JPS59214171A - Button-type air cell - Google Patents

Abstract

PURPOSE:To prevent completely any liquid leakage through an air supply hole provided in a positive case by interposing a porous electrolyte-absorbing member between a positive electrode and a water repellent film installed on the air-diffusion-side of the positive electrode. CONSTITUTION:A porous air-diffusion paper 3 principally consisting of for example cellulose is placed on the concave section of the inner bottom of a positive case 1 having an air supply hole 2 in its bottom. Next, a water repellent film 4 is placed on the porous air-diffusion paper 3. After that, a porous electrolyte-absorbing member 5 prinicpally consisting of cellulose, easily absorbs electrolyte and does not inhibit the diffusion of air into a positive catalyst layer, is placed on the water repellent film 4. As the electrolyte-absorbing member 5, filter paper, craft paper or the like having a thckness of around 0.05-0.1mm. is suitable.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a button-type air battery used in portable electronic equipment, and is intended to improve leakage resistance from an air supply hole.

Conventional Structure and Problems Since button type air batteries use oxygen in the air as the active material of the positive electrode (air electrode), they have an air supply hole at the bottom of the positive electrode case. Since batteries are used in portable electronic devices, they may be used in harsh environments. Therefore, an inconvenience arises in that the alkaline electrolyte leaks from the air supply hole of the positive electrode case.

Various proposals have been made to prevent this leakage. For example, a water-repellent resin such as fluororesin is used as the binder for the catalyst layer of the positive electrode, and a water-repellent film such as polytetrafluoroethylene is integrally attached to the air diffusion side of the resin, and a similar water-repellent film is further attached to the air diffusion side. For example, by overlapping them.

These improvements have significantly improved leakage resistance. However, it is difficult to completely prevent liquid leakage in harsh environments. This is because the water-repellent material cannot fix the electrolyte as described above.Objective of the Invention The present invention aims to absorb the electrolyte leaking from the water-repellent positive electrode to prevent leakage from the air supply hole of the positive electrode case. The purpose is to provide a button-type air battery without

Composition of the Invention The present invention provides a structure in which an alkaline electrolyte is easily absorbed between the positive electrode and a water-repellent membrane disposed on the air diffusion side of the positive electrode, and the membrane is extremely porous and does not impede the diffusion of air to the positive electrode. It is characterized by the presence of an electrolyte absorbing material.

This electrolyte absorbing material immediately absorbs electrolyte when it passes through the positive electrode catalyst layer and the water-repellent membrane that is pressed onto the catalyst layer. It is possible to completely block the diffusion of liquid into the battery, stop the power generation action of the battery, and prevent contamination of equipment due to leakage.

DESCRIPTION OF EMBODIMENTS A first embodiment of an air battery according to the present invention is shown in the figure. The battery size is 11.6 mm in outer diameter and 5.40 mm in total height.

1 is a positive electrode case having an air supply hole 2 on the bottom surface, and a porous air diffusion paper 3 mainly composed of cellulose is placed in the recessed part of the inner bottom of the positive electrode case, and then a porous air diffusion paper 3 made of cellulose as a main component is placed. Punched thickness 0.1-0.15mm, porosity 20-5
A water-repellent film 4 made of 0% polytetrafluoroethylene is placed. Further, on this membrane 4, an electrolyte absorbing material 5 is placed, which is composed mainly of cellulose, which easily absorbs the electrolyte, is porous, and does not hinder the diffusion of air to the positive electrode catalyst layer.

Next, a metal net is filled with a mixture of activated carbon, a conductive material, and polytetrafluoroethylene as a binder to a thickness of 0.1 to 0.
．． A positive electrode composed of a positive electrode catalyst layer of 5 mm and a water-repellent film 7 made of polytetrafluoroethylene with a thickness of 0.1 to 0.2 mm and pressure-bonded to the catalyst layer 6 was made to have the same diameter as the case 1. The punched membrane 7 is inserted so as to be in contact with the electrolyte absorbing material 5.

Finally, cellophane, microporous polyethylene, or polypropylene having a diameter approximately equal to the inner diameter of the case 1 is placed on the catalyst layer 6 as a separator 8. The positive electrode side assembly is completed through the above steps.

On the other hand, a sealing plate 10 fitted with a nylon sealing ring 9
The negative electrode active material 11 is filled with zinc powder and an aqueous solution of potassium hydroxide as an electrolytic solution to form a negative electrode side assembly. The button-type air cell is completed by fitting this negative electrode side assembly and the above-mentioned positive electrode side assembly, and tightening the opening of the positive electrode case to a sealing plate via a sealing ring.

The electrolyte absorbing material 5 has a thickness of 0.05 to 0.1 m.
M-sized filter paper, kraft paper, etc. are suitable.

In addition, nonwoven fabrics made of synthetic fibers can also be used.

In the second embodiment, the electrolyte absorbing material 5 supports a substance that absorbs and solidifies the electrolyte, such as Portland cement. In this case, a method is used in which Portland cement is dispersed in an organic solvent such as methanol, acetone, toluene, etc., and the porous electrolyte absorber 5 is impregnated with this.

Further, as a third embodiment, when the electrolyte absorbing material 5 is impregnated with an organic acid, which is a substance that neutralizes the electrolyte, the organic acid is dissolved in water, and the electrolyte absorbing material 5 is immersed in it. The organic acid can be supported by drying.

Battery A of the present invention using kraft paper as the electrolyte absorbing material 5 and Comparative Battery B in which the electrolyte absorbing material 2 was not used and the water-repellent films 4 and 7 were in contact were subjected to various discharges at room temperature. When comparing the number of batteries that leaked from the air supply hole, the results are shown in the table below. Note that the number of test batteries was 50 in each case.

Effects of the Invention As described above, according to the present invention, it is possible to completely prevent liquid leakage from the air supply hole formed in the positive electrode case, and to eliminate contamination of battery-using equipment due to leaked electrolyte.

[Brief explanation of the drawing]

The figure is a sectional view of essential parts of a button-type air battery according to an embodiment of the present invention. 1...Positive electrode case, 2...Air supply hole, 4
, 7... Water repellent membrane, 5... Electrolyte absorber, 8... Separator, 11... Negative electrode.

Claims (3)

[Claims] (1) A button-type air cell characterized in that a porous electrolyte absorbing material is interposed between an air electrode and a water-repellent membrane disposed on the air diffusion side. (2) The button-type air battery according to claim 1, wherein the electrolyte absorption material includes a substance that absorbs and solidifies the electrolyte. (3) The button-type air cell according to claim 1, wherein the electrolyte absorbing material contains a substance that neutralizes the electrolyte.