1. Field of the Invention
The invention relates to a rechargeable battery system having a plurality of electrodes in an electrolyte space filled with electrolytes and tapped with the aid of an electrical tap, in which at least one of the electrodes is constructed as a substantially insoluble electrode of the second type and in which at least the substantially insoluble electrode of the second type has a separator arrangement, through which it is possible to reduce at least the structural and/or shape changes of the electrode during cyclic charging and discharging linked with the sinking of mechanically unstable discharge products; to a rechargeable battery system having a plurality of electrodes in an electrolyte space filled with electrolytes and tapped with the aid of an electrical tap, in which at least one of the electrodes is constructed as a substantially insoluble electrode of the second type and in which at least the substantially insoluble electrode of the second type has an electrochemically active coating provided with a surface profile or relief having a plurality of depressions and/or elevations, through which it is possible to reduce at least the structural and/or shape changes of the electrode during cyclic charging and discharging linked with the sinking of mechanically unstable discharge products; and to the use of one of the preceding battery systems in a rechargeable metal/air depolarized battery, and in particular in a zinc/air depolarized battery.-Page
2. Related Art
Batteries and battery systems are becoming increasingly important for primary and secondary energy supply. This increasing relevance is more particularly due to the ever increasing demands made with regards to environmental compatibility of energy supply systems in the sense of emission protection and reusability or recyclability of raw materials and energy.
This firstly relates to the end user and consequently private households and secondly public installations, particularly the infrastructure and traffic which are being equipped with more environmentally compatible energy sources. Already mobile devices, such as e.g. portable micro-devices and also vehicles, particularly road, rail or water vehicles, are being equipped with environmentally friendly, reusable or rechargeable energy supports in. the form of accumulators or batteries. Such energy supports in the form of battery systems are also being increasingly used in immobile devices, such as stand-alone devices and as emergency power supplies.
In conjunction with the private end user, as well as public installations, use is being increasingly made of metal/air depolarized batteries as rechargeable primary batteries, e.g. in hearing aids or heart pacemakers, as well as in telecommunications engineering and in signal installations.
Such metal/air depolarized batteries are more particularly suitable due to their high energy density and their cost-effective, environmentally compatible active materials as decentralized and rechargeable power sources. It is particularly appropriate to use zinc as the material for a metal electrode. This is due to the low equivalence mass and the high hydrogen overpotential of zinc, which prevents a spontaneous dissolving of the Zn electrode in an aqueous and in particular alkaline electrolyte and simultaneously permits recharging with a high current efficiency.
In the case of rechargeable accumulators or battery systems, the problem is known that during recharging structural and shape changes occur at the metal electrodes or electrochemically active coatings. This problem has also been observed in the case of zinc/air depolarized batteries. The shape change of the metal electrode with an increasing number of recharging cycles, in certain circumstances and in a secondary manner, leads to internal short-circuits of the electrode or to passivation phenomena. Thus, with an increasing number of recharging cycles the electrode capacity drops, so that the life of the battery or battery system is drastically shortened.
The prior art has evolved numerous methods in order to reduce the harmful influences of structural and shape changes to the metal electrode or electrochemically active coatings of the actual shape change.
It is e.g. known to perform the recharging of the electrodes externally and a discharged battery to virtually renew from the beginning by a mechanical replacement of the spent electrodes by new electrodes.
Admittedly this enables a discharged battery after "recharging" with a new electrode to have the original battery capacity, but a rapid, flexible electrical recharging by the customer in suit is impossible. Thus, in the prior art manufacturing and marketing organizations for such battery systems have had to simultaneously offer a service for the reprocessing of discharged electrodes.
The prior art also discloses so-called magazine systems for receiving electrode configurations with a mechanically unstable, gel-like or pulverulent electrochemically active coating, which surrounds the corresponding electrode configurations and is intended to mechanically stabilize the coating. However, this mechanical stabilization relates to the electrode material as such, if it is e.g. a gel or a powder and is intended to facilitate the handling of the electrode configuration during change and incorporation. The structural and shape change of the electrodes during recharging, however, takes place on the microscopic and mesoscopic size scale and is not prevented in the known magazine systems.
The prior art also discloses so-called small-pored separators, which are substantially in contact with the electrode and in the case of certain electrode types reduces the extent of the structural and shape change on the electrodes during recharging caused by so-called electroosmosis. This procedure is possible with substantially soluble electrodes of the first type.
In the case of the latter, as a result of such a small-pored separator, the formation of electroosmotically driven convection currents and therefore the occurence of certain concentration gradients can be reduced, so that there can also be a reduction in the structural and shape changes of the electrode configuration during cyclic recharging.
However, in all these known measures and configurations according to the prior art, a considerable proportion of the structural and shape changes of the electrode configuration during cyclic recharging is not covered, so that only a very small number of recharging cycles is left for the user of a rechargeable battery system until the latter and in particular the electrodes contained therein have to undergo a fundamental renewal, which leads to not inconsiderable costs.