Sulfur‐Deficient TiS2‐x for Promoted Polysulfide Redox Conversion in Lithium‐Sulfur Batteries

Abstract Sulfur‐deficient TiS2–x is prepared through high temperature vacuum annealing. Electron spin resonance (ESR) and X‐ray photoelectron spectroscopy (XPS) data confirm the presence of sulfur vacancies in TiS2–x. Effective polysulfide adsorption and promotion to polysulfide redox conversion was proven by adsorption simulation experiments and electrochemical measurements. Thus, TiS2–x is used as cathode promoter for Li−S half‐cells to improve the overall electrochemical performance. As expected, the TiS2–x/S electrode shows a high and stable capacity of 751 mAh g−1 even after 500 cycles and a fade rate as low as 0.04 % per cycle at 1 C. Besides, the high sulfur loading of the electrode of 4 mg cm−2 also displays an admirable cycling performance of 963 mAh g−1 with a capacity retention up to 91.7 % over 50 cycles at 0.2 C.