Triazine Ring and Sulfhydryl-Enabled Binder Design: A Path to Superior Zinc Ion Batteries with Enhanced Ion Transport

Aqueous zinc ion batteries (AZIBs) are hindered from extensive application due to the sluggish kinetics of hydrated zinc ions and cathodic dissolution, which leads to the deficiency of cycling performance in zinc ion batteries. This work elucidates a series of sulfhydryl-rich binding agents (STN, SON, SSN). The sulfhydryl groups suspended by the binders interact with the cations in the electrolyte, facilitating the transport of Zn²⁺, enhancing redox kinetics, and improving the cycling stability of the cell. Additionally, the formation of dynamic S–S bonds after the oxidation of sulfhydryl groups further restricts the volume expansion in the cathode during charge and discharge cycles, ensuring structural stability. The STN binder exhibits the most optimal performance. The N-containing triazine ring interacts with Zn²⁺, while the sulfhydryl group forms a dynamic coordination bond with Zn²⁺, thereby enhancing the Zn²⁺ storage and promoting the Zn²⁺ intercalation. This dual function ultimately produces a synergistic effect to optimize the electrochemical performance of AZIBs. The initial specific discharge capacity of the cell with STN binder is 123 mAh g⁻¹ at 1 C multiplicity, which exceeds the 68 mAh g⁻¹ capacity of the cell with PVDF binder.