Interfacial Molecule Engineering Builds Tri-Functional Bilayer Silane Films with Hydrophobic Ion Channels for Highly Stable Zn Metal Anode

Abstract

The vulnerable Zn electrode interface with uncontrolled Zn dendrite growth and severe parasitic side reactions constrains the practical application of aqueous zinc-ion batteries (AZIBs). General interface engineering of Zn offers a promising approach to relieve these issues but is limited by the confined functionality, low affinity, and additional weight of the protective layer. In this study, a bilayer silane film (SF) is developed with hydrophobic, ion-buffering, and strong interfacial adhesion properties through the precise assembly of silane coupling agents. The well-designed SF layer enables Zn²⁺ to undergo continuous processes, including being captured by –CF₃ groups, followed in sequence by inducing desolvation, directed diffusing through silane nanochannels, and buffered diffusion. This multiple process contributed to the accelerated [Zn(H₂O)₆]²⁺ desolvation, stabilized Zn²⁺ transport, and inhibited side reactions. Consequently, dendrite-free and highly reversible SF@Zn anodes are realized, exhibiting an ultra-long lifetime (more than 4300 h), a high Coulombic efficiency (CE) (99.1% after 2600 cycles), and a superior full cell capacity retention (83.2% after 1000 cycles). This innovative strategy provides a novel method to enhance Zn anode stability via molecular-level interfacial layer design by multicomponent silane coupling reaction, offering new insights into the advanced interface design for AZIBs.