Tailoring Anion Association Strength Through Polycation‐Anion Coordination Mechanism in Imidazole Polymeric Ionic Liquid‐Based Artificial Interphase toward Durable Zn Metal Anodes

Abstract Artificial interface layer engineering is an efficacious modification strategy for protecting zinc anode from dendrite growth and byproducts formation. However, the high bulk ionic conductivity of most artificial interfacial layers is mainly contributed by the movement of anions (SO 4 2− ), which is the source of parasitic reactions on zinc anode. Herein, a high zinc ion donor transition (σZn 2+ = 3.89 × 10 −2 S cm −1 ) imidazole polymeric ionic liquid interface layer (1‐carboxymethyl‐3‐vinylimidazolium bromide monomer, CVBr) for Zn metal protection is designed. The N + atom of imidazole rings is connected by chains to form the cavities and the anions are confined within these cavities. Thus, the hindering effect of surrounding units on the anions leads to the subdiffusive regime, which inhibits the diffusion of SO 4 2− in interface and increases Zn 2+ transference number. Besides, the polycation‐anion coordination mechanism of PolyCVBr ensures accelerated Zn 2+ transition and realizes rapid internal Zn 2+ migration channel. As a result, the Zn@CVBr||AM symmetry cells deliver high bulk ionic conductivity (4.42 × 10 −2 S cm −1 ) and high Zn 2+ transference number (tZn 2+ = 0.88) simultaneously. The Zn@CVBr||AM‐NaV 3 O 8 pouch cells display the capacity retention of 88.9% after 190 cycles under 90° bending, verifying their potential practical application.