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

Abstract 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 Co 3 O 4 scaffolds as the core, ultrathin NiO nanosheet‐arrays as the shell, well‐aligned core‐shell structured Co 3 O 4 @NiO were constructed on carbon cloth (CC/Co 3 O 4 @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 Co 3 O 4 core, the NiO shell with large specific surface area, and close conductive linkages between the core and shell, CC/Co 3 O 4 @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/Co 3 O 4 @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/Co 3 O 4 @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.