Fluorinated Self-Assembled Monolayers for Highly Reversible Anode-Free Zinc Batteries

Anode-free zinc batteries offer a promising route to maximize energy density, yet their viability is compromised by uncontrolled Zn nucleation and severe parasitic reactions at the anode side. Herein, we address this issue by designing a dual-functional fluorinated interphase on a Cu current collector, which couples high zincophilicity with robust hydrophobicity. This design leverages the electronegative fluorine atoms to enhance the zincophility of the sulfonyl tail group and guide uniform nucleation, while the fluorinated chains establish a compact hydrophobic barrier thermodynamically suppressing water-induced side reactions. As a proof-of-concept, we employ molecularly tunable self-assembled monolayers (SAMs) of benzene-based thiols on Cu. By designing a series of ligands with stepwise increased fluorination (non-fluorinated CPM → mono-fluorosulfonyl MPM → di-fluorosulfonyl DMPM), we demonstrate that higher fluorine content progressively enhances zincophilic site density and hydrophobic shielding. Consequently, the DMPM-modified Cu electrode achieves highly reversible dendrite-free Zn plating/stripping with an average Coulombic efficiency of 99.56% over 1000 cycles. This fluorinated interface exhibits universal robustness across capacitive (graphite), intercalation (Zn_xV₂O₅), and conversion (ZnI₂) cathodes, with practical viability demonstrated in a 0.2 Ah pouch cell. This work establishes a molecular-level design paradigm for constructing robust interfaces for high-energy, long-life anode-free batteries.