JP4329682B2 - 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.

  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 diffused widely with air diffusion paper placed in the bottom recess of the positive electrode case, to the water repellent film and the air electrode Supplied with.

  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 a predetermined position, it is not completely stored in the bottom concave portion of the positive electrode case, and a part of the air diffusion paper protrudes from the bottom concave portion (hereinafter referred to as diffusion paper). 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 adhesion 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 the battery is assembled, but may also occur due to the passage of time or when the battery is used and discharged. Since 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 the diffusion paper displacement does not occur after the water repellent film is inserted, the above-described problem does not occur if the diffusion paper displacement is eliminated after the water repellent film is inserted in the process of battery assembly. Therefore, an image sensor is used to detect the position of the air diffusion paper through the water repellent film after insertion of the water repellent film, and to select and eliminate the diffusion paper misalignment (see, for example, Patent Document 1). ).
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 microporous film of polytetrafluoroethylene resin (PTFE), and the air permeability and the transparency of the microporous film vary depending on the thickness and the porosity. The extruded sheet of PTFE is completely transparent, but with increasing porosity due to stretching to give the sheet breathability,
Air permeability increases, but transparency decreases and turns white. Further, the air diffusion paper made of vinylon or mercerized pulp is white. Therefore, when the air diffusing paper and the water repellent film are both white and a water repellent film having a large air permeability is used, the water repellent film has low transparency. After inserting the water film, it was difficult to detect the position of the air diffusing paper through the water repellent film and eliminate the diffusing paper misalignment.

  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.

  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 battery in which the gelled zinc negative electrode is disposed to face the air electrode via a separator, wherein the air diffusion paper is dyed with a fluorescent dye.

  When air diffusion paper is dyed with a fluorescent dye, the fluorescent dye itself emits light by blocking natural light and irradiating ultraviolet rays when detecting the diffusion of paper, and even if a water repellent film with high air permeability is used, the water repellent film After insertion, it becomes easy to detect the position of the air diffusing paper through the water-repellent film using an image sensor. This makes it possible to select and eliminate the battery in which the diffusing paper misalignment occurred 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. This is because the fluorescent dye utilizes the property of emitting light when exposed to ultraviolet rays, and the reason why the natural light is blocked is to increase the contrast of the fluorescent dye.

  According to the present invention, the problem that the air diffusion paper protrudes from the concave portion at the bottom 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 to solve the liquid and stabilize the quality. 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, a 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 laminated on the inner surface of the bottom recess of the positive electrode case 1. On the other hand, a seal tape (not shown) is attached to 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 4 is made of polytetrafluoroethylene (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 mass% potassium hydroxide aqueous solution. In the negative electrode case 7, a polyamide resin-based insulating gasket 9 is interposed between the portions to be sealed with the positive electrode case 1.

  In the air zinc battery having the above structure, the air diffusion paper 3 was dyed with a fluorescent dye. At this time, the color emitted by ultraviolet rays may be any color as long as it can be discriminated by the image sensor, and the fluorescent dye can be any color as long as it does not impair the function of supplying oxygen of the air diffusion paper 3. Those that are good and emit strong light are preferred. Moreover, the color which can be seen with natural light may be any color and may be colorless.

Example 1
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.

  The material of the air diffusion paper 3 is a non-woven fabric made of vinylon having a thickness of 0.13 mm, and is a fluorescent whitening agent that is colorless under natural light as a fluorescent dye (trade name: Keicol BULC, chemical composition 4,4′-bistriazinylaminostilbene- 2,2 ′ disulfonic acid derivative (manufactured by Nippon Soda Co., Ltd.) was used. The dyeing operation was carried out by immersing 1000 m of a hoop-shaped diffusion paper having a width of 15 mm in a fluorescent whitening aqueous solution and then drying, and then processing the paper into a predetermined size. The dyeing method may be immersed in the dyeing solution while unwinding the hoop-like diffusion paper, dried and wound up, or may be pre-dyed on the fibers of the nonwoven material.

  Water is applied to the bottom concave portion of the positive electrode case 1, the air diffusion paper 3 is arranged and fixed, the water repellent film 4 is inserted, natural light is blocked, ultraviolet light is irradiated using black light, and an image sensor is used. The position of the air diffusion paper 3 is detected, the air diffusion paper 3 protrudes from the concave portion at the bottom of the positive electrode case, and the one located at the close contact portion between the positive electrode case 1 and the water repellent film 4 is selected and excluded from the assembly process. And assembled the battery.

(Comparative Example 1)
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 the air is not dyed with a fluorescent dye. A battery was assembled using diffusion paper. At this time, since the permeability of the water repellent film was low, and the position of the air diffusion paper could not be detected by the image sensor, the battery was assembled without sorting out the diffusion paper misalignment by the image sensor.

(Comparative Example 2)
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 the air is not dyed with a fluorescent dye. The battery was assembled using diffusion paper. At this time, the water-repellent film is highly permeable, and the position of the air diffusion paper can be detected by the image sensor even under natural light. Assembled the battery.

  After assembling the batteries of Examples, Comparative Example 1 and Comparative Example 2, 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 20 mA required for a high-power type hearing aid. The results are shown in Table 1.

  Table 1 shows that no leakage occurred in the batteries of Examples and Comparative Example 2 of the present invention, whereas leakage occurred in the battery of Comparative Example 1. When these leaked batteries are analyzed, all of the air diffusion paper protrudes from the concave part at the bottom of the positive electrode case and is located in the close contact part between the positive electrode case and the water repellent film, and electrolyte leakage occurs from this part. 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 20 mA required for a high-power type hearing aid, the battery of the example and the comparative example 1 was stably discharged, but the battery of the comparative example 2 had a low porosity of the water repellent film, Discharge was impossible due to insufficient oxygen permeation required for the battery reaction.

  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. High-reliability batteries without leakage can be supplied.

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

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 (1)

Air diffusion paper, water repellent film, air electrode, and separator are sequentially stacked on the positive electrode case with air holes, and the gelled zinc negative electrode housed in the negative electrode case is placed opposite to the air electrode through the separator. Button-type zinc-air battery, wherein the air diffusion paper is dyed with a fluorescent dye.

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