Regulating Desolvation and Directional Ion Flux by an Ion-Capturing Carboxyl-Functionalized Separator for Stable Aqueous Zinc Batteries.

Abstract

The wide application of aqueous zinc-ion batteries (AZIBs) is limited by uncontrolled zinc dendrite growth and sluggish ion transport dynamics. This study develops a carboxyl-functionalized separator integrated with the metal-organic framework MOF-801 on a glass fiber substrate (MGS) via an in situ growth strategy. The innovative design features dual mechanisms: fundamentally, the uniform nanochannels of MOF-801 regulate Zn²⁺ flux distribution through spatial confinement effects. Beyond this, DFT calculations and Raman analyses demonstrate that the grafted carboxyl groups selectively capture Zn²⁺ via dynamic coordination interactions, simultaneously inducing localized high-concentration electrolyte formation within the channels and effectively suppressing interfacial concentration polarization. The MGS enables Zn||Zn cells to achieve exceptional stability exceeding 8000 h at 1 mA cm^-2 and practical Zn||MnO₂ pouch cells to deliver a capacity of 108 mA h g^-1 at 0.1 A g^-1. This work provides novel insights for the design of multifunctional separators and the regulation of metal ion transport.