PANI/DBSA/H2SO4: A promising and highly efficient electrode material for aqueous supercapacitors

We report the utilization of polyaniline (PANI), co-doped with DBSA and sulfuric acid (PANI/DBSA/H2SO4), as a novel and promising electrode material for aqueous supercapacitors. The co-doped PANI/DBSA/H2SO4 salts were characterized by in situ conductance measurements, in situ UV-vis spectroelectrochemistry, cyclic voltammetry (CV) and UV-vis NIR spectroscopy. Elemental analysis of the synthesized PANI salt revealed its remarkable (50%) doping level while intrinsic viscosity indicated its highest molecular weight. Furthermore, PANI salt with best set of properties was tested for application in supercapacitors. For this purpose a systematic study was carried out in selected acidic electrolytes (HClO4, H2SO4, and H3PO4) by employing CV, Galvanostatic Charge-Discharge (GCD), and Electrochemical Impedance Spectroscopy (EIS). Different parameters such as applied potential limits, current density as well as type and concentration of electrolytes were optimized. The kinetics of the electrochemical degradation as well as specific capacitance of the PANI film was determined in the above mentioned electrolytes, which helped in choosing the appropriate conditions and electrolyte for the maximum exploitation of this material for supercapacitor. All the results suggest 0.5 M HClO4, along with other optimized parameters, as the most appropriate electrolyte solution. The PANI film showed electroactivity even after 6000 cycles applied through cyclic voltammetry. A capacitance retention of 57% after 1000 charge discharge cycles was observed in this electrolyte. Similarly, the film exhibited a specific capacitance value of 516 F g−1 with a relatively high energy density and power density of 34 W h kg−1 and 11.51 K W kg−1, respectively. As compared with the literature, the prepared polymer can be used as an electrode material for supercapacitors.