Low-Temperature Synthesis and Electrochemical Properties of Mesoporous Titanium Oxysulfides

This paper describes the synthesis and electrochemical properties of mesoporous titanium oxysulfides prepared through the chemical treatment of pristine mesoporous titanium oxide under various synthesis conditions. The materials were doped with sulfur by using hexamethyldisilathiane (HMDST), a strategy that was developed to improve the conductivity of the material, whilst also retaining the porosity and thermal stability. Varying amounts of HMDST and different synthesis temperatures were tested to optimize the surface area and electrochemical performance. Lower temperatures generally yielded materials with superior properties and, even though the conductivity was improved by using higher loading levels of HMDST, it also led to a drop in initial capacity at the highest synthesis temperature of 200 °C (137–41 mAh g−1). The best performing material was, thus, synthesized by using the highest level of HMDST (3.5 mL) at lower heating temperatures (100–150 °C). This set of conditions maximizes the combination of surface area, initial capacity, conductivity, and capacity retention, the latter of which was notably superior to that of the pristine material (81 vs. 35 %), emphasizing the overall success of this doping strategy in improving the electrochemical properties of these otherwise insulating materials.