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

Abstract

This effort dispenses an unprecedented electrochemical performance of highly porous nano-needles, stacked nano-needles, nano-plates and nano-flowers like morphological β-NiS thin films, synthesized through an anion exchange process using hydrothermally prepared Ni(OH)2 thin films. The stacked nano-needle structured β-NiS thin film shows maximum specific capacitance (Cs) of 415.78Fg−1 at current density of 0.5mAcm−2 in 2M 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 β-NiS thin films and polyvinyl alcohol-lithium perchlorate (PVA–LiClO4) as a polymer gel electrolyte, shows acceptable Cs of 55.83Fg−1 at scan rate of 10mVs−1 within operating potential window of 1.2V. The symmetric FSS-SCs device manifests maximum specific energy density of 9.30Whkg−1 and specific power density of 666Wkg−1 along with better electrochemical stability of 90% after 1500CVcycles. More interestingly, symmetric FSS-SCs device easily light up the panel of 40 red light emitting diodes (LEDs) texted as ‘CDL’ for 45s after charging for 30s.