Poly(p-phenylenediamine)/graphene nanocomposites for supercapacitor applications

Herein, we report new nanocomposite materials based on poly(p-phenylenediamine) (PpPD) and hydrogen exfoliated graphene (HEG) sheets as efficient binder-free electrode materials for supercapacitors. The nanocomposites are synthesized via chemical oxidative polymerization of a para-phenyldiamine monomer in the presence of graphene sheets in acidic medium. The initial weight ratio of monomer to graphene is varied to get nanocomposites of different polymer to graphene weight ratios. The electrochemical performances of these nanocomposites as a supercapacitor electrode are investigated by cyclic voltammetry (CV), chronopotentiometry (CP) and electrochemical impedance spectroscopy (EIS) techniques in two electrode configuration. The nanocomposite with polymer to graphene weight ratio 1 : 2 shows a maximum specific capacitance of 248 F g(-1) at a specific current density of 2 A g(-1) and also demonstrates high rate capability. The maximum energy density of the fabricated symmetrical supercapacitor cells based on the mass of active electrodes is calculated to be 8.6 W h kg(-1) and 5.8 W h kg(-1) at a power density of 0.5 kW kg(-1) and 5 kW kg(-1), respectively. The nanocomposites retain 72% of their initial capacitance after 1000 cycles of charge-discharge at a high specific current density of 10 A g(-1).