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DEVELOPMENT OF SECONDARY POLYMER CELLS FOR CONSUMER APPLICATIONS

Objective


A major issue of electrolyte investigation is the development of electrolytes showing specific conductivity, even at high concentrations. Electrolytes with high concentrations are required for cells with positive polymer electrodes, where an exchange of anions between electrolyte and electrode is involved in the polymer's redox reaction. Common electrolytes like Li Cl O4- propylene carbonate (PC) exhibit maximum molarities of 3 mole/ kg and maximum conductivity of 4 Ms/cm. New electrolytes with maximum concentrations up to 13 mole/kg and maximum conductivity up to 33 Ms/cm were found.

First experiments on positive electrode materials showed that polyaniline, synthesized by common methods, is a promising candidate. These materials show superior, specific capacities of more than 100 Ah/kg over more than 100 cycles.

It was found that polyanilines prepared by common methods have extremely high contents of carcinogenic benzidine as an undesirable side product. As a result of this observation, further work concentrated on developing polyanilines with tolerable benzidine content. These new polyanlile types have acceptable benzidine contents - less than 100 parts per million. but this material does not show sufficient specific capacities to allow application.

Continued development of alternative redox polymers produced polymers with good electro-activities but poor specific capacities (less than 30 Ah/kg) and poor cycle lives, but with possibilities for being processed easily into various battery forms.

Considerable attention was also focused on developing suitable negative counter electrodes and electrolytes. The cycling efficiency and specific capacity of these components strongly affect the energy density of the target cell.

As a result of the negative electrode development, a thin layer of lithium aluminium electrodes was obtained, showing superior cycle life (over 500 cycles) and a capacity of 380 Ah/kg.
IT HAS BEEN DEMONSTRATED THAT ELECTRICALLY CONDUCTING POLYMER MATERIALS CAN BE USED PRINCIPALLY FOR ELECTRODES OF RECHARGEABLE BATTERIES.

HOWEVER, VERY LITTLE KNOWLEDGE IS AVAILABLE ON THE DETERIORATION REACTIONS OF POLYMER ELECTRODES DURING CYCLING AND SELF DISCHARGE. THE DEVELOPMENT OF AN APPROPRIATE ELECTRODE STRUCTURE IS STILL IN A PRIMITIVE STAGE.

THE OBJECTIVE OF THE PROGRAMME IS TO DEVELOP PROTOTYPE RECHARGEABLE CELLS USING IN A FIRST STEP POLYMERS ALREADY EXISTING AND, IN A SECOND STAGE, NEW POLYMERS TO SERVE AS ELECTRODE MATERIALS WITH A HIGHER ENERGY DENSITY THAN PRESENT SYSTEMS.

Funding Scheme

CSC - Cost-sharing contracts

Coordinator

Commissariat à l'Energie Atomique (CEA)
Address
Centre D'études De Grenoble Avenue Des Martyrs
38041 Grenoble
France

Participants (3)

BASF AG
Germany
Address
Carl-bosch-straße 38
67063 Ludwigshafen
National Institute for Higher Education-Dublin
Ireland
Address
Glasnevin
9 Dublin
Varta Batterie AG
Germany
Address
Gundelhardtstraße 72
65779 Kelkheim