Designed Construction of Hierarchical Cobalt Sulfide Nanonetwork as a High-Capacity and Binder-Free Cathode for Hybrid Supercapacitors

Abstract

Development of metal sulfide nanostructures using simple synthesis methods, enhanced electrochemical properties, and superior redox activity are highly desirable for the scalable fabrication of hybrid supercapacitors (HSCs). In this study, we presented a unique nanonetwork architectured cobalt sulfide on Ni-foam (Co x S y @NF) using an in situ wet-chemical method at lowtemperature. The as-grown hierarchical Co x S y nanostructures on the nickel skeleton enable strong adhesion with highly conductive, fast redox reactions, and superior electrochemical energy storage. The Co x S y nanonetwork exhibited a remarkable specific capacity of 838 C/g (2148 F/g), excellent rate performance of 66.8%, and cyclic stability of 97% over 6000 GCD cycles. The elevated redox properties of Co x S y nanostructures can be achieved due to the improved transport properties. The hierarchical architectured Co x S y @ NF was further used as a redox-type electrode for HSCs. The fabricated hybrid Co x S y //AC SC device exhibited a high energy density of 28.5 W h/kg with a device voltage of 1.55 V and a capacitance retention of 96% over 6000 cycles. The outstanding electrochemical properties and high mechanical integrity of the Co x S y nanonetwork can be used as advanced electrode material for scalable energy storage devices.