Enhancing Distorted Metal-Organic Framework-Derived ZnO as Anode Material for Lithium Storage by the Addition of Ag2S Quantum Dots

Abstract

The lithium storage properties of the distorted metal-organic framework-derived nanosized ZnO@C are significantly improved by the introduction of Ag<inf>2</inf>S quantum dots (QDs) during the processing of the material. In the thermal treatment, the Ag<inf>2</inf>S QDs react to produce Ag nanoparticles and ZnS. The metal nanoparticles act to shorten electron pathways and improve the connectivity of the matrix, and the partial sulfidation of the ZnO surface improves the cycling stability of the material. The electrochemical properties of ZnO@C, Ag<inf>2</inf>S QDs-treated ZnO@C, and the amorphous carbon in ZnO@C have been compared. The small weight ratio of Ag<inf>2</inf>S QDs to ZnO@C at 1:180 shows the best performance in lithium storage. The exhibited specific capacities are improved and retained remarkably in the cycling at high current rates. At low current densities (200 mA g^-1), treatment of ZnO@C with Ag<inf>2</inf>S QDs results in a 38% increase in the specific capacity.