The rational investigation of bimetallic selenides as electrode materials for hybrid supercapacitors

Cobalt is an ideal material for application in energy storage devices owing to its superior stability and redox activity. However, there has been a rise in demand for cobalt-based energy storage devices, which cannot be satisfied because of cost considerations. To balance demand and cost, cost-effective alternatives like copper can be envisaged. The present work underlines the potential of nickel-copper selenide as a suitable replacement for nickel-cobalt selenide electrodes for hybrid supercapacitor (HSCs) application. In half cell testing, NiCuSe and NiCoSe deliver a specific capacity of 127.2 mAh g−1 and 177.2 mAh g−1, respectively, at a current density of 3 A g−1. NiCuSe exhibits more stable charge storage than NiCoSe at high current densities owing to its superior conductivity. Aqueous HSCs, NiCuSe// modified activated carbon (MAC) and NiCoSe//MAC deliver an energy density and power density of 26.56 Wh kg−1 at 2.732 kW kg−1 and 28.78 Wh kg−1 and 2.571 kW kg−1, respectively. NiCuSe//MAC shows superior rate capability, and both devices exhibit superior cycle life for 12,000 cycles. [Display omitted] .