Amorphous nanosheets constructed nickel cobalt hydroxysulfide hollow spheres as cathode materials for hybrid supercapacitors

Abstract

Tailoring architecture and multi-composition of electrode materials via a facile and cost-effective strategy are highly favorable to optimize physiochemical properties for developing energy storage devices. Herein, hierarchical nickel cobalt hydroxysulfide hollow spheres decorated with amorphous nanosheets and dual-ligands (denoted as NiCo-DHS) are synthesized through hydrolysis of self-templating metal alkoxides, followed by room-temperature anionic exchange process. The resultant dual-ligands hydroxysulfide possesses weak metallicity, reduced band gap and enhanced conductivity owing to the electronic regulation of the formed M−OH/S bonds. Additionally, the nanosheet-constructed amorphous structure contributes to accelerating ions diffusion and enlarging specific surface area, further exposing more active sites to enrich redox reactions. Benefiting from the compositional and structural superiorities, the optimized NiCo-DHS-12 electrode presents desirable electrochemical performance, including high specific capacity of 973.6 C g−1 (1 A g−1) and stable durability over 8000 cycles with a small capacity loss of 7.4 % at 10 A g−1. Moreover, the hybrid device assembled with NiCo-DHS-12 and porous activated carbon delivers an energy density of 65.91 Wh kg−1 at a power density of 0.89 kW kg−1 and considerable cycling stability. These encouraging results demonstrate a simple and reliable approach in constructing high-performance electrode materials for advanced supercapacitors in potential.