Synthesis of nickel sulfide-graphene oxide composite microflower structures to enhance supercapacitor performance

摘要

Ni_xS_y in various crystal phases (NiS, NiS_2, and Ni_3S_4) was synthesized on thermally reduced graphene oxide (TRGO) by a one-step hydrothermal process. Microstructures and morphologies of as-prepared Ni_xS_y-TRGO composites were characterized. Ni_xS_y was formed as microflowers with average size of 1.1-2.3 μm, which grew homogeneously on the curved TRGO nanosheets. Electrochemical performance of Ni_xS_y-TRGO was revealed with high specific capacitance of 1602.2 F g~(-1) at 1 A g~(-1) and favorable cycling retention of 90.81% after 3000 cycles at 5 A g~(-1). An asymmetric supercapacitor device based on Ni_xS_y -TRGO‖TRGO exhibited a superior energy density of 39.78 Wh kg~(-1) at the power density of 0.75 kW kg~(-1) with an cycling stability of 91.2% capacitance retention after 3000 cycles. Thus, the as-prepared Ni_xS_y-TRGO could be an advanced supercapacitor electrode material.