MnO2 nanoflake/polyaniline nanorod hybrid nanostructures on graphene paper for high-performance flexible supercapacitor electrodes

Abstract

A facile two-step strategy is adopted to construct a free-standing composite paper of MnO₂ nanoflake/polyaniline (PANI) nanorod hybrid nanostructures on reduced graphene oxide (RGO) for flexible supercapacitor electrode application. MnO₂ nanoflakes are first grown on RGO paper via an electrodeposition method, followed by assembly of PANI nanorods between MnO₂ nanoflakes by in situ polymerization using camphorsulfonic acid as a dopant. The morphology and structure of the composite paper are characterized and the electrochemical properties are systematically investigated. The interconnected PANI nanorods deposited on the interlaced MnO₂ nanoflakes have a length of ∼100 nm and a diameter of ∼30 nm, creating plenty of open porous structures which are beneficial for ion penetration into the electrode. The RGO/MnO₂/PANI composite paper shows a large specific capacitance of 636.5 F g⁻¹ at 1.0 A g⁻¹ in 1.0 M Na₂SO₄ electrolyte and excellent cycling stability (85% capacitance retention after 10⁴ cycles). The optimized composite structure with more electroactive sites, fast ion and electron transfer, and strong structural integrity endows the ternary composite paper electrode with outstanding electrochemical performance.