Construction and electrochemical performance of MnCo-S@Ni(OH)₂ nanosheet arrays

To solve the problems of low rate performance and poor cycle performance of metal sulfides, MnCo-S@Ni(OH)₂ nanosheet arrays on carbon cloth were synthesized by two-step electrodeposition. After testing the phase of the sample, it is proved that the nanosheet array are composed of Co₃S₄, MnS and Ni(OH)₂. The morphology test shows that the nanosheet array is uniformly deposited on the carbon cloth, and the dense structure of Ni(OH)₂ can constrain the volume expansion of the electrode material during the charge and discharge process of the metal sulfide. The elemental analysis also shows that the elements of the electrodeposited nanosheet array are evenly distributed. The as-obtained MnCo-S@Ni(OH)₂ nanosheet arrays exhibits a high specific capacitance(1 746.1 F·g⁻¹ at1 A·g⁻¹ ) and excellent rate performance as a supercapacitor cathode material(capacitance retention at 10 A·g⁻¹ about 68.4% of the capacitance at 1 A·g⁻¹). Compared with MnCo-S and Ni(OH)₂, the electrochemical performance is significantly improved. The asymmetric supercapacitor made of MnCo-S@Ni(OH)₂ as the positive electrode, AC(Activated carbon) as the negative electrode shows a specific capacitance of 108.2 F·g⁻¹ at 1 A·g⁻¹ and the asymmetric supercapacitor still has 94.3% retention when the current density is 10 A·g⁻¹ compared with 1 A·g⁻¹. Capacity retention of 75.5% after 2 000 cycles at a current density of 2 A·g⁻¹. Furthermore, the asymmetric supercapacitor has a high energy density of 38.5 Wh·kg⁻¹ and a power density of 811.7 W·kg⁻¹.