Polymer of Intrinsic Microporosity-Derived Artificial SEI With Electronegative Sub-1-nm Channels for Robust Li-Metal...

An unstable Li-electrolyte interface remains a major bottleneck for next-generation Li-metal batteries practically operated at high current densities (≥ 3 mA cm^-2) and large areal capacities (≥ 3 mAh cm^-2). Here, we propose a geometric-electronic-chemical triple-engineering strategy to develop a new multifunctional artificial solid-electrolyte interphase (ASEI) based on well-designed electronegative subnanometer-channeled polymer of intrinsic microporosity (SCFPIM) for attaining ultrastable, ultrahigh-rate, and ultralarge-capacity Li-metal anodes. The SCFPIM features intrinsic ∼0.57 nm pores and incorporates crown-ether and -CF₃ functionalities connected via Tröger's base units, enabling unique multi-regulation effects that achieve a balance among Li⁺ conductivity, selectivity, and interfacial stability. Specifically, the sub-nanometer channels impose a geometric confinement effect that selectively sieves electrolyte species for increased Li⁺ transference number (0.85) and lowered Li⁺ desolvation barrier, while electronegative channel environments suppress anion accumulation and promote continuous low-energy-barrier Li⁺ transport. Concurrently, the preferential decomposition of -CF₃ moieties favorably induces a robust bilayer SEI with a LiF-rich inner layer, reinforcing interfacial stability under high Li⁺ flux. Thus, SCFPIM-modified Li anodes achieve ultrastable Li plating/stripping over 6000 h at extreme conditions of 40 mA cm^-2/40 mAh cm^-2, superior to reported Li anodes, endowing SCFPIM@Li||LiFePO₄ full cells with remarkably-enhanced rate and cycling performance over 3500 cycles at 10 C.