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

摘要

Artificial interface layer engineering is an efficacious modification strategyfor protecting zinc anode from dendrite growth and byproducts formation.However, the high bulk ionic conductivity of most artificial interfacial layers ismainly contributed by the movement of anions (SO_4~(2?)), which is the sourceof 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 interfacelayer (1-carboxymethyl-3-vinylimidazolium bromide monomer, CVBr) for Znmetal protection is designed. The N~+ atom of imidazole rings is connected bychains to form the cavities and the anions are confined within these cavities.Thus, the hindering effect of surrounding units on the anions leads tothe subdiffusive regime, which inhibits the diffusion of SO_4~(2?) in interfaceand increases Zn~(2+) transference number. Besides, the polycation-anioncoordinationmechanism of PolyCVBr ensures accelerated Zn~(2+) transition andrealizes rapid internal Zn~(2+) migration channel. As a result, the Zn@CVBr||AMsymmetry cells deliver high bulk ionic conductivity (4.42 × 10~(?2) S cm~(?1)) andhigh Zn~(2+) transference number (tZn~(2+) = 0.88) simultaneously. TheZn@CVBr||AM-NaV_3O_8 pouch cells display the capacity retention of 88.9% after190 cycles under 90° bending, verifying their potential practical application.