Direct interfacial growth of MnO2 nanoparticles on carbon nanofiber surfaces for high-performance asymmetric supercapacitors

Facile interfacial growth of MnO2 nanoparticles on carbon nanofibers (MnO2CNF) and the application of this material as a high-performance positive electrode material in asymmetric supercapacitors are presented. Rational combination of MnO2CNF 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.