Designing chain-like nickel pyro-vanadate porous spheres as an advanced electrode material for supercapacitors

Abstract

Recently, porous-structured electrode materials with high electrochemical activity and redox chemistry have attracted widespread attention for the development of high-performance electrochemical supercapacitors. In the present study, porous Ni₂V₂O₇ microsphere-chains (NV MCs) were successfully prepared using a single-step synthesis via a facile propanetriol (PT)-assisted hydrothermal technique, followed by thermal decomposition. By varying the PT volume in the growth solution, the morphological evaluation of Ni₂V₂O₇ was performed. After thermal treatment, the crystallinity of NV MCs was improved along with the generation of nanocaves inside the MCs. Capitalizing on the advantages of high porosity, good crystallinity, and the open-apertures of the NV MCs, the prepared material demonstrated an excellent battery-type redox behavior with a high areal capacity of 65 μA h cm⁻² (at 2 mA cm⁻²) and good cycling stability of 82.3% (at 7 mA cm⁻²) in 1 M KOH electrolyte, which were comparatively higher than the samples prepared with various PT volumes. The improved performance in energy storage is predominantly attributed to the short-diffusion path owing to the bilaterally connected microspheres in the MCs and to the activation of the entire NV microspheres by the deep penetration of electrolyte into the nanocaves through the open-apertures of the MCs. This facile method for the preparation of porous metal vanadate nano/micro-architectures opens up a new avenue for the development of an efficient positive electrode material for energy storage devices.