Batteries from a Printer
Researchers at the University of Jena have used screen printing to produce prototypes of very thin and flexible film batteries have used the screen printing process to produce prototypes of very thin and flexible batteries in the form of film. At present, these batteries still contain metals; in the future, it is expected that they will consist entirely of polymeric materials. Stable radicals with unpaired electrons are used to store the electrical energy. Examples of these so-called active units include nitroxide radicals or special acrylates such as PTMA. The structure of the active units determines the electric voltage of the batteries.
The batteries also contain conductive additives such as graphite or nanofibers, for instance, as well as a binder. In addition, the materials for the anode and cathode must be matched. Since a number of known cathode materials exist, research is concentrating on polymeric materials for the anode. Synthesis of the electrode mixture should be as simple and economical as possible in order to ensure low-cost industrial production.
These organic radical batteries have great potential for mass production, since the conductive polymers can be printed out in the form of a paste or liquid ink in a few minutes by means of screen or ink jet printing. When using ink jet printing, the shape of the battery can be customized to its application. With screen printing, thicker and thus more powerful batteries can be manufactured. According to the information provided, the batteries can be charged up to 1,000 times. The charging process lasts only a few minutes.
Of course, the paper-thin plastic batteries have considerably less capacity than conventional metal-containing rechargeable batteries. For many applications, however, this capacity is enough, for example, for LEDs or intelligent packaging that indicates whether the expiration date has been exceeded or the cold chain interrupted.
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