Novel\nQuaternary Chalcogenide/Reduced Graphene Oxide-Based\nAsymmetric Supercapacitor with High Energy Density

Abstract

In this work we have\nsynthesized quaternary chalcogenide Cu₂NiSnS₄ (QC) nanoparticles grown in situ on 2D reduced\ngraphene oxide (rGO) for application as anode material of solid-state\nasymmetric supercapacitors (ASCs). Thorough characterization of the\nsynthesized composite validates the proper phase, stoichiometry, and\nmorphology. Detailed electrochemical study of the electrode materials\nand ASCs has been performed. The as-fabricated device delivers an\nexceptionally high areal capacitance (655.1 mF cm^–2), which is much superior to that of commercial micro-supercapacitors.\nFurthermore, a remarkable volumetric capacitance of 16.38 F cm^–3 is obtained at a current density of 5 mA cm^–2 combined with a very high energy density of 5.68 mW h cm^–3, which is comparable to that of commercially available lithium thin\nfilm batteries. The device retains 89.2% of the initial capacitance\nafter running for 2000 cycles, suggesting its long-term capability.\nConsequently, the enhanced areal and volumetric capacitances combined\nwith decent cycle stability and impressive energy density endow the\nuniquely decorated QC/rGO composite material as a promising candidate\nin the arena of energy storage devices. Moreover, Cu₂NiSnS₄ being a narrow band gap photovoltaic material, this work\noffers a novel protocol for the development of self-charging supercapacitors\nin the days to come.