Modifying Electronic Structure of Bismuth Telluride Through S Doping and Te Vacancy Engineering for Enhanced Zn-Ion...

Bismuth chalcogenides are used as cathode materials in Zn-proton hybrid ion batteries, which exhibit an ultraflat discharge plateau that is favorable for practical applications. Unfortunately, their capacity is not competitive, and their charge storage mechanisms are ambiguous, both of which hinder their further development. In this study, S-doped Bi₂Te_{3- x} (SBT) nanosheets are prepared by tellurizing a Bi₂O₂S precursor using a hydrothermal process. As revealed by density functional theory analyses, the S dopant and its induced Te vacancies can distinctly manipulate the electronic structure of SBT, resulting in decent electrical conductivity and more negative adsorption energy to Zn²⁺. These advantages boost the Zn²⁺ storage ability of SBT materials. Consequently, compared with defect-free Bi₂Te₃, the SBT cathodes have superior specific capacity, rate capability, and cycling stability.