Synthesis of Layered Copper Selenide on Reduced Graphene Oxide Sheets via SILAR Method for Flexible Asymmetric Solid-State Supercapacitor

Abstract Along with growing use of electrochemical energy storage systems, there is a requirement for investigating electrode materials which assure applications in portable and wearable electrical energy storage devices. In this study, facile successive ionic layer adsorption and reaction (SILAR) method was employed to composite CuSe2 with reduced graphene oxide (rGO). The X-ray diffraction study showed orientation of CuSe2 nanoparticles from (200) to (221) plane with rGO composition. The field emission-scanning electron microscope images showed that CuSe2 nanoparticles are uniformly anchored onto the surface of rGO sheets. The composite CuSe2@rGO material offered a higher specific surface area (84 m2 g-1) compared to CuSe2 (24 m2 g-1) with the specific capacitance (Cs) of 612 F g-1 at a scan rate of 2 mV s-1. Moreover, the flexible solid-state asymmetric supercapacitor (ASC) fabricated with configuration CuSe2@rGO/PVA-KOH/CuS exhibited specific energy of 28.3 Wh kg-1 at the specific power of 1538 W kg-1. The device retained about 89% of the initial Cs at a bending angle of 165°. For practical manifestation, two series connected ASC devices charged with 2.8 V delivered 19.6 mW cm-2 of initial power and illuminated LED panel made of 211 red LED’s for 150 s.