JPS61126777A - Gas diffusion electrode for air cell - Google Patents

Abstract

PURPOSE:To obtain an excellent gas diffusion electrode together with preventing occurrence of crack by forming a baked face on one face of a porous fluorine resin film and sticking the unbaked face of the film on a catalyst layer by way of pressing or contact. CONSTITUTION:Polytetra-fluoro-ethylene (PTFE) resin is molten in a solvent to form a porous PTFE film through heating and dry. Subsequently, the PTFE film is rotatingly driven out from a reel 2 around which the film 1 of long size is wound and a thermal sensor 17 achieves adjustment and heating so that the surfacial temperature of the STFE film on a metal cylinder 3 is set at 330 deg.C-500 deg.C. The PTFE film 11 having one baked face, obtained by such adjustment is superior to the unbaked film in terms of tensile strength and to the baked film in terms of elongation. Therefore, a gas diffusion electrode 6 is produced through such a process that a current collector 7 of nickel net is integrally stuck to a catalyst layer 15 through pressing and thereafter the porous PTFE film 11 having one baked face is stuck through pressing or contact with its unbaked face facing the catalyst layer 15.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to an air battery (an excellent gas expansion magnetic pole with two components).

[Conventional technology]

Conventional air battery C: The gas diffusion electrodes used were Catalyst I- (= porous method fluororesin membrane 9, which was crimped, and Shishitomo, which was crimped while heating. 34
No. 568 (2) A button in which the cotton water-based resin layer is composed of a plurality of porous fluorine sebaceous glands, at least one of which has an arc of granite and H9, and the remaining membrane is an unfired body. There was a 4 hour air battery.

[Problem that the invention seeks to solve]

Usually, the catalyst layer (the porous membrane that is bonded with two pressures) is a fluororesin membrane that has not been subjected to sintering.

However, the tensile strength of the film that has not been subjected to firing treatment is low, and the tensile strength of the film that has been subjected to firing treatment (compared to
It was 10 degrees. When this unfired film was used in a Buttonya air zinc battery (two-sided), cracks appeared during discharge, which caused the electrolyte to leak, making it impossible to achieve the specified discharge capacity. The reason why the membrane cracks is because the zinc in the negative electrode is discharged; it reacts with oxygen in the air and expands to form zinc oxide, pushing the gas diffusion electrode and deforming it, causing the membrane to receive tension. In addition, some batteries used porous fluororesin membranes that were fired entirely to strengthen the ! If the bonding properties are poor and the pressure bond is weak, the dissolution liquid may accumulate between the unfired fluororesin membrane and the unfired fluororesin membrane during release or storage, which prevents the supply of the element in the air to the catalyst 71. In addition, the reason why the adhesion of the fired membrane to the catalyst layer 1 is weak is because it has less elongation than the unfired membrane (2). Due to the low elongation, the unevenness of the surface of the catalyst layer cannot be absorbed, resulting in weaker adhesion.Increasing the pressure to strengthen the adhesion will crush the small pores at the waist (two), impairing air permeation. However, there was a problem that the required amount of oxygen could not be supplied.

The present invention aims to provide a porous fluororesin membrane with a single side I:@formed surface (Secondly, the purpose is to prevent the occurrence of cracks and to obtain an excellent air-magnetoelectric gas diffusion electrode.

[Means to solve the problem]

The present invention is characterized by forming one surface of a porous fluororesin membrane (forming an amorphous surface), and forming a reticulated metal ferromagnetic material (-) by mixing activated carbon and fluorine V4 fat powder and pressing it together. catalyst t
tiit = adhering the ungrained surface of the membrane by pressing or pressing.

[For 1] As mentioned above, in the present invention, the unfired surface of the fluororesin film is bonded to the catalyst layer (= bonding), so the surface of the catalyst layer has fine irregularities (= the surface of the membrane is intruded, due to the wedge effect). Such a gas diffusion magnetic pole can obtain a sufficient supply of oxygen, and since no cracks occur in the membrane, there is no leakage of electrolyte.

〔Example〕

First, polytetrafluoroethylene (PTFE1) resin is dissolved in a solvent and dried by heating to form a porous PTFE membrane. (2. As shown in Figure 3) (2. Width 101. Thickness - g
PTFI g is pulled out while rotating from the winding wheel 2 on which 0.1 g of long porous non-w8 polytetrafluoroethylene (PTFE) g 1 is wound. While rotating the surface of a metal cylinder 3 with a width of 21 Jtx and a diameter of α filled with water,
to move it. On the metal cylinder 3 (Secondly, IKW's outer fiber heater 16 was reinstalled, and the surface of the PTFE membrane on the metal cylinder was
330℃~soo c% desirably 360℃~380℃
(Adjust with J knee heat sensor 17 so that it is two.

In addition, heating with a laser beam may be used, or any method that can heat the entrance surface of PTFE A to a melting point of 327°C or higher (= heating time may be determined by heating temperature). etc. (adjust from 2, metal cylinder 3
This is done by changing the rotation speed of the

That is, one surface of the unfired PTFIi3 film 1 is heated C; thus, a part of the surface is heated. - and then fire, leaving the other side unfired (leave 2).
The crystal structure of the TFE film is in the longitudinal direction (two lines in a row).
The random direction (two different directions, the length direction and the direction perpendicular to it) is the one that determines the tensile strength.

The retirement stiffness and elongation rate per width 1 cIIL of the single-sided fired PTFE membrane obtained by adjusting the
Table (; summarized.

As shown in Table 1, it can be seen that the PTFE membrane fired on one side is superior to the unfired film in terms of tensile strength and superior to the fired film in terms of elongation.

In addition, we tested the tensile strength and elongation force of a fluororesin membrane made of 2-fluoroethylene-xafluoropropylene copolymer (ETFI) (even if there were two), and tested the tensile strength and elongation strength.

It can be seen that the fired ETFI film is superior to the unfired film in terms of tensile strength and superior to the fired film in terms of elongation C.

Here, press the nickel net onto the porous PTF'E membrane, which has been fired on one side, and then press the catalyst layer (2) with a roller so that the unfired side contacts the catalyst layer (2) The gas expansion 11CX electrode of the air cell of the present invention is formed by bonding or bonding with an adhesive.

P using the gas diffusion ``aL electrode as the air electrode as described above.
R44fi Button Reduced Air Zinc Grinding Basin (Two will be explained with reference to Figure 2.

Figure 2 (2, 4 is the positive electrode can that also serves as the positive electrode terminal, [
I: Has air supply holes 5. 6 is Gas Luka vrt=
It holds the RT solution, has liquid retention, and is alkali-resistant (the knee is made of nonwoven fabric or porous material, and is in contact with the negative electrode 9 made of a gel-filled plate. 10 is breathable (two excellent) The bottom of the positive electrode 4 is made of paper and is in contact with the gas diffusion plate 6 through the PTFE membrane 11 which has been fired on one side and has many micropores, and the opposite side is the bottom of the positive electrode 4 where the air supply holes 5 are provided. 12 is a negative electrode type, and the battery is sealed by bending the opening of the positive fjA can 4 via a gasket 13. 14 is a sealing material that seals the air supply hole 5. .

The gas diffusion electrode 6 of the air battery of the present invention is as shown in FIG.
: Contains an oxygen reduction catalyst. Add and mix 3 parts of PTFE powder, which is an aqueous material, to the activated carbon att part (2 parts) to form a sheet with a thickness of 0.2 to Q, 3++i+ (2 parts to form a catalyst Jri 115, and this catalyst layer 15 After the Tsukernet current collector 7 is integrated by pressure bonding, the negative side is baked and the fc porous PTFE membrane 11 is attached by pressure bonding or adhesive with the other unfired side facing the catalyst layer 15. In addition, the gas diffusion magnetic pole of the air battery of the present invention is.

In addition, in this example, polytetrafluoroethylene (PT
FE) g and tetrafluoroethylene-xafluoropropylene copolymer (ETFE) As mentioned above, other fluororesin films, such as polychlorotrifluoroethylene (PCTB□E), poly7onated vinyliso7 (F
Similar results were obtained with VdF), PVF), etc.

Effects of the Invention] As described above (2. The gas diffusion magnetic pole of the present invention, which is made of -11jI fired 7'c7 tree A￥11@ as a catalyst layer:: Adhesion or pressure bonding, has good adhesion with the catalyst layer, and (= There are no cracks, and even if the button-type air cell is used on two sides, the cell solution will not leak, and the magnetic discharge capacity can be improved.)

[Brief explanation of drawings]

Fig. 1 is a partially enlarged sectional view of the gas diffusion magnetic pole of the air battery of the present invention, Fig. 2 is a Wlrm diagram of a button-type air pond using the gas diffusion S4 pole of the present invention, and Fig. 3 is a partial enlarged sectional view of the gas diffusion magnetic pole of the air cell of the present invention. This is a principle diagram of an apparatus for firing one side of a fluororesin film.

Claims (1)

[Claims] In a gas diffusion electrode for an air cell in which a catalyst layer is attached to one surface of a porous fluorine resin membrane, a fired layer is formed on one surface of the membrane, and a catalyst layer is attached to the other unfired surface. A gas diffusion electrode for air batteries that is characterized by: