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

Abstract

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.