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

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 WS@NiCoO 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 can be achieved for WS@NiCoO/CC at a current density of 1 mA cm. Benefiting from the core-shell of the WS@NiCoO heterostructure, the capacitive property of the flexible WS@NiCoO/CC electrode is better than those of WS/CC and NiCoO/CC electrodes. Based on WS@NiCoO/CC electrodes, the assembled flexible solid-state symmetric supercapacitor (FSS) device shows a high energy density of ∼45.67 W h kg at a power density of 992.83 W kg. Meantime, the WS@NiCoO/CC-assembled FSS device also exhibits high cycling stability with an excellent capacity retention of ∼85.59% after 5000 cycles.