High-performance flexible asymmetric supercapacitors based on 3D porous graphene/MnO2nanorod and graphene/Ag hybrid thin-film electrodes

Abstract

We demonstrate a simple method for preparing flexible, free-standing, three-dimensional porous graphene/MnO₂ nanorod and graphene/Ag hybrid thin-film electrodes using a filtration assembly process. These graphene hybrid films, which accelerate ion and electron transport by providing lower ion-transport resistances and shorter diffusion-distances, exhibit high specific capacitances and power performances, and excellent mechanical flexibility. A novel asymmetric supercapacitor (SC) has been fabricated by using a graphene/MnO₂ nanorod thin film as the positive electrode and a graphene/Ag thin film as the negative electrode. These devices exhibit a maximum energy density of 50.8 W h kg⁻¹ and present a high power density of 90.3 kW kg⁻¹, even at an energy density of 7.53 W h kg⁻¹. The bent hybrid nanostructured asymmetric SC is connected to spin a fan, which also proved the high power density of the fabricated asymmetric SCs. These results suggest that such asymmetric graphene/MnO₂ nanorod and graphene/Ag hybrid thin-film architectures are promising for next-generation high-performance flexible supercapacitors.