Porous Co(OH)2/Ni composite nanoflake array for high performance supercapacitors

Porous Co(OH)(2)/Ni composite nanoflake array is prepared by combing hydrothermal synthesis and electrodeposition methods. The as-prepared Co(OH)(2)/Ni composite nanoflake array exhibits a highly porous array structure composed of free-standing nanoflakes with thicknesses of 35-40 nm. The pseudocapacitive behavior of the Co(OH)(2)/Ni composite nanoflake array is investigated by cyclic voltammograms (CV) and galvanostatic charge-discharge tests in 2 M KOH. As cathode material for supercapacitor, the porous Co(OH)(2)/Ni composite nanoflake array exhibits weaker polarization, higher electrochemical activity and better cycling performance as compared to the unmodified Co(OH)(2) nanoflake array. The Co(OH)(2)/Ni composite nanonake array shows specific capacitances of 1310 F g(-1) at 1 A g(-1) and 1148 F g(-1) at 40 A g(-1), much higher than those of the unmodified Co(OH)(2) nanoflake array (1017 Fg(-1) at 1 A g(-1) and 775 F g(-1) at 40 A g(-1)). The enhancement of supercapacitor properties is due to the introduction Ni in the composite array, which improves the electric conductivity of the film electrode with fast reaction kinetics. (C) 2012 Elsevier Ltd. All rights reserved.