Performance Comparison of Reduced Graphene Oxide (rGO)-polyaniline (PANI) Supercapacitors with LiCl, Li2SO4, and H2SO4 Electrolytes

Reduced graphene oxide (rGO)-polyaniline (PANI) supercapacitors (SCs) are tested with 1 M LiCl, Li2SO4, and H2SO4 electrolytes. The SC performance is evaluated by electrical impedance spectroscopy, cyclic voltammetry (CV), and galvanostatic charging/discharging measurements. Electrochemical experiments indicate that rGO-PANI SCs with lithium salt electrolytes show a large pseudocapacitance (PC) effect whereas that with H2SO4 electrolyte shows a large electrical double-layer capacitance (EDLC) effect. The rGO-PANI SC with H2SO4 electrolyte has the largest areal capacitance of 48.83 mF/cm2, whereas those with LiCl and Li2SO4 electrolytes have the areal capacitances of 31.69 mF/cm2 and 22.35 mF/cm2, respectively. After a 10,000-cycle CV stability test, the rGO-PANI SC with Li2SO4 electrolyte shows some ion embedding, resulting in better cycling stability than those of SCs with LiCl and H2SO4 electrolytes.