JPH0684533A - Humidifying means for solid high polymer type fuel cell - Google Patents

Abstract

PURPOSE:To achieve the miniaturization and the light weight of a solid high polymer type fuel cell by preventing a high polymer electrolyte film from being dryed, and achieving the high output density, and proofing the fuel cell against moisture without its performance lowered, and also preventing the overheat thereof. CONSTITUTION:An anode electrode 103 bearing platinums catalyser and a cathode electrode 104 are arranged on both sides of a high polymer electrolyte film 105, and a collector plate 102 with a groove is arranged, hydrophilic resin is buried within the anode electrode. The collector plate 102 is formed of a mixture of compressed, sintered and graphitized particles and a binder. For a method of supplying hydrophilic resin with water, a chamber filled up with water is provided in the circumferential part of the cathode electrode 104, and water is supplied from that part thereto with penetration.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel cell, and more particularly to a humidifying means for a polymer electrolyte fuel cell.

[0002]

2. Description of the Related Art Conventionally, it has been known to generate an electric current by using oxygen and hydrogen in a fuel cell. One of the fuel cells conventionally used is a fuel cell using a polymer electrolyte membrane. This type of fuel cell unit is composed of a plurality of fuel cells. Each fuel cell comprises a polymer electrolyte membrane and electrodes containing a catalyst so as to sandwich the polymer electrolyte membrane from both sides.

This polymer electrolyte membrane must always be kept in a wet state. Therefore, in order to keep the polymer electrolyte membrane in a healthy state, it is always necessary to supply water.

The mechanism of electric power generation in this polymer electrolyte membrane type fuel cell is well known. That is, for example, fuel such as hydrogen gas is injected to the electrode on the anode side, and strong oxidizing substance such as oxygen gas is injected to the electrode on the cathode side.

The anode and the cathode are mainly composed of a conductive material carrying a catalyst with fluorocarbon as a binder. Incidentally, platinum is mainly used as the catalyst.

In a normal polymer electrolyte fuel cell,
As is well known, the catalyst on the surface of the polymer electrolyte membrane in the anode ionizes the fuel to generate ions and free electrons.
These free electrons flow by suitable means from one terminal of the fuel cell to the other terminal connected to the cathode, through which they are used for the reduction of oxidizing substances such as oxygen gas.

[0007]

On the other hand, the ions permeate the polymer electrolyte membrane and are sent to the cathode provided on the opposite side of the polymer electrolyte membrane. Along with the movement of the ions, water molecules of several molecular weight are transported. Transport of water by ions is carried out by electroosmotic or protonic pumps.
p). Therefore, on the anode side of the polymer electrolyte membrane, drying progresses as water is transported. In order to prevent this, the fuel gas injected into the anode is generally humidified. However, in a high current region where more water is transported to the cathode side than the water supplied by humidifying the gas, the polymer electrolyte membrane dries, increasing the membrane resistance and decreasing the battery performance. However, there has been a problem in increasing the power density of the fuel cell. Therefore, a method for achieving high power density while preventing the polymer electrolyte membrane from drying is desired.

Therefore, an object of the present invention is to reduce the size and weight of a fuel cell by a method of increasing the power density while preventing the polymer electrolyte membrane of the fuel cell from drying. To provide.

[0009]

Means for Solving the Problems In a polymer electrolyte fuel cell comprising a polymer electrolyte membrane and an electrode having a catalyst, a hydrophilic resin or a hydrophilized porous membrane is used in or around an electrode or a membrane. It is a humidifying means for a polymer electrolyte fuel cell, which is installed on a surface and supplies water through a porous membrane. As a hydrophilic resin, -C is added to the functional group.
OOH, -COC-, -OH, -RNR ', -SO
Any resin having ₃ H or the like may be used, and the same functional group may be attached to the hydrophilic treatment.

[0010]

The reason why the high power density can be achieved while preventing the drying of the polymer electrolyte membrane of the fuel cell by the above measures is as follows.

As shown in FIG. 1, a porous membrane made of a hydrophilic resin or subjected to a hydrophilization treatment is incorporated into the anode, and water is permeated or passed through the film by a capillarity.
Water can be supplied to the anode side, and the hydrogen gas can be humidified to prevent the polymer electrolyte membrane from drying.

[0012]

Embodiments of the present invention will be described below with reference to the accompanying drawings. An actual battery has a structure in which these cells are laminated.

Embodiment 1) FIG. 1 shows a part of a single cell structure according to the present invention. Anode electrode 103 (a mixture of conductive carbon and polytetrafluoroethylene) and a cathode electrode 104 (conductive carbon and poly) which carry a platinum catalyst on both sides of a polymer electrolyte membrane 105 (Nafion (registered trademark) 117: manufactured by DuPont). Mixture of tetrafluoroethylene)
And a current collector plate 102 with a groove is arranged. A hydrophilic resin 101 is embedded in this anode electrode.

The current collector plate 102 is formed of a mixture of compressed, sintered, graphitized carbon particles and a fixing material.
The hydrophilic resin 101 is a film of a copolymer resin of ethylene and methacrylic acid, and its shape is shown in FIG.

As a method of supplying water to the hydrophilic resin, as shown in FIG. 1, an O-ring 1 is provided around the anode electrode.
A chamber filled with water is provided by 11 and water is supplied from this portion by permeation.

A polymer electrolyte fuel cell having this structure was used at a cell temperature of 55 ° C. at 1 atm of hydrogen and 1 atm of oxygen at 1 A / cm ²
Power was generated at the current density of. As a result, the output was not reduced even after 1 hour. In the figure, 106 is humidifying water, 107 is a hydrogen inlet, 108 is an oxygen inlet, 109 is a hydrogen outlet, and 110 is an oxygen outlet.

Embodiment 2) FIG. 2 shows a part of a single cell structure according to the present invention. Anode electrode 103 (a mixture of conductive carbon and polytetrafluoroethylene) and a cathode electrode 104 (conductive carbon and poly) which carry a platinum catalyst on both sides of a polymer electrolyte membrane 105 (Nafion (registered trademark) 117: manufactured by DuPont). Mixture of tetrafluoroethylene)
And a current collector 102 with a groove is arranged. The hydrophilic porous film 101 is brought into contact with this anode electrode side.

The current collector 102 is formed from a mixture of compressed, sintered, graphitized carbon particles and a fixing material.

In FIGS. 1 and 2, reference numeral 101 denotes a fluororesin porous membrane (Poreflon (registered trademark) manufactured by Sumitomo Electric Industries, Ltd.), on which polyvinyl alcohol is carried by an electron beam graft polymerization method to make the surface hydrophilic. It is a thing. This was cut out into a width of 3 mm, pressed onto the surface of the solid polymer electrolyte membrane as shown in FIGS. 1 and 2, and the operation of the fuel cell was tested while supplying water through the hydrophilized porous membrane. In the system in which only a part of the surface of the polymer electrolyte membrane was coated with the hydrophilized porous film, the exposure rate of the surface of the polymer electrolyte membrane was unified to 90%.

A polymer electrolyte fuel cell having this structure is used for hydrogen 1
Power was generated at a current density of 1 A / cm ² at atmospheric pressure and 1 atm of oxygen. As a result, the output was not reduced even after running for 1 hour.

Embodiment 3) FIGS. 1 and 2 show a part of a single cell structure according to the present invention. Ion exchange membrane 105 (Nafion
(Registered trademark) 117: manufactured by Dupont Co., Ltd., and an anode electrode 103 (a mixture of conductive carbon and polytetrafluoroethylene) and a cathode electrode 104 carrying platinum catalysts on both sides.
(A mixture of conductive carbon and polytetrafluoroethylene) is arranged, and a current collector plate 102 having a groove is arranged.

The current collector plate 102 is formed from a mixture of compressed, sintered, graphitized carbon particles and a fixing material.

Example 2. In place of the surface-hydrophilized porous membrane 101 used in step 1, a partially acetalized polyvinyl alcohol, which is a hydrophilic resin, is supported on the surface of the solid electrolyte membrane, and water is supplied through this resin while starting power generation. The change with time of the electromotive force and the change with time of the utilization rates of hydrogen gas and oxygen gas are described. The acetalization ratio of the polyvinyl alcohol resin used was 10%, 25%, 50%.
% And changed.

As shown in Table 1, the decrease in electromotive force is suppressed as compared with Comparative Example 1, but a slight decrease in electromotive force is also observed for the acetalization ratio of 10%. This is because polyvinyl alcohol, which has a low acetalization ratio, has strong solubility in water, and this resin covered the entire polymer electrolyte membrane while the battery was operating, making it difficult to supply gas. it is conceivable that.

[0025]

[Table 1]

Comparative Example 1) FIG. 3 shows a part of a single cell structure according to a comparative example of the present invention. Ion exchange membrane 105 (Nafion
(Registered trademark) 117: manufactured by Dupont Co., Ltd., and an anode electrode 103 (a mixture of conductive carbon and polytetrafluoroethylene) and a cathode electrode 104 carrying platinum catalysts on both sides.
(A mixture of conductive carbon and polytetrafluoroethylene) is arranged, and a current collector plate 102 having a groove is arranged.

The current collector plate 102 is formed of a mixture of compressed, sintered, graphitized carbon particles and a fixing material.

1 atm of hydrogen and 1 atm of oxygen moistened with saturated steam at 70 ° C. were supplied to the cell having a cell temperature of 55 ° C. As a result, the output voltage became 0 V or less 90 seconds after the start of operation.

[0029]

As described above, according to the present invention, a hydrophilic resin or a hydrophilized porous membrane is installed in the electrode or in the periphery of the electrode or on the membrane surface, and the hydrophilic resin or the porous membrane is interposed between the hydrophilic resin and the porous membrane. Water is supplied to prevent the polymer electrolyte membrane from drying, achieve a high power density ratio, dehumidify without degrading the performance of the fuel cell, prevent overheating, and reduce the size of the fuel cell. It achieves weight reduction.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a single cell structure according to a first embodiment of the present invention.

FIG. 2 is a sectional view of a single cell structure of Example 2 of the above.

FIG. 3 is a cross-sectional view of the single cell structure of Comparative Example 1 above.

FIG. 4 is an enlarged plan view of a hydrophilic resin used in the present invention.

[Explanation of symbols]

 101 Hydrophilic Resin 102 Current Collector Plate 103 Anode Electrode 104 Cathode Electrode 105 Polymer Electrolyte Membrane 106 Humidifying Water 107 Hydrogen Inlet 108 Oxygen Inlet 109 Hydrogen Outlet 110 Oxygen Outlet

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Toru Kashiwagi 1-3-3 Shimaya, Konohana-ku, Osaka City Sumitomo Electric Industries, Ltd. Osaka Factory (72) Inventor Koji Hanafusa 1-chome, Shimaya, Osaka No. 3 Sumitomo Electric Industries, Ltd. Osaka Works

Claims (1)

[Claims] 1. In a polymer electrolyte fuel cell comprising a polymer electrolyte membrane and an electrode having a catalyst, a hydrophilic resin or a hydrophilized porous membrane is installed in the electrode, in the periphery of the electrode or on the membrane surface. And supplying water through a hydrophilic resin or a porous membrane that has been subjected to a hydrophilization treatment.