A Self-Recognition Separator for Ion Management to Customize Selective Zn2+ Channels Toward Dendrite-Free Zinc Metal Anodes

Aqueous zinc-ion batteries (ZIBs) are promising candidates for next-generation energy storage, but the problems related to Zn dendrites and side reactions severely hinder their practical applications. Herein, a self-recognition separator based on a Bi-based metal-organic framework (GF@CAU-17) is developed for ion management to achieve highly reversible Zn anodes. The GF@CAU-17 has self-recognition behavior to customize selective Zn2+ channels, effectively repelling SO42- and H2O, but facilitating Zn2+ conduction. The inherent properties of CAU-17 result in the repulsion of SO42- ions while disrupting the hydrogen bond network among free H2O molecules, restraining side reactions and by-products. Simultaneously, the zincophilic characteristic of CAU-17 expedites the desolvation of [Zn(H2O)(6)](2+), leading to a self-expedited Zn2+ ion pumping effect that dynamically produces a steady and homogeneous Zn2+ ion flux, and thereby alleviates concentration polarization. Consequently, a symmetric cell based on the GF@CAU-17 separator can achieve a long lifespan of 4450 h. Moreover, the constructed Zn//GF@CAU-17//MnO2 cell delivers a high specific capacity of 221.8 mAh g-1 and 88.0% capacity retention after 2000 cycles.