Novel organic–inorganic poly (3,4-ethylenedioxythiophene) based nanohybrid materials for rechargeable lithium batteries and supercapacitors

Synthesis and characterization of poly (3,4-ethylenedioxythiophene) (PEDOT) interleaved between the layers of crystalline oxides of V and Mo is discussed with special emphasis on their application potential as electrodes for rechargeable Li batteries and supercapacitors. The expansion of the interlayer spacing of crystalline oxides (for example, V2O5 causes expansion from 0.43 to 1.41 nm) is consistent with a random layer stacking structure. These hybrid nanocomposites when coupled with a large-area Li foil electrode in 1 M LiClO4 in a mixture of ethylene and dimethylcarbonate (1:1, v/v), give enhanced discharge capacity compared to pristine oxides. For example a discharge capacity of~350 mAh g−1, in the potential range 4.2–2.1 V (versus Li+/Li) is obtained for PEDOT–V2O5 hybrid which is significantly large compared to that for simple Li-intercalated V2O5. The improvement of electrochemical performance compared with that of pristine oxides is attributed to higher electric conductivity, enhanced bi-dimensionality and increased structural disorder. Although these conducting polymer-oxide hybrids delivered more than 300 mAh g−1 in the potential range 1.3–4.3 V, their cycle life needs further improvements to realize their commercial potential. Similarly, the double layer capacitance of MoO3 increases from~ 40 mF g−1 to~ 300 F g−1 after PEDOT incorporation in the interlayer gap of MoO3 under similar experimental conditions and the nanocomposite displays intriguing effects with respect to electrochemical Li+ insertion. The PEDOT–MoO3 nanocomposite appears to be a promising electrode material for non-aqueous type supercapacitors.