Facile Assembly of Co-Ni Layered Double Hydroxide Nanoflakes on Carbon Nitride Coated N-doped Graphene Hollow Spheres with High Electrochemical Capacitive Performance

High specific capacitance, large surface area, good flexibility and super durability are recognized as advantageous characteristics to acquire ideal supercapacitor, but it is a great challenge to realize them at the same time. Here, a novel cobalt-nickel layered double hydroxide nanoflakes grow on carbon nitride coated N-doped graphene hollow spheres is successfully assembled by a facile chemical bath deposition method. The carbon nitride coated N-doped graphene hollow spheres scaffold not only possesses large surface area for increasing loading of electroactive material but also has hollow structure for accelerating electron and ion transport. Owing to synergistic contributions, the resulting Co1Ni1 layered double hydroxide nanoflakes on carbon nitride coated N-doped graphene hollow spheres with large surface area of 268 m(2) g (1) exhibited enhanced specific capacitance (1815 F g (1) at 1 A g (1)) and excellent cycling stability (82.1% retention after 4,000 cycles even at 20 A g (1)). In addition, the capacitance retention still keeps 90.7% after rolling-up about 360 degrees due to wonderful flexibility. Finally, an asymmetric supercapacitor is assembled to further investigate its practical application, which exhibited high energy density of 28.9 Wh kg (1) at an average power density of 1875 W kg (1) and outstanding capacitance retention (no any losses of initial specific capacitance after 10,000 cycles). These advantageous characteristics demonstrate that the new electrode gives a comprehensive application prospect in miniaturized and flexible energy storage. (C) 2017 Elsevier Ltd. All rights reserved.