Overcoming challenges of protonation effects induced by high isoelectric point amino acids through a synergistic strategy towards highly stable and reversible zinc electrode-electrolyte interface

Abstract

Amino acids are among the most commercially promising additive solutions for achieving stable zinc anodes. However, greater attention should be given to the limitation arising from the protonation effects induced by high isoelectric point amino acids in the weakly acidic electrolytes of aqueous zinc-ion batteries (AZIBs). In this study, we introduce histidine (HIS) and ethylenediaminetetraacetic acid (EDTA) as hybrid additives into the aqueous electrolyte. Protonated HIS is adsorbed onto the anode interface, inducing uniform deposition and excluding H₂O from the inner Helmholtz plane (IHP). Furthermore, the addition of EDTA compensates for the limitation of protonated HIS in excluding solvated H₂O. EDTA reconstructs the solvation structure of Zn²⁺, resulting in a denser zinc deposition morphology. The results demonstrate that the Zn||Zn battery achieved a cycling lifespan exceeding 1480 h at 5 mA cm^-2 and 5 mAh cm^-2. It also reached over 900 h of cycling at a zinc utilization rate of 70 %. This study provides an innovative perspective for advancing the further development of AZIBs.