JPH0670155U - Organic electrolyte secondary battery - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide an organic electrolyte secondary battery having an open / close type safety valve. [Construction] It has a safety valve in which a valve body made of rubber is tightened with a cap. On the surface of the valve body made of rubber, a thin metal layer having a soft property against organic electrolyte is formed.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to an organic electrolyte secondary battery having a safety valve that opens when the battery internal pressure rises and closes when the battery internal pressure falls.

[0002]

[Prior art]

 Conventional aqueous solution batteries, such as sealed nickel-cadmium batteries, generally have a safety valve (hereinafter referred to as an open-close type safety valve) that opens when the battery internal pressure rises and closes when the battery internal pressure falls. There was (Actual Kaihei No. 62-1369). On the other hand, in organic electrolyte batteries, it is common to attach a safety valve (hereinafter referred to as a burst type safety valve) that opens when the internal pressure of the battery rises and does not close once it opens. -311558, JP-A-1-309254, JP-A-1-309253, and JP-A-2-284350).

[0003]

[Problems to be solved by the device]

 The organic electrolyte secondary battery equipped with a burst type safety valve has a drawback that once the safety valve is activated, the battery cannot be used again. This was because water in the air was mixed into the organic electrolytic solution through the open gas discharge port, and the organic electrolytic solution was evaporated / dissipated from the battery.

The material of the valve body of the on-off safety valve used for the battery is generally rubber, which is an elastic body. Rubber has a large water vapor transmission rate, a large organic electrolyte transmission rate, and swells with organic solvents.Therefore, use an open / close safety valve with a valve element made of rubber for the organic electrolyte secondary battery. I couldn't.

That is, (1) Water vapor enters the battery to deteriorate the active material of the organic electrolyte secondary battery. (2) It is dangerous because the invading water is decomposed to generate hydrogen and oxygen during charging. (3) When the rubber valve body absorbs the organic solvent and swells, the rubber elasticity becomes weak, the contact surface pressure of the rubber valve body with respect to the battery container becomes small, water vapor penetrates through the contact surface, and the organic solvent escapes. It will be easier. There was such a problem.

[0006]

[Means for Solving the Problems]

 The present invention uses an opening / closing safety valve in which a thin metal layer is formed on the rubber surface of a rubber valve body (hereinafter referred to as a rubber valve body) for an organic electrolyte secondary battery. Thin metal layers such as gold, silver or aluminum are impermeable to water vapor and organic solvents. Further, even if a thin layer of soft metal such as gold, silver or aluminum is formed on the rubber valve body, the rubber elasticity of the rubber valve body is not impaired. As the metal of the thin metal layer formed on the surface of the rubber valve body, any metal may be used as long as it is soft and resistant to the organic electrolyte, and tin, lead, etc. can be used in addition to gold, silver and aluminum. The thickness of the thin metal layer is preferably about 0.2 μm to 20 μm. If it is less than 0.2 μm, water vapor and organic solvent may permeate due to pinholes, and if it is more than 20 μm, rubber elasticity may be impaired. As a method for forming the thin metal layer, there are a vacuum vapor deposition method, a sputtering method, an electroless plating method and the like.

Examples of the rubber used for the rubber valve body include nitrile rubber, acrylic rubber, chloroprene rubber, chlorosulfonated polyethylene, epichlorohydrin rubber, butyl rubber, and fluororubber.

The opening / closing safety valve may be attached at any position in the battery container, but the surface contacting the rubber valve body is preferably a flat surface, and the surface of the rubber valve body contacting the battery container is also preferably a flat surface. This is because if they are flat surfaces, the contact surface will be wider and it will be less likely that water vapor will invade through the contact surface and that the organic solvent will not leak when the on-off safety valve is closed. It is desirable that both surfaces where the rubber valve body and the battery container come into contact be as smooth as possible.

If the entire surface of the rubber valve body is covered with a thin metal layer, the rubber will not be deteriorated by oxygen gas, ultraviolet rays, organic solvents, etc., so that the rubber elasticity does not change and the rubber valve body can be used as a battery container. The contact pressure against it does not change either.

[0010]

[Action]

The water vapor transmission rate of rubber varies depending on the type of rubber. Torr · L · cm (cm ² · sec · atm) ⁻¹ , nitrile rubber is 7.3 × 10 ⁻⁷ , chloroprene rubber is 8.8 × 10 ⁻⁷ , butyl rubber Is 7.7 × 10 ^-8 , but the water vapor permeability of the metal is substantially zero. Further, rubber has a poor resistance to organic electrolytes, and when it comes into contact with an organic electrolyte, rubbers permeate an organic solvent, swell, and dissolve, but metals such as gold, silver, and aluminum do not have such properties. Therefore, when a thin metal layer is formed on at least the plane of the rubber valve body that is in contact with the organic electrolyte, water vapor does not penetrate through the rubber valve body and the organic solvent does not escape.

The hardness of metal is measured by various test methods. When expressed in Brinell hardness, gold is 25, silver is 26, aluminum (soft) is 23, copper is 80, zinc is 91, and steel is 200. Is. As the metal of the thin metal layer formed on the rubber valve body, a soft and easy-to-extend metal that is easily deformed according to the unevenness of the surface of the battery container in contact is preferable, and leakage can be stopped even with a small contact pressure.

[0012]

【Example】

 The present invention will be described with reference to the drawings. 1 is a sectional view of a safety valve showing an embodiment of the present invention, and FIG. 2 is a sectional view of an organic electrolyte secondary battery showing an embodiment of the present invention. In the figure, 1 is an open / close type safety valve, 2 is a cap, and 3 is a flange portion. Reference numeral 4 denotes a rubber valve body made of chloroprene rubber. Reference numeral 5 is a thin metal layer formed on the flat surface of the rubber valve body, and is made of gold with a thickness of 3 μm.

Reference numeral 6 is a battery container, and 7 is a gas discharge port. 8 is a gas discharge port opened in the cap. The cap and the battery container are made of stainless steel or nickel-plated steel, and are integrated by spot welding or laser welding. Reference numeral 9 denotes an electrode plate group, which comprises TiS _{2 as} a positive electrode, lithium or carbon material as a negative electrode, and multi-pore polypropyne as a separator. 10 is a terminal. Reference numeral 11 denotes an organic electrolytic solution, which comprises propylene carbonate as an organic solvent and LiClO _{4 as a} solute.

[0014]

[Effect of device]

 Since the present invention uses an open / close type safety valve, even if the internal pressure of the battery rises and the safety valve operates during overcharge, the gas discharge port is closed if the internal pressure of the battery falls. Therefore, it enables an organic electrolyte secondary battery that can be used even when the safety valve is activated. Since a thin metal layer is formed on the rubber valve body, the safety valve operates stably for a long time without deterioration of the battery due to invasion of water vapor and swelling of rubber by the organic solvent.

[Brief description of drawings]

FIG. 1 is a sectional view of a safety valve showing an embodiment of the present invention.

FIG. 2 is a cross-sectional view of an organic electrolyte secondary battery showing an embodiment of the present invention.

[Explanation of symbols]

 1 Open / close type safety valve 2 Cap 4 Rubber valve body 5 Metal thin layer 6 Battery container 7 Gas discharge port 11 Organic electrolyte

Claims (1)

[Scope of utility model registration request] 1. An organic electrolyte secondary battery having a safety valve in which a valve body made of a rubber material is fastened with a cap, wherein the surface of the valve body made of a rubber material is a soft metal thin film against an organic electrolyte solution. An organic electrolyte secondary battery having a layer formed.