Core-shell Fe3O4@carbon aerogels assembled aqueous zinc ion hybrid capacitor with ultra-wide voltage window

The unsatisfactory energy density seriously hinders the practical application of supercapacitors. Herein, core shell Fe3O4@carbon aerogels (Fe3O4@CAs) with high specific capacity are synthesized by the hydrothermal self-assembly method, which can contribute both electric double-layer capacitance (EDLC) and pseudo capacitance under the synergistic mechanism of Fe3O4 and CAs. The zinc ion hybrid supercapacitor (ZHSC) is constructed using Fe3O4@CAs, zinc foil, and 2 M ZnSO4 as the cathode, anode, and electrolyte, respectively. The assembled ZHSC exhibits an ultra-wide voltage window (0-2.1 V in the aqueous electrolyte) and high specific capacitance (342.1 F g-1 at a current density of 0.5 A g-1) characteristics, successfully achieving an attractive energy density (284.7 Wh kg- 1 at a power density of 210 W kg 1). This study provides a highly universal hydrothermal self-assembly method for the composite preparation of Fe3O4 and various carbon materials.