Dynamic Zn²⁺-Conductive Protective Layer for Durable Zinc Anode in Aqueous Zinc-Ion Batteries.

Abstract

The Zn anode in aqueous zinc-ion batteries (AZIBs) suffers from hydrogen evolution reaction (HER), by-product accumulation, and dendrite growth, severely restricting practical viability. To address these challenges concurrently, we propose a dynamic Zn²⁺-conductive protective layer strategy, which involves constructing an in situ ZnOHF layer on the Zn anode and incorporating F^- into the electrolyte. Zn²⁺-conductivity and reducibility of ZnOHF layer guide uniform Zn nucleation and deposition, thereby inhibiting dendrite formation. Crucially, the addition of F^- to the electrolyte enables the dynamic regeneration of the ZnOHF layer during cycling and the conversion of detrimental by-products into favorable ZnOHF. Additionally, HER is effectively suppressed by isolating the Zn anode from the aqueous electrolyte via ZnOHF interfacial layer, and decreasing water activity through F^--induced elevation of electrolyte pH from 4.1 to 5. As a result, the protected Zn anode enables the symmetrical cell to operate stably for 3100 h at 0.5 mA cm^-2, and a full cell to retain 85% capacity after 4000 cycles at 10 A g^-1. Moreover, a 90 cm² pouch cell delivers an initial capacity of 240 mAh and maintains 70% capacity after 200 cycles, highlighting its practical viability. This work presents an effective and scalable interface engineering approach to realize durable Zn anodes for practical AZIBs.