Chemistry: electrical current producing apparatus – product – and – Means externally releasing internal gas pressure from closed... – Blowout type
Patent
1995-05-22
1997-01-21
Kalafut, Stephen
Chemistry: electrical current producing apparatus, product, and
Means externally releasing internal gas pressure from closed...
Blowout type
429 94, H01M 200
Patent
active
055958354
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a sealed type battery, and more particularly to an improvement of safety in a sealed type battery.
BACKGROUND ART
A battery having a completely sealed structure, which provides enhanced sealing and excellent storage. But, where it is heated to high temperatures, used in an abnormal manner such as charging at a high voltage and large current, or short-circuited internally so that the internal temperature becomes abnormally high, the internal pressure of the battery increases. As a result, the battery can explode and hence the contents of the battery will scatter. This may cause damage to people and instruments in the vicinity of the battery.
For this reason, in order to prevent the pressure within the battery from exceeding the pressure at which the battery explodes, a proposal for a sealed type battery was made in which a cut or check is previously made and the pressure is released through its tearing (e.g. Examined Japanese Utility Model Publication No. Sho 58-17332 (1983), Unexamined Japanese Utility Model Publication No. Sho 60-65970 (1985)).
In the conventional sealed type battery in which a cut is made at a portion of the battery can, it is difficult to control precisely a variation in the remaining thickness of the cut in a machining such as stamping or wet etching. Thus, although the above conventional sealed type battery can improve the safety for explosion, when external shock is applied to the battery can, the sealing state of the battery can is likely to be broken. For this reason, a safety valve device was demanded which can operate stably and precisely at a desired pressure within a pressure range where safety is assured.
Accordingly, for the sealed type battery, in order to provide a safety valve device which operates stably and precisely at a desired pressure in accordance with an increase in the internal pressure, there was proposed. An explosion proof safety valve for the sealed type battery in which a check is formed at a portion of a battery can characterized in that at least a portion of the battery can has a multi-layer structure composed of two or more metal plates bonded together and at least one of the metal plates is made of a metal plate having a single or plural holes or through-groves (Unexamined Japanese Patent Publication No. Hei 5-314959 (1993)).
The above proposal intends to control the remaining thickness of the cut by the thickness of the metal plates bonded together so that the processing accuracy of the remaining thickness of the cut is enhanced and a variation in the operating pressure of the explosion-proof mechanism for a battery can is removed.
As described above, it was very efficient to provide a safety valve device for the battery cell so as to improve the safety performance of the sealed type battery. But, it is also very important to apply the technique of effectively preventing the internal short-circuiting of the battery, which may be a cause of battery explosion, to the internal structure of the battery.
Specifically, as one of the conventional sealed type batteries, there was proposed a sealed type battery having a specific structure in which a group of spiral electrodes composed of band-like positive electrodes and negative electrodes wound in an elliptical spiral shape through a separator are inserted into the battery can from the square or elliptical opening face of a tubular case in its section in such a manner that the winding axis of the group of spiral electrodes is in parallel to the opening face of the battery can and thereafter the opening face is hermetically sealed. Such a battery has a problem of mechanical short-circuiting caused when the positive electrodes and negative electrodes winding-slip are brought into direct contact with each other because of vibration shock or the like, or indirectly short-circuited with each other through the battery can.
Further, the above sealed type battery having the group of spiral electrodes described above in which the positive electrode is made of lithium
REFERENCES:
patent: 418483 (1889-12-01), Woolf
patent: 3530001 (1970-09-01), Harivel
patent: 4345611 (1982-08-01), Ikeda et al.
patent: 4783383 (1988-11-01), Machida et al.
patent: 5415954 (1995-05-01), Gauthier et al.
Kogure Masanori
Kojima Tetuzo
Maki Takao
Miyamoto Ken'ichi
Tukamoto Hisashi
Japan Storage Battery Co., Ltd.
Kalafut Stephen
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