Performance evaluation of symmetric supercapacitor based on cobalt hydroxide [Co(OH)_2] thin film electrodes

摘要

In the present investigation, we have successfully assembled symmetric supercapacitor device based on cobalt hydroxide [Co(OH)_2] thin film electrodes using 1 M KOH as an electrolyte. Initially, potentiodynamic electrodeposition method is employed for the preparation of Co(OH)_2 thin films onto stainless steel substrate. These films are characterized for structural and morphological elucidations using X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. The XRD reveals formation of β-Co(OH)_2 material with hexagonal crystal structure. The SEM images show formation of nanoflakes like microstructure with average flake width 100 nm. Electrochemical characterizations of Co(OH)_2 based symmetric supercapacitor cell are carried out using cyclic voltammetry, charge-discharge and electrochemical impedance spectroscopy (EIS) techniques. In the performance evaluation the maximum values of specific capacitance, specific energy and specific power are encountered as 44 Fg~(-1), 3.96 Wh kg~(-1) and 42 kW kg~(-1). The value of equivalent series resistance (ESR) is estimated as 2.3 Ω using EIS.