Highly stable lamellar array composed of CoSe2 nanoparticles for supercapacitors

Abstract Two-dimensional hierarchical structures of transition metal selenides with more active sites and shorter electrolyte diffusion channels hold great potential for application in supercapacitors. A lamellar array electrode composed of well-patterned CoSe2 nanoparticles, using leaf-like ZIF-67 as a precursor, is successfully fabricated by a two-step calcination method. Primarily, the cobalt selenide particles were anchored to the carbon skeleton, as to obtain lammellar array and keep stable in electrochemical measurements. The novel CoSe2/carbon (CoSe2/C) electrode shows excellent electrochemical performance, with a specific capacitance of 462 F g-1 at a current density of 5 A g-1, and a 100% capacitance retention at 10 A g-1 after 10000 cycles. Meanwhile, an asymmetric supercapacitor is assembled and it exhibits an energy density of 20.6 Wh kg-1 with a power density of 698.8 W kg-1 and an outstanding cycling stability. Concisely, benefiting from the effective method of controllable morphology, we construct the lamellar array composed of CoSe2 particles, and confirm it is of great potential in application for stable supercapacitors.