Boosting the Practical Applications of Zinc-Ion Batteries via Zwitterion-Mediated Solvation and Interfacial Chemistry

The thermodynamic instability of Zn anode in aqueous electrolyte, driven by corrosion and hydrogen evolution reactions, severely restricts the practical applications of aqueous zinc-ion batteries. Herein, a zwitterion-mediated solvation chemical and interfacial engineering strategy is proposed to address these challenges. By introducing aniline blue (AB) with (-SO3H) and amine (-NH2) groups as a multifunctional electrolyte additive, the interfacial pH fluctuations are dynamically stabilized, together with the reconstructed electrode/electrolyte interface and Zn2+ solvation structure. Real-time measurements show that the AB enables in-situ pH-buffering during both shelving and working time, suppressing parasitic hydrogen evolution and the self-corrosion of Zn. The parasitic reactions are further inhibited by the preferential absorption of AB at the Zn surface, which reshapes the electrical double layer, creating a water-deficient micro-environment at the Zn/electrolyte interface and homogenizes Zn2+ deposition. Simultaneously, AB participates the solvation structure, resulting in fast electrochemical kinetics. This strategy enables the Zn||Zn cells with over 1600 h calendar aging time, high reversibility and robust stability under harsh conditions (a 220 h durable time even under 80% depth of discharge, DoD). Especially, the Zn||V2O5 full cells retain a high capacity of 105 mAh g-1 after 3000 cycles at 5000 mA g-1. Even at an ultralow negative to positive (N/P) ratio of 2, the full batteries can still deliver a high capacity of 153 mAh g-1 after 120 cycles.