Building TiO2-Ti3C2Tx heterojunction by microwave-assisted hydrothermal as an amphiphilic nanoreactor for high-performance lithium sulfur batteries

Abstract

The adoption of lithium-sulfur (Li-S) batteries faces significant obstacles due to the notorious lithium polysulfides (LiPSs) shuttle effect and sluggish electrochemical reaction kinetics. To tackle these issues, MXene, with the unique layered structures and metal centers, have emerged as promising additives in Li-S batteries, effectively hindering the migration of polysulfides through physical and chemical confinement mechanisms. However, MXenes inherently lack robust anchoring sites for LiPSs, leading to suboptimal cycle stability. Here, TiO₂-Ti₃C₂T_x (TT) heterojunction derived from MXene is constructed by the microwave-assisted hydrothermal (MAH). This innovative TT composite incorporates an amphiphilic nanoreactor that synergistically adsorbs, catalyzes LiPSs, and stabilizes the lithium anode in Li-S batteries. The optimally exposed surface of Ti₃C₂T_x and nano-sized TiO₂ within the TT architecture collaborate to “conduct, adsorb and transform” LiPSs, while the heterogeneous interface and crumpled sheets provide an efficient three-dimensional transport pathway for Li⁺ in the electrolyte, collaboratively enhancing the stability of Li-S batteries. Therefore, the TT-160 as an interlayer for Li-S battery exhibits an ultra-low capacity attenuation of each cycle of 0.022 % after 1000 cycles at 2 C. Furthermore, the conductive interlayer facilitates a uniform distribution of Li⁺ transport, enabling a Li//Li symmetric cell assembled with TT-160 to achieve remarkable stability over 1000 h. This work pioneeringly demonstrates the potential of MXene-derived TiO₂-Ti₃C₂T_x heterojunction, synthesized via MAH for high-performance Li-S batteries, opening up new avenues for material design and optimization.