Rational construction of CoFe-S/rGO composites with enriched sulfur vacancies for high-performance supercapacitor

Abstract

A composite named CoFe-S/rGO-x (where x indicates the quantity of graphene oxide (GO) added during the synthesis process) was prepared by combining self-assembly and hydrothermal methods to load CoS2/FeS nanocubes (designated as CoFe-S) onto reduced graphene oxide (rGO) nanosheets. Subsequently, this composite was utilized for the positive electrode of an asymmetric supercapacitor. The experiments indicate that CoFe-S/rGO-0.7 exhibits the best capacitive performance. CoFe-S/rGO-0.7 demonstrates an exceptionally high specific capacitance of 4474.1F g−1 at a current density of 1 A/g. The asymmetric supercapacitor, assembled using CoFe-S/rGO-0.7 and activated carbon (AC) as the positive and negative electrodes, respectively, delivers an ultra-high energy density of 107.6 Wh kg−1 at a power density of 918.2 W kg−1. Even at a power density of 8893.1 W kg−1, it maintains an energy density of 77.32 Wh kg−1. The stable structure and the introduction of sulfur vacancies contribute to the outstanding cycling stability of the CoFe-S/rGO-0.7//AC asymmetric supercapacitor. The capacitance retention rate after 10,000 charge–discharge cycles is 96.2 %. The results indicate that the sulfur-enriched CoFe-S/rGO-0.7 positive electrode material exhibits excellent energy storage and stability performance, making it a potential candidate for electrode materials in the field of supercapacitors.