Well-Organized FeS/Fe2O3 Nanocomposite for the Electrode in Asymmetric Supercapacitors

FeS and Fe₂O₃ have attracted great interest as electrode materials for supercapacitors owing to their high electrochemical performance. However, the performance of Fe₂O₃ is restricted by its low conductivity and poor cyclic stability, while FeS exhibits admirable electrical conductivity and acceptable theoretical capacity, thus making it a favorable choice as an additive for composite electrodes. In this work, an FeS/Fe₂O₃ composite is successfully fabricated by hydrothermal reaction and ball milling for use as electrode material in a supercapacitor. The composite FeS/Fe₂O₃ exhibits desirable specific capacitance of 524 Fg⁻¹ in the three-electrode system, much greater than that of pristine FeS and Fe₂O₃ electrodes. Furthermore, in a two-electrode asymmetric supercapacitor (ASC) with an FeS/Fe₂O₃ composite electrode, high specific capacitance of 154 Fg⁻¹ and energy density of 61 W/kg are achieved. In addition, a desirable capacitive retention of 71% is also attained at 1 Ag⁻¹ after 500 charge/discharge cycles, suggesting the high feasibility of the composite FeS/Fe₂O₃ in supercapacitor applications.