High-performance MgCo2O4 nanocone arrays grown on three-dimensional nickel foams: Preparation and application as binder-free electrode for pseudo-supercapacitor

Uniform MgCo2O4 nanocone arrays (NCAs) grown radially on three-dimensional (3D) nickel foams were fabricated through a facile hydrothermal process. These MgCo2O4 NCAs were characterized by X-ray diffractometry, X-ray photoelectron spectroscopy, N-2 adsorption Brunauer-Emmett-Teller method, scanning electron microscopy and transmission electron microscopy. The MgCo2O4 NCAs were directly used as a binder-free integrated electrode for electrochemical pseudocapacitors. The electrode yielded a high specific capacitance of 750 F g(-1) with high cycling ability at a charge-discharge current density of 1 A g(-1) (84.0% of initial specific capacitance was remained after 1000cycles) and it was much higher compared with the powder MgCo2O4 (320 F g(-1) at 0.5 A g(-1)). Evidently, MgCo2O4NCAs achieved excellent electrochemical performance owing to the unique 3D nickel-foam-based in-situ self-assembly, which accelerated electron transport and diffusion as well as intimate electrode/electrolyte contact. The remarkable performance of the aqueous symmetric supercapacitor device without addition of binders or conductive additive is attributed to the close-knit combination of MgCo2O4 nanocone with highly conductive origin nickel foam, as well as the enlarged specific surface area (335.8 m(2) g(-1)). This study approves the future applications of the MgCo2O4 NCAs inspired large-scale supercapacitor grown on low-cost nickel foams. (C) 2016 Elsevier B.V. All rights reserved.