Surface Enhanced Raman Scattering Studies on Poly(3,4-ethylene dioxythiophene)/Single-Walled Carbon Nanotubes Composites and Their Application to Rechargeable Lithium Batteries

In this paper, surface enhanced Raman scattering (SERS) studies on the chemical polymerization of 3,4-ethylene dioxythiophene (EDOT) in the presence of single-walled carbon nanotubes (SWNTs) are reported. Both a non-covalent and covalent functionalization of SWNTs with poly(3,4-ethylene dioxythiophene) (PEDOT) is invoked as a result of the following variations induced in the SERS spectra of PEDOT and SWNTs: (i) the appearance of a Raman line at 140 cm⁻¹ indicating the formation of a new covalent bond between PEDOT and SWNTs; (ii) an increase in the intensity of the Raman line at 705 cm⁻¹, associated with the deformation vibration mode of C–S–C bond, the result of a steric hindrance effect induced by the bonding of PEDOT on SWNTs; and (iii) the enhancement of the Raman band with maximum at 1540 cm⁻¹ (G⁻ component) in SWNTs when the PEDOT weight in the PEDOT/SWNTs composite increases. Using the PEDOT/SWNTs composite as a positive electrode and an electrolytic solution containing LiPF₆, the charge–discharge characteristics of the rechargeable lithium cells are determined. High specific discharge capacity are reported for the PEDOT/SWNTs composite (ca. 218 mAh g⁻¹ in comparison with PEDOT doped with FeCl⁻₄ ions (ca. 25 mAh g⁻¹).