Charge storage mechanism of aqueous bismuth telluride–zinc batteries with high rate capability

In the last decade, aqueous zinc-based batteries (AZBs) have attracted significant research attention owing to their intrinsic security, low cost, and eco-friendliness. Nevertheless, the development of AZBs has been hindered by the sluggish kinetics of cathode materials. Bismuth chalcogenides were recently employed as cathode materials for AZBs, and they exhibited high electrochemical performance and practicability. However, the rate performance of bismuth chalcogenides needs to be improved further, and the corresponding charge storage mechanism needs to be elucidated. In this study, we synthesized Bi2Te3 with hexagonal nanoflake morphology (BHN) as a cathode for high-performance bismuth telluride-zinc batteries. The charge storage mechanisms of BHN were investigated through electrochemical tests and ex situ characterization. Three electrochemical processes were found to occur in the aqueous BHN–Zn battery: (1) proton insertion/extraction, (2) Zn4SO4(OH)6·0.5H2O generation/decomposition, and (3) conventional Zn2+ insertion/extraction. The proton insertion/extraction process was predominant, which was responsible for the excellent rate capability, cycling durability, and low-temperature performance of the BHN cathode. This work has the potential to facilitate the development of high-performance AZBs.