NiCoP@CoS tree-like core-shell nanoarrays on nickel foam as battery-type electrodes for supercapacitors

Abstract

• NiCoP@CoS tree-like core-shell nanoarrays for supercapacitors. • The 3D hierarchical architecture integrates 1D NiCoP as core and 2D CoS as shell. • Superior battery-type electrochemical supercapacitor performance is achieved. High-performance supercapacitors as the promising energy storage devices have attracted considerable research interests, due to the apparent merits of high power density, fast charge/discharge, and long lifetime. However, their further practical applications are still greatly hindered by the limited energy density, as well as low capacitance, inferior rate capability and poor cycling performance of the electrode materials. Herein, three-dimensional (3D) hierarchical NiCoP@CoS tree-like core-shell nanoarrays (NAs) on nickel foam (NF) are obtained with the vertically grown NiCoP nanowires as core via phosphorization of NiCo 2 O 4 nanowires arrays, and the subsequently electrodeposited CoS nanosheets as shell. The 3D hierarchical tree-like core-shell nanoarrays take advantages of one-dimensional (1D) core as “hyperchannel” for electron transfer, coupling with two-dimensional (2D) vertical shell for fast ion diffusion meanwhile enhancement of cycling stability. The proposed NiCoP@CoS NAs/NF electrode exhibits superior battery-type electrochemical supercapacitor performance via the synergy of NiCoP nanowires and CoS nanosheets, which delivers a high specific capacitance of 1796 F g −1 at 2 A g −1 , outstanding rate capability and good cycling stability with high capacitance retention of 91.4% after 5000 cycles even at 10 A g −1 . Furthermore, the asymmetric supercapacitor assembled by NiCoP@CoS NAs/NF and activated carbon achieves a high energy density (35.8 Wh kg −1 ) at a power density of 748.9 W kg −1 . The as-fabricated NiCoP@CoS tree-like core-shell nanoarrays hold great promise as novel battery-type electrodes for high-performance supercapacitor applications.