Engineering Aqueous Electrolytes with Vicinal S-based Organic Additives for Highly Reversible Zinc-Ion Batteries

The commercial deployment of aqueous zinc-ion batteries (AZIBs) is hampered by dendrites, the hydrogen evolution reaction (HER), and corrosion reactions. To tackle these challenges, we have introduced 3,3'-dithiobis-1-propanesulfonic acid disodium salt (SPS), a symmetrical sulfur-based organic salt, as an electrolyte additive for AZIBs. Unlike conventional electrolyte additives that favor (002) deposition, SPS enables dense (100) growth through a unique symmetrically aligned concentration-controlled adsorption network, affording structural uniformity and compactness to the Zn deposit layer. The dual-action symmetrical SPS additive adsorbs onto the Zn surface via vicinal sulfur atoms, blocking electrolyte access to the Zn anode, enhancing the transportation kinetics of Zn²⁺, and simultaneously promoting desolvation by displacing water molecules from the solvation shell. This synergistic effect improves the stability of the Zn anode by mitigating HER and corrosion, resulting in over 1100 h of cycling at 5 mA cm^-2, 5 mAh cm^-2, stable operation at even 15 mA cm^-2, 15 mAh cm^-2, and achieving impressive Coulombic efficiency (CE) of 99.41%. As validation, the Zn/NaV₃O₈·1.35H₂O cell with SPS-additive afforded high cycling stabilization and excellent capacity retention of 95.5%. This study offers valuable insights for advancing AZIBs and other metal-based batteries.