Polyhydroxy Sodium Salt Additive to Regulate Zn²⁺ Solvation Structure and Zn Deposition Texture for High-Stability...

Electrolyte additives are commonly employed in aqueous zinc-ion batteries (ZIBs) to suppress dendrite growth, corrosion, and hydrogen evolution. However, rational design principles and systematic mechanistic studies for selecting suitable additives to regulate reversible Zn plating/stripping chemistry are worth in-depth study. Using L-ascorbic acid sodium (LAAS) as the representative, theoretical calculations combined with in situ experimental analyses manifest that polyhydroxy-sodium-salts preferentially chemisorbed on Zn surface to construct the H₂O-poor interfacial microenvironment, suppressing undesirable water-related side reactions. Concurrently, sodium ions provide an armor shielding layer to regulate the electric field to guide (002) Zn deposition texture. Specifically, sodium-salts replace H₂O molecules in the coordinated shell of hydrated Zn²⁺ ions, improving the electrochemical stability window (ESW) to extend the working voltage of the aqueous ZIBs. Therefore, Zn||Zn symmetric cell with polyhydroxy-sodium-salts additive exhibits impressive cumulative capacity of 7875 mAh cm^-2 at high current density of 30 mA cm^-2. Even when the discharge voltage expands to 1.8 V, Zn||V₂O₅ full cell realizes a capacity retention of 98.26% for over 500 cycles. This work quickens the design of advanced aqueous ZIBs by green and cheap electrolyte additive, which is expected to herald an innovative phase of research on high-stability aqueous batteries.