Hierarchical WS₂@NiCo₂O₄ Core–shell\nHeterostructure Arrays Supported on Carbon\nCloth as High-Performance Electrodes for Symmetric Flexible Supercapacitors

Abstract

Nowadays, rationally preparing heterostructure\nmaterials can not\nonly make up for the shortage of individual components, but also exert\nunexpected performance through synergistic interactions between the\ncomponents. Herein, a core–shell of WS₂@NiCo₂O₄ screw-like heterostructure arrays grown on carbon\ncloth (CC) was prepared by a two-step solvothermal method for supercapacitors.\nAs a binder-free flexible electrode, a high areal capacitance of 2449.9\nmF 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\nthe flexible WS₂@NiCo₂O₄/CC electrode\nis better than those of WS₂/CC and NiCo₂O₄/CC electrodes. Based on WS₂@NiCo₂O₄/CC electrodes, the assembled flexible solid-state symmetric\nsupercapacitor (FSS) device shows a high energy density of ∼45.67\nW h kg^–1 at a power density of 992.83 W kg^–1. Meantime, the WS₂@NiCo₂O₄/CC-assembled\nFSS device also exhibits high cycling stability with an excellent\ncapacity retention of ∼85.59% after 5000 cycles.