Rational design of core-shell ZnTe@N-doped carbon nanowires for high gravimetric and volumetric alkali metal ion storage

Abstract

Among the various semiconductor materials, zinc telluride possesses the lowest electron affinity and ultrafast charge separation capability, facilitating improved charge transfer kinetics. In addition, ZnTe has a relatively high density, contributing to high volumetric capacity. Here, 1D N-doped carbon-coated ZnTe core-shell nanowires (ZnTe@C) are designed and prepared via a facile ion-exchange and carbonization technique. When evaluated as anode for metal ion batteries, it demonstrates superior electrochemical performance in both Li and Na ion storage, including high gravimetric and volumetric capacities (1119 mA h g−1 and 906 mA h cm−3, respectively, at 100 mA g−1 for Li ion storage), excellent high-rate capability, and long-term cycling stability. This remarkable electrochemical performance is attributed to the low electron affinity and high density of ZnTe, and the amorphous nature of the N-doped carbon layer in the heterostructured ZnTe@C nanowires, which not only provide fast charge transfer paths, but also effectively maintain the structural and electrical integrity of the ZnTe. The strategy of embedding high density and high-performance active materials in highly conductive nanostructures represents an effective way of achieving electrode materials with excellent gravimetric and volumetric capacities towards superior energy storage systems.