Hierarchical WS2@NiCo2O4 Core-shell Heterostructure Arrays Supported on Carbon Cloth as High-Performance Electrodes for Symmetric Flexible Supercapacitors.

Abstract

Nowadays, rationally preparing heterostructure materials can not only make up for the shortage of individual components, but also exert unexpected performance through synergistic interactions between the components. Herein, a core–shell of WS2@NiCo2O4 screw-like heterostructure arrays grown on carbon cloth (CC) was prepared by a two-step solvothermal method for supercapacitors. As a binder-free flexible electrode, a high areal capacitance of 2449.9 mF cm–2 can be achieved for WS2@NiCo2O4/CC at a current density of 1 mA cm–2. Benefiting from the core–shell of the WS2@NiCo2O4 heterostructure, the capacitive property of the flexible WS2@NiCo2O4/CC electrode is better than those of WS2/CC and NiCo2O4/CC electrodes. Based on WS2@NiCo2O4/CC electrodes, the assembled flexible solid-state symmetric supercapacitor (FSS) device shows a high energy density of ∼45.67 W h kg–1 at a power density of 992.83 W kg–1. Meantime, the WS2@NiCo2O4/CC-assembled FSS device also exhibits high cycling stability with an excellent capacity retention of ∼85.59% after 5000 cycles.