JPS62126547A - Alkaline battery - Google Patents

Abstract

PURPOSE:To suppress increase in internal resistance by forming a thin layer comprising a mixture of a gelling agent which hardly reduces a cathode active material and fine conductive powder on the surface, which is in contact with a cathode active material, of a separator between the cathode active material and an anode active material. CONSTITUTION:A thin layer 5 comprising a mixture of a gelling agent which hardly reduces a cathode active material, such as carbonyl polymer, and fine conductive powder is formed on the surface which is in contact with a cathode active material 2, of a separator 4 between the cathode active material 2 and an anode active material 8. The separator 4 is placed on the cathode active material 2 accommodated in a cathode can 1, and an electrolyte holding material 6 is placed thereon, then the negative active material 8 is combined with them to form an alkaline battery using silver oxide as the cathode. Thereby, generation of wrinkles in the separator 4 in a small battery in which electrolyte necessary for gelling of the gelling agent is difficult to contain is prevented. Therefore, increase in internal resistance is prevented and high rate discharge performance is increased.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an alkaline battery using silver oxide, mercury oxide, manganese dioxide, etc. as an anode active material, and in particular a gel on the side of the isolation membrane in contact with the anode active material. The present invention relates to an alkaline battery in which a thin film layer is formed of a mixture of a curing agent and a conductive fine powder.

[Conventional technology]

Conventional alkaline batteries use an anode can made of nickel-plated iron, into which a molded anode mixture and a metal pellet ring are sequentially inserted and filled under pressure, and electrolysis is applied to the anode mixture surface. liquid was injected. Furthermore, in order to suppress drying and increase in internal resistance between the anode active material and the isolation membrane,
A liquid holding material was placed on the anode mixture surface, or an electrolyte holding material made of a separator membrane and a nonwoven fabric was placed and inserted after dropping a gel electrolyte. To assemble such a battery, a nylon backing is molded onto a cathode can made of a three-layer copper-stainless-nickel clad material, and a gelling agent, such as carboxyvinyl, is applied inside the cathode can.

After filling the cathode active material made of a mixture of alkali polymer, caustic alkaline electrolyte, and frozen zinc powder and fitting it above the electrolyte holding material, press the opening of the anode can inward and bend it. By sealing the opening, the alkaline battery was completed.

[Problem that the invention seeks to solve]

However, in conventional batteries, when placing a punched electrolyte holding material on the anode mixture surface, the holding material must be made of a material that is easily wetted by the electrolyte, so cellulose fiber is used as the material. (Rayo 7, Kotton) was often used. However, this cellulose fiber has a problem in that it is oxidized by silver oxide and the silver oxide is consumed. Also,
When dropping gel electrolyte onto the anode mixture surface, if too much gel electrolyte is dropped, the gel electrolyte may be Liquid sometimes leaked from between the nylon backing and the anode can. In addition, the gel-like electrolyte has stringability, so a string is drawn between the tip of the dripping nozzle and the mixture surface, and this adheres to the inner wall of the anode can and later becomes a leakage path for the electrolyte. There was a risk of leakage. In order to solve the above problems, the present inventors formed a thin film layer of a gelling agent on the side of the isolation membrane in contact with the anode active material by reducing the active material.
Although we first tried to prevent an increase in internal resistance due to drying between the anode mixture and the isolation membrane and wrinkles in the isolation membrane,
(Japanese Patent Laid-Open No. 60-160561) As batteries have rapidly become smaller and thinner in recent years, it has become necessary to increase the amount of electrolyte to completely gel the thin layer of gelling agent formed on the surface of the isolation membrane.
In addition to the electrolyte required for the discharge reaction of positive and negative active materials, some batteries have appeared that are difficult to incorporate into the battery. , a problem occurred in that the internal resistance increased due to the occurrence of wrinkles in the isolation membrane.

In order to solve these problems, as a result of repeated studies, we solved the above drawbacks by forming a thin film made of a mixture of gelling agent and conductive fine powder on the side of the isolation membrane that comes into contact with the anode mixture. I found out what I can do.

[Failure to solve the problem]

The method for forming a thin film of a mixture of a gelling agent and a conductive fine powder on an isolation membrane was as follows.

5wt% carboxyvinyl polymer and average particle size 2μm
1. A mixture of 5 wt% carbon powder with a maximum particle size of 4 μm and 90 wL% ethyl alcohol is applied to one side of the separator membrane and dried. The maximum particle size is 4 μm.

〔Example〕

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

In the figure, reference numeral 1 denotes an anode can made of nickel-plated iron, and the bottom of this anode can 1 is filled with an anode active material 2 under pressure. Stainless steel pellets 3 are press-fitted between the inner wall of the anode can 1 and the anode active material 2.

Reference numeral 4 denotes a separator membrane, and is provided with a thin film layer 5 made of a mixture of a gelling agent such as carboxyvinyl polymer and conductive carbon powder, which is difficult to reduce the anode active material 2 of the separator membrane 4 .

On the other hand, the upper part of the isolation membrane 4 is made of polypropylene.

An electrolyte holding material 6 made of non-woven fabric or woven fabric such as polyamide is provided. 7 is a cathode cap made of a three-layer clad material of copper-stainless steel-nickel, and inside thereof is a gel-like cathode active material 8 made of a mixture of carboxyvinyl polymer, an electrolyte such as caustic soda, and frozen zinc powder.
is placed on top of the electrolyte holding material 6.

A backing 9 made of plastic such as polyethylene or polyamide is interposed between the peripheral edge of the cathode cap 7 and the anode can, and a sealed opening is provided by bending the open end of the anode can 1. . In a battery having such a configuration, a thin film layer 5 made of a gelling agent and conductive carbon powder that is difficult to reduce the active material 2 is formed on the side of the isolation membrane 4 that is in contact with the anode active material 2, so that the cathode side The mixed gel and anode mixture absorb an appropriate amount of the stain-resolving solution and form a gel, retaining the electrolyte between the separator membrane and the anode mixture, and combining the ionic conductivity of the electrolyte and the electronic conductivity of the conductive carbon powder. , it is possible to maintain good electrical conductivity.

Therefore, in a small and thin battery, even if the gelling agent is not sufficiently gelled, the internal resistance of the battery does not increase, and the large current discharge characteristics can be improved.

Height 1.6 mm, outer diameter 11.0 mm with the configuration of this invention
The table below shows the results of a comparison of the characteristics of AM's silver oxide battery and a conventional battery of the same size that does not contain conductive carbon powder and has a thin film layer made of only a gelling agent.

That is, the battery (A) of the present invention is one in which carboxyvinyl bolimate conductive carbon powder is formed on the side of the isolation membrane in contact with the anode mixture, and the battery (B) with the conventional configuration is as follows:
A thin film of carboxyl vinyl polymer is formed on the side of the isolation membrane that comes into contact with the anode mixture. 1 each of these
00 pieces were assembled and the large current discharge characteristics at low temperature were compared.

Table As is clear from this table, compared to the conventional product, the product of the present invention has an average value of 0.02V higher in closing voltage after 5 seconds at 100Ω at -10" OK, and a variation (maximum and minimum values). When the difference in o and oiv is small, the performance is clearly improved and the large current characteristics can be improved.

〔Effect of the invention〕

As described above, according to the present invention, by forming a thin film layer of a gelling agent that is difficult to reduce the active material and a conductive fine powder on the side of the isolation membrane in contact with the anode active material, the gelling agent can be sufficiently applied. In small and thin batteries where it is difficult to contain enough electrolyte to gel, it is possible to prevent an increase in internal resistance due to wrinkles between the anode mixture and the separator, and improve high current discharge performance. Alkaline batteries can be provided.

Note that the present invention is not limited to the above-mentioned embodiments, and can be implemented with various modifications without changing the gist.

[Brief explanation of drawings]

The drawing is a vertical sectional view showing a schematic configuration of an embodiment of the present invention. 2...Anode active material 4.Isolation membrane 5...Thin film layer made of a mixture of gelling agent and conductive fine powder

Claims (1)

[Claims] In an alkaline battery having a structure in which an anode active material and a cathode active material are filled in a metal container with an isolation membrane interposed therebetween, a gelling agent that makes it difficult to reduce the active material and a conductive material are provided on the side of the isolation membrane that is in contact with the anode active material. An alkaline battery characterized by forming a thin film layer made of a mixture of fine powders.