Ag-modified FeO nanoparticles on a carbon cloth as an anode material for high-performance supercapacitors.

By exploiting the storage performance of supercapacitors, iron has the potential to be used as a new anode material. However, this potential is limited by unsatisfactory electrical conductivity and poor cycling stability which impact the energy and power density. Consequently a foundation for improving the electrical conductivity and cycling stability of iron materials to obtain good storage performance is needed. In this work, Ag-modified FeO nanoparticles on carbon cloth were synthesized as an anode material for supercapacitors. The specific capacitance of the composite material reaches 10.39 F cm (2734.2 F g) at a current density of 1 mA cm and remains at 83% of this value after 12 000 cycles. The energy density is 379.8 Wh kg at a power density of 131.6 W kg and remains at 123.9 Wh kg at a power density of 2631.6 W kg. The electrical conductivity and interfacial effect created between Ag@FeO is confirmed with density functional theory calculations. The packaged asymmetric supercapacitor devices have flexibility and can light ten LEDs for 2 min 30 s, with an energy density of 60.3 Wh kg that can be reached at a power density of 1063.8 W kg and remain at 16 Wh kg even at a power density of 4255.3 W kg.