Electrochemical Preparation of Porous Poly(3,4-ethylenedioxythiophene) Electrodes from Room Temperature Ionic Liquids for Supercapacitors

Abstract

© 2016 The Electrochemical Society.Poly(3,4-ethylenedioxythiophene) (PEDOT) electrodes were prepared using current pulse method from different room temperature ionic liquids electrolytes (1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([BMI][TFSI]), 1-butyl-3-methylimidazolium tetrafluoroborate ([BMI][BF4]), 1-allyl-3-(2-methoxyethyl)-imidazolium bis(trifluoromethylsulfonyl)imide ([AMO][TFSI]), and organic solution (0.1 M LiClO4 in acetonitrile)). The SEM and XPS studies show that the PEDOT films electropolymerized in [BMI][BF4] are highly porous and have a higher anion doping level than those electropolymerized in [BMI][TFSI], [AMO][TFSI], and LiClO4/ACN electrolytes. The electrochemical performance of the symmetrical supercapacitor based on PEDOT electrodes were investigated in 0.1 M KClO4 aqueous electrolyte by cyclic voltammetry and galvanostatic chargedischarge test. The PEDOT electrodes prepared from ionic liquids exhibit higher capacitative performance than those prepared from conventional solvent (ACN). Especially, the PEDOT electrodes prepared from a [BMI][BF4] ionic liquid exhibited high specific capacitance (191 F/g) with an obvious improvement in energy density and power density as comparison to the PEDOT electrodes prepared from ACN solution (100 F/g) in aqueous electrolyte. The symmetrical supercapacitor based on PEDOT electrodes prepared from [BMI][BF4] ionic liquid shows maximum specific energy of 5.37 Wh/Kg and good cycle durability. This study shows using ionic liquids as electrolytes for preparing PEDOT electrodes is an efficient way to improve performance of supercapacitors.