ELECTROCHEMICAL LI INSERTION INTO CONDUCTIVE POLYMER V2O5 NANOCOMPOSITES/

Electrochemical insertion of Li into a series of ''nanocomposites'' co mprised of alternating V2O5 sheets and conductive polymer layers [poly pyrrole (PPY) and polyaniline (PANI)] was examined and compared to the pristine V2O5 material in terms of reversibility, Li site occupancy, and Li diffusion coefficients, and to the materials after oxidation tr eatment. The electrochemical characteristics are very sensitive to the nature of the polymer, its content, and location. The presence of sur face polymer hinders Li insertion in these materials (by comparison to materials without surface polymer) and appears to result in the parti al entrapment of Li ions. For modified [PANI](0.4)V2O5, polymer incorp oration results in better reversibility and increased Li capacity in t he nanocomposite. [PPY](0.40)V2O5 displays a greater first discharge c apacity than the respective PANI material, but is not as cyclable as i n O-2-[PANI](0.40)V2O5. O-2-treatment results in the reformation of a high-potential Li site that is lost during the reductive intercalative polymerization. Li chemical diffusion coefficients are greater for th e O-2-[PANI]V2O5 nanocomposite than the xerogel by one order of magnit ude, resulting in better performance at high current densities. Most i mportant, the electrochemical response of these nanocomposites is grea ter than the sum of the two components (inorganic and organic), underl ining the synergy of these hybrid materials.