Superior mixed Co-Cd selenide nanorods for high performance alkaline battery-supercapacitor hybrid energy storage

Battery-supercapacitor hybrid (BSH) devices are regarded as promising energy storage systems to accomplish remarkable electrochemical properties with high energy and power performances. In this work, mixed Co-Cd selenide (Co-Cd-Se) nanorods are fabricated on nickel foam via a two-step hydrothermal route. The obtained selenide shows a specific capacity of 124 mAh g−1 at a high current density of 20 A g−1, and 95.3% capacity retention can be obtained after cycling 1000 times at 2 A g−1. This excellent performance suggests its potential application as a superior cathode in BSH systems. By paring the prepared Co-Cd-Se cathode with a carbon-coated Fe nanoparticle anode, an alkaline aqueous BSH system is assembled, which shows high energy/power density with good cycling stability. Two cells in series can easily light a light-emitting diode lamp brightly, further demonstrating the high energy storage capability of the prepared Co-Cd-Se mixed selenide material.