JP2008147104A - Button type alkaline battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a button type alkaline battery having high capacity, and improving sealing performance. <P>SOLUTION: This button type alkaline battery has a structure where an end of a negative electrode case doubling as a negative electrode collector is covered with one or more kinds of metals selected from Zn, Sn and Cu, or an alloy of them. In the button type alkaline battery, the inside volume thereof is increased by using a structure without having a fold by changing an end surface structure of a negative electrode case, and an electrolyte leakage characteristic in discharge or storage is improved. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a button-type alkaline battery, and more particularly to a button-type alkaline battery with excellent safety and high performance that suppresses the occurrence of liquid leakage and prevents performance deterioration during storage.

  An air battery represented by an air zinc battery is a battery that directly takes in oxygen from the air and uses it as a positive electrode active material. Therefore, there is no need to pack the positive electrode active material in the battery in advance. If so, it is possible to pack more negative electrode active materials. Therefore, the air battery has a feature that a large capacity can be obtained as compared with an alkaline manganese battery, a silver oxide battery, or the like in which another positive electrode active material must be secured in the battery. In particular, button-type zinc-air batteries are used in hearing aids as an alternative to conventional button-type mercury batteries, and coin-type zinc-air batteries are used in devices such as pagers, and the demand is increasing.

Also, in recent years, with increasing interest in environmental issues and the development of other applications, measures for portable devices are being studied. In order to cope with this type of equipment, it is necessary to increase the battery capacity as well as for large currents and thinning. Conventionally, as disclosed in Patent Document 1, the end face structure of the negative electrode container is a folded structure, and the liquid leakage characteristics can be maintained by caulking the outer wall portion of the positive electrode container inward.
JP-A-7-302581

  However, in order to increase the battery capacity, it is essential to reduce the thickness of various components. As one countermeasure, the internal volume of the negative electrode case, which also serves as the negative electrode current collector, is changed by using a structure that does not turn back. When enlarging the battery, the folded part of the negative electrode case that also serves as the negative electrode current collector and the inner wall of the sealing gasket are lost. There is a high possibility that the problem will occur. In addition, if the end structure of the negative electrode case that also serves as the negative electrode current collector is changed to a structure that does not fold back, the end becomes easier to come into contact with the electrolyte, and the metal at the end reacts with the electrolyte to generate gas. By doing so, there is a high possibility that a problem that the internal pressure of the battery rises and the leakage characteristics of the air holes also deteriorates will occur.

  The present invention has been made to solve the above-mentioned problems, and its object is to provide a button-type alkaline battery that can be increased in capacity by using the above-described means and that has improved sealing performance.

  In order to solve the above-mentioned problems, the present invention covers the end of a negative electrode case that also serves as a negative electrode current collector with one or more metals selected from Zn, Sn, Cu, or alloys thereof. It is possible to provide a button-type alkaline battery with improved leakage characteristics during discharge or storage.

  In other words, by suppressing the reactivity between the negative electrode active material and the negative electrode case termination that also serves as the negative electrode current collector, gas generation is prevented, and leakage of the electrolyte from the inside is suppressed. In comparison, the occurrence probability of liquid leakage can be suppressed to a low level.

  ADVANTAGE OF THE INVENTION According to this invention, while improving the end surface structure of a negative electrode container and aiming at expansion of an internal volume using the structure without a folding | turning, a high performance button-type alkaline battery without a liquid leakage and gas generation can be provided. .

  In addition, the present invention can also be applied to the inside of the battery from the contact interface between the negative electrode case side wall that also serves as the negative electrode current collector and the sealing gasket, and between the positive electrode container inner wall and the sealing gasket, even in various environments where the battery is used or stored. Suppresses leakage of the electrolyte that constitutes the negative electrode active material, gas generation from the air holes of the positive electrode container, and leakage of the electrolyte, and is resistant to leakage under severe conditions of high temperature and high humidity as well as normal storage environments. An air battery with improved liquid characteristics can be provided.

FIG. 1 is a cross-sectional view of an air battery (PR41 type) which is an embodiment of the present invention.
In FIG. 1, reference numeral 1 denotes a positive electrode container (positive electrode case) having an air hole 2 on a bottom wall surface and one end being an open type. In the positive electrode container 1, a positive electrode catalyst layer 6 and a separator 7, which are press-molded on a bottom wall surface of the air diffusion paper 3, a water repellent film 4, and a metal current collector 5 as a support, are sequentially laminated. The water repellent layer 8 is pressure-bonded to the lower surface of the positive electrode catalyst layer 6. These constitute the positive electrode assembly 9.

  The air diffusion paper 3 is made of kraft paper, and the water repellent film 4 is made of polytetrafluoroethylene (PTFE). The positive electrode catalyst layer 6 is obtained by mixing activated carbon, manganese oxide, graphite and PTFE powder as a conductive material, and press-molding them into a sheet shape, and the separator 7 is made of a polypropylene microporous film.

  Reference numeral 10 denotes a gelled zinc negative electrode disposed on the separator 7 of the positive electrode assembly 9. This gelled zinc negative electrode 10 is mainly composed of a polymer compound in an electrolytic solution composed of about 30 to 40 wt% potassium hydroxide aqueous solution. It consists of a gelling agent as a component and a gelled zinc negative electrode mixture prepared by blending zinc powder or zinc alloy powder. Reference numeral 12 denotes an insulating sealing gasket interposed between the negative electrode case 11 and the sealed portion of the positive electrode container 1. The negative electrode case 11 is made of a three-layer clad made of nickel, stainless steel and copper, and the insulating sealing gasket 12 is of a polyamide resin type.

  By the way, the air diffusion paper 3 has a function of allowing the air taken in from the air holes 2 to be distributed as uniformly as possible not only in the vicinity of the air holes on the water-repellent surface arranged across the space.

Examples of the present invention and comparative examples will be described below.
(Example 1)
A three-layer clad material of nickel-stainless-copper was formed into a negative electrode case 11 that also served as a negative electrode current collector for a PR41 type zinc-air battery as shown in FIG. 1, and the end portion was covered with Zn. On the other hand, a zinc alloy negative electrode 10 was prepared by stirring and mixing zinc alloy powder, a 35 wt% aqueous potassium hydroxide solution, and polyacrylic acid. Using this negative electrode case 11 and the gelled zinc negative electrode 10, a PR41 type zinc-air battery as shown in FIG. 1 was prepared.

(Example 2)
A three-layer clad material of nickel-stainless-copper was formed into a negative electrode case 11 that also served as a negative electrode current collector for a PR41 type zinc-air battery as shown in FIG. 1, and the end portion was covered with Sn. On the other hand, a zinc alloy powder, a 35 wt% potassium hydroxide aqueous solution, and polyacrylic acid were mixed with stirring to prepare a gelled zinc negative electrode 10. Using this negative electrode case 11 and the gelled zinc negative electrode 10, a PR41 type zinc-air battery as shown in FIG. 1 was prepared.

(Example 3)
A nickel-stainless-copper three-layer clad material was formed into a negative electrode case 11 that also served as a negative electrode current collector for a PR41 type zinc-air battery as shown in FIG. 1, and the ends were covered with Cu. On the other hand, a zinc alloy powder, a 35 wt% potassium hydroxide aqueous solution, and polyacrylic acid were mixed with stirring to prepare a gelled zinc negative electrode 10. Using this negative electrode case 11 and the gelled zinc negative electrode 10, a PR41 type zinc-air battery as shown in FIG. 1 was prepared.

(Comparative Example 1)
A nickel-stainless-copper three-layer clad material was formed into a negative electrode case 11 serving also as a negative electrode current collector for a PR41 type zinc-air battery as shown in FIG. On the other hand, a zinc alloy negative electrode was prepared by stirring and mixing zinc alloy powder, 35% by weight potassium hydroxide aqueous solution and polyacrylic acid. Using this negative electrode case 11 and the gelled zinc negative electrode 10, a PR41 type zinc-air battery as shown in FIG. 1 was prepared.

The total battery height, open circuit voltage, and internal resistance of each of the batteries of Examples and Comparative Examples prepared as described above were measured. Moreover, 1.5 kΩ continuous discharge capacity was measured, and the discharge performance of the air battery of the present invention was investigated. Furthermore, 20 batteries after undischarged and discharged evaluation were stored for 30 days at 45 ° C. with a seal tape attached, and then the leakage from the air holes and the state of gas generation were visually inspected. Table 1 shows the results of these tests.

  As is apparent from Table 1, the characteristics of the batteries of Examples 1 to 3 subjected to the coating treatment were good, and the battery not subjected to the coating treatment of Comparative Example 1 was confirmed to have a large number of leakages and gas generation. It was.

  As described above, leakage and gas generation can be suppressed by performing the processing as in the above embodiments.

  In addition, this invention is not limited by the said Example, It is this invention about elements, such as a zinc alloy powder, a gelatinizer, electrolyte solution concentration, a positive electrode catalyst, and a negative electrode case material, which do not affect this invention directly. Changes may be made without departing from the scope of Moreover, although the battery used for the Example and the comparative example is an air zinc battery, it can apply to all the button type batteries which used the negative electrode case which served as the negative electrode collector.

Sectional drawing of the air battery used by the Example and comparative example of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Positive electrode container (positive electrode case), 2 ... Air hole, 3 ... Air diffusion paper, 4 ... Water-repellent film, 5 ... Positive electrode collector, 6 ... Positive electrode catalyst layer, 7 ... Separator, 8 ... Water-repellent layer, 9 ... positive electrode assembly, 10 ... gelled zinc negative electrode, 11 ... negative electrode case, 12 ... insulating sealing gasket.

Claims (2)

  In a button-type alkaline battery in which a zinc-like zinc negative electrode composed of a zinc alloy powder, an alkaline electrolyte and a gelling agent is housed in a negative electrode case that also serves as a negative electrode current collector, the end of the negative electrode case is made of metal A button-type alkaline battery characterized by being coated with an alloy thereof.   2. The button-type alkaline battery according to claim 1, wherein the material covering the end of the negative electrode case that also serves as the negative electrode current collector is one or more metals selected from Zn, Sn, Cu, or alloys thereof. A button-type alkaline battery characterized by being.

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