JPS58197655A - Battery - Google Patents

Abstract

PURPOSE:To improve environmental resistance by coating the battery surface enclosed by a high polymer film with a water absorbing polymer and/or a coating material with water repellency. CONSTITUTION:Lead-out electrode terminal parts 7, 8 constituted by the corrosion resistant sheet metal of stainless or aluminum are bonded and fixed on terminal taking- out windows 3, 4. Then, a negative electrode collector 6 and positive collector 5 are stuck to high polymer films 1, 2 using an epoxy adhesive. Further, a negative electrode active material 9 of sheet metallic lithium and paste like positive electrode active material 10 are respectively stuck to the collectors 5, 6. Polypropylene-made non-woven supporting member 11 is immersed in an electrolyte, and it is arranged together with a polypropylene made separator 12 between the negative electrode active material 9 and the positive active electrode active material 10, allowing them to be assembled. And, an adhesive 14 was applied on the outer circumference part 13 of the high polymer films 1, 2, and thereafter they were heated and bonded. Then, a coating material 15 containing a water absorbing polymer was spread over the whole surface of a battery, allowing the battery to be completed. For the water absorbing polymer, methacrylate ester, and a copolymer of acrylate ester and vinyl acetate, or a polyvinyl pyrolidone series copolymer are used.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to improving the environmental resistance of batteries encapsulated with polymeric films.

Conventional panel batteries with power generation elements wrapped in polymer film,
Paper batteries are well known, and have the advantage of being thinner, more flexible, and easier to shape than metal batteries. However, polymer films generally have relatively low gas barrier properties, and in various environments impurities such as moisture, gas, and ions can penetrate the polymer film and enter the battery, causing chemical reactions with power generation elements. This causes adverse effects such as corrosion of gas generating electrodes and capacity deterioration due to internal battery formation. In addition, the sealing part of the battery is formed by bonding polymer films together using heat pressure bonding or an adhesive, but the heat pressure bonded part itself has poor gas barrier properties, and the adhesive should also be used in consideration of its adhesion to the polymer film. Since resin adhesives are used as adhesives, they have high moisture permeability and gas permeability, which causes problems in various environments.

An object of the present invention is to provide a highly reliable battery that prevents deterioration of battery performance even in various usage environments.

The present invention will be explained below based on examples, but the present invention is not limited to the extent that it does not go beyond the gist of the present invention.

Example 1 FIG. 1 shows a sectional view of this embodiment.

20mm long and 60mm wide with terminal extraction windows 3 and 4 in some parts
In polymer films 1 and 2 made of polyethylene and having a thickness of 80 μm and 80 μm, extraction electrode terminal portions 7 and 8 made of corrosion-resistant thin metal plates of stainless steel or aluminum are adhesively fixed to the terminal extraction windows 3 and 4. Next, the cathode current collector 5 and the anode current collector 6 are attached to the polymer films 1 and 2 using an epoxy adhesive. For adhesion to the lead-out electrode terminal parts 7 and 8, a conductive adhesive was used in which 15 wt % of carbon powder was added to a polymeric medium mainly composed of epoxy resin. Furthermore, a cathode active material 9 of sheet metal lithium and a paste anode active material 10 made of a mixture of manganese dioxide, a conductive agent, a binder, and a glue agent are laminated onto the current collectors 5 and 6, respectively. Although a conductive adhesive is used at this time as well, the conductive filler is preferably gold powder, which does not easily react with metallic lithium and manganese dioxide.

An electrolytic solution prepared by dissolving lithium perchlorate at a concentration of 1 l/l in a mixed solvent of propylene carbonate and 1,2-dimethoxyethane is impregnated into the holding member 11 made of polypropylene nonwoven fabric, and the surface area is The cathode active material 9 is installed between the cathode active material 10 and the polypropylene separator 12, which is larger than the material reaction area but smaller than the polymer film, and the polymethyl film is placed on the outer periphery 13 of the polymer films 1 and 2. An adhesive 14 containing a 10:1 mixture of an enylsiloxane main agent and a curing agent is applied, and the periphery of the separator is sandwiched between polymer films 1 and 2.
A pressure of kg/cm2 was applied and heat bonding was carried out at 150°C for 10 minutes. Next, the lead electrode terminal portions 7 and 8 are masked, and a paint 15 containing a water-absorbing polymer is applied by spraying to the entire surface of the battery. After sufficiently drying, the masking is removed to complete the battery.

As the water-absorbing polymer, a methacrylic acid ester such as a butyl methacrylate homopolymer, an iso-butyl methacrylate polymer, an ethyl methacrylate homopolymer, a copolymer of an acrylic acid ester and vinyl acetate, or a polyvinylpyrrolidone copolymer is used. Alternatively, a mixed product of an organosiloxane-oxyalkylene block copolymer and a sulfosuccinic acid derivative may be used.

As a copolymer of acrylic ester and vinyl acetate, for example, 40 parts by weight of methyl acrylate, 60 parts by weight of vinyl acetate, 0.5 parts by weight of benzoyl peroxide, and 3 parts by weight of partially saponified polyvinyl alcohol are mixed with 300 parts by weight of pure water. Examples include suspension polymerization by heating at 65° C. for 6 hours. 2 parts by weight of polyvinylpyrrolidone, polyoxyethylene di(perfluorohexenyl ether)
For example, 0.25 parts by weight and 97.75 parts by weight of isopropyl alcohol are mixed, heated at 60° C. for 5 hours to disperse the product, and the product is dried.

As the paint 15, a mixture of 100 parts by weight of epoxy resin, 50 parts by weight of polyamine, and 4 parts by weight of butyl methacrylate homopolymer was used, and the coating material had a thickness of approximately 500 μm to 600 μm.
Ten batteries were prepared by coating and drying the film to a film thickness of
When a high temperature and high humidity test was conducted at 0° C. and relative humidity of 90%, there was no abnormality in the output voltage even after 65 days, and no problems such as expansion or leakage occurred.

Comparative Example 1 Ten batteries were manufactured in the same manner as in Example 1 except that paint 15 was not applied, and a high temperature and high humidity test was conducted in the same manner as in Example 1. After 65 days, 3 out of 10 batteries failed. This caused expansion due to gas generation.

The water-absorbing polymer shown in Example 1 has good affinity with polymer films, and many of them are highly transparent, and have little negative effect on the adhesion of paints to polymer films. Even when applied, the color of the battery itself is not damaged, and even if the battery is bent, cracks and peeling are less likely to occur, coating work is easy, and high quality mass production is possible.

Example 2 As paint 15, a copolymer of methyl acrylate and vinyl acetate was soaked in a 40 wt% caustic soda aqueous solution and heated at 60°C.
100 parts by weight of epoxy resin and 50 parts by weight of polyamine were used in the same manner as in Example 1 except that 100 parts by weight of epoxy resin and 50 parts by weight of polyamine were used. When a high-temperature, high-humidity test was conducted in the same way as in Example 1, there was no abnormality in the output voltage even after 100 days, and there were no problems such as expansion or leakage.
None occurred.

Comparative Example 2 When the high temperature and high humidity test in Example 1 was continued, 10
After 0 days, 2 out of 10 samples expanded due to gas generation.

By saponifying the polymer as described above, the water absorption rate is further increased, so that durability and reliability especially in high temperature and high humidity environments can be obtained.

Further, the same effect can be obtained by using a paint containing a water-repellent substance in addition to a paint containing a water-absorbing polymer. As the water repellent material, fluorine polymer, silicone polymer, polyethylene, SBR, natural rubber, etc. are used. A paint containing both a water-absorbing polymer and a water-repellent substance may be used, and in this case, particularly high durability against moisture and moisture can be obtained.

As described above, the present invention is configured so that a battery encapsulated with a polymer film is protected from the external environment, particularly moisture, gas, and ionic impurities, so that the battery performance is maintained even under these environments. , maintains functionality, provides high reliability, and expands the range of applications for polymer film-clad batteries.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing one embodiment of the present invention. 1, 2...Polymer film 3.4...Window for terminal extraction 5...Cathode current collector 6...
...Anode current collectors 7, 8...Extraction electrode terminal portion 9...Cathode active material 10...Anode active material 11...
...Holding member 12...Separator 13...Outer periphery 14...Adhesive 15...Coating ■

Claims (1)

[Claims] 1. In a battery in which a power generation element is encapsulated in a polymer film and hermetically sealed with adhesive, the outer surface of the battery is pulled out, excluding the electrode terminals, and a water-absorbing polymer and/or water-repellent substance is applied. A battery characterized by being coated with a paint containing: 2. The battery according to claim 1, wherein the water-absorbing polymer is one of the following 1) to 4). 1) Methacrylic ester 2) Copolymer of acrylic ester and vinyl acetate 3) Polyvinylpyrrolidone copolymer 4) Above 1),
A mixture 3 of two or more of 2) and 3) The battery according to claim 1 or 2, wherein the water-absorbing polymer is saponified.