High performance graphene-poly (o-anisidine) nanocomposite for supercapacitor applications

Our previous exciting results on graphene (G)-conducting polymer (polyaniline (PANI) and polyethylenedioxythiophene (PEDOT)) supercapacitors have prompted the investigation of G-substituted conducting polymer nanocomposites used as electrode materials in supercapacitors. The solubility of ortho-substituted PANI derivatives in a few common solvents has allowed the fabrication of stretchable films by the casting technique. The G-poly (o-anisidine) (G-POA) nanocomposites were synthesized with different weight ratios of G to o-anisidine by chemical methods, and characterized by various techniques, such as, scanning electron microscopy, transmission electron microscopy, UV-visible spectroscopy, Raman spectroscopy, thermogravimetric analysis and cyclic voltammetry. The electrical conductivity and specific capacitance obtained for the G-POA nanocomposites were found to be dependent on the weight ratios of G to o-anisidine. The specific capacitance and the charging-discharging behavior of the POA and G-POA supercapacitors were investigated in a 2 M H2SO4, 0.2 M LiClO4 and 1 M 1-butyl-3-methylimidazolium hexafluorophosphate (BMIM-PF6) ionic liquid. The specific capacitance of 380 F g−1 was calculated for the 1:1 weight ratio of G to o-anisidine based G-POA supercapacitor in 2 M H2SO4. The presence of the electron-donating group (-OCH3) in the o-anisidine allows the electrons through the lone pair of nitrogen atoms to enhance the electronic charge transport inside the G-POA supercapacitor electrodes. However, the G-POA-based supercapacitors showed a 27% decrease in the specific capacitance in H2SO4 and 16% decrease in the ionic liquid (BMIM-PF6) after 1000 cycles of charging and discharging. The higher stability and rate capability of the G-POA based supercapacitor in an ionic liquid (BMIM-PF6) as compared to an aqueous electrolytic supercapacitor opens the door for the fabrication of stable supercapacitors for practical applications.