Surfactant-assisted electrochemical deposition of α-cobalt hydroxide for supercapacitors

A N-methylpyrrolidone (NMP) assisted electrochemical deposition route has been developed to realize the synthesis of a dense α-Co(OH)2 layered structure, which is composed of nanosheets, each with a thickness of 10 nm. The capacitive characteristics of the as-obtained α-Co(OH)2 are investigated by means of cyclic voltammetry (CV), charge/discharge characterization, and electrochemical impedance spectroscopy (EIS), in 1 M KOH electrolyte. The results indicate that α-Co(OH)2 prepared in the presence of 20 vol.% NMP has denser and thin layered structure which promotes an increased surface area and a shortened ion diffusion path. The as-prepared α-Co(OH)2 shows better electrochemical performance with specific capacitance of 651 F g−1 in a potential range of −0.1 to 0.45 V. These findings suggest that the surfactant-assisted electrochemical deposition is a promising process for building densely packed material systems with enhanced properties, for application in supercapacitors.