JPS58223267A - Alkaline thin battery - Google Patents

Abstract

PURPOSE:To improve storage life and electrolyte leakage resistance of a battery by bonding to an outer jacket the surface, which was faced to plating liquid during electroforming, of a cathode current collector except for a terminal with an adhesive comprising a copolymer containing glycidyl methacylate. CONSTITUTION:This alkaline thin battery is consisted of a separator 10, an anode layer 12, a cathode layer 14, an anode current collector 16, and a cathode current collector 18, and an anode and a cathode terminals 20 and 22 are exposed in the center of the current collectors 16 and 18 respectively, then they are heat-sealed with two pieces of outer jacket 24 and 24. The outer jacket 24 consists of three layer laminted film. The surface, which was faced to plating liquid during electroforming and was made rough, of the current collector 18 obtained by forming nickel plating 18b on the both surfaces of iron foil 18a which is made by electroforming is bonded to polyethylene film 24a of the outr jacket 24. Reaction type hot melt adhesive layer 28 of a copolymer containing glycidyl methacrylate is placed in between.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an alkaline thin battery, particularly to improving its leakage resistance.

A thin Ayakali battery R1", which is generally referred to as a paper type battery, has an anode layer and a cathode layer stacked on both sides of the separator in the form of a sandwich with an electrolyte such as KOH. A power generation element is constructed by forming a layer of metal current collecting plates on the surface thereof, and the power generation cable is covered with an insulating exterior body except for both terminals, and the peripheral edge is sealed.

Conventionally, in bonding between the metal current collector or metal terminal and the exterior body in this type of battery, (1) After simply degreasing the metal surfaces to be bonded with an organic solvent, ethylene-vinyl acetate 1, ethylene-acrylic 1, Katsutake methacrylic acid copolymer, ethylene-acrylic acid ester or methacrylic acid ester copolymer, ionomer, polyamide type, polyester type, carboxyl mV
Adhere to the exterior body via a hot melt adhesive layer such as A.

(2) After the metal surface is roughly solidified by mechanical or chemical etching such as sandblasting, the metal surface is bonded to the exterior body via the hot melt adhesive as described above.

(3) An electrolyte-resistant and repellent sealant such as polybutene, polyisobutylene, silicone grease, etc. is interposed between the current collector plate and the exterior body.

(4) Bond the metal surface and the exterior body with an adhesive sealant made of aliphatic polyamide.

A variety of bonding means and metal surface treatment techniques have been implemented.

However, with these bonding methods, poor adhesion occurs between the metal surface and the adhesive layer when the battery is stored at high temperatures for a long period of time or when it is exposed to an atmosphere with temperature cycles. Furthermore, once poor adhesion occurs, the electrolyte easily penetrates into the metal due to its large surface energy, and this penetration causes leakage, resulting in insufficient reliability.

This invention was made in view of the shortcomings of the various prior art techniques as described above, and its purpose is to strengthen the bonding between the metal current collector and the exterior body compared to the conventional bonding means, thereby improving preservation. The objective is to further improve the performance and side leakage performance.

In order to achieve the above object, the present invention provides an alkaline thin battery in which a power generating element is covered with an exterior body except for a terminal part,
The anode current collector is made of iron foil obtained by electroforming and nickel plated, and a part of the anode current collector is exposed to the outside to serve as the anode terminal, and the terminal is removed and the exterior is removed. The surface of the anode current collector facing the body facing the plating solution during electrolysis is bonded via a reactive hot melt adhesive made of a copolymer containing glycidyl methacrylate. An embodiment of the present invention will be described in detail below with reference to the drawings.

In FIG. 1, the alkaline thin battery according to the present invention is
A cathode layer 12 and an anode layer 14 are laminated in a sandwich pattern on the upper and lower surfaces of the separator 10 made of an alkali-resistant nonwoven fabric, and a cathode current collector plate 16 and an anode layer are laminated on the upper surface of the cathode layer 12. 3) The anode current collector plate 18 laminated on the lower surface of the layer 14 constitutes a power generation element, and the center of each current collector plate 16, 18 of the power generation element is connected to the cathode and anode terminal portions 20.22 and 1.2. Two exterior bodies 24.2 are made by selectively encasing the stiffness from the top and bottom while exposing it to the outside, and heat-sealing the periphery to seal it.
From 4.

The cathode layer 12, which constitutes the power generating element, is made by gelling amalgamated zinc powder with a synthetic glue and an electrolyte INC liquid, and the anode layer 14 is formed by molding a mixture of manganese dioxide and graphite, and adding an electrolytic solution. 1 da in the electrolyte.
5% KOH is used.

Furthermore, as shown in FIG. 2, the exterior body 24 is made of a three-layer laminate film with an inner surface made of polyethylene 24a, an outer surface made of polyester 24t), and an aluminum foil 240 laminated in the middle. The three-layer structure is designed to isolate the inside and outside of the battery and improve film strength, with the polyethylene film 24a side facing each of the current collector plates 16 and 18.

(4) Adhesive layers 26.28 are interposed on the joint surfaces of the current collector plates 16.18 and the exterior body 24, and the polyethylene of the exterior body 24 is It is adhered to the film 24a side.

In the above configuration, the anode current collector plate 18 is made of nickel on both sides of a 50 m thick iron foil 18a obtained by peeling off a layer adhered to the '-electrode by electrolysis in a ferrous chloride bath. (See Figure 2).

The iron foil obtained by this electroforming method has a smooth electrode surface during electrodeposition to make it easier to peel off from the electrode surface. The side that contacts the electrode is smoothed, and the surface that comes into contact with the plating solution is roughened, and this roughened surface is attached to the exterior body 24 as shown in FIG. They are facing each other.

In addition, the iron foil 18a obtained by the electroforming method as described above,
Compared to steel foil produced by the conventional rolling method, oils and fats do not adhere to it, so surface treatment such as degreasing during bonding can be greatly simplified, and the surface to be bonded will not be roughened during manufacturing. , there is no need to roughen the surface to obtain an anchoring effect on the surface to which it is attached, and furthermore, it has advantages and characteristics such as being highly flexible and easy to handle.

Furthermore, applying nickel plating 18b to the surface of this iron foil 18a not only has the effect of preventing iron from oxidizing, but also has the effect of keeping the adhesive surface stable for a long time in an alkaline electrolyte because nickel has extremely good alkalinity. .

Next, the adhesive #28 for bonding the cathode current collector plate having the above configuration] 8 and the exterior body 24 is a reactive hot-melt adhesive in the form of a film with a thickness of lOOμ made of a combination of ethylene-glycidyl methacrylate-vinyl acetate. The agent was interposed between the anode current collector plate 18 and the exterior body 24, and then heated at 180C.

By hot pressing for 10 minutes at a pressure of 4 Ky/cffl, the two are firmly bonded.

It should be noted here that the glycidyl methacrylate constituting the adhesive layer 28 is a thermosetting resin (7) that hardens by causing a crosslinking reaction when heated, and also contains epoxy in its molecules. Contains groups. Therefore, the hot melt adhesive made of a copolymer containing a core component has excellent adhesion to metal, that is, the anode current collector plate 18, and at the same time, the adhesive layer 28 has a strong cohesive force. However, the thermal adhesiveness of the exterior body 24 to the polyethylene 24a is extremely excellent.

Therefore, the alkaline thin battery according to the present invention has not only the anchoring effect of the grain surface of the iron foil constituting the anode current collector, but also the strong adhesiveness of the reactive hot melt adhesive made from the copolymer containing glycidyl methacrylate. This makes it possible to strengthen the bond between the current collector and the exterior body more than any conventional bonding means.

Next, in order to explain the above effects more specifically, we will discuss the alkaline thin battery with dimensions of 50 m s x 30 m x 2.5 m thick obtained in the above example, and a conventional alkaline thin battery. The battery was stored at 60C, and the presence or absence of leakage from the anode terminal was examined, and the results shown in the table below were obtained.

(8) Conventional product A uses a nickel-plated iron foil with a thickness of 50 J1 m obtained by a rolling method as the anode current collector, and the exterior is coated with a hot-melt adhesive based on ethylene-Nisdale acrylic acid copolymer. The other parts are exactly the same as the product of the present invention, and the conventional product B has the same anode concentration 1 as the conventional product.
It is a board, and the adhesive is an ionomer hot melt adhesive.

As is clear from the table above in Table 60C storage area, the product of the present invention is the conventional product A,
The leakage resistance was extremely superior to that of either B and this suggests that the bond between the anode current collector and the exterior body according to the present invention is extremely strong.

[Brief explanation of the drawing]

11*l is a cross-sectional view showing the overall structure of the alkaline thin battery according to the present invention, and FIG. 2 is a partially enlarged cross-sectional view showing the main part of the present invention. 10... Separator 12... Cathode layer 14... Anode layer 16... Cathode current collector plate 18 ......Anode current collector plate 18a...Iron foil 18b...Nick" plating 20...Cathode terminal portion 22...・・・・・・Anode terminal part 24・・・・・・Exterior body 26, 28・・・Adhesive layer Patent Applicant: Fuji Electrochemical Co., Ltd. Agent
Patent Attorney - Ken Iro

Claims (1)

[Claims] (1) In an alkaline thin battery in which the power generating element is covered with an exterior body except for the terminals, a positive current collector is made of iron foil obtained by electroforming and plated with nickel. A part of the mechanical current collector is exposed to the outside to serve as an anode terminal part, and the surface of the anode current collector facing the exterior body, excluding the terminal part, on the plating solution side during electroforming, contains glycidyl methacrylate. An alkaline thin battery characterized by being bonded via a reactive hot-melt adhesive made of a copolymer.