Gold sputtering-assisted conductive electrospun nanofibers mat decorated with MnO₂ nanospheres for flexible, high-performance supercapacitor electrodes

Electrospun nanofibers (ENFs) and mats are regarded as ideal electrode candidates for electrochemical energy storage devices such as supercapacitors (SCs), due to their large specific surface area, three-dimensional (3D) nano architecture, light weight, high porosity, and low cost. However, the technique of electrospinning usually produces polymeric nanofibers, the inferior conductivity of polymers dramatically hinders their direct applications in electrochemistry. In this work, magnetron sputtering is utilized to coat a layer of uniform gold onto the surface of electrospun poly(vinylidene fluoride-trifluoroethylene) (PVDF-TrFE) nanofibers to achieve a highly conductive 3D network, followed with electrodeposition of manganese dioxide (MnO₂) nanospheres as pseudocapacitive materials. The advanced SCs electrode exhibits integrated features of high specific capacitance (ca. 385 F g^-1 at 1 A g^-1), decent rate capability (ca. 50 % retention as the current density is increased from 1 A g^-1 to 20 A g^-1), long cycling life (ca. 94% retention after 2000 charging/discharging cycles), and attractive flexibility. This facile strategy of "sputtering-electrodeposition" shows a great potential to open up a new route for developing various kinds of ENFs-based energy storage devices for flexible electronics.