Hierarchically structured Fe2O3@C hollow acanthospheres on carbon cloth as anodes for high-performance asymmetric supercapacitors

The use of hematite (α-Fe2O3) as anode materials remains challenging because α-Fe2O3 with poor conductivity and sluggish ionic transportation in the oxide lattice during energy storage. Herein, the hierarchically structured hollow acanthospheres (Fe2O3 @C-HASs), for the first time, were prepared on carbon cloth (CC) by facile solvothermal method and self-sacrifice template method. Benefiting from its unique hierarchical hollow acanthospheres structures, a large specific surface area, transition-metal oxides and graphitized carbon layer, the hierarchically structured CC/Fe2O3 @C-HASs electrode delivers an outstanding areal capacitance of 1712.1 mF cm−2 at 5 mA cm−2, which are far superior to CC/Fe2O3-HASs (777.8 mF cm−2 at 5 mA cm−2). A 1.7 V flexible solid-state asymmetric supercapacitor (ASC) was successfully assembled with CC/Fe2O3 @C-HASs as the anode, NiO on carbon cloth (CC/NiO) as the cathode, exhibiting a maximum volumetric energy density of 2.87 mWh cm−3 at a volumetric power density of 40.20 mW cm−3, and excellent cycling stability (82.1% after 10,000 cycles). In this work, CC/Fe2O3 @C-HASs can be used as an ideal anode material, which can provide a reference for the rational design and preparation of electrode material to asymmetric supercapacitors.