The synthesis and electrochemical performance of core-shell structured Ni-Al layered double hydroxide/carbon nanotubes composites

We report a fabrication of nano-flakes consisting of Ni-Al layered double hydroxide grown on functionalized carbon nanotube bundles by a hydrothermal method for energy storage application. This nano-flake structure is denoted as Ni-Al LDH/CNTs. The morphology characterization indicates that the composite displays a three-dimensional architecture with a well-defined core-shell configuration and large surface area. Due to its unique core-shell structure, the Ni-Al LDH/CNTs electrode with a mass loading of 50 mg/cm2 reaches a high electrochemical performance of 1017C/g (the corresponding area-normalized capacity is 50.85C/cm2) at a current density of 1 A/g, and excellent rate performance (remains 85% when the current density increases to 10 A/g). Furthermore, the composite exhibits good behavior during life testing with a decrease of the specific capacity of 88% after 1000 cycle tests at a current density of 2 A/g, indicating the composite has adequate high-current electrochemical behavior. The attractive electrochemical performance of this Ni-Al LDH/CNTs illustrates its unique advantage for energy storage systems. In addition, the rational design demonstrated here a blueprint for a cheap synthesis of a CNTs-based three-dimensional nano core-shell structure.