A Multifunctional Electrolyte Additive Enhances The Long-Cycle-Life of Aqueous Zinc-Ion Batteries

Abstract

Aqueous zinc-ion batteries offer advantages of low cost and environmental friendliness, yet their practical applications are hindered by uncontrolled dendrite growth and parasitic reactions. Herein, we introduce a gelatin electrolyte additive to stabilize the Zn/electrolyte interface and extend battery lifespan. Unlike previous gelatin-based strategies mainly focusing on defect self-healing and electrostatic shielding, this work reveals a functional-group-mediated regulation mechanism for stabilizing Zn anodes. The –OH groups preferentially anchor gelatin onto the Zn surface through Zn–O interactions and regulate interfacial water activity, while –COOH and –CONH₂ groups modify Zn2+ solvation structures through weak coordination. This synergistic interfacial and solvation regulation promotes uniform Zn deposition and suppresses side reactions. The gelatin-modified electrolyte delivers enhanced reversibility and stability, achieving a Coulombic efficiency of 99.12% in Zn||Cu cells, over 4000 h cycling in Zn||Zn cells, and a specific capacity of 185.2 mAh g⁻¹ after 1000 cycles at 1 A g⁻¹ in Zn||V2O5 cells. This work presents a facile and effective approach to stabilize zinc anodes via interfacial modulation, using cost-effective and environmentally friendly gelatin additive, enlightening development of long-life aqueous zinc-ion batteries.