A novel ordered hollow spherical nickel silicate- nickel hydroxide composite with two types of morphologies for enhanced electrochemical storage performance

摘要

Herein, a facile strategy was developed for the preparation of a nanostructured nickel silicate-nickel hydroxide composite (NiSi-Ni(OH)2) with two types of morphologies, including coated hollow nanospheres (NiSi@Ni(OH)2) and platelet-assembled hollow spheres (Ni(OH)2-Si) as a positive electrode material in hybrid supercapacitors. This strategy involved the use of nano-sized SiO2 derived from the Stober method as the silicon source and a single-step hydrothermal method. The as-synthesized NiSi-Ni(OH)2 composite exhibited a battery-like redox behavior and relatively high charge storage property (476.4 F g1 at 2 A g1 ) when measured in a three-electrode system. It also delivered high stability during long-term cycling (103.3% after 10 000 cycles), which is mainly due to the synergistic effect after the combination of the two materials, where the hollow spherical structures facilitate the fast diffusion of electrolyte ions and enable the fast transmission of electrons. Considering its practical applications, a hybrid asymmetric supercapacitor (HSC) device was assembled using NiSi-Ni(OH)2 as the positive electrode and porous activated carbon as the negative electrode in PVA-KOH electrolyte gel.