Nanoflake-like cobalt hydroxide/ordered mesoporous carbon composite for electrochemical capacitors

Nanocomposites consisting of mesoporous carbon CMK-3 and cobalt hydroxide nanoflakes are synthesized by a chemical precipitation method. The successful growth of nanometer-sized Co(OH)(2) flakes on the surface of CMK-3 is confirmed by scanning electron microscopy. The Co(OH)(2)/CMK-3 composite electrodes are investigated for its use in the electrochemical capacitors with cyclic voltammograms, chronopotentiometric measurements, and electrochemical impedance spectroscopy. Experimental studies reveal that the Co(OH)(2)/CMK-3 composite electrode with the 20 wt.% CMK-3 presents excellent electrochemical performance with specific capacitance of 750 F/g (or 910 F/g after being corrected for the weight percentage of the Co(OH)(2) phase). The overall improved electrochemical behavior accounts for the unique structure design in the Co(OH)(2)/CMK-3 composite in terms of porous nanostructure, large specific surface area, and good electrical conductance. The Co(OH)(2)/CMK-3 composite electrode also shows better rate capability and cyclic stability, suggesting its potential applications as the electrode materials for electrochemical capacitors.