Engineered morphologies of β-NiS thin films via anionic exchange process and their supercapacitive performance

This effort dispenses an unprecedented electrochemical performance of highly porous nano-needles, stacked nano-needles, nano-plates and nano-flowers like morphological beta-NiS thin films, synthesized through an anion exchange process using hydrothermally prepared Ni(OH)(2) thin films. The stacked nano-needle structured beta-NiS thin film shows maximum specific capacitance (C-s) of 415.78 Fg(-1) at current density of 0.5 mA cm-(2) in 2 M KOH electrolyte with electrochemical stability up to 91% after 2000 cyclic voltammetry (CV) cycles. In addition, symmetric flexible solid state supercapacitor (FSS-SCs) device fabricated using beta-NiS thin films and polyvinyl alcohol-lithium perchlorate (PVA-LiClO4) as a polymer gel electrolyte, shows acceptable C-s of 55.83 Fg(-1) at scan rate of 10 mV s-(1) within operating potential window of 1.2 V. The symmetric FSS-SCs device manifests maximum specific energy density of 9.30 Wh kg(-1) and specific power density of 666 Wkg(-1) along with better electrochemical stability of 90% after 1500 CV cycles. More interestingly, symmetric FSS-SCs device easily light up the panel of 40 red light emitting diodes (LEDs) texted as 'CDL' for 45 s after charging for 30 s. (C) 2016 Elsevier Ltd. All rights reserved.