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Synthesis of MnCo2O4@MnCo2S4 core/shell micro-nanostructures on Ni foam for high performance asymmetric supercapacitors

Wang, Xin, Xu, Lei, Song, Kun, Yang, Rui, Jia, Lihua, Guo, Xiangfeng, Jing, Xiaoyan, Wang, Jun
Colloids and surfaces 2019 v.570 pp. 73-80
aqueous solutions, capacitance, carbon nanotubes, electrodes, energy density, foams, hot water treatment, nickel, oxygen, sulfur, synergism
A flower-like of MnCo2O4 micro-nanostructures on Ni foam was prepared using a calcination-process assisted hydrothermal method. Following immersion of the MnCo2O4 precursor in NaHS aqueous solution, S2+ reaches the outer surface of MnCo2O4, and sulfur replaces the oxygen to form MnCo2S4, and hierarchical MnCo2O4@MnCo2S4 core/shell is generated. The as-prepared core-shell micro-nanostructure revealed its component advantages and a synergistic effect for electrode materials of supercapacitors. The materials deliver a specific capacitance of 1933.33 F·g−1 at a current density of 1 A·g−1 with a superior rate performance in a three-electrode system. An asymmetric supercapacitor was assembled with MnCo2O4@MnCo2S4 core/shell micro-nanostructure arrays as positive electrode and carbon nanotubes (CNTs) as negative electrode. The device delivers a high energy density of 50.75 W·h·kg−1 at a power density of 1260 W·kg−1 and an excellent cycling stability of 96% capacitance retention after 5000 cycles.