A Dual‐Functional Electrolyte Additive for Highly Reversible Zinc‐Ion Batteries

ABSTRACT Aqueous zinc‐ion batteries (AZIBs) have emerged as a promising storage solution, yet their practical application is hindered by severe parasitic reactions in mild acidic electrolytes. In this study, tetrabutylammonium bromide (TBAB) is introduced as a synergistic electrolyte additive to regulate the hydrogen‐bonding environment and ameliorate electrode/electrolyte interfacial chemistry. Combined spectroscopic and computational analyses revealed that TBAB addition could perturb the hydrogen‐bonding network of water molecules and reduce water activity to restrain parasitic reactions, while TBA + adsorption on the zinc surface improved interfacial wettability and homogenized Zn 2+ deposition via electrostatic shielding. This dual mechanism effectively suppressed side reactions and dendrite growth. Zn||Zn symmetric cells with TBAB additive demonstrated prolonged cycling lifespan of over 2400 h at 4 mA cm −2 , 4 mAh cm −2 , an 11‐fold improvement compared to additive‐free cells (220 h). Furthermore, Zn||MnO 2 full cells using 1.0TBAB electrolyte delivered high rate capability and cycling stability, retaining 104 mAh g −1 after 500 cycles (at 0.5 A g −1 ) and 85.5 mAh g −1 after 1000 cycles (at 1.0 A g −1 ). This work highlights the effectiveness of the dual‐functional additive and offers a novel design strategy for engineering aqueous electrolytes for high‐performance AZIBs.