Ultrathin nanosheets of cobalt-nickel hydroxides hetero-structure via electrodeposition and precursor adjustment with excellent performance for supercapacitor

A homogeneous better-dispersed ultrathin nanosheets (ca. 5 nm) of cobalt-nickel layered double hydroxides (LDH) supported on nickel foam scaffold was synthesized using controllable electrodeposition approach for high efficiency electrode materials of new supercapacitor. The morphology and electrochemical performances of the samples can be controlled by adjusting the precursor ratio, i.e., Ni(OAc)(2)/Co(NO3)(2) molar ratio in the electrodeposition approach. With the increase of this molar ratio, the electrochemical performances give a volcano trend. When the optimized molar ratio is 0.64/0.36, the hybrid delivered a high specific capacitance of 1587.5 F g(-1) at a current density of 0.5 A g(-1), with good rate capability (1155 F g(-1) was retained even at 10 A g(-1)) and a robust recycle stability (remaining 91.5% after 10 0 0 cycles at 5 A g(-1)). The good performance could be attributed to the enlarged interlayer spacing, ultrathin nanosheets and synergistic effects between Co(OH)(2) and Ni(OH)(2). Furthermore, an asymmetric supercapacitor with a high energy density of 34.5 Wh kg(-1) at 425 W kg(-1) and excellent cycling stability of 85.4% after 50 0 0 charge-discharge cycles at 2 A g(-1) was fabricated. We believe that this fantabulous new electrode material would have encouraging applications in electrochemical energy storage and a wide readership. (C) 2017 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by Elsevier B.V. and Science Press. All rights reserved.