Solvation Chemistry and Interfacial Modulation by Zwitterionic 2-Cyclohexylaminoethanesulfonic Acid for Highly Reversible Aqueous Zinc Batteries.

The practical application of aqueous zinc-ion batteries (AZIBs) is hindered by Zn dendrite growth, water-induced parasitic reactions, and interfacial instability at the Zn anode. Herein, we propose a multifunctional molecular engineering strategy by introducing 2-cyclohexylaminoethanesulfonic acid (CHES), an amphiphilic electrolyte additive containing sulfonic acid, amino, and hydrophobic cyclohexyl groups, to regulate the Zn anode microenvironment. Experimental investigations and theoretical calculations reveal that CHES coordinates with Zn2+ to reconstruct the solvation structure, while its multifunctional groups reorganize the hydrogen-bond network and reduce the reactivity of interfacial water, thereby suppressing hydrogen evolution and interfacial corrosion. Meanwhile, CHES molecules preferentially adsorb onto the Zn surface to form a stable molecular protective layer, which homogenizes Zn2+ flux, promotes uniform nucleation, and enables compact Zn deposition. The hydrophobic cyclohexyl moiety further provides steric shielding against water attack, enhancing interfacial stability. Consequently, Zn||Zn symmetric cells achieve stable cycling for over 3000 h at 2 mA cm-2 and 1 mAh cm-2. Moreover, Zn||NVO full cells retain 84% of their capacity after 3000 cycles at 5 A g-1. This work highlights the importance of multi-site molecular regulation in constructing durable Zn anodes and provides a versatile strategy for advanced aqueous zinc-ion batteries.