Chemistry: electrical current producing apparatus – product – and – Current producing cell – elements – subcombinations and... – Electrode
Reexamination Certificate
2001-02-08
2003-10-14
Ryan, Patrick (Department: 1745)
Chemistry: electrical current producing apparatus, product, and
Current producing cell, elements, subcombinations and...
Electrode
C429S211000, C429S234000
Reexamination Certificate
active
06632570
ABSTRACT:
BACKGROUND AND SUMMARY OF THE INVENTION
This application claims the priority of German patent document 100 05 415.3, filed Feb. 8, 2000, the disclosure of which is expressly incorporated by reference herein.
The present invention relates to a fibrous-structure electrode framework web strip, electrode plates produced therefrom and a process for producing a fibrous-structure electrode framework web strip.
For about 17 years, a new type of electrode frameworks has been in use industrially in the field of electrode technology for alkaline and acid storage batteries, namely the fibrous-structure electrode type. Fibrous-structure electrodes are distinguished by the fact that, unlike, for example, sintered electrodes, pocket-plate electrodes or even lead-grid electrodes, to hold the active compound they have a porous framework for the current discharge and fixing the active compound, instead of purely metallic holding or conductor elements. The porous framework is produced by chemical and subsequent electrodeposition metallization of a nonconductive plastic substrate of fibrous structure.
Storage batteries for storing electrical energy in the form of chemical energy which can then be extracted again as electrical energy were known as long ago as the end of the nineteenth century. Even today, the lead storage battery is in widespread use. In this battery, the electrodes or plates consist of the active material, which is the actual energy store, and a lead support (grid) which accommodates the active material. For some time, there have been storage batteries with a new type of electrode in which the framework has a fibrous structure. There is extensive known prior art for this type of electrode.
For example, German patent document DE-C 40 04 106 describes a metallized plastics-fiber electrode framework based on a nonwoven for battery electrodes with increased load-bearing capacity. German patent documents DE-C 36 31 055, DE-C 36 37 130, DE-C 38 43 903, DE-C 39 25 232, DE-C 41 06 696, DE-C 40 33 518, DE-C 42 42 443, and DE-C 196 27 413 have described the activation and chemical metallization and suitable processes, and German patent document DE-C 42 16 966 has described a process and an apparatus for the electroplating of nonwoven and needled-felt webs. The fundamentals of the electrodeposition of metal are described, by way of example, in Dettner-Elze: Handbuch der Galvanotechnik, Volume I/1, pp. 136 ff., C. Hanser Verlag Munich (1963) und in “Die galvanische Vernickelung” [The Electrodeposition of Nickel], from Galvanotechnik, editor: Professor Robert Weiner; Eugen G. Leuze Verlag, Saulgau/Württemberg.
German patent documents DE-C 38 17 817, DE-C 38 17 826, DE-C 40 10 811 and DE-C 42 35 884 specify aqueous nickel hydroxide and/or cadmium oxide pastes for the vibratory filling of foam- and fibrous-structure electrode frameworks.
German patent document DE-C 38 22 209 has disclosed a device for the vibratory filling of porous electrode frameworks, and German patent document DE-C 38 22 197 has disclosed a process for the quasi-continuous filling, and German patent document DE-C 38 16 232 a process for the vibratory filling, of foam- or fibrous-structure electrode frameworks. German patent document DE-C 38 22 197 also includes cleaning excess paste off the electrode framework after the mechanical impregnation, preferably using brushes. German patent document DE-C 40 18 486 has disclosed a process for the production of fibrous-structure electrodes in which the framework, which has been calibrated prior to the mechanical impregnation, is calibrated again after the filling operation by being compressed over its entire surface. German patent documents DE-C 40 40 017 and DE-C 41 03 546 each describe a process for filling fibrous-structure electrode frameworks provided with current discharge lugs for storage batteries containing an active-compound paste with simultaneous calibration of the framework, in which in the first case the framework is rolled during the filling operation and in the second case the framework is pressed during the filling operation.
The technical teaching relating to the welding of current discharge lugs of various designs to a fibrous-structure electrode framework of the type described is listed in the German patent documents DE-C 42 25 708, DE-C 41 04 865, DE-C 39 35 368, DE-C 36 32 352, DE-C 36 32 351, DE-C 31 42 091.
The above compilation, which in no way claims to be complete, shows that fibrous-structure electrode technology is a field which is currently the subject of intensive work. In practice, there are nevertheless constantly recurring difficulties and inadequacies during the production of fibrous-structure electrode frameworks, in particular relating to the process steps of activation, metallization, reinforcement by electrodeposition, filling with active compound and cleaning off the excess paste after the filling operation. Such difficulties and inadequacies may have an adverse effect during assembly of the filled, dried fibrous-structure electrodes, the unfilled nickel-fiber frameworks in the case of FNC recom cells and the separators in the case of gastight or open Ni/Cd cells of narrow design. On the other hand, such adverse effects may emerge only when the cells are operating, on account of the constantly changing volume work of the electrodes (primarily the positive electrodes in this system) resulting from the charging and discharging, so that, for example, the separators fitted are in certain zones exposed to excessive loads.
The activation and the subsequent metallization of plastics-fiber frameworks and the subsequent electrodeposition surface treatment of the various substrates are by now sufficiently well known. The technique involving deposition of metal alloys or of individual metals on the surface of substrates is used primarily if the layer which is to be electrodeposited is to impart certain properties, such as electrical conductivity, shine, reflectivity, chemical resistance, etc., to the treated substrate which the substrate itself does not have to a sufficient extent.
Now that, in practice, an ever increasing range of substrates made from plastic fibers is being used for a very wide range of applications, an electrodeposition surface treatment has become customary for these substrates as well, not only for substrates which themselves have metallic properties. For this purpose, the electrically nonconductive plastics surfaces are initially “activated” by the deposition of a catalytically active substance, and are then “metallized” by chemical means. Therefore, the electrically nonconductive plastics surfaces are provided with a metallic coating which is then suitably reinforced by electrodeposition of the same metal and/or a different metal. The application of the above technology to textile woven fabrics, nonwovens, needled felts or open-pore foams has opened up completely new application areas for these materials.
The subsequent electrodeposition surface treatment of metallized substrates has hitherto been carried out in such a way that the substrate which is to be electroplated, in a plurality of strips arranged above one another, is applied to a plurality of electroplating stands arranged next to one another—spatially close together—and the electroplating frame is clamped in place by the movable upper parts. The substrate is connected to the electroplating stand with sufficient electrical conductivity. Other than at the contact points with the substrate, the electroplating stand has an insulating layer over the rest of its surface. In this arrangement, an electroplating stand is fitted with a plurality of substrate strips and, at the same time, a plurality of electroplating stands next to one another in one electroplating tank are fitted with continuous premetallized substrate strips.
After the immersion of the electroplating stands which bear the substrate webs and after the electroplating process, metallized fibrous-structure framework strips are then formed. To obtain a reinforced edge, as is described in principle in Germa
Imhof Otwin
Kistrup Holger
Noreikat Karl-Ernst
Crowell & Moring LLP
Deutsche Automobilgesellschaft mbH
Dove Tracy
Ryan Patrick
LandOfFree
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