Flexible solid-state supercapacitor based on ternary nanocomposites of reduced graphene oxide and ruthenium oxide nanoparticles bridged by polyaniline nanofibers

Abstract

The rising demand for wearable electronics has driven research effort tremendously into flexible and compact supercapacitor materials furnished with high energy density, while retaining high-power density, cyclic stability, and durability. In this regard, we, herein, embedded ruthenium oxide nanoparticles (RuO2 NPs) and polyaniline nanofibers (PAni NFs) in the interplanar spaces of reduced graphene oxide (rGO) to prevent their re-stacking to maximize its electric double layer capacitance. It also integrates the pseudo-capacitance of RuO2 and PAni to the ternary nanocomposites (NCs), while the PAni NFs act as interconnecting conducting transmission channel between RuO2 and rGO to regulate charge-transfer kinetics within the system. The resultant ternary NCs display maximum areal capacitance of 1.66 F·cm−2 at a current density of 2 mA·cm−2. A flexible symmetric solid-state device (FSSSD), obtained by assembling the ternary NCs based electrode, attains a specific capacitance of 677 mF·cm−2 with 87 % coulombic efficiency at 2 mA·cm−2 and faster charge transport characteristics (Rct = 5.5 Ω). The device demonstrates maximum energy density of 60.18 μW·h·cm−2 at a power density of 0.8023 mW·cm−2. The functionality of the device is confirmed by turning on a red LED for up to 180 s with three FSSSDs connected in series.