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

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 –CF 3 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 –CF 3 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||LiFePO 4 full cells with remarkably‐enhanced rate and cycling performance over 3500 cycles at 10 C.