Synthesis and Electrochemical Properties of TiO2-Ti3C2 Quantum Dots with a Layered Structure as Efficient Sulfur Hosts for High-Performance Lithium-Sulfur Batteries

Abstract

Purpose: An ideal sulfur-supporting material for lithium-sulfur (Li-S) batteries would exhibit both minimal volume expansion and high electrical conductivity because these properties are essential for improving cycling stability, and enable implementation in large-scale applications. Methods: In this work, we developed TiO2 quantum dots on Ti3C2 (QDs TiO2-Ti3C2) MXene nanosheets using a simple hydrothermal synthesis. The sulfur was loaded in the QDs TiO2-Ti3C2 MXene via a simple melt-diffusion method. Results: The TiO2 quantum dots increased the interlayer space and prevented restacking of the MXene nanosheets. The QDs TiO2-Ti3C2@S electrode showed a higher initial capacity at a C-rate of 0.5, 921.6 mAh/g, compared with the corresponding value for the Ti3C2@S (499.0 mAh/g). Moreover, the QDs TiO2-Ti3C2@S electrode demonstrated excellent cyclic stability, retaining a capacity of 342.7 mAh/g after 150 cycles. Conclusion: The QDs TiO2-Ti3C2@S electrode showed significantly enhanced long-term cyclability and rate capability, demonstrating a new prospect for the development of rapid and stable Li-S batteries.