Cycling stability of Fe₂O₃ nanosheets as supercapacitor sheet electrodes enhanced by MgFe₂O₄ nanoparticles

The Fe₂O₃ material is a common active material for supercapacitor electrodes and has received much attention due to its cheap and easy availability and high initial specific capacitance. In the present study, we prepared adhesive-free Fe₂O₃ sheet electrodes for supercapacitors by growing Fe₂O₃ material on nickel foam by hydrothermal method. The sheet electrode exhibited a high initial specific capacitance of 863 F g^-1, but we found that the sheet lost its specific capacitance too quickly through cyclic stability tests. To solve this problem, Fe₂O₃/MgFe₂O₄ composites were grown on nickel foam (NF). It was found through testing that the cycling stability of the sheet electrode gradually increased as the content of MgFe₂O₄ material increased. When the molar ratio of Fe₂O₃ to MgFe₂O₄ material was 1 : 1, the initial specific capacitance of the sheet electrode was 815 F g^-1 and the capacitance remained at 81.25% of the initial specific capacitance after 1000 cycles. The better cycling stability results from the more stable structure of the composite, the synergistic effect leading to better reversibility of the reaction.