Chemistry: electrical current producing apparatus – product – and – Current producing cell – elements – subcombinations and... – Plural cells
Patent
1997-01-06
1997-11-25
Skapars, Anthony
Chemistry: electrical current producing apparatus, product, and
Current producing cell, elements, subcombinations and...
Plural cells
429 4, 429162, 296232, H01M 646, H01M 600
Patent
active
056910797
DESCRIPTION:
BRIEF SUMMARY
This application is the national phase of international application PCT/DK95/00295 filed Jul. 7, 1995 which designated the U.S.
TECHNICAL FIELD
The invention relates to a battery formed of stacked flat cells comprising an electro-chemical battery system having an anode and a cathode, the casings of said cells being formed of upwardly open plastic trays stacked to form a unit, the upwardly facing edge of a subjacent tray in the stack being sealingly connected with a circumferential edge portion of the bottom of the superjacent tray along the entire periphery, the upper edges of the trays and the circumferential edge portions of the bottom having essentially complementary guiding and joining faces.
BACKGROUND ART
Plastic cells may be fused together by immersing cells pressed against each other in a solvent, such alcohol, confer e.g. German patent No. 900.958.
Danish patent application No. 2661/81, further, discloses a battery of the above type having complementary guiding and joining faces and provided with a plurality of circumferential cavities adapted to stop any leaking of electrolyte fluid.
It is, however, difficult to obtain an effective fusion of the cells, as these typically only are fused in the outermost surface, the fused layer thus being fairly thin and sensitive to wearing during the assembly process and to formation of pressure in the stack of cells usually containing an alkaline electrolyte. It is extremely important that the stack remains tight, as the alkaline electrolyte possesses a considerable leakage ability. The alkaline electrolyte is an aggressive medium which will damage the equipment, in which the battery is mounted, if the battery leaks.
BRIEF DESCRIPTION OF THE INVENTION
According to the invention, a battery of the above type is characterised in that the circumferential edge portion in the bottom of the tray and/or the upper edge of the tray is provided with fluid permeable means (such as a rough surface, ridges, grooves or the like roughness suitable to form a small gap between the joining faces) to facilitate intrusion of the solvent by capillary effect at joining of the trays. Accordingly, improved solvent intrusion is obtained as well as increased contact area available for joining two trays than if the surfaces had been smooth. As a result, an increased minimum wall thickness of the fused stack is obtained and thus a product being ensured against leaking of electrolyte fluid is obtained.
Preferably, in order to enhance the intrusion of solvent by capillary effect at fusion of the trays, the vertical inner faces of the tray are provided with fluid permeable means in a band along the upper edge of the faces and/or along the vertical outer faces of the circumferential edge portion in the guiding faces of the bottom. The fluid permeable means are preferably formed as ridges, grooves or channels defined by ridges, preferably in such a manner that narrow grooves or channels, having a width of approximately 0.2 mm and a depth of approximately 0.06 mm, are formed between the ridges.
The grooves or ridges on the vertical faces are preferably arranged opposite the corresponding ridges or grooves on the horizontal portion of the circumferential bottom edge portion of the tray and/or on the horizontal portion of the upper edge of the tray.
It is preferable that the fluid permeable means coact with one or more essentially circumferential cavities acting as interference for the capillary effect and thus forming a barrier for the solvent intruding from the outside as well as for the electrolyte fluid in the interior of the tray.
Moreover, the invention relates to a method as defused in claim 10 for joining the trays to form a completely sealed stack.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention is explained in details in the following based on a preferred embodiment and with reference to the drawings, in which
FIG. 1 illustrates a stackable flat cell in a bottom view,
FIG. 2 is a vertical sectional view through the above embodiment along the line II--II in FIG. 1,
FIG. 3 is a
REFERENCES:
patent: 2658936 (1953-11-01), Rock
patent: 2677716 (1954-05-01), MacFarland
patent: 2774806 (1956-12-01), Jobe et al.
patent: 2820081 (1958-01-01), Daley et al.
patent: 2889389 (1959-06-01), Tamminen
patent: 3907599 (1975-09-01), Fanciullo et al.
patent: 4203202 (1980-05-01), Esaian et al.
Alkaline Batteries A/S
Skapars Anthony
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