Electrochemical activation endows iodine-doped bismuth telluride with rich vacancies for highly performance aqueous zinc-based battery

Abstract

Researchers are increasingly interested in bismuth chalcogenides (BCs) as cathode materials for aqueous zinc-based batteries (AZBs) due to their ultra-flat voltage plateau. However, the practical application of BCs is limited by their insufficient capacity, which results from poor conductivity and slow ion diffusion. To address these challenges, we propose a novel approach utilizing iodine-doped Bi₂Te₃ (IBT) sheets with a unique porous structure as a cathode material. Density functional theory calculations indicate that iodine doping significantly reduces the energy barrier for tellurium vacancy formation. Due to its abundant defects, IBT demonstrates a superior ion diffusion coefficient in comparison to pure Bi₂Te₃ (BT). Additionally, the introduction of iodine heteroatoms imparts conductor-like properties to IBT, thereby enhancing its electronic conductivity. Consequently, the IBT cathode exhibits a satisfactory capacity of 320 mA h g⁻¹ at a current density of 0.5 A g⁻¹. When cycled at 20 A g⁻¹, the IBT cathode shows an initial capacity of 176.6 mA h g⁻¹ and maintains a substantial capacity of 150.5 mA h g⁻¹ after 2000 cycles. This study conclusively demonstrates that halogens can serve as effective dopants to modify the physicochemical characteristics of BC materials, suggesting a promising strategy for the development of high-performance cathodes in AZBs.