Chemistry: electrical current producing apparatus – product – and – Current producing cell – elements – subcombinations and... – Electrode
Reexamination Certificate
1997-10-31
2001-03-06
Nuzzolillo, Maria (Department: 1745)
Chemistry: electrical current producing apparatus, product, and
Current producing cell, elements, subcombinations and...
Electrode
C029S623100
Reexamination Certificate
active
06197449
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to an electrode arrangement for an electrochemical device, such as batteries, electrochemical batteries or the like, to an electrochemical device constructed from such an electrode arrangement, and a method for the manufacture of an electrochemical device.
BACKGROUND OF THE INVENTION
By way of example, conventional lead-acid batteries are provided with at least two mutually opposing plate-shaped electrodes, which are either coated with PbO
2
gel, or modelled in the form of two lead plates one of whose plate surfaces is converted to PbO
2
after a Planté coating. In both cases, the reactive surface of the electrode corresponds to the plate surface and is therefore restricted to the dimensions of the latter. Furthermore, conventional lead-acid batteries have only limited mechanical stability on account of the plate-shaped design of the electrodes. While PbO
2
gel electrochemical batteries do supply high currents, they have a short service life. While in contrast, stationary batteries with Planté-coated electrodes do have a long service life, they cannot supply high currents because the reactive surface layer is small in relation to the complete electrode. Accordingly, the latter have a relatively high volume and a relatively high weight in relation to their power yield.
On these grounds, a great many attempts have been made to enlarge the surface area of the electrodes, as is to be seen, for example, from German Patents DE 42 01 420 A1, DE 26 39 881 A1 and DE-PS 146 063. While an enlargement of the surface is provided in all cases by means of sometimes relatively complicated design and manufacturing measures, there still remain the disadvantages of restricted mechanical stability and compared with the power yield, a relatively high volume and weight.
SUMMARY OF THE INVENTION
An object of the present invention is therefore to provide an electrode arrangement for cells of batteries, electrochemical batteries or the like electrochemical devices and an electrochemical device of the type mentioned at the outset manufactured with an electrode arrangement of this kind, which will satisfy present-day requirements for high storage capacities at comparatively low volume and weight and can thereby achieve a higher yield output. A further object of the present invention is to provide a method of manufacturing an electrochemical device of this kind which is neither labour-intensive nor cost-intensive.
The noted objects are achieved by providing an electrode arrangement wherein two electrodes are provided each having a three-dimensional grid-type structure and arranged interleaved with one another in all directions in space. Preferably, one of the grid-type structures of the electrodes is provided with an electrolytically separating intermediate wall in the separating plane of the other grid-type structure. And by providing a method which incorporates two mutually offset continuous recesses in at least two mutually perpendicular planes and in at least two planes offset therefrom by 45° of an unfinished body in order to obtain a three-dimensional grid-type overall structure, and by the opening up of the overall structure into at least two individual structures representing the electrodes or the electrode parts.
A development of the electrodes each as a spatial body which has a large surface area in relation to its own volume is achieved with the measures in accordance with the present invention. The volume of the spatial body can be so reduced in the process that, with the exception of a very small supporting component, the entire volume of the two electrodes of a cell is comprised of material involved in the electrochemical reaction. The two electrodes are spatially interleaved in such a way that the distances between the electrodes can become very small, thereby producing a great many cell-type reaction chambers in which the electrochemical reaction proceeds.
The features according to which the two electrodes are identical in structure and are preferentially held at essentially the same distance fro one another are provided in a preferred embodiment of the present invention which advantageously results in a large number of cell-type reaction chambers each being of equal size and preferentially in the distances between the spatial bodies of the two electrodes being essentially of identical size at each point or in each area. This results in uniform electrochemical reactions within the entire space of the electrode arrangement without any manner of preferential direction arising. This is also due to the fact that the entire space of an electrochemical device is occupied uniformly and in equal parts by the two electrodes. Accordingly, both electrode surfaces cut in every section through the space are equal in size.
A further advantageous embodiment envisages the features whereby each electrode is formed of several three-dimensional grid elements comprised of approximately vee-shaped, bar-type element-component pairs extending from a node in two mutually perpendicular planes. This means that the spatial body has a constantly repeating geometric shape comprised of a node with four bars projecting from same. Each of these bars remains constantly at the same angle in relation to each other bar. In accordance with one variant according to which the approximately vee-shaped, bar-type element-component pairs are connected next to and/or above one another by their respective ends at least in part to further element-component pairs or grid elements, beginning with one node, a further node is placed on the bars of same in each direction in such a way that the bars of the further node represent the continuation of the bars of the first node. This method produces an entirely regular spatial grid-structured body which is so modelled that a further body of the same kind can be intercalated in the spaces within that body. This intercalated body (the second electrode) does not come in contact with the first body (the first electrode) at any point. The distances between the intercrossing bars of both bodies are always within a constant tolerance.
In accordance with the features, in accordance with which the cross-sections of the bar-type element components can be uniform or non-uniform over their length, either one of which cross-sections being preferred as a function of the method of manufacture of the electrode arrangement with reference to manufacturing costs and production requirements.
In accordance with the features whereby the three-dimensional grid-type structure of te electrodes is constructed three-dimensionally interleaved by sections, it is possible for the electrode arrangement to have a structural design. A further useful development of the electrode design, which is at least suitable for certain sizes of such an electrochemical device, is provided by the features whereby the three-dimensional grid-type structure of the electrodes is formed, in an unfinished body, of mutually offset, throughgoing recesses in at least two mutually perpendicular planes and in at least two planes rotated through 45° in relation to same. Devices of almost any spatial form can be produced in this manner. Useful developments are provided by the features whereby the recesses are formed by drilled holes, are formed of square recesses from two mutually perpendicular directions and of hexagonal recesses from two mutually perpendicular diagonal directions and are preferentially cut by laser, wherein the separation of the electrodes is formed by at least partial separation of a wall plate on all sides of the unfinished body, or in that the electrodes are separated by removal, for example by drilling or for example by laser cutting of certain bars or by the production of separating recesses between the two electrodes.
Depending on the mechanical strength or admissible weight to be achieved, the question of materials is solved either in accordance with the features whereby the grid-type structure is plastic and is provided with an appropriate coating, or with those whereby
Hoffmann Hans
Siemonsen Sven
Jones Tullar & Cooper P.C.
Nuzzolillo Maria
Tsang Susy
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