Synthesis of layered α-Ni(OH)2/RGO composites by exfoliation of α-Ni(OH)2 for high-performance asymmetric supercapacitors

Ultrathin alpha-Ni(OH)(2) nanosheets are prepared by exfoliation of a-Ni(OH)(2) intercalated with SDS in formamide. Layered ci-Ni(OH)2IRGO composites are further synthesized through a facile electrostatic self-assembly method combined with a hydrazine-reduction approach. The resulting alpha-Ni(OH)(2)/RGO composites show high specific capacitance of 15683 F g(-1) at 1 A g(-1) and good rate capability even at a high current density in a three-electrode system. Furthermore, alpha-Ni(OH)2/RGO//AC ASC exhibits a wide cell-voltage of 1.8 V and a maximum specific capacitance of 168.8 F g(-1) with an energy density up to 76 Wh kg(-1). It can still deliver a high energy density of 51.5 Wh kg(-1) at a high power density of 8512.6 W kg(-1), and achieve a superior cycling stability with 92.4% retention after 2000 cycles. The outstanding characteristic of a-Ni(OH)2/RGO composite suggests it is a promising candidate for super capacitor devices and energy-storage applications. (C) 2017 Elsevier B.V. All rights reserved.