Facile interfacial growth of MnO2 nanoparticles on carbon nanofibers (MnO2/CNF) and the application of this material as a high-performance positive electrode material in asymmetric supercapacitors are presented. Rational combination of MnO2/CNF positive and CNF negative electrode materials enabled asymmetric devices with extended operating voltage windows of 1.8 V, and much higher power densities (4434 W kg−1) and energy densities (36 W h kg−1) compared with similar devices being reported. The assembled novel hybrid aqueous asymmetric capacitor shows excellent cycling stability with 90.9% capacity retention for 1000 cycles. The asymmetric supercapacitors were based on low cost and environmental friendly materials and have great potential for practical devices.
