Carbon-fiber composites of organometallic intercalated polyaniline and polypyrrole doped with sodium polystyrene sulfonate as electrodes for lithium-ion batteries

Carbon fiber (CF) composites of organometallic intercalated polyaniline (Pani) and polypyrrole (Ppy) doped with polystyrene sulfonate (PSS) were electrochemically synthesized and tested as electrodes for lithium-ion batteries. From the results obtained by cyclic voltammetry, X-ray photoelectron spectroscopy, and energy-dispersive X-ray spectroscopy, it was concluded that the incorporation of copper(II) ions in the polymeric composite was successfully attained by adsorption of Cu2+ ions and 2,5-dimercapto-1,3,4-thiadiazole (DMcT) monomers on the carbon microfibers. The experimental electrochemical impedance response of the obtained Pani(DMcT–Cu ion)/CF composite was simulated by adequate equivalent electrical circuits. After 20 charge/discharge cycles, the experimental discharge specific capacity of the Pani(DMcT–Cu ion)/CF composite was 118 mA h g−1 (100% coulombic efficiency) using a 1 mol L−1 LiClO4 solution in propylene carbonate, and 110 mA h g−1 when a polymeric electrolyte was used. In the charge/discharge tests of the Ppy-PSS/Pani/CF composite as anode, a high discharge specific capacity of 225 mA h g−1 was obtained after 20 cycles. The resulting Ppy-PSS/Pani/CF/polymeric electrolyte/Pani(DMcT–Cu ion)/CF battery presented a specific capacity of 62 mA h g−1 and could be charged up to 2.0 V, yielding an energy density 425 W h g−1, with a coulombic efficiency of about 98%.