Chemistry: electrical current producing apparatus – product – and – Current producing cell – elements – subcombinations and... – Cell enclosure structure – e.g. – housing – casing – container,...
Patent
1997-12-23
1999-12-14
Maples, John S.
Chemistry: electrical current producing apparatus, product, and
Current producing cell, elements, subcombinations and...
Cell enclosure structure, e.g., housing, casing, container,...
429178, 429304, 429324, H01M 202, H01M 230
Patent
active
060015055
DESCRIPTION:
BRIEF SUMMARY
This application is the national phase of international application PCT/JP97/01397, filed Apr. 23, 1997 which designated the U.S.
TECHNICAL FIELD
The present invention relates to a nonaqueous electrolyte battery used as a power source for electronic instruments.
BACKGROUND ART
In conjunction with a demand for electronic instruments having a smaller size, there has been an increasing demand for batteries having a smaller size to be used for their power source. In order to satisfy such a demand for batteries, thinned batteries have been taken into consideration. Known as such batteries are those in which an electrode and an electrolytic solution or the like are sealed into a bag made of a plastic or a combination of a plastic and a metal which are bonded together. Since the reliability of such batteries depends on its hermetic property, various studies have been made as explained in the following.
For example, Japanese Patent Application Laid-Open No. 56-71278 discloses a sheet-like battery. In this battery, while the part occupied by the heat-fusing portion is reduced, a lead which has been coated with a resin beforehand is used to improve the reliability of its heat fusion with respect to the bag.
The bag for sealing the battery system disclosed in Japanese Patent Application Laid-Open No. 56-71278, however, is formed by a single iodine-resistant fluorine resin. Consequently, in the case of a nonaqueous electrolyte battery whose electrolytic solution is volatile or of an organic solvent system, there is a strong tendency for the electrolytic solution to penetrate through the bag to leak out or for moisture to infiltrate therein from the outside, thereby yielding an inferior hermetic property.
On the other hand, Japanese Patent Application Laid-Open No. 3-62447 discloses a battery in which, as a material for a seal portion of a sealing bag, acrylic acid modified polyethylene or acrylic acid modified polypropylene is used.
The battery disclosed in Japanese Patent Application Laid-Open No. 3-62447, however, is disadvantageous in that, since a highly hygroscopic acrylic acid modified polyolefin is used in the bag, moisture is likely to infiltrate therein.
Accordingly, it is an object of the present invention to provide a nonaqueous electrolyte battery having high blocking properties against the nonaqueous electrolytic solution and steam.
DISCLOSURE OF INVENTION
The present invention provides a nonaqueous electrolyte battery comprising a nonaqueous electrolytic medium; positive and negative electrodes in contact with the nonaqueous electrolytic medium; a first lead having one end connected to the positive electrode and the other end extending to the outside; a second lead having one end connected to the negative electrode and the other end extending to the outside; and a bag for sealing the positive and negative electrodes, the nonaqueous electrolytic medium, and parts of the first and second leads therein, the bag being heat-sealed; wherein at least a heat-sealing portion of the bag has a layer comprising a maleic acid modified polyolefin.
The nonaqueous electrolytic medium refers to a nonaqueous electrolytic solution containing an electrolyte, or a solid electrolyte. When the nonaqueous electrolytic medium is a nonaqueous electrolytic solution, in order to prevent it from diffusing, the battery further comprises a separator positioned between the positive and negative electrodes.
The maleic acid modified polyolefin has a low hygroscopicity and a low compatibility with the nonaqueous electrolytic solution. Consequently, at the heat-sealing portion, the blocking properties (barrier properties) against the nonaqueous electrolytic solution and steam are enhanced, thereby improving the hermetic property of the bag.
Also, the heat-sealing portion may be formed at a peripheral part of the bag.
In this case, when the bag is made of a film, its hermetic property is enhanced at the peripheral part.
Also, the present invention may be configured such that peripheral parts of the first and second leads are coated
REFERENCES:
patent: 5270133 (1993-12-01), Bammann, III
Fukuda Yutaka
Hanafusa Koji
Tanaka Keiichi
Maples John S.
Sumitomo Electric Industries Ltd.
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