Facile fabrication of N-doped RGO decorated CoS2 nanoparticles as advanced integrated electrode for enhanced supercapacitor performance

Abstract

Transition metal sulfides (TMSs) are a class of advanced electrode materials for new energy storage devices with superior performance due to their many advantages, such as high specific capacity, good conductivity, low electronegativity, high redox activity, rich variety and low price. Herein, we developed N-doped reduced graphene oxide (N-RGO) decorated CoS₂ nanoparticles nanohybrids (N-RGO/CoS₂, denoted as NGCS) by a facile hydrothermal method. The doped-N process enriches the specific surface area and porosity of RGO nanosheets, which not only forms rich network nanostructures conducive to rapid charge/ion transport, but also promotes more dispersed anchoring of CoS₂, resulting in the formation of smaller-sized CoS₂ nanoparticles that can provide rich and exposed electroactive sites. Therefore, such unique hierarchical porous nanostructures help all components in the nanohybrids to “complement each other's strengths”, so that the fabricated NGCS electrode exhibits a high specific capacitance of 797.1 F g⁻¹ at 0.6 A g⁻¹ and an excellent rate capability with 77.5 % retention (20 A g⁻¹). Furthermore, the assembled NGCS//AC hybrid supercapacitor (HSC) delivers excellent energy density of 41.4 Wh kg⁻¹ (at 719.7 W kg⁻¹) and long-term cyclability with 86.02 % capacitance retention after 13,000 cycles, presenting a promising application potential in new high-performance energy storage and conversion devices.