Flower-like Fe2O3@multiple graphene aerogel for high-performance supercapacitors

Abstract The paper reports one strategy for synthesis of flower-like Fe 2 O 3 @multiple graphene aerogel (F-Fe 2 O 3 @MGA). First, Fe 3+ was combined with 2-methylimidazole in an ethylene glycol medium containing polyvinyl pyrrolidone surfactant to form Fe(III)-2-methylimidazole complex. Due to the template effect of polyvinyl pyrrolidone, the complex shows a flower-like morphology that consists of ultrathin Fe 2 O 3 plates. Then, Fe 3+ in the complex was oxidized into F-Fe 2 O 3 in air at 350 °C for 2 h and at 500 °C for 0.5 h. Finally, the F-Fe 2 O 3 was hybridized with graphene via a multiple gelation method. The as-prepared F-Fe 2 O 3 @MGA gives well-defined three-dimensional structure. The F-Fe 2 O 3 crystals are well dispersed on the dense graphene frameworks networks. The unique structure achieves to high electron/ion conductivity and structural stability. The composite electrode for supercapacitors exhibits a high specific capacitance (1119 F g −1 at the current density of 1 A g −1 ) and high rate-capability (630 F g −1 at the current density of 10 A g −1 and 492 F g −1 at the current density of 20 A g −1 ) in a 3.0 M KOH electrolyte. The asymmetric supercapacitor of F-Fe 2 O 3 @MGA/activated carbon provides the energy density of 95.3 W h kg −1 at the power density of 800 W kg −1 and 45 W h kg −1 at the power density of 8000 W kg −1 . The outstanding capacitive performance makes F-Fe 2 O 3 @MGA can be used as an electrode material for next-generation high-performance supercapacitors.