Conformation-Induced Ion Transport "Channels" in Artificial Polymer Solid Electrolyte Interphase for Aqueous Zn-Metal...

Artificial polymer solid electrolyte interphases (SEIs) are crucial for inhibiting side reactions and regulating Zn²⁺ flux in aqueous Zn-metal batteries, where tuning the affinities and bond types between Zn²⁺ and functional groups is considered the most effective strategy. However, the underlying determinant-polymer conformation control-is often overlooked. In this work, it is discovered that a high exposure degree of zincophilic sites is the prerequisite for establishing interaction. Due to the extraction effect of highly hydrophilic SO₃ ^-, the copolymer chain becomes more extended, and imidazole groups hidden within the conformation core are exposed and interact with Zn²⁺. Ion transport "channels" are thus constructed and characterized by dynamic light scattering, atomic force microscopy, and molecular dynamics simulation. The resultant copolymer (poly(1-vinylimidazole-co-sodium 4-styrenesulfonate, P(Im-SS)) SEI leverages the advantages of both functional groups, exhibiting fast charge transfer kinetics and regulated diffusion behavior. In situ and post-mortem characterizations reveal that side reactions, surface passivation, and dendrite formation are attenuated. Using P(Im-SS) SEI, long-term cycling of 2800 h for Zn/Zn cell and 3000 cycles with 99.7 % average coulombic efficiency for Zn/Cu cell are achieved. P(Im-SS)@Zn/NaV₃O₈·1.5H₂O full cells exhibited prolonged cycle lifetime and delivered a high areal capacity of ≈2 mAh cm^-2 at 5.7 mA cm^-2.