Three-dimensional hierarchical NiCo hydroxide@Ni3S2 nanorod hybrid structure as high performance positive material for asymmetric supercapacitor

Abstract

Three-dimensional hybrid structure with Ni3S2 nanorod arrays as core material and NiCo hydroxide nanosheets as shell material is fabricated directly on flexible Ni foam. This hierarchical hybrid structure without any additives and binders behaves good electrochemical properties including a high specific capacitance of 1833.7Fg−1 (5.13Fcm−2) at a current density of 1Ag−1, good rate capability with 88.27% capacitance retention at a current density of 20Ag−1 and great cyclic stability. Moreover, an asymmetric supercapacitor (ASC) based on NiCo hydroxide@Ni3S2 hybrid structure on Ni foam as positive electrode and activated carbon as negative electrode is successfully assembled to further evaluate the electrochemical properties of the hybrid structure in a full-cell configuration. The ASC device also performs excellent electrochemical properties including a large potential window of 0–1.8V, a high specific capacitance of 215.8Fg−1 at a current density of 1Ag−1 and long-term cycling performance. In the meantime, the ASC device also delivers a high energy density of 92.8Whkg−1 at a power density of 1.0KWkg−1. These results suggest that 3D NiCo hydroxide@Ni3S2 hybrid structure has promising potential for use in high-performance supercapacitor.