Abstract
This work reported the synthesis of cobalt hydroxide using different cobalt precursors via a simple, operable and rapid microwave-assisted method and their electrochemical capacitors application. The experimental results demonstrated that cobalt precursors remarkably impacted on not only microscopic dimensions and morphologies but also crystalline phase. Especially, the loose-packed lamellar a-cobalt hydroxide was synthesized using cobalt sulfate as the precursor. The electrochemical properties of the as-obtained samples were investigated in detail by cyclic voltammetry and galvanostatic charge/discharge tests. The results of electrochemical tests demonstrated that the loose-packed lamellar structure endowed the cobalt hydroxide with a superior specific capacitance of 711.3 F/g in a potential window of 0-0.55 V. In addition, the asymmetric supercapacitor, fabricated by using the obtained cobalt hydroxide as positive electrode material and oxygen-rich porous carbon as negative electrode material, exhibited excellent rate performance. This work held an important guideline value for the development of cobalt-based electrochemical capacitors. (C) 2015 Elsevier B.V. All rights reserved.