Chemistry: electrical current producing apparatus – product – and – Current producing cell – elements – subcombinations and... – Separator – retainer or spacer insulating structure
Patent
1980-09-30
1983-02-22
LeFevour, Charles F.
Chemistry: electrical current producing apparatus, product, and
Current producing cell, elements, subcombinations and...
Separator, retainer or spacer insulating structure
429143, H01M 218
Patent
active
043749089
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a tubular electrode for an electrochemical accumulator in the shape of an electrode plate with a number of electrolyte-permeable tube casings essentially parallelly arranged adjacent each other, containing an active material and conductors connected to a common collecting bar.
The demand for an improved capacity in conventional electrochemical current sources have increased considerably over the last years. An important task has been to replace petrol-powered vehicles with electrically powered ones to the greatest possible extent, whereby different details in lead batteries have been modified. However, the geometrical conditions as a development object have only been studied to a lesser extent. This concerns in particular the nowadays well documented tubular electrode constructions.
In these tubular electrode constructions the tube casings are normally provided with a circular or a rectangular and in certain cases a sqaure cross section. A circular cross section renders a comparatively large surface exposed to the electrolyte as the adjacent tubes merely contact each other along a line. This permits a good electrolyte flow and furthermore the disposal of generated heat. Hereby rather extensive current outputs are made possible which is a necessity in most batteries for tractionary or stationary use. On the other hand, tube casings with a circular cross section result in a relatively low output of energy per unit of weight, which is a disadvantage especially in a continuous average current load and accelerating use of energy. A method to increase the possible output of energy per unit of weight is to decrease the diameter of the tube casing, e.g. from 8-9 mm to 6-7 mm, though the material costs will simultaneously rise considerably.
Another method of increasing the possible output of energy per unit of weight is to provide the tube casings with rectangular, possibly square cross sections, and to pack the casings quite densely with the sides adjacent each other. Although a certain increase of the electron conductivity is hereby achieved, the maximum output, however, becomes relatively low due to an inferior electrolyte diffusion and convection as well as a consequent risk for overheating.
In the literature also other arrangements have been proposed, as triangular, rhombic and polygonal shapes of cross sections in the tube casings, but these solutions have proven less suitable in cells working in practice, among others as a consequence of considerable transport passages for the electrolyte as well as deformation risks.
The object of the invention is to achieve an improved tubular electrode for an accumulator of the kind stated in the preamble, especially a lead accumulator, whereby the above mentioned disadvantages are eliminated and an improved performance is obtained. A higher energy density (Wh/kg) is hereby especially strived for, this higher energy density being required for the driving of an electrically powered vehicle. Further objects are to achieve an accumulator permitting a good electrolyte flow, high outputs, a maintained high capacity even after several charging cycles, as well as a lower weight per unit of volume.
These and other objects are obtained through a tubular electrode according to the invention, the tube casings of which have an elongated, preferably almost elliptical cross section and are inclined so that the plane through the major axis of the cross sections forms an angle between 25.degree. and 50.degree. to the central plane of the plate and each pair of the adjacent tube casings contact each other along a line.
The invention will be described further by means of a lead accumulator and with reference to the attached drawing where
FIGS. 1a and 1b schematically illustrate two conventional tubular electrode configurations in cross section;
FIG. 2 schematically illustrates a tubular electrode configuration in accordance with the invention;
FIG. 3 illustrates a diagram showing a comparison in discharge processes between an ordinary tubular electrode configuratio
REFERENCES:
patent: 1479527 (1924-01-01), Wilson
patent: 4276359 (1981-06-01), Sundberg
patent: 4279974 (1981-07-01), Nishio
Lindholm Alfons S. M.
Magnusson Rolf C. G.
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