Electropolymerization of ionic liquid substituted polyphenylene as supercapacitors materials

A new type of polyphenylene, ionic liquid (IL) 1,3-methylimidazolium hexafluorophosphate substituted, has been prepared by electrodeposition on Au electrode surface via pulse galvanostatic method in 1-butyl-3-methylimidazolium hexafluorophosphate solution. The obtained polymer film had a spherulitic morphology with smallest grains of around 500 nm. Infrared spectrometry revealed that polyphenylene was deposited to a certain extent. The capacitive behavior of the IL substituted polyphenylene was investigated by cyclic voltammetry (CV) and galvanostatic charge–discharge method in 0.2 mol L⁻¹ H₂SO₄ aqueous solutions or pure IL bmim]PF₆. The specific capacitance of the polymer at the charge–discharge current density of 1 mA cm⁻² equaled 206 F g⁻¹ in acidic aqueous solution or 164 F g⁻¹ in bmim]PF₆. Additionally, excellent charge–discharge cycle stability (over 85% value of specific capacitance remained after 600 charge–discharge cycles) and power characteristics of the polymer electrode were observed in both electrolytes.