Synthesis of Cobalt Sulphide Thin Film Electrode by Modified Chemical Bath Deposition Route and Its Supercapacitors Performance.

Abstract

Cobalt Sulphide (CoS) thin films were synthesized on stainless steel (SS) substrates using a modified chemical bath deposition route. The supercapacitive properties of this compound were studied by cyclic voltammetry, galvanostatic charge-discharge test and electrochemical impedance spectroscopy. The as-prepared CoS thin film electrode has excellent electrochemical capacitive characteristic with potential range 0 to +0.7 V Vs Ag/AgCl at constant concentration 2M KOH solution. In cyclic voltammetry (CV) studies, effect of scan rate reveal that the CoS electrodes yield values of 531 Fgm-1 and 244 Fgm-1 for specific capacitance at scan rates of 10 mVs-1 and 100 mVs-1 respectively. Effect of concentration of electrolyte shows that, the specific capacitances values are increased from 60 to 351 Fgm-1 with increasing the concentration 1 M to 3 M of KOH. Stability studies at 50 mVs-1 scan rate reveal that the specific capacitance values are decreased from 322 to 186 Fgm-1 with increasing number of scan cycle. Charge-discharge behaviors have been observed that the supercapacitive parameters such as, specific energy (S.E.), specific power (S.P.) and coulombic efficiency (η%) are 11.4 Whkg −1 , 7.4 KWkg −1 and 31%, respectively. Impedance spectroscopic analysis revealed that the equivalent series resistance (ESR) is 1.8 Ω at the imaginary axis.