Poly(pyrrole) and poly(thiophene)/vanadium oxide interleaved nanocomposites: positive electrodes for lithium batteries

Lithium insertion has been examined in a series of conductive polymer-V2O5 nanocomposites that have a structure comprised of layers of polymer chains interleaved with inorganic oxide lamellae. Poly(pyrrole), [PPY]; poly(aniline) [PANI]; poly(thiophene), [PTH] and its derivatives constituted the polymer component; PTH was prepared from the monomers bithiophene, terthiophene, 3-methylthiophene and 2,5-dimethylthiophene. Compositions of the corresponding nanocomposites were [PANI]0.4V2O5, [PPY]xV2O5 (x≈0.4, 0.9), and [PTH]xV2O5 (x≈0.3–0.8). We find that for modified [PANI]0.4V2O5, polymer incorporation results in better reversibility, and increased Li capacity in the nanocomposite compared to the xerogel. For PPY and PTH nanocomposites, the electrochemical response is highly dependent on the preparation method, nature of the polymer, and its location. Reversible Li insertion was maximized in the case of PTH when it was prepared from 3-methyl or terthiophene as the monomers, suggesting that chain conjugation length and polymer order area important factors. In some of these materials, the Li insertion capacity can be increased by 40% by subjecting the electrode to an initial charge step.