Manipulating Zn2+/H+ migration kinetics and anode interfacial stability via bio-derived gelatin toward robust aqueous Zn metal batteries

The development of aqueous zinc metal batteries (AZMBs) is still compromised by hydrogen evolution (HER), corrosion, and dendrite formation at the Zn anode. Herein, we propose a bio-derived gelatin electrolyte additive to simultaneously mitigate these challenges. The bio-derived gelatin molecules, featuring abundant electron-acceptor group (–COOH) and electron-donor group (−NH 2 ), spontaneously adsorb onto the Zn surface, constructing a robust hydrophilic protective layer that suppresses parasitic reactions and corrosion. DFT and dynamic analysis demonstrate that the gelatin-derived protective layer can efficiently manipulate Zn 2+ /H + migration kinetics, which facilitate Zn 2+ transport and even plating, as well confine H + transport, effectively relieving Zn dendrite growth and HER. Therefore, AZMBs with bio-derived gelatin additive electrolyte (GZS) exhibit an outstanding electrochemical performance. The Zn||Zn symmetric cell delivers an extraordinary lifespan exceeding 5100 h at 1 mA cm −2 . In addition, the Zn||I 2 full cells with GZS deliver a reversible specific capacity of 337.6 mAh g −1 under 1.0 A g −1 , and reach a capacity retention of 93.0% after 500 cycles. Moreover, the GZS system reach 203.2 mAh g −1 and without obvious capacity degradation under 5.0 A g −1 . This work underscores the dual role of gelatin in stabilizing Zn anodes and offers a bio-inspired pathway for electrolyte engineering in high-performance AZMBs.