Rapid construction of three-dimensional sulfur doped graphene supported by NiFeS2 interconnected networks as convenient electron/ion transport channels for flexible supercapacitors

Developing a convenient synthetic strategy to achieve graphene based composites with ideal electrochemical properties is still a huge challenge. In this work, three-dimensional sulfur doped graphene supported by nickel-iron bimetallic sulfides (NiFeS₂/3DSG) as high performance supercapacitors electrode are fabricated by one-step microwave alcohothermal method, in which mercaptoacetic acid is applied as sulfur source of doped graphene as well as precursor of nickel-iron sulfide. The 3DSG not only exhibits space laminated structure with ideally pore sizes and large specific surface area, but also increases the binding of nickel-iron precursor through chemical bonds of sulfur. NiFeS₂/3DSG electrode has reflected in the specific capacitance of 643.9 C g⁻¹ (1073.2 F g⁻¹) at the current density of 1 A g⁻¹ in 6.0 M KOH electrolyte. Furthermore, the asymmetric supercapacitor device is constructed of NiFeS₂/3DSG electrode as positive electrode and 3DSG as negative electrode (NiFeS₂/3DSG//3DSG), which delivers a superior energy density of 45.7 Wh kg⁻¹ at a power density of 222 W kg⁻¹ under a wide potential range of 1.6 V. After 5000 cycles of charge and discharge, the specific capacitance of this device hold the retention rate of 82%. These results indicate that the graphene based hybrid with outstanding electrochemical performance could be a strong competitive prospect in the applications of supercapacitor.