Lignin@Nafion Membranes Forming Zn Solid–Electrolyte Interfaces Enhance the Cycle Life for Rechargeable Zinc-Ion Batteries

Metallic zinc is an ideal anode material for rechargeable zinc-ion batteries (ZIBs), taking us beyond the lithium-ion era. In-depth understanding of the Zn metal surface is currently required owing to diverse but uncorrelated data about the Zn surface in mild environments. Herein, the surface chemistry of Zn is elucidated and the formation and growth of a zinc layer hydroxide is verified as an effective solid–electrolyte interface (SEI) during stripping/plating in mild electrolyte. The effects of battery separators/membranes on the growth of an effective SEI and deposited Zn are then investigated from the perspectives of structure, morphology, compositions, and interfacial impedance. Nafion-based membranes enable the formation of a planar SEI, which protects the metal surface and prevents short circuiting. Biomass@Nafion membranes are developed and assessed with a long cycle life of over 400 h compared with below 200 h for physical separators. The mechanism behind this is attributed to interaction between the membranes and Zn²⁺, which enables reshaping of the Zn²⁺ coordination in an aqueous medium. Together with the advantages of using the membranes in β-MnO₂|ZnSO₄|Zn, our work provides a feasible way to design an effective SEI for advancing the use of Zn anodes in rechargeable ZIBs.