Ultrathin Reed Membranes: Nature's Intimate Ion-Regulation Skins Safeguarding Zinc Metal Anodes in Aqueous Batteries

The practical realization of aqueous zinc-ion batteries relies crucially on effective interphases governing Zn electrodeposition chemistry. In this study, an innovative solution by introducing an ultrathin (≈2 µm) biomass membrane as an intimate artificial interface, functioning as nature's ion-regulation skin to protect zinc metal anodes is proposed. Capitalizing on the inherent properties of natural reed membrane, including multiscale ion transport tunnels, abundant ─OH groups, and remarkable mechanical integrity, the reed membrane demonstrates efficacy in regulating uniform and rapid Zn²⁺ transport, promoting desolvation, and governing Zn (002) plane electrodeposition. Importantly, a unique in situ electrochemical Zn─O bond formation mechanism between the reed membrane and Zn electrode upon cycling is elucidated, resulting in a robustly adhered interface covering on the zinc anode surface, ultimately ensuring remarkable dendrite-free and highly reversible Zn anodes. Consequently, the approach achieves a prolonged cycle life for over 1450 h at 3 mA cm⁻²/1.5 mAh cm⁻² in symmetric Zn//Zn cells. Moreover, exceptional cyclic performance (88.95%, 4000 cycles) is obtained in active carbon-based cells with an active mass loading of 5.8 mg cm⁻². The approach offers a cost-effective and environmentally friendly strategy for achieving stable and reversible zinc anodes for aqueous batteries.