Biocrust-inspired interface layer with dual functions towards highly reversible zinc metal anodes

The commercialization of aqueous zinc-ion batteries is still challenging owing to the undesirable dendrite growth and serious side reactions occurring at the anode surface. However, in situ construction of solid electrolyte interfaces (SEI) can effectively improve the stability of the zinc anode. Herein, a bioinspired crust strategy implementing eflornithine (DFMO) electrolyte additive was proposed to construct a ZnF₂-rich SEI, which can adjust the interfacial chemistry of zinc anode. This functional SEI, akin to biological crust, not only suppressed the side reactions by blocking the direct contact between the anode and the electrolyte but also enhanced the anode stability at high current owing to its high ionic conductivity and excellent mechanical properties. Additionally, the carbonyl group regulated the solvated structure of Zn²⁺ and reconstructed the hydrogen bond networks. Accordingly, using DFMO, a prolonged cycling lifespan and an ultrahigh average coulombic efficiency (CE) of 99.87% at 5 mA cm⁻² and 1 mA h cm⁻² were realized for zinc anodes. Furthermore, the DFMO-based Zn//NVO pouch cell achieved an excellent cycle stability, confirming the feasibility and superiority of the proposed bioinspired crust strategy. Thus, this work offers valuable insights into the construction of ZnF₂-rich SEI by electrolyte addition and provides a novel perspective for the protection of zinc anodes.