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The in‐depth understanding of the composition‐property‐performance relationship of solid electrolyte interphase (SEI) is the basis of developing a reliable SEI to stablize the Zn anode‐electrolyte interface, but it remains unclear in rechargeable aqueous zinc ion batteries. Herein, a well‐designed electrolyte based on 2 M Zn(CF3SO3)2‐0.2 M acrylamide‐0.2 M ZnSO4 is proposed. A robust polymer (polyacrylamide)‐inorganic (Zn4SO4(OH)6.xH2O) hybrid SEI is in situ constructed on Zn anodes through controllable polymerization of acrylamide and coprecipitation of SO42− with Zn2+ and OH−. For the first time, the underlying SEI composition‐property‐performance relationship is systematically investigated and correlated. The results showed that the polymer‐inorganic hybrid SEI, which integrates the high modulus of the inorganic component with the high toughness of the polymer ingredient, can realize high reversibility and long‐term interfacial stability, even under ultrahigh areal current density and capacity (30 mA cm−2~30 mAh cm−2). The resultant Zn||NH4V4O10 cell also exhibits excellent cycling stability. This work will provide a guidance for the rational design of SEI layers in rechargeable aqueous zinc ion batteries. [ABSTRACT FROM AUTHOR]

Routine electrolyte additives are not effective enough for uniform zinc (Zn) deposition, because they are hard to proactively guide atomic‐level Zn deposition. Here, based on underpotential deposition (UPD), we propose an "escort effect" of electrolyte additives for uniform Zn deposition at the atomic level. With nickel ion (Ni2+) additives, we found that metallic Ni deposits preferentially and triggers the UPD of Zn on Ni. This facilitates firm nucleation and uniform growth of Zn while suppressing side reactions. Besides, Ni dissolves back into the electrolyte after Zn stripping with no influence on interfacial charge transfer resistance. Consequently, the optimized cell operates for over 900 h at 1 mA cm−2 (more than 4 times longer than the blank one). Moreover, the universality of "escort effect" is identified by using Cr3+ and Co2+ additives. This work would inspire a wide range of atomic‐level principles by controlling interfacial electrochemistry for various metal batteries. [ABSTRACT FROM AUTHOR]

Aqueous zinc‐ion batteries have drawn increasing attention due to the intrinsic safety, cost‐effectiveness and high energy density. However, parasitic reactions and non‐uniform dendrite growth on the Zn anode side impede their application. Herein, a multifunctional additive, ammonium dihydrogen phosphate (NHP), is introduced to regulate uniform zinc deposition and to suppress side reactions. The results show that the NH4+ tends to be preferably absorbed on the Zn surface to form a "shielding effect" and blocks the direct contact of water with Zn. Moreover, NH4+ and (H2PO4)− jointly maintain pH values of the electrode‐electrolyte interface. Consequently, the NHP additive enables highly reversible Zn plating/stripping behaviors in Zn//Zn and Zn//Cu cells. Furthermore, the electrochemical performances of Zn//MnO2 full cells and Zn//active carbon (AC) capacitors are improved. This work provides an efficient and general strategy for modifying Zn plating/stripping behaviors and suppressing side reactions in mild aqueous electrolyte. [ABSTRACT FROM AUTHOR]