Experimental and Theoretical Investigation of the Energy-Storage Behavior of a Polyaniline-Linked Reduced-Graphene-Oxide– SnO2 Ternary Nanohybrid Electrode

Abstract

Hybrid capacitors are one type of emerging devices in the realm of energy storage. Here, we report the interactions of reduced graphene oxide (RGO) on ${\mathrm{Sn}\mathrm{O}}_{2}$ and polyaniline (PANI) on RGO/${\mathrm{Sn}\mathrm{O}}_{2},$ leading to improved electronic and structural properties and enhanced charge-storage performance for the ternary hybrid RGO/${\mathrm{Sn}\mathrm{O}}_{2}/\mathrm{p}$olyaniline (GSP). The synthesized ternary hybrid exhibits an excellent specific capacitance of 340 F/g at 2 A/g (current density) with 98% capacitance retention for 1000 charge-discharge cycles. The constructed asymmetric GSP||RGO hybrid exhibits an energy density of 12 Wh/kg at a power density of 1.07 kW/kg. We present an insight into the physics behind the enhanced charge-storage performance using density functional theory simulations, along with an analysis of the structural and electronic properties of the hybrid structure and computation of quantum capacitance. There is charge transfer between PANI and RGO/${\mathrm{Sn}\mathrm{O}}_{2},$ resulting in hydrogen bonding between graphene and PANI, which facilitates enhanced charge-storage performance for the ternary nanohybrid structure. Our experimental measurements and theoretical insight predict that the excellent electrochemical performance is due to the synergistic effect of rapid electron transportation between RGO/${\mathrm{Sn}\mathrm{O}}_{2}$ and PANI, and the system may be used as potential electrochemical charge-storage device.