High-performance cobalt-doped carbon cloth supported porous Fe2O3 flexible electrode material in quasi-solid asymmetric supercapacitors

Iron oxide, as a promising anode material, has environmental friendliness, high theoretical capacitance, and a wide voltage window. Cobalt-doped iron oxide was loaded on flexible carbon cloth (Co-Fe 2 O 3 @CC) via hydrothermal reaction. Cobalt doping changes the iron oxide’s crystal structure and improves the conductivity of the iron oxide. At the same time, it also increases the oxidation state of iron oxide and improves the pseudocapacitance of the electrode material. The reaction conditions were controlled to prepare iron oxide nano-spheres having porous morphology. The porous structure increases the area where the electrode material is reacted. The area-specific capacitance of the Co-Fe 2 O 3 @CC electrode material is 315.6 mF cm -2 , which is 137.2% higher than that of pure Fe 2 O 3 @CC(133 mF cm -2 ). The capacitance is unchanged before and after 200 times of 90° bending. The voltage window of assembled Co-Fe 2 O 3 @CC//Ni-MnO 2 @CC asymmetric supercapacitors is 0-2 V. The energy density is 0.96 mWh cm -3 and the power density is 28.6 mW cm -3 , which has excellent electrochemical performance. After 4000 cycles at a current density of 10 mA cm -2 , the capacitance is maintained at 85%. Flexible asymmetric supercapacitors have potential applications in the field of flexible wearables. • Cobalt was doped into Fe 2 O 3 @CC electrode material (Co-Fe 2 O 3 @CC) via hydrothermal reaction. • Co-Fe 2 O 3 formed nanospheres with nanopores inside. • Co-Fe 2 O 3 @CC electrode material had large area capacitance and good flexibility. • Flexible asymmetric supercapacitors had large area specific capacitance and excellent energy density.