LAUSR

A new composite NbOF–GO and FeOF–GO electrode material was synthesized by the screw-capped pressure tube method for a supercapacitor with specific capacitance values of 599 and 459 F g−1 at current densities of 0.5 and 0.2 A g−1. The NbOF–GO electrode has excellent cycling stability (capacitance retention of 88% after 5500 cycles at a current density of 5 A g−1), possesses a cubic morphology and excellent surface area, and it improves the number of ions near the surface area for charge storage, in addition to shortening the ion distance over a thin dimension and it is reported to have excessive specific capacitance. The synthesized asymmetric supercapacitor (ASC) device produces a maximum voltage of up to 1.2 V, a high specific energy of 51 W h kg−1 and a specific power of 1496 W kg−1, with an excellent cycling lifespan of only 2% capacitance loss after 10 000 cycles.