Porous nanorods of nickel-cobalt double hydroxide prepared by electrochemical co-deposition for high-performance supercapacitors

Nickel-cobalt double hydroxides (Ni-Co DHs) combined with cost-effectively commercial expanded graphite (EG) was prepared via a facile in situ electrodeposition in mixed solvents of N,N-dimethylformamide and water. By simply adjust molar ratios of Ni2+/Co2+ a Ni-Co DHs/EG electrode in which Ni-Co DHs showing a porous-nanorod microstructure was fabricated. Thanks to synergistic effects between Ni(OH)(2) and Co(OH)(2) as well as the unique morphology of porous nanorods, an optimal Ni-Co DHs/EG electrode with a total mass loading of 4.0 mg cm(-2) can deliver a specific capacitance of 1246 F g(-1) at 1 A g(-1), a rate capability of 91.8% as the discharging current density increasing from 1 to 10 A g(-1), and a capacitance retention of 80.1% after 1000 cycles charged/discharged at 10 A g(-1). Thus we can draw a conclusion that the Ni-Co DHs/EG electrode possesses a satisfactory specific capacitance, extremely superior rate performance, and good cycle stability, therefore it can be very competitive for practical applications in supercapacitors. (C) 2019 Elsevier Inc. All rights reserved.