In Situ Growth of Ultrathin NiO Nanosheet-Arrays on MOF-Derived Porous Co3O4 Scaffolds as High-Performance Cathode for Asymmetric Supercapacitors

The ever-increasing market for portable and wearable electronic devices creates a demand for high-efficiency electrochemical energy storage devices with excellent flexibility. Herein, MOF-derived porous Co3O4 scaffolds as the core, ultrathin NiO nanosheet-arrays as the shell, well-aligned core-shell structured Co3O4@NiO were constructed on carbon cloth (CC/Co3O4@NiO) via facile chemical bath methods. Composition, morphological structure, and electrochemical performance of the hybrid nanomaterials were analyzed in detail. Benefiting from the MOF-derived porous Co3O4 core, the NiO shell with large specific surface area, and close conductive linkages between the core and shell, CC/Co3O4@NiO presents an outstanding areal capacitance of 3015.1 mF cm(-2) (1206 F g(-1)) at 5 mA cm(-2) and an exceptional rate performance. Additionally, the flexible SASC device assembled with the CC/Co3O4@NiO cathode possesses an ultra-high volumetric energy density of 3.11 mWh cm(-3) at a volumetric power density of 116 mW cm(-3) with a satisfactory cycling stability (90.1 % of after 10000 cycles). These values are superior to the great majority of the state-of-the-art flexible electrochemical capacitors. Thereby, the core-shell structured CC/Co3O4@NiO is a promising candidate material for energy storage devices, and this work can provide a reference for the structural design and constructing of electrode materials.