Reduced graphene oxide/polyaniline/vanadium pentoxide/stannic oxide quaternary nanocomposite, its high energy supercapacitance and green electrolyte.

Challenge of achieving high energy density (E) comparable with Li-ion batteries in supercapacitors, with low potential window offering aqueous electrolytes (1.2 V) has been overcome by using the electrode material composed of rGO 3.70%:PANI 51.86%:V2O5 33.33%:SnO2 11.11% (GPVS). The GPVS exhibited different extents of energy storage in the presence of 1 M sulphuric acid (H2SO4) and acidified supernatant liquid (ASL), a green electrolyte. Here, the ASL is the by-product, which is obtained as supernatant liquid after the synthesis of GPVS composites in an in situ synthetic method, and acidified using conc. H2SO4. The energy storage obtained in the presence of ASL is 38% higher than the energy storage obtained in the presence of H2SO4. The GPVS exhibited a remarkable feature of amelioration of energy storage with increase in CV cycles in the presence of H2SO4. The GPVS exhibited an extraordinary cyclic stability up to 41,300 cycles. The energy storage parameters achieved in the presence of H2SO4 after 33,800 cycles are, a specific capacitance (Cs) of 694.44 F g‒1, an E of 138.88 W h kg‒1 (comparable with E of Li-ion batteries) and a power density (P) of 2.1020 kW kg‒1 at 1 A g‒1. The energy storage parameters achieved in the presence of ASL are, a Cs of 212.31 F g‒1, an E of 42.46 W h kg‒1 (comparable with E of Ni–Cd batteries) and a P of 3.1583 kW kg‒1 at 2 A g‒1. It is satisfying that all these high energy characters are achieved with the real two electrodes–supercapacitor cell step up. The green supercapacitors are made by using the by-product, which is obtained as supernatant liquid after the synthesis of GPVS as its electrolytes. [ABSTRACT FROM AUTHOR]