Construction of CoO/Co-Cu-S Hierarchical Tubular Heterostructures for Hybrid Supercapacitors.

Hierarchical hollow structures for electrode materials of supercapacitors could enlarge the surface area, accelerate the transport of ions and electrons, and accommodate volume expansion during cycling. Besides, construction of heterostructures would enhance the internal electric fields to regulate the electronic structures. All these features of hierarchical hollow heterostructures are beneficial for promoting the electrochemical properties and stability of electrode materials for high-performance supercapacitors. Herein, CoO/Co-Cu-S hierarchical tubular heterostructures (HTHSs) composed of nanoneedles are prepared by an efficient multi-step approach. The optimized sample exhibits a high specific capacity of 320 mAh g-1 (2300 F g-1 ) at 2.0 A g-1 and outstanding cycling stability with 96.5 % of the initial capacity retained after 5000 cycles at 10 A g-1 . Moreover, an all-solid-state hybrid supercapacitor (HSC) constructed with the CoO/Co-Cu-S and actived carbon shows a stable and high energy density of 90.7 Wh kg-1 at a power density of 800 W kg-1 .