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 nanoflake 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 F g−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.