Enhanced Lithium Ion Storage by Titanium Dioxide Addition to Zinc Telluride-Based Alloy Composites.

Abstract

A nanostructured ZnTe-TiO₂-C composite is synthesized, via a two-step high-energy mechanical milling process, for use as a new promising anode material in Li-ion batteries (LIBs). X-ray diffraction and X-ray photoelectron spectroscopy results confirm the successful formation of ZnTe alloy and rutile TiO₂ phases in the composites using ZnO, Te, Ti, and C as the starting materials. Scanning electron microscopy, transmission electron microscopy, and energy dispersive X-ray spectroscopy mapping measurements further reveal that ZnTe and TiO₂ nanocrystals are uniformly dispersed in an amorphous carbon matrix. The electrochemical performances of ZnTe-TiO₂-C and other control samples were investigated. Compared to ZnTe-TiO₂ and ZnTe-C composites, the ZnTe- TiO₂-C nanocomposite exhibits better performance, thereby delivering a high reversible capacity of 561 mAh g-1 over 100 cycles and high rate capability at a high current density of 5 A g-1 (79% capacity retention of its capacity at 0.1 A g-1). Furthermore, the long-term cyclic performance of ZnTe-TiO₂-C at a current density of 0.5 A g-1 shows excellent reversible capacity of 528 mAh g-1 after 600 cycles. This improvement can be attributed to the presence of a TiO₂-C hybrid matrix, which acts as a buffering matrix that effectively mitigates the large volume changes of active ZnTe during repeated cycling. Overall, the ZnTe-TiO₂-C nanocomposite is a potential candidate for high-performance anode materials in LIBs.