NEW METHODS FOR THE SYNTHESIS OF LITHIUM-POLYACETYLENE INTERCALATION COMPOUNDS

We have developed new methods for the synthesis of large amounts of binary lithium-rich polyacetylene compounds. The first one consists in a direct reaction between powdered lithium and divided polyacetylene, under pressure and at room temperature. The richest yellow coloured compound obtained is formulated (Li0.16CH)(x). It has been characterized by diffraction techniques and it exhibits a RT electrical conductivity close to 250 S.cm(-1). The other methods are based on the electrochemical intercalation of polyacetylene into appropriate electrolytes presenting an extended redox stability especially at potentials close to that of metallic lithium. Both galvanostatic and cyclic voltammetry experiments give evidence for different reversible redox transformations. The richest compound synthesized by these electrochemical methods appears to be similar to the material obtained by our chemical method and therefore does not contain any trace of cointercalated solvent molecules. Some properties of the compounds described in this paper and of the complexes previously mentioned in the literature and synthesized by different techniques are discussed for comparison.