Synergistic effect between S and Te enhancing the electrochemical behavior of heteroatomic TeS-x cathodes in aqueous Zn–TeS batteries

Aqueous Zn–S batteries (AZSBs) have garnered increasing attention in the energy storage field owing to their high capacity, energy density , and cost effectiveness. Nevertheless, sulfur (S) cathodes face challenges, primarily stemming from sluggish reaction kinetics and the formation of an irreversible byproduct (SO 4 2− ) during the charge, hindering the progress of AZSBs. Herein, Te–S bonds within S-based cathodes were introduced to enhance electron and ion transport and facilitate the conversion reaction from zinc sulfide (ZnS) to S. This was achieved by constructing heteroatomic TeS-x@Ketjen black composite cathodes (HM-TeS-x@KB, where x  = 36, 9, and 4). The HM-TeS-9@KB electrode exhibits long-term cycling stability, maintaining a capacity decay rate of 0.1 % per cycle over 450 cycles at a current density of 10 A g −1 . Crucially, through a combination of experimental data analysis and theoretical calculations, the impact mechanism of Te on the charge and discharge of S active materials within the HM-TeS-9@KB cathode in AZSBs was investigated. The presence of Te–S bonds boost the intrinsic conductivity and wettability of the HM-TeS-9@KB cathode. Furthermore, during the charge, the interaction of preferentially oxidized Te with S atoms within ZnS promotes the oxidation reaction from ZnS to S and suppresses the irreversible side reaction between ZnS and H 2 O. These findings indicate that the heteroatomization of chalcogen S molecules represents a promising approach for enhancing the electrochemical performance of S cathodes in AZSBs.