Fe-Co-S-Se-O nanoarrays for ultrahigh specific capacitance asymmetric supercapacitors

Developing multicomponent transition-metal sulfides has become an efficient way to improve the capacitive performance of single-component transition-metal sulfides. However, reports on quinary sulfides for supercapacitor applications are still scarce. A typical hydrothermal approach is carried out to introduce simultaneously S2- and Se2- in Fe-Co precursor to prepare an efficient quinary sulfur selenide metal material. The resulting Fe-Co-S-Se-O hybrid material nanoarrays manifest an ultrahigh specific capacitance of 2117 F g(-1) at 1 A g(-1), which is one of the best activities reported so far. In addition, 3D alpha-Fe2O3 material supporting on nickel foam as a cathode electrode was also prepared by a facile hydrothermal and calcining treatment process, which displays superior activity of 166 F g(-1) at 1 A g(-1). Moreover, an asymmetric supercapacitor (ASC) was constructed, employing Fe-Co-S-Se-O nanoarrays as the anode materials and alpha-Fe2O3 as the cathode materials in alkaline electrolytes, which presents a superior energy density of 36 W h kg(-1) at 745 W kg(-1) and a capacitance conservation rate of 96.7% after 8000 cycles. According to the results of density functional theory, the Co3S4 mainly improves the electrical conductivity of the material and the Se doped Fe2O3 mainly promotes the electrochemical behavior of the material. This work demonstrates that the Fe-Co-S-Se-O nanoarrays have potential applications in energy conversion and transportation and provides novel ideas for the design of robust, environmentally friendly and low cost electrodes. (C) 2021 Elsevier B.V. All rights reserved.