JP3310737B2 - Gas collection type gas diffusion electrode and electrolytic cell using the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention
The present invention relates to a gas trapping type gas diffusion electrode for trapping bubbles of a reaction gas bubbled in the electrolytic solution, a fuel cell using the same, and an electrolytic cell for various electrolysis.

[0002]

2. Description of the Related Art Generally, a gas diffusion electrode is formed by laminating a reaction layer and a gas diffusion layer, and is used by completely separating a gas chamber side and an electrolyte side. However, the conventional gas diffusion electrode has problems such as liquid leakage, gas leakage, and difficulty in mass transfer.To solve this problem, the present inventor is immersed in an electrolytic solution and bubbled in the electrolytic solution. A gas-collecting gas diffusion electrode for collecting bubbles of the reaction gas was taken into consideration.

[0003]

However, in this gas trapping type gas diffusion electrode, since the reaction gas is bubbled in the electrolyte, if the bubbles enter the reaction layer, the resistance of the electrolyte increases. There is a defect. There is also a problem that the attachment to the electrolytic cell becomes uncertain. Accordingly, an object of the present invention is to provide a gas trapping type gas diffusion electrode capable of preventing an increase in the resistance of an electrolytic solution and an electrolytic cell capable of securely mounting the same.

[0004]

Means for Solving the Problems To solve the above problems, the first gas-trapping gas diffusion electrode of the present invention is immersed in an electrolytic solution to remove bubbles of a reaction gas bubbled in the electrolytic solution. A gas trapping type gas diffusion electrode for trapping gas, which allows an electrolytic solution to penetrate between a gas-permeable water-repellent layer (hereinafter simply referred to as a water-repellent layer) and a reaction layer and forms bubbles of the reaction gas. It is characterized in that a metal net that cannot pass through is interposed, and the metal net extends outside the reaction layer. The second gas-collecting gas diffusion electrode is immersed in the electrolytic solution,
A gas trapping type gas diffusion electrode for trapping bubbles of a reaction gas bubbled into the electrolyte, which allows the electrolyte to penetrate between the water-repellent layer and the reaction layer, and removes bubbles of the reaction gas. It is characterized in that a metal net that cannot pass through is interposed, and the metal net is exposed to many through holes provided in the reaction layer and the water-repellent layer. On the other hand, in the electrolytic cell using the first gas-collecting gas diffusion electrode, the gas-collecting gas diffusion electrode is
It is characterized in that it is attached to a metal frame or a metal rib of the electrolytic cell through a peripheral portion of the metal net so as to partition the inside of the electrolytic cell by the metal net. In addition, the electrolytic cell using the second gas-collecting gas diffusion electrode has an exposed metal mesh so that the second gas-collecting gas diffusion electrode partitions the inside of the electrolytic cell with the gas diffusion electrode. It is characterized by being attached to a metal frame or a metal rib of the electrolytic cell through the intermediary.

[0005]

In the first and second means, bubbles of the reaction gas do not enter the electrolyte on the reaction layer side. In the third and fourth means, each gas diffusion electrode is attached to the electrolytic cell via a metal frame or a metal rib, and each metal net functions as a current collector or a power feeder.

[0006]

Embodiments of the present invention will be described below with reference to the drawings. 1 and 2 are a cross-sectional view and a side view, respectively, showing one embodiment of a gas-trapping gas diffusion electrode of the present invention. The gas-trapping gas diffusion electrode 1 allows the electrolyte to penetrate between the gas diffusion layer 3 to which the water-repellent layer 2 is joined and the reaction layer 4 to be joined thereto, and allows the reaction gas bubbles to pass through. A metal net such as a titanium net with nickel baked or platinum net baked to function as a current collector or a power feeder.
(For example, 40 to 50 mesh), and a metal net 5 is appropriately extended outside from the reaction layer 4 and the gas diffusion layer 3.

In order to manufacture the above-mentioned gas trapping type gas diffusion electrode 1, a reaction layer 4 and a gas diffusion layer 3 are sandwiched between a metal mesh 5
Is hot-pressed with a part of the Teflon interposed therebetween so that the Teflon porous body is joined to the gas diffusion layer 3 as the water-repellent layer 2. The metal net 5 may be formed by laminating a plurality of metal nets having different pores, or only the exposed portion may be reinforced with a thick metal net. Further, a hydrophilic porous body such as a glass filter may be joined to the exposed portion of the metal net 5.

[0008] The gas trapping type gas diffusion electrode 1 having the above-described structure is constructed as follows.
As shown in FIG. 3, spot welding of the peripheral edge of the metal net 5 is left on the frame-shaped metal frame 6 of the electrolyzer (not shown) so as to partition the inside of the electrolyzer by the metal net 5. Installed by.

In order to apply an electrolytic cell using the above-described gas-collecting gas diffusion electrode 1 to a fuel cell, as shown in FIG. The gas diffusion electrode 1 is installed so as to partition the inside of the electrolytic cell 7 of the fuel cell by the respective metal nets 5, and the frame-shaped metal frame 6 of the electrolytic cell 7 is provided through the peripheral portion of each metal net 5. Installed by spot welding. In FIG. 4, reference numeral 9 denotes an oxygen nozzle for bubbling oxygen gas (O ₂ );
Denotes a hydrogen nozzle for bubbling hydrogen gas, 11 denotes an oxygen discharge pipe for discharging oxygen gas, and 12 denotes a hydrogen discharge pipe for discharging hydrogen gas. Reference numerals 13 and 14 denote water-repellent baffles for increasing the efficiency of trapping air bubbles and dispersing the air bubbles throughout the electrode.

Here, the metal net 5 of the gas trapping type gas diffusion electrode 1 is formed by baking platinum on a 50-mesh titanium net, and a hydrogen-oxygen fuel cell is constructed using sulfuric acid having a concentration of 20% as an electrolyte. However, the distance between the poles could be reduced to 0.5 mm. When the electrolyte was filled and each gas was supplied, the gas worked as a battery, and almost no bubbles were mixed between the electrodes, and the output was 0.6 V at 540 mA / cm ² . Furthermore,
By inserting a glass filter having a thickness of 0.2 mm between the poles, the distance between the poles could be further reduced without contacting the poles. The output at this time was 650 mA / cm ² at 0.6 V.

On the other hand, the gas collecting type gas diffusion electrode 1
As shown in FIG. 5, in order to apply an electrolyzer using an electrolyzer to the electrolysis of a saline solution by an ion exchange membrane method, as shown in FIG. The gas diffusion electrode 1 is connected to the cathode chamber 17 by the metal mesh 5.
And is attached to the frame-shaped metal frame 18 of the cathode chamber 17 via the peripheral portion of the metal net 5 by spot welding. At this time, the distance between the cation exchange membrane 16 and the upper and lower portions of the metal net 5 is changed by the distance between the reaction layer 4 and the cation exchange membrane 16.
It is bent so as to be larger than that described above to facilitate the supply of the electrolytic solution and is attached. 5, reference numeral 19 denotes an insoluble anode disposed in the anode chamber 20, reference numeral 21 denotes a saline solution supply pipe for supplying a saturated saline solution to the anode chamber 20, and reference numeral 22 denotes chlorine gas (Cl ₂ ) generated from the anode chamber 20, It is a saline solution discharge pipe for discharging the saline solution. Reference numeral 23 denotes an oxygen nozzle for bubbling oxygen gas into the cathode chamber 17 on the water repellent layer 2 side, and reference numeral 24 denotes a cathode chamber 17 on the reaction layer 4 side.
A sodium hydroxide aqueous solution supply pipe 25 for supplying a thin sodium hydroxide aqueous solution to the aqueous sodium hydroxide solution, and a sodium hydroxide aqueous solution discharge pipe 25 for discharging a concentrated sodium hydroxide aqueous solution together with oxygen gas from the cathode chamber 17 on the water repellent layer 2 side. 26 is a water-repellent baffle,
This is for increasing the efficiency of collecting bubbles and dispersing the bubbles throughout the oxygen cathode. The electrolytic layer 15 is not limited to the case where the electrolytic layer 15 is installed vertically.
May be tilted or leveled so as to be located below to facilitate the collection of oxygen gas. Also, irregularities may be formed on the surface of the water-repellent layer 2 of the gas-trapping gas diffusion electrode 1 to improve the flow of the electrolytic solution and the trapping of bubbles.

FIG. 6 is a side view schematically showing another embodiment of the electrolytic cell using the gas trapping type gas diffusion electrode 1. As shown in FIG. In this electrolytic cell, the gas trapping type gas diffusion electrode 1 is attached to each window frame of the lattice-shaped metal frame 27 by spot welding at the periphery of the metal net 5 except for the upper or lower part of the metal net 5. In addition, the size of the electrolytic cell has been increased. In order to increase the size of the electrolytic cell, a large number of gas collecting gas diffusion electrodes 1 are joined to a lath material having a thickness of about 1 mm, and this is joined to a grid-like metal rib of the electrolytic cell. Is also good. At this time, the lath material may be located on either the reaction layer 4 side or the water repellent layer 2 side of the gas trapping gas diffusion electrode 1.

FIGS. 7 and 8 are a sectional view and a side view showing another embodiment of the gas collecting type gas diffusion electrode of the present invention. The gas-trapping gas diffusion electrode 28 allows the electrolyte to penetrate between the gas diffusion layer 30 to which the water-repellent layer 29 is joined and the reaction layer 31 to be joined thereto, and allows the reaction gas bubbles to pass through. Metal nets such as titanium nets baked with platinum or nickel nets to function as current collectors or power feeders.
(For example, 40 to 50 mesh), and a metal net 32 is exposed to a large number of through-holes 33 provided through the reaction layer 31, the gas diffusion layer 30, and the water-repellent layer 29.

The gas trapping type gas diffusion electrode 28 having the above structure is
Although not shown, the gas collecting gas diffusion electrode 28 partitions the inside of the electrolytic cell into a frame-shaped metal frame or a lattice-shaped metal rib of the electrolytic cell for electrolysis of a saline solution by a fuel cell or an ion exchange membrane method. Metal mesh 32 exposed from appropriate through holes 33
Are mounted by spot welding.
In the above embodiment, the example in which the gas diffusion layer 3 is provided has been described, but the present invention is not limited to this, and the gas diffusion layer 3 may not be provided.

[0015]

As described above, according to each gas trapping type gas diffusion electrode of the present invention, since bubbles of the reaction gas do not enter the electrolyte on the reaction tank side, the resistance of the electrolyte increases. Can be prevented. In addition, according to the electrolytic cell using each gas collecting gas diffusion electrode, the gas collecting gas diffusion electrode can be easily and reliably attached.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing one embodiment of a gas trapping type gas diffusion electrode of the present invention.

FIG. 2 is a side view of the gas collecting gas diffusion electrode of FIG.

FIG. 3 is a side view schematically showing an embodiment of an electrolytic cell using the gas trapping type gas diffusion electrode of FIG.

FIG. 4 is a conceptual diagram showing a case where an electrolytic cell using the gas trapping type gas diffusion electrode of FIG. 1 is applied to a fuel cell.

FIG. 5 is a conceptual diagram showing a case where an electrolytic cell using the gas trapping type gas diffusion electrode of FIG. 1 is applied to electrolysis of a saline solution using an ion exchange membrane.

6 is a side view schematically showing another embodiment of the electrolytic cell using the gas trapping type gas diffusion electrode of FIG.

FIG. 7 is a cross-sectional view showing another embodiment of the gas trapping type gas diffusion electrode of the present invention.

8 is a side view of the gas trapping type gas diffusion electrode of FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Gas-collecting gas diffusion electrode 2 Water-repellent layer 3 Gas-diffusion layer 4 Reaction layer 5 Metal net 6 Metal frame 7 Electrolyzer 15 Electrolyzer 17 Cathode room 18 Metal frame 28 Gas-collecting gas diffusion electrode 29 Water-repellent layer 30 Gas diffusion layer 31 Reaction layer 32 Metal net 33 Through hole

Claims (4)

(57) [Claims] A gas-collecting gas diffusion electrode that is immersed in an electrolytic solution and captures bubbles of a reactive gas that is bubbled in the electrolytic solution, wherein the gas-permeable water-repellent layer and the reaction layer A gas net, wherein a metal net that allows the electrolyte to penetrate and does not allow air bubbles of the reaction gas to pass through is interposed, and the metal net extends outside the reaction layer. Gas diffusion electrode. 2. A gas-collecting gas diffusion electrode that is immersed in an electrolytic solution and captures bubbles of a reaction gas that is bubbled in the electrolytic solution, wherein the gas-collecting gas diffusion electrode is bonded to a gas-permeable water-repellent layer. Between the reaction layer and the reaction layer to be formed, a metal net was interposed between the reaction layer and the gas-permeable water-repellent layer. A gas trapping type gas diffusion electrode exposed to a large number of through holes. 3. The gas-collecting gas diffusion electrode according to claim 1, which is attached via a metal frame or a rib of the electrolytic cell via a peripheral portion of the metal mesh so as to partition the inside of the electrolytic cell by the metal mesh. An electrolytic cell using a gas collecting gas diffusion electrode. 4. The gas collecting type gas diffusion electrode according to claim 2, wherein the gas diffusion electrode separates the inside of the electrolytic cell through an exposed metal net through a metal frame or a metal rib of the electrolytic cell. An electrolytic cell using a gas-collecting gas diffusion electrode, which is attached.