Enhanced Electrochemical Performance of Multilayer WO3/MnO2 Thin Films via Sputtering on Graphene substrate for High-Stability Supercapacitors

Abstract

The hybrid approach presents substantial opportunities to utilize the characteristics of both carbon and metal oxide-based electrochemically active materials for enhancing the energy and power density of supercapacitors (SC). To optimize the overall electrochemical performance, we have engineered a composite SC electrode featuring a multilayer assembly of metal oxides (WO3/MnO2) via the sputtering technique and supported by a flexible graphene sheet. This sputtered layered by layered (4 LBL) configuration with desirable composition and topographical structure facilitates superior electrical conductivity, increases the number of active chemical reaction sites, and reduces the migration distance for charge carriers. By capitalizing on these welldesigned structural features and enhancing structural stability, the proposed multilayer, i.e., 4 LBL@graphene nanostructures, demonstrates significantly enhanced electrochemical properties, such as a high gravimetric capacitance of 494.2 F/g at a scan rate of 5 mV/s and excellent rate capability. The 4 LBL@graphene flexible symmetric SC device demonstrates a stable operating potential window of 0.8V with an energy density of 44 Wh/kg at a power density of 521 W/g with a low solution resistance of 2.40 Ω. Furthermore, the 4 LBL@graphene device exhibits good cyclic life with capacity retention of 89% after 10,000 charge-discharge cycles at 10 A/g, and excellent mechanical flexibility. These electrochemical performances surpass those of reported symmetric SC, indicating that these hybrid nanostructures hold significant promise for high-performance energy storage applications.