Core–Shell Structured Ws2Nixcoys4 Composites and Activated Carbon Derived from Rose Flowers as High-Efficiency Hybrid Supercapacitors

Abstract: Hybrid supercapacitors (HSC) have the advantages of high output power and long service life, and are considered as a kind of efficient and practical energy storage device. For improve the electrochemical performance in terms of specific capacitance, rate performance and cyclic stability, a metal-organic frameworks (MOFs)-encapsulated-polyoxometalate (POM)-template strategy followed vulcanization was employed for core-shell structure electrode materials. As a result, a series of core-shell structures WS2@NixCoyS4 using phosphotungstate/metal-organic framework as precursors by two-step hydrothermal method, and systematically studied the effect of Ni and Co ratio on the morphology and electrochemical properties of the composites. The core-shell structure exposes many active sites for fast Faraday reactions and ensures the high utilization of electrode materials. It was found that the battery-type WS2@Ni2.62Co1.10S4 electrode material has a high specific capacitance of 1920.3 F·g-1 at 1 A·g-1 and good rate performance as well as excellent cycle stability. Biomass carbon with layered porous structure was prepared by activating rose with salt sealing technology, which showed good electrochemical performance. Using this carbon as the negative electrode and WS2@Ni2.62Co1.10S4 as positive electrode a hybrid supercapacitor device was assembled and it exhibited a superior potential window and high energy density, and could also light up small bulbs. Based on these good properties, the designed HSC device has substantial application prospects