Optimization of metal-organic framework derived transition metal hydroxide hierarchical arrays for high performance hybrid supercapacitors and alkaline Zn-ion batteries

The rational microstructure design of transition metal compound arrays using metal-organic frameworks (MOFs) as intermediates has been proved effective but is very challenging to achieve high electrical energy storage capacity. Herein, we report the synthesis of a Setaria viridis-like multi-component core-shell nanostructure, Co(OH)2@NiCo-layered double hydroxide nanowire arrays (A-Co(OH)2@NiCo-LDH), directly on carbon fiber cloths. The Setaria viridis-like unique nanostructure provides a large surface area, rich redox active sites, and stable microstructure for electrical energy storage. Consequently, the as-prepared A-Co(OH)2@NiCo-LDH hierarchical array exhibits a high specific capacity of 285.9 mAh g-1 at 0.5 A g-1. Moreover, the electrode exhibits an excellent capacity retention of 72.9% in the range from 0.5 A g-1 to 50 A g-1. A hybrid supercapacitor (HSC) and an alkaline Zn-ion battery (AZIB) based on the A-Co(OH)2@NiCo-LDH cathode were assembled for practical application, which delivered outstanding energy densities of 40.6 Wh kg-1 (at a power density of 1.78 kW kg-1, based on the mass of the active materials of both electrodes) and 489.6 Wh kg-1 (at a power density of 0.38 kW kg-1, based on the mass of the A-Co(OH)2@NiCo-LDH cathode) and long lifetimes of 10 000 and 1000 GCD cycles, respectively. The excellent electrochemical performance of A-Co(OH)2@NiCo-LDH proves its great promise as an electrode material for fabricating advanced energy storage devices for industrial applications.