Binder-Free Hierarchical Urchin-like Manganese–Cobalt Selenide with High Electrochemical Energy Storage Performance

Transition metal selenides are widely considered as good electron conductor materials, showing bright prospect in energy storage and conversion. However, binary metal selenides as supercapacitor electrode materials are rarely reported. Herein, a simple and binder-free hydrothermal method is employed to grow hierarchical urchin-like MnCo-selenide on nickel foam. The unique hierarchical microstructure, synergetic effect, and excellent conductivity enable the electrode exhibit outstanding supercapacitor performance compared with counterpart oxide and sulfide, including high specific capacitance (1656 F g–1 at 1 A g–1) and extraordinary cycle performance (8.2% capacity decline after 8000 cycles). Additionally, the asymmetric supercapacitor (ASC), employing MnCo-selenide and AC as anode and cathode, exhibits remarkable energy density of 55.1 Wh kg–1 at 880 W kg–1, confirming the as-prepared urchin-like MnCo-selenide is a satisfactory material for the energy storage system.