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

A flower-like of MnCo(2)O(4)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 Wh.kg(-1 )at a power density of 1260 Wkg(-1) and an excellent cycling stability of 96% capacitance retention after 5000 cycles.