Multiphase Cu-Ni selenide nanocomposite electrode materials for high-performance hybrid supercapacitors

Metal vanadates/selenides are an advantageous electrode candidate for energy storage and conversion devices, owing to their low cost, good structural stability, high electroactivity, and abundance. Herein, firstly, copper oxide/nickel-vanadium oxide (CuO/Ni3V2O8) (CuO/NVO) nanosheets were rationally prepared via a facile hydrothermal method, followed by calcination process. Furthermore, the evolution of morphology was systematically examined at different growth times of 7, 9, and 11 h. Among the prepared samples, the CuO/NVO electrode synthesized for 9 h (CuO/NVO-9 h) revealed a high areal capacity (CA) value of 183.1 µAh cm−2 (specific capacity (CS) value of 89 mAh g−1). Additionally, to boost the electrochemical performance of the CuO/NVO-9 h electrode, selenium (Se) was introduced in the N2 gas atmosphere. The resultant Cu6.0Se5.22/Ni2.0V4.0Se8.0 (CuSe/NiVSe) electrode with mixed morphology exhibited an improved CA value of 236.1 µAh cm−2 (CS value of 94.4 mAh g−1) with good cycling retention of 103.8%. Moreover, the constructed CuSe/NiVSe(+)//AC(−) hybrid supercapacitor (HSC) device delivered a good energy density value of 0.173 mWh cm−2 (40.7 Wh kg−1) at a power density value of 16.1 mW cm−2 (3040.4 W kg−1). Finally, the real-time application of the HSC device was also tested by energizing various electronic gadgets.