Rapid and simplistic microwave assisted method to synthesise cobalt selenide nanosheets; a prospective material for high performance hybrid supercapacitor

Metal selenides, particularly transition metal selenides, are the superb potential electrode materials for electrochemical energy storage applications. Herein, the cobalt selenide (Co0.85Se) nanosheets are successfully synthesized by a rapid, simplistic, and economical technique via the microwave-assisted method. It is found that Co0.85Se achieves the large specific surface area (104 m(2) g(-1)), and delivers a higher specific capacitance (1580 F g(-1) at 1 A g(-1) and 500 F g(-1) at 20 A g(-1)) as a positive electrode for hybrid supercapacitor. Further, a full-cell hybrid supercapacitor is assembled by using Co0.85Se as an anode and activated carbon as the cathode, which shows excellent energy density 51.2 W h kg(-1) at power density 800 W kg(-1), and maintains 28.4 W h kg(-1) when power density increases to 12,800 W kg(-1). Moreover, the full-cell device shows remarkable stability of 10,000 cycles, having a wider operating potential window ranging from 0 to 1.6 V. Such excellent performance of Co0.85Se exhibits that it is a favorable material for the energy storage applications.