JPS58115756A - Silver oxide battery - Google Patents

Abstract

PURPOSE:To increase the preservation performance of a silver oxide battery by installing a separator which has on its positive electrode side a macromolecular film prepared by graft-copolymerizing monomers which contain sulfides and have hydrophilic groups, and has on its negative electrode side a porous macromolecular film which contains calcium hydroxide and has specific hole diameters. CONSTITUTION:A silver oxide battery is constituted by installing a positive active material 2 principally consisting of silver oxide, a separator 3 and a negative active material 4 principally consisting of zinc into a positive can 1 also working as a positive terminal, and sealed with both a negative can 5 also working as a negative terminal and a gasket 6. A separator 3 is composed of a macromolecular film (A), a regenerated cellulose film (B) and a porous macromolecular film (C). The film (A) is prepared by graft-copolymerizing monomers which contain sulfides and have hydrophilic groups. The film (C) is a porous film which contains calcium hydroxide and has a mean hole diameter of 0.01-100mum. By the means mentioned above, the long-period preservation performance of the battery can be increased by preventing any internal short-circuit which might be caused by argenate ions or zincate ions.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement of a silver oxide battery that prevents deterioration of storage performance due to long-term storage.

Conventionally, separators used in silver oxide batteries have a hydrophilic polymer membrane with strong oxidation resistance placed on the anode side, and a liquid retention material such as nonwoven fabric or microporous polymer membrane with excellent liquid retention properties placed on the cathode side. It had a six-layer structure with a regenerated cellulose membrane in the middle. In the separator having the above configuration, silver acid ions eluted from the anode active material are reduced by the regenerated cellulose membrane and captured as metallic silver in the regenerated cellulose membrane, thereby preventing short circuits due to silver growth. However, because the battery dimensions are limited, the size of the cellulose membrane itself is also limited, which naturally limits the silver capture performance, and in fact, some batteries that have been stored for a long time are short-circuited due to silver growth. There was something I had to do. In addition, on the cathode side, zincate ions are eluted from the cathode active material, which is reduced and precipitated, grows in the liquid retaining material, and reaches the anode side, causing defects that cause short circuits. Ta.

Due to the above reasons, the long-term storage performance of silver oxide batteries has been problematic.

The present invention solves the above-mentioned problems, and will be explained in detail with reference to Examples below.

In the separator used in the present invention, in the membranes arranged on the anode side and the cathode side, a polymer membrane containing sulfide and graft copolymerized with a monomer having a hydrophilic group is arranged on the anode side, and a polymer membrane is arranged on the cathode side. contains calcium hydroxide.
A porous polymer membrane of 1 μm to 100 μm is arranged.

The above-mentioned sulfides capture silver acid ions as silver sulfide, and -
Calcium hydroxide has the function of capturing zincate ions, and therefore, the sulfide may be either organic or inorganic, but zinc sulfide, calcium sulfide, magnesium sulfide, etc. are preferred. Further, as the polymer membrane to be graft copolymerized, olefin resins such as polyethylene and polypropylene, which are easily graft copolymerized, are preferable. These resins are made by kneading sulfide into a homogeneous compound before forming the film, and then forming it into a film. Before or after forming the film, a monomer having a hydrophilic group, such as acrylic acid or methacrylic acid, is used to impart hydrophilicity. Graft copolymerize with acids, etc. The graft copolymerization in the present invention may be carried out by a method using a melting medium or by a method using ionizing radiation, but the latter is preferable when the graft copolymerization is carried out uniformly in a solid-phase polymer. On the other hand, the porous polymer membrane has the function of a liquid retaining material, with pores formed by calcium hydroxide and a wall of polymer material, pores formed only by polymer, and pores formed by calcium hydroxide alone. It has formed pores. The polymer membrane material is preferably polystyrene, polysulfone, polyvinyl chloride, etc., and the average pore size is appropriately small so that zincate ions moving into the membrane can easily collide, and appropriately large so that the electrical resistance does not become high. It needs to be made into something.

As a result of various experiments, the average pore diameter was varied from 0.01 μm to 100 μm.
μm range is suitable, especially 0.1μm to 10μm
was highly effective.

Next, a silver oxide battery using the above-described separator will be explained with reference to the drawings. 1 is an anode can that also serves as an anode terminal, 2
is an anode active material mainly composed of silver oxide, Ro is a separator, 4
5 is a cathode can which also serves as a cathode terminal, and 6 is a gasket. The structure of the separator B according to the present invention is that A is a polymer membrane graft-copolymerized with a monomer containing a sulfide and having a hydrophilic group according to the present invention, B is a regenerated cellulose membrane, and C is a water-based membrane according to the present invention. Consists of a porous polymer membrane containing calcium oxide. To explain a specific example, the polymer membrane A is made by processing a compound consisting of 50 parts of zinc sulfide and 50 parts of low-density polyethylene resin into a sheet with a thickness of 60 μm using an inflation method, and applying an acceleration voltage of 50 Kev.

An electron beam of 50 Mrad was irradiated with an accelerating current of 5 mA. This sheet was mixed with 50 parts of acrylic acid, 50 parts of water, Mohr's salt,
259 (25° C.) for 5 hours.

The thickness of the sheet obtained after further washing with water was 55.1 m,
The electrical resistance was 120 mΩ-d/sheet (measured in a 25% KOH solution at 25° C.), and this film was referred to as a zinc sulfide-containing graft film. Polymer porous membrane C consists of 60 parts by weight of calcium hydroxide, 15 parts by weight of polystyrene, and 6 parts by weight of tetrahydrofuran.
Next, 24 parts by weight of isopropyl alcohol was added to obtain a homogeneous mixed solution, and this mixed solution was impregnated and coated on a vinylon nonwoven fabric (trade name: Papillon BFHNo) and dried. The thickness of this sheet is 60μm and the electrical resistance is 90I? IΩ·−7 sheets, and the average pore diameter was 2 μm. This film is called a calcium styrene film.

Between the above two membranes is a cellophane membrane (product name: DuPont P).
The separator 5 is what holds the UDO 154) in between.

In addition, as a comparative example, the membrane disposed on the anode side was composed of 7 graft membranes with a thickness of 65 μm and an electrical resistance of 100 mΩ, which did not contain sulfide, and the membrane disposed on the cathode side was 60 μm thick and did not contain calcium hydroxide. Batteries a and b were manufactured using a styrene membrane having an electrical resistance of 80 Ω·−7 and an average pore diameter of 5 pm, or a membrane consisting of a vinylon nonwoven fabric.

Regarding the above batteries, immediately after manufacture and after high temperature storage,
Discharge to a load resistance of 30Ω at 24℃, final voltage 1.4V
The table below shows the capacity deterioration ratio when the discharge capacity of the battery immediately after manufacture is taken as 100. Note that the values are values when stored in an atmosphere at a temperature of 60° C. and a humidity of 90%.

Table (Note) Parameter of the battery of the present invention: IEEI/Il zinc-containing 7 membrane + styrene M/e 41 pond a O separator: ■/Gut membrane 17/% + styrene 1x/θtab separator: /graft membrane 17-hole + vinylon nonwoven fabric/e As shown in the above results, the battery according to the present invention suppresses the capacity decrease after storage compared to batteries a and b. , which is a significant improvement.

In the above example, the sulfide-containing polymer film was brought into direct contact with the anode active material, but the same effect can be obtained even if a separator made of other material is placed between them. It is something that can be done.

As described above, the present invention uses a silver oxide battery using a polymer membrane containing sulfide on the anode side, a porous polymer membrane containing calcium hydroxide on the cathode side, and a separator with cellophane arranged in the center. It prevents internal short circuits caused by silverate ions or zincate ions and improves long-term storage performance, and its industrial value is great.

[Brief explanation of the drawing]

The drawing is a sectional view of a silver oxide battery according to an embodiment of the present invention. 2. Anode active material 5. Separator 4. Cathode active material Applicant Yuasa Battery Co., Ltd.

Claims (1)

[Claims] A polymer membrane containing sulfide on the silver oxide anode active material side and graft-copolymerized with heptamer having a hydrophilic group is used, and a calcium hydroxide-containing polymer membrane with an average pore size of 0 on the zinc cathode active material side.
．． A silver oxide battery using a separator consisting of multiple layers in which porous polymer membranes of 0.01 to 100 μm are arranged.