JP2001076747A - Solid polymer fuel cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel cell with suppressed whole thickness, enhanced gas diffusion property, and enhanced reaction efficiency by specifically improving the form of a gas diffusion layer. SOLUTION: A fuel cell has an electrolyte layer A made of a solid polymer electrolyte membrane; a positive electrode side catalyst layer and a negative electrode side catalyst layer formed on each side of the electrolyte layer A; conductive gas diffusion layers 4, 5 arranged on the outer side of each of the catalyst layers; and gas impermeable separators 8, 9 arranged on the outer side of each of the gas diffusion layers 4, 5 and fastening the whole part from the electrolyte layer A to the gas diffusion layers, and carbon paper is arranged on the inner surface of each of the separators 8, 9 as the gas diffusion layers 4, 5, and a zigzag cut is formed in the carbon paper.

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 using a polymer electrolyte membrane as an electrolyte layer, and more specifically to a fuel cell in which the constitution of a gas diffusion layer and a separator is devised. About.

[0002]

2. Description of the Related Art Conventionally, although not shown, a solid polymer electrolyte membrane is used as an electrolyte layer, and a catalyst layer on the cathode (positive electrode) side is provided on one surface of this layer, and an anode (negative electrode) side is provided on the other surface. The catalyst layers are bonded to each other to form a membrane electrode assembly, each catalyst layer is sandwiched between gas diffusion layers having conductivity, and these gas diffusion layers are sandwiched on the outside with gas impermeable separators. It is known that a unit cell of a fuel cell is formed by tightening the whole into one block-shaped laminate.

[0003] In the unit cell of the fuel cell, various proposals have hitherto been made regarding the material and form of the material used for each constituent member. For example, the electrolyte layer can be made thinner while maintaining mechanical strength, or the catalyst layer can be made of CO or CO ₂
Providing a gas separation layer so as not to be exposed to water is a part of those examples.

[0004]

DISCLOSURE OF THE INVENTION The present invention relates to a known polymer electrolyte fuel cell, in which the shape of the gas diffusion layer is made unique and the gas diffusion property is improved while suppressing the thickness of the whole cell. It is a first object to provide a fuel cell with improved reaction efficiency as a battery. Accordingly, the present invention provides a fuel cell in which the thickness of the unit cell of the fuel cell is suppressed by the above-described device in addition to the configuration of the gas diffusion layer, and the thickness when the unit cells are stacked or stacked is not increased. This is the second issue. In addition, the present invention devises a configuration of a separator of a unit cell of a fuel cell so that a reaction state of a fuel gas and a reaction gas as a fuel cell can be observed from outside the unit cell, and also significantly reduces cost. A third object of the present invention is to provide a fuel cell which is suitable for experiments, teaching materials, and fuel cell material tests, and can be manufactured at a low price. is there.

[0005]

Means for Solving the Problems The fuel cell of the present invention, which has been made to solve the above-mentioned problems, comprises an electrolyte layer made of a solid polymer electrolyte membrane, a cathode-side catalyst layer formed on both surfaces of the layer, and a negative electrode. Side catalyst layer, conductive gas diffusion layer disposed on the outer surface side of each catalyst layer, gas impermeable disposed on the outer surface side of the gas diffusion layer to tightly sandwich the electrolyte layer to the gas diffusion layer in a stacked state In a fuel cell comprising the separator described above, carbon paper is disposed as a gas diffusion layer on the inner surface of the separator, and a zigzag cut is made in the carbon paper.

In the fuel cell of the present invention, instead of the above structure, a transparent resin material is used for the separator, and a reactive gas flow path is formed on the inner surface of the separator. It can also be configured to be externally observable through

Further, in the fuel cell of the present invention, the gas flow path may be formed on the inner surface of the separator by attaching carbon paper having a gas flow path formed by cutting into the inner surface of the separator.

[0008]

Next, an embodiment of a fuel cell according to the present invention will be described with reference to the drawings. 1 is a front view of an example of the fuel cell of the present invention, FIG. 2 is a plan view of the fuel cell of FIG. 1, FIG. 3 is an exploded front view of components of the fuel cell of FIGS. 6 is a back view of an example of the separator used in the fuel cell of FIGS. 1 to 3; FIG. 5 is a front view of the separator of FIG.
FIG. 4 is a plan view showing another example of the configuration of the separator and carbon paper in the fuel cell of the present invention.

In FIG. 3, reference numeral 1 denotes a Nafion film for forming an electrolyte layer A, and reference numerals 2 and 3 denote a positive electrode and a negative electrode of the electrolyte layer A formed on both surfaces of the film 1, for example, mainly composed of platinum-supported carbon. Formed by the catalyst. Reference numerals 4 and 5 denote gas diffusion layers on the positive electrode side and the negative electrode side made of carbon paper having a thickness of about 0.3 to 0.4 mm disposed on the surfaces of the positive electrode 2 and the negative electrode 3 of the electrolyte layer A, respectively. Annular packing (or gasket) arranged so as to cover the outer periphery of the gas diffusion layers 4 and 5.

Numerals 8 and 9 denote separators which are placed over the packings 6 and 7, and the above-mentioned fuel cell components 1 to 7 are tightly integrated in a stacked state on the outer periphery thereof, and are formed as shown in FIGS. Hole for tightening bolt B for forming a fuel cell
In this example, eight separators 8a and 9a are formed, and a terminal 1 for electrical extraction is provided at the center of both separators 8 and 9.
Terminal holes 8b and 9b for mounting 0 and 11 are formed respectively. The separator 8 on the positive electrode side supplies and discharges oxygen or air inside the portion where the packing 6 contacts.
While 8c and 8d are formed, hydrogen supply and discharge 9c and 9d are formed in the separator 9 on the negative electrode side corresponding to the holes 8c and 8d. The packings 6 and 7 and the Nafion film 1 also have holes (not shown) corresponding to the bolt holes 8b and 9b in the separators 8 and 9.

The above members 1 to 7 are sequentially laminated, terminals 10 and 11 are attached to the terminal holes 8b and 9b in the separators 8 and 9 respectively, and the terminals are stacked in the laminated shape. An example of the fuel cell of the present invention is formed by inserting and fastening the bolt B to the bolt holes 8a and 9a.

In the fuel cell of the present invention,
Since the carbon papers 4 and 5 having a thickness of about 0.3 to 0.4 mm smaller than the material of the conventionally used gas diffusion layer are used for the gas diffusion layer, the thickness is increased in a known fuel cell of this type. The thickness of the gas diffusion layer, which has been an element to be reduced, can be reduced. By the way, the known gas diffusion layer, because the gas flow path is formed by pressing or the like, the thickness thereof needs to be about 0.8 mm to 1.0 mm at least, so according to the present invention, a single cell The thickness can be reduced to about half or less.

Further, zigzag cuts (or slits, not shown in the drawings) are formed in the carbon papers 4 and 5 as an example, thereby promoting or activating the diffusion of gas, so that the fuel cell can be used as a fuel cell. The response is improved. The notches (slits) that promote the gas diffusion are formed with a thickness of about 1/2.
Even if the gas diffusion performance of the carbon paper is about half that of a known gas diffusion layer, the gas diffusion performance calculated per unit volume of the fuel cell is almost the same even if the carbon paper has a gas diffusion performance of about half that of a known gas diffusion layer. become.

In the present invention, the separators 8 and 9 in the above example are formed of a transparent resin material as illustrated in FIGS.
When the separator 12 is formed, the condition of the reaction gas can be seen from the outside of the separators 8 and 9. Therefore, when the operating conditions of the fuel cell (for example, gas temperature, pressure, flow rate, humidity, etc.) are variously changed, hydrogen gas and air Changes in (or oxygen) status can be seen, which is extremely useful in selecting and setting operating conditions for the fuel cell.

Since the fuel cell of the present invention has a very simple structure and shape as shown in FIGS. 1 to 3, the constituent members, for example, the materials and materials of the electrolyte membrane 1, the electrodes 2 and 3, the packing 6 , 7 etc. are formed from materials and materials different from those in the above example, and these are operated as a replacement fuel cell and evaluated. It can also be used as an evaluation cell for evaluating performance and the like. In this regard, in the fuel cell of the present invention, the materials of the separators 8 and 9 may be selected from aluminum, stainless steel, copper, expanded graphite, and the like, depending on the purpose, in addition to the above resin materials.

According to the present invention, in the fuel cell of the above-described example, gas flow paths 12 are punched and formed in carbon papers 4 and 5 provided as gas diffusion layers as shown in FIG. A structure in which a gas diffusion layer is formed on the inner surfaces of the separators 8 and 9 can be obtained by bonding and integrating the inner surfaces of the separators 8 and 9. The pattern of the flow path 12 and the positions of the gas supply / discharge holes 9c are not limited to the example shown in the figure, but are arbitrary. In the present invention, by adopting the above configuration,
When the zigzag gas flow path 12 is formed in the carbon papers 4 and 5 having a small thickness (for example, about 0.3 to 0.4 mm), there is a disadvantage that the groove of the flow path hangs down due to its own weight. Can be completely prevented. In addition, it is not necessary to form a gas flow path on the inner surfaces of the separators 8 and 9.

[0017]

The present invention is as described above. By using thin carbon paper for the gas diffusion layer and using a transparent resin material for the separator, the unit cell of the polymer electrolyte fuel cell can be made thin. In addition to being able to observe the state of the reaction inside from outside, it is extremely useful particularly as a fuel cell for teaching materials, experiments or material tests.

When the gas flow path is formed in the carbon paper, the gas flow path formed in the carbon paper can be prevented from being deformed by bonding the gas flow path to the inner surface of the separator and integrating it with the separator. In addition, when the separator in this case is a transparent resin material, it is not necessary to form a groove of a gas flow path for reaction gas observation in the separator.

[Brief description of the drawings]

FIG. 1 is a front view of an example of the fuel cell of the present invention.

FIG. 2 is a plan view of the fuel cell of FIG.

FIG. 3 is an exploded front view showing constituent members of the fuel cell shown in FIGS. 1 and 2;

FIG. 4 is a back view of an example of a separator used in the fuel cell shown in FIGS.

FIG. 5 is a front view of the separator of FIG. 4;

FIG. 6 is a plan view showing another example of the configuration of the separator and carbon paper in the fuel cell of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Nafion membrane 2 Positive electrode 3 Negative electrode A Electrolyte layer 4, 5 Gas diffusion layer 6, 7 Packing 8, 9 Separator 10, 11 Terminal 12 Gas flow path

Claims (3)

[Claims] 1. An electrolyte layer made of a solid polymer electrolyte membrane, a cathode-side catalyst layer and a cathode-side catalyst layer formed on both sides of the layer, a conductive gas diffusion layer disposed on the outer surface side of each catalyst layer, and the gas diffusion layer. In a fuel cell including a gas-impermeable separator that is arranged on the outer surface side of the layer and tightly clamps the electrolyte layer to the gas diffusion layer in a stacked state, on the inner surface of the separator,
A polymer electrolyte fuel cell, wherein carbon paper is disposed as a gas diffusion layer, and zigzag cuts are formed in the carbon paper. 2. The separator according to claim 1, wherein a transparent resin material is used for the separator, and a reaction gas flow path is formed on the inner surface of the separator so that the state of the reaction gas on both the positive and negative electrode sides can be externally observed through the separator. Solid polymer fuel cell. 3. The polymer electrolyte fuel cell according to claim 1, wherein a carbon paper having a cut formed a gas flow path is adhered to an inner surface of the separator.