JP4576846B2 - Button-type zinc-air battery - Google Patents

Description

  The present invention relates to an alkaline battery using an air electrode as a positive electrode and gelled zinc as a negative electrode, a so-called air zinc battery.

  Zinc-air batteries use an air electrode that uses oxygen in the air as a positive electrode active material, and as a power source that can be used economically and without maintenance for a long time, various devices such as for navigation signs, various communications, telephones, etc. Has been applied to. Among them, the button-type zinc-air battery has a wide range of applications because it has features such as high energy density, light weight, and economy compared to other batteries having the same shape. The main application is the power supply for hearing aids.

  Generally, in button-type zinc-air batteries, oxygen in the air is taken into the battery from the air holes provided in the positive electrode case, and is diffused widely by air diffusion paper placed in the bottom recess of the positive electrode case. It is configured to be supplied to the pole.

  In the process of assembling this button-type zinc-air battery, after an air diffusion paper is disposed in the bottom recess of the positive electrode case, a water-repellent film is inserted thereon and brought into close contact with the positive electrode case. The air diffusion paper has been fixed with glue in the past, but there is a problem that the glue blocks the air holes. For example, as described in Patent Document 1, the air diffusion paper is fixed by applying water.

  However, since the fixing with water is not strong, the air diffusion paper may be disposed at a predetermined position in the bottom concave portion of the positive electrode case in the assembly process, and may move from the position. If the water repellent film is inserted while the air diffusion paper is moved from the predetermined position, it is not completely stored in the bottom concave portion of the positive electrode case, and one end of the air diffusion paper protrudes from the bottom concave portion (hereinafter referred to as diffusion paper misalignment). Occurs). Since one end of the air diffusion paper protruding from the bottom recess is sandwiched between the positive electrode case and the water repellent film, the sealing property between the positive electrode case and the water repellent film is impaired. This causes a problem that the electrolytic solution leaks out of the battery from the air hole through the air diffusion paper. This liquid leakage is not only generated immediately after battery assembly, but may also occur due to the passage of time or when the battery is used and discharged. Since the leakage of the electrolyte solution not only lowers the discharge performance but also damages the device, it is desirable to completely eliminate this diffusion paper misalignment when assembling the battery.

Since there is no diffusion paper misalignment after insertion of the water repellent film, the above-described problems will not occur if the misalignment of the diffusion paper is eliminated after insertion of the water repellent film in the middle of battery assembly. Therefore, after insertion of the water-repellent film, an image sensor is used to detect the position of the air diffusing paper through the water-repellent film by a change in brightness, and the diffusing paper misalignment is selected and eliminated. . That is, the image is taken with a camera from the upper surface, and the image is analyzed to quickly determine whether it is good or bad.
JP-A-1-320782

However, on the other hand, the higher output of hearing aids has required higher output of the zinc-air battery itself. For this higher output, the size of the air holes and The number is increased or the air permeability of the water repellent film is increased. The water repellent film is a polytetrafluoroethylene (PTFE) microporous film, and the air permeability and transparency of the microporous film vary depending on the thickness and porosity. The PTFE extruded sheet is completely transparent, but the air permeability increases as the porosity increases due to stretching to make the sheet breathable, but the transparency decreases and the whiteness decreases. Come on. Further, the air diffusion paper made of vinylon or mercerized pulp is white. Therefore, air diffusion paper is white, and when a water-repellent film with high air permeability is used, the water-repellent film has low transparency and becomes white. After inserting the water film, it is difficult to detect the position of the air diffusing paper through the water-repellent film by a change in light and dark, and it is difficult to select and eliminate the diffusing paper misaligned product.

  Also, instead of increasing the air permeability of the water-repellent film, it is possible to increase the output by increasing the number of air holes in the positive electrode case. This is not preferable because the unit cost increases due to an increase in mold costs and a decrease in processing speed.

  An object of the present invention is to solve the above-mentioned problems, and an object of the present invention is to provide a button-type zinc-air battery with high reliability and high output by selectively removing the diffusion paper misalignment generated in the assembly process.

In order to solve the above-described problems, the button-type zinc-air battery of the present invention includes an air diffusion paper, a water repellent film, an air electrode, and a separator, which are sequentially stacked on a positive electrode case having air holes and accommodated in the negative electrode case. A button-type zinc-air zinc battery in which the gelled zinc negative electrode is disposed to face the air electrode through the separator, and the air diffusion paper is colored using a colorant that reacts with the alkaline electrolyte and changes color. It is characterized by being.

  Even if a water repellent film with high air permeability is used by coloring the air diffusion paper, the camera is photographed from the top surface after inserting the water repellent film, and the position of the air diffusion paper through the water repellent film using the image sensor Can be detected based on changes in color tone and brightness, so that it is possible to select and eliminate batteries that have diffused paper misalignment during battery assembly. Therefore, since the diffusion paper misalignment is eliminated, a highly reliable and high output button type air zinc battery without the occurrence of leakage from the air holes caused by the misalignment of the diffusion paper can be supplied to the market.

  According to the present invention, the problem is that the air diffusion paper protrudes from the bottom recess of the positive electrode case, and one end thereof is located in the close contact portion between the positive electrode case and the water repellent film, thereby causing leakage. A stable high output button-type zinc-air battery can be provided.

  Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a cross-sectional view of a button-type zinc-air battery in this embodiment. In FIG. 1, the positive electrode case 1 has an air hole 2 in a bottom recess, and has a shape in which an upper end is an open type. An air diffusion paper 3, a water repellent film 4, an air electrode 5, and a separator 6 are sequentially stacked on the inner surface of the bottom recess of the positive electrode case 1. On the other hand, a seal tape (not shown) is stuck on the outer surface of the bottom concave portion of the positive electrode case 1 so as to close the air hole 2 when the battery is not used. By removing the seal tape from the positive electrode case 1, Oxygen enters the battery and an electromotive reaction is started. The positive electrode case 1 is made of nickel-plated iron. The air diffusion paper 3 uniformly diffuses air taken from the air holes 2 and is made of a material such as vinylon or mercerized pulp. The water repellent film 5 is made of PTFE, and prevents oxygen supply to the air electrode 5 and leakage of the electrolytic solution to the outside of the battery. The negative electrode case 7 is combined with the positive electrode case 1 to form a battery container. The inner wall surface of the negative electrode case 7 is in electrical contact with the zinc negative electrode 8 while the opening of the positive electrode case 1 is sealed. The zinc negative electrode 8 is in the form of a gel, and is prepared by blending carboxycellulose (gelling agent) and zinc powder or zinc alloy powder into an electrolytic solution composed of a 34% by mass potassium hydroxide aqueous solution. A polyamide resin insulating gasket 9 is interposed between the negative electrode case 7 and the positive electrode case 1.

  In the button-type zinc-air battery having the above structure, the air diffusion paper 3 is colored blue with indigo carmine. At this time, any color can be used as long as it can be discriminated by the image sensor, and the colorant may be any color as long as it does not impair the function of supplying the oxygen of the air diffusion paper 3, but it is blue with indigo carmine. It is preferable that the color is colored in that the difference in color tone becomes clear when photographed with a camera. Table 1 shows examples of colorants.

  The colorants in Table 2 are known as PH indicators and change color with alkaline electrolyte. By using a colorant that changes color with such an alkaline electrolyte, if the diffusion paper misalignment cannot be detected due to a malfunction of the image sensor, the water repellent film is broken and the electrolyte penetrates from the inside. When the alkaline electrolyte has permeated into the air diffusion paper 3 in the previous stage of leakage from the air hole 2 to the outside of the battery, the initial slight leakage is observed by observing the air diffusion paper 3 through the air hole 2. The liquid can be detected by a color change.

(Example)
As an example, a “PR44” button-type alkaline battery (JIS standard) having a diameter of 11.6 mm and a height of 5.4 mm was produced and evaluated as a button-type zinc-air battery having the above structure. Here, a positive electrode case 1 having four holes with a diameter of 0.5 mm was used as the air holes 2, and a PTFE microporous film having a thickness of 0.1 mm and a porosity of 20% was used as the water repellent film 4.

The material of the air diffusion paper 3 was a non-woven fabric made of vinylon having a thickness of 0.13 mm, and was used by coloring with a coloring amount of 0.2 g / m ² using a 2.5 g / l indigo carmine aqueous solution. The coloring operation was carried out by immersing 1000 m of a hoop-like diffusion paper having a width of 15 mm in an indigo carmine aqueous solution and then drying, and thereafter processing the paper into a predetermined size. In addition, the coloring method may be immersed in a coloring liquid while unwinding the hoop-like diffusion paper, dried and then wound, or the fibers of the nonwoven material may be colored in advance.

  Water is applied to the bottom recess of the positive electrode case 1, the air diffusion paper 3 is arranged and fixed, the water repellent film 4 is inserted, and then the camera is photographed from above, and the position of the air diffusion paper 3 is detected by the image sensor. Detecting the change in color tone and brightness, the air diffusion paper 3 protrudes from the concave part at the bottom of the positive electrode case, and selects the one located in the close contact part between the positive electrode case 1 and the water repellent film 4 and excludes it from the assembly process. The battery was assembled with the air diffusion paper 3 correctly disposed in the concave portion at the bottom of the positive electrode case.

(Comparative example)
A positive electrode case having four holes with a diameter of 0.5 mm is used as the air hole 2, a PTFE microporous film having a thickness of 0.1 mm and a porosity of 20% is used as the water repellent film, and an uncolored air diffusion paper is used. A battery was assembled. At this time, since the water repellent film has low permeability and the color tone is almost the same, even if it was taken with the camera from the top, it was difficult to detect the position of the air diffusion paper as a change in brightness, so it could not be detected. Batteries were assembled without sorting out the diffusion paper misalignment by the image sensor.

(Conventional example)
A positive electrode case having four holes with a diameter of 0.5 mm is used as the air hole 2, a PTFE microporous film having a thickness of 0.1 mm and a porosity of 10% is used as the water repellent film, and an uncolored air diffusion paper is used. I assembled a battery. At this time, the water repellent film is highly permeable, and even if it is not colored, the image sensor can detect the position of the air diffusion paper only by changes in light and darkness when taken with a camera from the top. The misaligned material was selected and discharged, and the battery was assembled with the air diffusion paper correctly disposed in the concave portion at the bottom of the positive electrode case.

  After assembling the batteries of Examples, Comparative Examples, and Conventional Examples, the presence or absence of liquid leakage was inspected after one week. Further, after the battery was assembled, continuous discharge was performed at a final voltage of 0.9 V at a current consumption of 2 mA for a normal hearing aid and a current consumption of 15 mA required for a high-power type hearing aid. The results are shown in Table 3.

  As shown in Table 3, while no leakage occurred in the examples of the present invention and the conventional example, leakage occurred in the comparative example. When these leaked batteries are analyzed, all of the air diffusion paper protrudes from the concave portion at the bottom of the positive electrode case and is located in the close contact portion between the positive electrode case and the water repellent film, and electrolyte leakage occurs from this portion. It was. In addition, at a current consumption of 2 mA of a normal hearing aid, discharge was stable under any conditions, and there was no difference in discharge time. However, at a current consumption of 15 mA required for a high-power type hearing aid, discharge was stably performed in the examples and comparative examples, but the porosity of the water-repellent film was low in the conventional example, which is necessary for battery reaction. Discharge was impossible due to insufficient oxygen permeation.

  INDUSTRIAL APPLICABILITY The present invention is used for an alkaline battery using an air electrode as a positive electrode and gelled zinc as a negative electrode, that is, a so-called air zinc battery. Highly reliable button-type zinc-air battery without leakage.

Sectional drawing which shows the structure of the button-type zinc-air battery in one Example of this surface.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Positive electrode case 2 Air hole 3 Air diffusion paper 4 Water-repellent film 5 Air electrode 6 Separator 7 Negative electrode case 8 Negative electrode 9 Insulation gasket

Claims (2)

An air diffusion paper, a water repellent film, an air electrode, and a separator are sequentially stacked on a positive electrode case having an air hole, and a gelled zinc negative electrode accommodated in the negative electrode case is attached to the air electrode via the separator. A button-type zinc-air battery that is opposed to each other, wherein the air diffusion paper is colored with a colorant that reacts with an alkaline electrolyte and changes color . The button-type zinc-air battery according to claim 1, wherein the colorant is indigo carmine.

Images