Highly stable lamellar array composed of CoSe2 nanoparticles for supercapacitors

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 CoSe 2 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 CoSe 2 /carbon (CoSe 2 /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 10,000 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 CoSe 2 particles, and confirm it is of great potential in application for stable supercapacitors.