The robust reduced graphene oxide (rGO)/vanadium pentoxide (V2O5) /polyaniline (PANI) nanocomposite with a weight percentage of rGO - 5.88%: V2O5 - 11.76%: PANI - 82.36%, was synthesized by facile insitu single step chemical method and fabricated into a supercapacitor device. The supercapacitor exhibited high energy density of 54.62 W h kg(-1) and an exceptionally high sustainability of its performance up to 13,000 rechargeable cycles at high charge/discharge rate. The high energy density was further confirmed when the supercapacitor containing the afore mentioned composite, acted as an excellent secondary power source to store and deliver energy for substantially long time when charged at an exceptionally high current using a commercial 9 V battery. Further, its energy storage and delivery capabilities were established by using it in a real time switched capacitor converter circuit and the obtained performance for potential step up and step-down purposes were gratifying. The obtained electrochemical parameters included a maximum specific capacitance of 273F g(-1) specific capacity of 327.6C g(-1), energy density of 54.62 W h kg(-1) and a power density of 1636.5 W kg(-1) at a current density of 1 A g(-1). (C) 2019 Elsevier Inc. All rights reserved.