AMINO ACID-REGULATED ELECTROLYTES FOR RECHARGEABLE ZINC BATTERIES

Aqueous zinc batteries (AZBs) are promising candidates for energy storage batteries due to their safety, low cost, and environmentally friendly nature. However, obstacles such as dendritic zinc growth, hydrogen evolution reaction (HER), electrochemical irreversibility at lower temperature, etc. have partially limited their application. In this study, a perchlorate-based aqueous electrolyte (2.0 molar (M) Zinc Perchlorate Zn(ClO₄)₂) was investigated systematically, where it was modified using bio-inspired amino acid additives, L-histidine (0.02 M) and L-glutamic acid (0.05 M). Through electrochemical techniques, including cyclic voltammetry (CV), linear sweep voltammetry (LSV), Tafel analysis and plating/stripping tests, it was found that the L-amino acids additives modulate Zn²⁺ solvation, stabilize HER and allow the possibility for highly reversible plating/stripping with Coulombic efficiencies near 98%. Full-cell Zn∥α-MnO₂ tests also revealed that histidine helped long-term capacity retention (>80 mAh g⁻¹ after 100 cycles) while glutamic acid stabilized the kinetics. Both amino acid additives displayed near 100% Coulombic efficiency at sub-zero temperatures (−20 °C). The combined results reveal that coupling chaotropic perchlorate electrolytes with amino acid additives delivers high reversibility, cycle stability, and reliable subzero operation, underscoring their potential for grid-scale storage and cold-climate applications.