Cobalt hydroxide nanoflakes prepared by saccharide-assisted cathodic electrochemical deposition as high performance supercapacitor electrode material

Abstract

Cobalt hydroxide flake-like nanostructures are prepared through green electrochemical synthesis procedure. In this way, an aqueous solution of 0.005M cobalt chloride and 1g/L starch was used as an electrosynthesis bath. The cobalt hydroxide deposit was prepared in a two-electrode system containing stain less steel cathode and graphite anode by applying current density of 10 mA cm-2. The structural characterization by XRD, IR, FE-SEM and TEM confirmed that the deposited sample is composed of β-cobalt hydroxide with flake-like morphology. The charge storage ability of the prepared nanoflakes was further evaluated using cyclic voltammetry (CV), galvanostat charge-discharge (GCD) cycling and electrochemical impedance spectroscopy (EIS). The electrochemical measurement revealed that the prepared cobalt hydroxide has low equivalent series resistance (Rs) and charge transfer resistance (Rct), which enabled the fabricated electrode to deliver specific capacitances as high as 1125.4, 992, 849.3, 701.6 and 452.5 F g-1 at 1, 2, 3, 5 and 10 A g-1, respectively, and capacity retentions 93.48% and 80.17% after 2000 GCD at the current loads of 1 and 5 A g-1. These results supported the proper characteristics of the prepared nanomaterials for the supercapacitor applications.