired fuel cell 1 shown in FIG.
Is completed.

Next, the principle of power generation in the fuel cell 1 will be described with reference to FIG. In use, a load such as a motor is electrically connected as an external circuit between the hydrogen electrode 4A and the oxygen electrode 4B. In this state, the hydrogen electrode 4A
Hydrogen gas is continuously supplied together with water into the concave portion 2b through the groove 2a of the separator 2 on the side. Similarly, oxygen electrode 4
Oxygen gas is continuously supplied together with water into the concave portion 2b through the groove 2a of the separator 2 on the B side.

The hydrogen gas supplied via the separator 2 on the side of the hydrogen electrode 4A becomes hydrogen ions by a catalytic reaction at the hydrogen electrode 4A. The generated hydrogen ions move toward the oxygen electrode 4B while passing through the ion exchange membrane 3. The hydrogen ions reaching the oxygen electrode 4B side are
Reacts with oxygen gas by the catalytic reaction in the above to generate water. In the process in which such a reaction occurs, electrons move from the hydrogen electrode 4A to the oxygen electrode 4B. Therefore, current flows from the oxygen electrode 4B to the hydrogen electrode 4A, and as a result, an electromotive force can be obtained. Then, a direct current is supplied to the external circuit, and a motor, which is a load, is driven.

[0032]

EXAMPLES [Preparation of sample] As carbon powder, the particle size is about 25 μm to 50 μm and the impurity concentration is 200 p.
A flake-like graphite artificial graphite powder having a pm to 300 ppm was selected. This powder is heated at about 2100 ° C.
By treating with chlorine gas for a predetermined time, the impurity concentration was reduced to 5 ppm or less. In addition, a solid resole phenol resin was used as the thermosetting resin. The mixing ratio of the carbon powder and the phenol resin is as follows: A: B = 65 wt
%: 35 wt% was set.

After the heat-treated high-purity carbon powder and the phenol resin were mixed, methanol was added to the mixture as a solvent. After kneading this well using a kneader,
The obtained kneaded material was pulverized to obtain a raw material for molding. Next, the raw material for molding was press-molded by a general hot press molding machine to obtain a rectangular resin molded body to be used as the separator 2. As conditions for hot press molding, the temperature was set to 200 ° C., the pressure was set to 50 kg / cm ² , and the time was set to 30 minutes.
Minutes.

As a result, the concentration of base metal impurities having a higher ionization tendency than mercury was 5 pp in total.
m was obtained. In sample 1, the coefficient of thermal expansion of the ion exchange membrane 3 was set to 1 × 10 ⁻⁴ , and the coefficient of thermal expansion of the separator 2 was set to 2 × 10 ⁻⁶ . That is, the coefficient of thermal expansion of the separator 2 was set to 1/50 times the coefficient of thermal expansion of the ion exchange membrane 3. The sample 1 thus obtained was used as the separator 2 of Example 1.

In Samples 2 to 5 (Examples 2 to 5), the coefficient of thermal expansion of the ion exchange membrane 3 was similarly set to 1 × 10 ⁻⁴ . In Sample 2, the coefficient of thermal expansion of the separator 2 was set to 5 × 10 ⁻⁶ so as to be 1/20 times the coefficient of thermal expansion of the ion exchange membrane 3. In Sample 3, the thermal expansion coefficient of the separator 2 was set to 1 × 10 ⁻⁵ so as to be 1/10 times the thermal expansion coefficient of the ion exchange membrane 3. In Sample 4, the coefficient of thermal expansion of the separator 2 was set to 5 × 10 ⁻⁵ so as to be 倍 times the coefficient of thermal expansion of the ion exchange membrane 3. In Sample 5, the coefficient of thermal expansion of the separator 2 was set to 1 × 10 ^{-4 so as} to be one time (ie, equal to) the coefficient of thermal expansion of the ion exchange membrane 3.

On the other hand, a sample 6 was prepared without performing any chlorine gas treatment on the carbon powder and used as a separator of a comparative example. In the separator of the comparative example, the total concentration of the base metal impurities was 300 ppm or more. In sample 6, the coefficient of thermal expansion of the ion exchange membrane 3 was 1
× 10 ^-4 and the coefficient of thermal expansion of the separator 2 is 1 × 1
It was set to 0 ^-6 . That is, the coefficient of thermal expansion of the separator 2 is
The coefficient of thermal expansion of the ion exchange membrane 3 was set to 1/100 times.

The measurement of the base metal impurity concentration in each sample was carried out in accordance with a conventionally known emission spectroscopy. Incidentally, the electrical resistivity of the resin molded products of Samples 1 to 6 was 11 μΩ · cm to 20 μΩ · cm. [Comparative Test Method and Results] The above six types of samples of the separator 2 were respectively subjected to an ion exchange membrane 3 and a hydrogen electrode 4A.
And the oxygen electrode 4B, and individually
Was manufactured. Then, a heat cycle of several tens of degrees Celsius was given by repeatedly turning on and off the fuel cell 1 with the external circuit connected. After applying the heat cycle for a certain number of times, visual observation was performed to examine the occurrence of loosening or tearing in the ion exchange membrane 3.

As a result, it was found that, in the fuel cell 1 using the separator of the comparative example, the ion exchange membrane 3 was loosened or broken when the heat cycle was given a certain number of times or more. That is, the fuel cell 1 of the comparative example was inferior in durability. On the other hand, in the fuel cells 1 using the separators 2 of Examples 1 to 5, no slack or tear was observed in the ion exchange membrane 3 even after the same number of heat cycles. That is, the fuel cell 1 of each example was clearly superior in durability as compared with the comparative example.

Further, as conceptually shown in the graph of FIG. 4, in the fuel cell 1 using the separator of the comparative example, it is found that the voltage value fluctuates when a certain time or more has elapsed from the start of operation. Was. Therefore, it was expected that if the use was continued further, the ion exchange membrane 3 would be poisoned by the ionized impurities and the voltage value would surely drop. On the other hand, in the fuel cells 1 using the separators 2 of Examples 1 to 5, at least the voltage value did not change after the same time had elapsed. Therefore, the stability of the voltage value of the electromotive force was higher than the comparative example. That is, each of the examples had better power generation performance than the comparative example.

Therefore, according to each example of the present embodiment, the following effects can be obtained. (1) In the fuel cell 1 of each embodiment, the coefficient of thermal expansion of the separator 2 is 1/50 to 1 times the coefficient of thermal expansion of the ion exchange membrane 3.
It is set to double. Therefore, the difference between the thermal expansion coefficients of the two is smaller than that of the conventional one. Therefore, even when the apparatus encounters a heat cycle, a large tensile force that may damage the ion exchange membrane 3 does not act on the ion exchange membrane 3 via both the separators 2.

This is because the separator 2 and the ion exchange membrane 3
It is considered that as a result of the improvement of the material matching of the two, the two and 3 both thermally expand and contract together and to the same extent. Therefore, according to each of the above embodiments, the breakage of the ion exchange membrane 3 can be reliably prevented. Therefore, high power generation performance can be maintained for a long time, and the fuel cell 1 excellent in durability and practicality can be realized.

(2) Since the separator 2 of the fuel cell 1 of each embodiment contains carbon powder and a thermosetting resin as main components, it is made of a relatively inexpensive material. Further, since the separator 2 is manufactured through a resin molding method, it can be obtained at relatively low cost. In addition, with such a resin molded body, the separator 2 of the polymer electrolyte fuel cell 1 can be used.
Can be realized relatively easily. That is, suitable gas impermeability, low electric resistivity, acid resistance, light weight, and the like can be obtained.

(3) In the case of the separator 2 of each embodiment, the base metal impurity concentration contained in the resin molded product is 100 p.
pm or less, and in each case, the base metal impurity concentration is considerably lower than that of the conventional product. Therefore, even if the impurities are ionized, the ion exchange membrane 3 is not poisoned. Therefore, the fuel cell 1 using this
According to this, a stable electromotive force can be obtained over a long period of time.

(4) The separator 2 of the present embodiment is manufactured by treating a carbon powder with a chlorine gas under high-temperature heating, and then performing resin molding using the carbon powder. At this time, the chlorine gas and impurities contained in the carbon powder react with each other due to the heat to generate a metal chloride. Since compounds of this type are generally gaseous at high temperatures, the gaseous metal chloride can easily escape to the outside of the carbon powder. Therefore, if resin molding is performed using the carbon powder that has undergone such treatment, the concentration of impurities in the resin molded body can be easily and reliably reduced. Therefore, the above excellent separator 2 can be reliably obtained.

The embodiment of the present invention may be modified as follows. It is also possible to use a different type of carbon powder from that used in the above-described embodiment, or a different type of thermosetting resin from that used in the above-described embodiment.

The shape of the recess 2b in the separator 2 is not necessarily limited to a rectangular shape. If not necessary, the recess 2b may be omitted. The separator 2 of the present invention can be embodied not only as a component for a single cell type, but also as a component for other types (so-called multi-cell type). For example, a pair of separators 12 in another example of the fuel cell 11 shown in FIG.
A groove 2a and a concave portion 2b are provided on both surfaces thereof. The groove 2a formed on one surface and the groove 2a formed on the other surface have, for example, a relationship orthogonal to each other. The fuel cell 11 having the above-described structure is used in a state in which several tens to several hundreds are stacked to form a “fuel cell stack”. The individual fuel cells 11 as single cells are preferably connected in series to obtain sufficient electromotive force.

Next, in addition to the technical ideas described in the claims, the technical ideas grasped by the above-described embodiments are listed below together with their effects. (1) A membrane / electrode laminate in which mat-like electrodes made of inorganic fibers are arranged on both sides of an ion exchange membrane through which hydrogen ions can selectively pass, and the ion exchange membrane protruding from both electrodes In a polymer electrolyte fuel cell comprising an outer peripheral portion and a pair of separators accommodating the electrode in a recess provided inside thereof, the separator comprises a carbon powder and a thermosetting resin as components. And the thermal expansion coefficient of the resin molded body is 1/50 to 1 times (preferably 1/20 to 1 times, more preferably 1/10) of the thermal expansion coefficient of the ion exchange membrane. Polymer polymer fuel cell. Therefore, according to the invention described in the technical idea 1, a polymer electrolyte fuel cell excellent in durability and practicality can be provided.

(2) The method according to any one of claims 1 to 3, wherein the concentration of impurities contained in the resin molded product is 100 ppm or less (preferably 20 ppm or less, more preferably 10 ppm or less). thing. Therefore, according to the invention described in the technical idea 2, it is possible to stably generate power for a long period of time, and to further improve durability and practicality.

(3) A fuel characterized in that a plurality of the fuel cells according to any one of the technical ideas 1 and 2 are provided as single cells, and the single cells are stacked and connected in series. Battery stack. Therefore, according to the invention described in the technical idea 3, it is possible to provide a fuel cell stack capable of stably generating a sufficient amount of electromotive force for a long period of time.

(4) A membrane / electrode laminate in which electrodes are arranged on both sides of a flanged ion exchange membrane, and an outer peripheral portion (that is, a flange portion) of the ion exchange membrane protruding from both electrodes are sealed with a sealing member. In a solid polymer fuel cell comprising a pair of separators sandwiched between, the separator is made of a resin molded body mainly composed of carbon powder and a thermosetting resin, and has a coefficient of thermal expansion of the ion A polymer electrolyte fuel cell having a thermal expansion coefficient of 1/50 to 1 times the exchange membrane.

[0051]

As described in detail above, according to the first aspect of the present invention, it is possible to provide a polymer electrolyte fuel cell capable of preventing the ion exchange membrane from being damaged.

According to the second and third aspects of the invention, it is possible to more reliably prevent the ion exchange membrane from being damaged.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view of a polymer electrolyte fuel cell according to an embodiment of the present invention.

FIG. 2 is a schematic sectional view of the fuel cell according to the embodiment.

FIG. 3 is a diagram illustrating the principle of the fuel cell according to the embodiment.

FIG. 4 is a graph conceptually showing a result of a comparative test.

FIG. 5 is a schematic cross-sectional view of another example of a fuel cell.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Solid polymer fuel cell, 2 ... Separator, 3 ... Ion exchange membrane, 4 ... Electrode.

Claims (3)

[Claims] 1. A solid height comprising a membrane / electrode laminate in which electrodes are arranged on both sides of an ion exchange membrane, and a pair of separators sandwiching an outer peripheral portion of the ion exchange membrane protruding from both electrodes. In the molecular fuel cell, the separator is formed of a resin molded body containing carbon powder and a thermosetting resin as main components, and has a coefficient of thermal expansion 1/50 to 1 times the coefficient of thermal expansion of the ion exchange membrane. Polymer electrolyte fuel cell. 2. A solid height comprising a membrane / electrode laminate having electrodes disposed on both sides of an ion exchange membrane, and a pair of separators sandwiching an outer peripheral portion of the ion exchange membrane protruding from both electrodes. In the molecular fuel cell, the separator is formed of a resin molded body containing carbon powder and a thermosetting resin, and has a coefficient of thermal expansion that is 1/10 to 1 times the coefficient of thermal expansion of the ion exchange membrane. A solid polymer fuel cell. 3. The thermal expansion coefficient of the ion exchange membrane is 4 × 10.
^-5 to 1 × 10 ^-4 ° C. ^-1 , and the coefficient of thermal expansion of the separator is 1 × 10 ^-5 to 1 × 10 ^-4 ° C. ^-1. Molecular fuel cell.