Graphitic Carbon Coated CuO Hollow Nanospheres with Penetrated Mesochannels for High-Performance Asymmetric Supercapacitors

We have developed a simple solvothermal–calcination strategy to synthesize continuous graphitic carbon coated hollow CuO (H–CuO@GC) spheres with excellent electrochemical performance. The H–CuO@GC spheres exhibit a high specific surface area (106.6 m² g^–1), penetrated mesochannels (∼5–15 nm), a large pore volume (0.313 cm³ g^–1), a robust hollow structure, and an integral graphitic carbon layer. The H–CuO@GC sphere electrode presents high capacitance, good rate capability, and outstanding cycling ability in supercapacitors. In addition, the asymmetric supercapacitor (ASC) assembled by this structure exhibits a good rate capability (retain 75.7% at 10 A g^–1) and an excellent cycling stability (90.2% capacitance retention after 10000 cycles), as well as a high energy density (38.6 W h kg^–1 at a power density of 1.018 kW kg^–1). This work represents a novel design strategy for the improvement of low-conductive nanomaterials applied in many fields, especially in energy applications.