Self-supported phase-pure Ni3S2 sheet-on-rod nanoarrays with enhanced pseudocapacitive properties and high energy density

In this work, self-supported Ni 3 S 2 nanorod arrays on nickel foam substrate are prepared by a facile one-pot hydrothermal method. These phase-pure nanorods possess an interesting secondary structure: the surface is covered with ultrathin Ni 3 S 2 nanosheets. Such an integration of one-dimensional nanorod array with two-dimensional nanosheets combines the advantages of the two components, demonstrating enhanced pseudocapactive performance with a high and very stable areal capacitance over prolonged charge-discharge tests. When the as-prepared material is incorporated as the cathode in an asymmetric supercapacitor, where activated carbon is selected as the anode, the device exhibits highly reversible capacitance with insignificant decay over 3000 cycles. Excellent energy densities of 115 and 102 Wh kg −1 are achieved at power densities of 506 and 1094 W kg −1 , respectively. Such a performance can be attributed to the unique sheet-on-rod nanoarray on the nickel foam substrate.