Regulation of Proton Vehicle Migration for Synergetic Interfacial Stability Enables Long-Lasting Ah-Level Zinc-Ion Batteries.

Abstract

The practical implementation of aqueous zinc-ion batteries (AZIBs) is critically constrained by interfacial instabilities caused by parasitic hydrogen evolution reaction (HER) and uncontrolled zinc (Zn) dendrite growth, both of which originate from the facile Grotthuss-type proton diffusion along hydrogen bond (H-bond) networks. Here, a molecular-level strategy to disrupt this diffusion pathway is reported through the incorporation of pyridinium trifluoroacetate (PyF), which is an ionic liquid additive enriched in H-bond donors and acceptors. This PyF additive reconstructs the H-bonding landscape in the bulk, thereby slowing proton mobility and inducing a translation to a high-barrier vehicle-type mechanism. Thus, a proton-poor and Zn²⁺-rich electric double layer is generated, thereby suppressing the HER and promoting dendrite-free electrodeposition. Simultaneously, trifluoroacetate ion undergoes preferential reduction to form a hybrid organic/inorganic solid electrolyte interphase, further reinforcing the interfacial stability during dynamic cycling conditions. Expectedly, Zn//Zn symmetric cells achieve an exceptional cycling stability of 3900 h, while the Zn//NaV₃O₈ pouch cell with a capacity of 1.15 Ah maintains stable operation over 50 cycles at 0.2 A g^-1. This work offers a generalizable and scalable electrolyte engineering approach to address the intrinsic challenges of aqueous Zn metal anodes, paving the way toward high-performance, low-cost, and durable aqueous energy storage systems.