Synergistic “Anchor-Capture” Enabled by Amino and Carboxyl for Constructing Robust Interface of Zn Anode

Abstract

While the rechargeable aqueous zinc-ion batteries (AZIBs) have been recognized as one of the most viable batteries for scale-up application, the instability on Zn anode-electrolyte interface bottleneck the further development dramatically. Herein, we utilize the amino acid glycine (Gly) as an electrolyte additive to stabilize the Zn anode-electrolyte interface. The unique interfacial chemistry is facilitated by the synergistic "anchor-capture" effect of polar groups in Gly molecule, manifested by simultaneously coupling the amino to anchor on the surface of Zn anode and the carboxyl to capture Zn²⁺ in the local region. As such, this robust anode-electrolyte interface inhibits the disordered migration of Zn²⁺, and effectively suppresses both side reactions and dendrite growth. The reversibility of Zn anode achieves a significant improvement with an average Coulombic efficiency of 99.22% at 1 mA cm^-2 and 0.5 mAh cm^-2 over 500 cycles. Even at a high Zn utilization rate (depth of discharge, DOD_Zn) of 68%, a steady cycle life up to 200 h is obtained for ultrathin Zn foils (20 μm). The superior rate capability and long-term cycle stability of Zn-MnO₂ full cells further prove the effectiveness of Gly in stabilizing Zn anode. This work sheds light on additive designing from the specific roles of polar groups for AZIBs.