A Binder-Free Metal-Organic Framework Ion Osmosis Membrane for Stabilizing a Zn Anode

Aqueous zinc-ion batteries (AZIBs) have attracted considerable attention due to their low cost and high safety. However, their development is hindered by dendrite formation and complex anodic side reactions. In this study, a binder-free zirconium-based metal-organic framework (MOF) membrane, NUS-8, is proposed as an artificial solid electrolyte interphase (ASEI) for the Zn anode, with the aim to regulate Zn²⁺ desolvation and deposition processes, inhibit dendrite growth, and mitigate anodic side reactions. The microporous structure and abundant functional groups (-COOH, -OH) in the NUS-8 membrane enable ion flux control through an ion-confinement effect, reducing ion transfer resistance and providing stable pathways for Zn²⁺ migration. These characteristics enhance the hydrophilicity of the Zn anode surface, accelerate the desolvation process, and lower the activation energy barrier for Zn²⁺ migration from 28.73 to 26.10 kJ mol^-1. As a result, symmetric cells with NUS-8@Zn anodes exhibited a prolonged lifespan exceeding 1180 h at 1 mA cm^-2 and 1 mAh cm^-2, significantly outperforming bare Zn anodes (90 h). Additionally, the NUS-8@Zn||MnO₂ full cell demonstrated excellent cycling stability, with a capacity retention of 72.3% over 3000 cycles at 5 A g^-1. This work presents a promising strategy to enhance Zn anode performance and introduces a design approach for advancing AZIBs.