A highly electronic conductive cobalt nickel sulphide dendrite/quasispherical nanocomposite for a supercapacitor electrode with ultrahigh areal specific capacitance

composite with high electronic conductivity and a suitable porous structure was synthesized via a facile hydrothermal process. The morphology and structure of the Co1.5Ni1.5S4 nanocomposite were easily manipulated by tuning the hydrothermal reaction time. To the best of our knowledge, due to its good electronic conductivity and suitable structure for the electrochemical redox reaction, the Co(1.5)Ni(1.5)S4 electrode exhibited the highest areal specific capacitance of 41.0 F cm(-2). The electrochemical impedance spectroscopy (EIS) results demonstrate that Co(1.5)Nit(5)S(4) possesses a higher electronic conductivity and faster charge transfer than single-component sulphides (CoS and NiS) or cobalt-nickel hydroxides and oxides. These characteristics contribute to the high specific capacitance of the Co15Ni15S4 electrode even at high material loading, corresponding to an ultrahigh areal specific capacitance. An asymmetric supercapacitor, which was assembled with Co(1.5)Nit(5)S(4) as the positive electrode active material and HNOrtreated activated carbon as the negative electrode active material, exhibited a superior energy density of 32.4 Wh kg(-1) at a power density of 103.4W kg(-1) and 25.0 Wh kg(-1) at a high power density of 5.5 kW kg(-1). (C) 2015 Elsevier B.V. All rights reserved.