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

Abstract

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 SO₄^2– and H₂O, but facilitating Zn²⁺ conduction. The inherent properties of CAU-17 result in the repulsion of SO₄^2– 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.