AN IN SITU EPR STUDY OF ELECTROCHEMICALLY DOPED TRANS POLYACETYLENE

Nous avons étudié par EPR in situ, pendant des cycles charge/décharge répétés, le comportement d'une batterie comprenant une cathode de trans polyacétylène (PA) et une anode d'un alliage Li/Al. La diminution du rapport A/B observée est consistante avec une diminution de la conductivité dans l'état dopé, tandis que l'invariance de la largeur de raie EPR, avant et après dopage, suggère qu'une disparition massive de la conjugaison des chaines ne se produit pas pendant les cycles charge/décharge.An in situ EPR study has been carried out during repeated charge/discharge cycles of a battery consisting of trans polyacetylene (PA) as the cathode and Li/Al alloy as the anode. The detected spin concentration reversibly increased by less than a factor of two and the maximum A/B ratio decreased with each repeated cycle for ClO4- in propylene carbonate and BF4- in sulfolane as the dopants. While this decreasing A/B ratio is consistent with decreasing conductivity in the doped state, the observed invariance of ESR linewidth before and after doping suggests that massive disruption of chain conjugation does not occur during battery cycling