Design and fabrication of 3D petal-like FeS₂/r-GO nanocomposite as a high-performance electrode in hybrid supercapacitors

Novel materials are needed for high-performance energy storage devices (ESD) and metal sulfide-based materials with outstanding redox characteristics and high electrical conductivity are gaining attention. Based on a facile hydrothermal approach, a 3D petal-like FeS₂/r-GO nanocomposite was fabricated with a surface area of 27.33 m²/g, compared to 11.89 m²/g of pristine FeS₂. The electrode 3D petal-like FeS₂/r-GO structures’ rational design offers a synergistic effect, and fast ion transport. It enhances the redox reactionkinetic rate with a specific capacitance (C_sp) (capacity-C_Sc) of 748F/g (322C/g) at a current density (CD) of 0.5 A/g. The electrode exhibited remarkable cycle life capacitance retention (CR) and Coulombic efficiency (CE) of 85 % and 91 % after 10,000 charge-discharge (GCD) cycles at 8 A/g. The solid-state hybrid supercapacitor (HS) consists of FeS₂/r-GO and activated carbon (AC) as the positive and negative electrodes, whereas PVA/KOH gell serves as the electrolyte. The HS device achieved a 1.45 V and a C_Sp (C_Sc) of 110F/g (52 C/g) at 1 A/g with a power density (D_P) of 10,512 W/kg and an energy density (D_E) of 31.18 Wh/kg. It delivered a RE and CE of 83 %, and 90 % respectively, after 5,000 cycles.