Stable deep doping of vapor-phase polymerized poly(3,4-ethylenedioxythiophene)/ionic liquid supercapacitors

Liquid-solution polymerization and vapor-phase polymerization (VPP) have been used to manufacture a series of chloride- and tosylate-doped poly(3,4-ethylenedioxythiophen(PEDOT) carbon paper electrodes. The electrochemistry, specific capacitance, and specific charge were determined for single electrodes in 1-ethyl-3-methylimidazolium dicyanamide (emim dcionic liquid electrolyte. VPP-PEDOT exhibits outstanding properties with a specific capacitance higher than 300 Fg-1, the highest value reported for a PEDOT-based conducting polymer, and doping levels as high as 0.7 charges per monomer were achieved. Furthermore, symmetric PEDOT supercapacitor cells with the emim dca electrolyte exhibited a high specific capacitance (76.4 Fg^-1) and high specific energy (19.8 Whkg^-1). A Ragone plot shows that the VPP-PEDOTcells combine the high specific power of conventional (“pure”) capacitors with the high specific energy of batteries, a highly sought-after target for energy storage.