(348b) High-Performance Asymmetric Supercapacitors Based on Carbon Nanotubes@Ni(OH)2 Core-Shell Composites and Three-Dimensional Graphene Networks

Constructing aqueous electrolyte based asymmetric supercapacitors (ASCs) has captured great interest as their wide operation voltage and high ionic conductivity. To further boost the performance of ASCs, synthesis of electrode materials with judiciously designed nanostructure is quite important. In this study, we fabricated a novel ASC based on hierarchical carbon nanotubes@nickel hydroxide nanosheets (CNT@Ni(OH)₂) core-shell composites as positive electrode and three-dimensional (3D) graphene networks (3DGN) as negative electrode in aqueous KOH solution electrolyte. The CNT@Ni(OH)₂ core-shell composites were prepared through a facile chemical bath deposition method, while 3DGN were obtained by freeze-drying of graphene hydrogels. By virtue of their unique nanostructures, superb electrochemical properties have been achieved in three-electrode system, e.g., 1136 F g^-1 at 2 A g^-1 for the CNT@Ni(OH)₂ electrode within 0~0.5 V, and 203 F g^-1 at 1 A g^-1 for the 3DGN electrode within -1~0 V. Benefiting from these merits, the as-fabricated CNT@Ni(OH)₂//3DGN ASC shows maximum energy density of 44.0 Wh kg^-1 at a power density of 800 W kg^-1 and even retains 19.6 Wh kg^-1 at 16,000 W kg^-1 in the voltage region of 0~1.6 V. The outstanding electrochemical performance of CNT@Ni(OH)₂//3DGN ASC makes it a promising solution for future energy storage.