Chemistry: electrical current producing apparatus – product – and – Current producing cell – elements – subcombinations and... – Cell enclosure structure – e.g. – housing – casing – container,...
Patent
1996-04-15
1998-07-21
Skapars, Anthony
Chemistry: electrical current producing apparatus, product, and
Current producing cell, elements, subcombinations and...
Cell enclosure structure, e.g., housing, casing, container,...
429181, H01M 208
Patent
active
057833290
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention concerns an accumulator with a gas-tight and liquid-tight electrolyte filled casing in which electrodes are separated from each other by a separator and are respectively electrically connected to pole contacts that are accessible from outside of the casing.
2. Discussion of the Prior Art
Accumulators of that kind are known with a large number of different casing shapes. A conventional alkaline accumulator has a cylindrical casing which comprises metal and forms a pot-shaped, electrolyte-filled container both for the electrodes and also for the separator. The cover which holds the positive pole contact is fitted into the opening of the pot configuration. In that case the flanged-over edge forms a holding arrangement which is both gas-tight and also liquid-tight. However, a metal casing of that kind is difficult to produce when dealing with non-round and in particular rectangular cells.
The use of plastic casings is known for lead-acid accumulators and makes it possible to produce rectangular casings, while making good use of the available space. This construction however cannot be applied to all types of accumulators. The metal pole contacts which are cast into the plastic material casing or the metal feed-through ducting means thereof are of different coefficients of thermal expansion from the plastic material, but nonetheless may not became leaky upon an increase in temperature during charging or discharging at high current levels. It is necessary throughout the entire service life of the accumulator to ensure that neither gas nor electrolyte accidentally escapes. Accumulators with a very low internal resistance such as for example alkaline nickel-cadmium or nickel-metal hydride accumulators may build up greatly increased internal pressures under a high current loading, and such pressures should not result in leaks occurring in the region of the pole contacts.
Seals which are fitted between the casing and the pole contact, such as for example the elastic round-cord rings which are referred to as O-rings require an additional production step in terms of inserting and correctly positioning the seal and therefore have an adverse effect on the production costs of the accumulator. Difficult electrolytes which, by virtue of a high capillary action, have a tendency to creep under seals, such as for example caustic potash solution, which additionally exhibits a migration movement in the direction of negative potential, can escape from the casing if the seal is not correctly inserted or if the seal is subsequently mechanically displaced, and they can subsequently give rise to damage.
EP-A1-0 089 619 describes a gas-tight and liquid-tight pole sealing arrangement which is desired in particular for lead accumulators whose casing consists of plastic material. For sealing purposes, there is proposed therein a sealing system which comprises a plurality of layers of different materials and in which inter alia a free chamber is designed to surround the pole contact, and melt adhesives and further seals are arranged on that chamber. However that pole sealing arrangement can only be produced by a considerable number of production steps.
U.S. Pat. No. 5 197 994 discloses thermal casing welding procedures in respect of battery casings which comprise plastic material.
EP-A2-0 538 039 discloses an inserted cap which comprises a sealing means and which, in the case of a cylindrical battery, holds the central electrode and the pole contact relative to the casing and at the same time forms a seal for the battery casing to prevent fluid from escaping.
SUMMARY OF THE INVENTION
Consequently the object of the present invention is to provide an accumulator which is advantageous in terms of production from the manufacturing process point of view and which has a durably and reliably sealed casing which is not restricted in terms of its shape.
That object is attained by an accumulator with a gas-tight and liquid-tight electrolyte filled casing in which electrodes are
REFERENCES:
patent: 4212934 (1980-07-01), Salamon
patent: 4215187 (1980-07-01), Gnida et al.
patent: 4859547 (1989-08-01), Adams et al.
patent: 4957832 (1990-09-01), Ruggeberg et al.
patent: 5229223 (1993-07-01), Hyland
Christoph Emmerich GmbH & Co. KG
Skapars Anthony
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