Flexible MnO-encapsulated carbon nanofiber composites as high-performance freestanding supercapacitor electrodes

One-dimensional (1D) materials with good flexibility are of great interest for energy storage applications. Herein, MnO carbon nanofiber (CNF) composites are synthesized by electrospinning. During carbonization, MnO was crystallized as spherical nanoparticles (NPs) and embedded on CNFs. The MnO/CNFs composite exhibited the highest specific capacitance (C-s) of 460 Fg(-1) at 1 Ag-1 with an outstanding capacitance retention of 93.5% after 10,000 cycles. The assembled SC maintained 26 Fg(-1) even at a high current density of 5 Ag-1 and sustained capacitance retention of 82.5% for 10,000 cycles. Moreover, it showed a maximum energy density of 23.1 W h kg(-1). Hence, the simple and cost-effective strategy of fabricating freestanding electrodes with high flexibility and good conductivity is the most promising approach for addressing practical concerns at the device level, especially for lightweight and flexible electronics.