Asymmetric Supercapacitors Assembled by Dual Spinel Ferrites@Graphene Nanocomposites as Electrodes

Spinel-type ferrites are potential active materials for their highly theoretical capacity as electrodes of supercapacitors. Here, CoFe2O4@graphene nanocomposites were synthesized by a facile hydrothermal method and worked as cathode material. It was found that the performance of the electrode depended on the weight ratio of ferrites to graphene. The specific capacitance could be significantly increased to 579 F g–1 at 1 A g–1 when the content of graphene was 40% in the composite. Next an asymmetric supercapacitor (ASC) was fabricated by using the as-prepared Fe3O4@graphene nanocomposites as anode material. The ASC with 1.7 V working voltage delivered a high specific capacitance of 114.0 F g–1 and a promising energy density of 45.5 Wh kg–1 at a power density of 840 W kg–1, along with a highly cycling stability of 91% capacitance retention after 5000 cycles. It provided a new change to fabricate high performance ASCs using spinel ferrite-based graphene nanocomposites as electrodes.