Hybrid Molecular Sieve-Based Interfacial Layer with Physical Confinement and Desolvation Effect for Dendrite-free Zinc Metal Anodes.

Abstract

The side reactions and dendrite growth at the interface of Zn anodes greatly limit their practical applications in Zn metal batteries. Herein, we propose a hybrid molecular sieve-based interfacial layer (denoted as Z7M3) with a hierarchical porous structure for Zn metal anodes, which contains 70 vol % microporous ZSM-5 molecular sieves and 30 vol % mesoporous MCM-41 molecular sieves. Through comprehensive molecular dynamics simulations, we demonstrate that the mesopores (∼2.5 nm) of MCM-41 can limit the disordered diffusion of free water molecules and increase the wettability of the interfacial layer toward aqueous electrolytes. In addition, the micropores (∼0.56 nm) of ZSM-5 can optimize the Zn2+ solvation structures by reducing the bonded water molecules, which simultaneously decrease the constraint force of solvated water molecules to Zn2+ ions, thus promoting the penetrability and diffusion kinetics of Zn2+ ions in Z7M3. The synergetic effects from the hybrid molecular sieves maintain a constant Zn2+ concentration on the surface of the Zn electrode during Zn deposition, contributing to dendrite-free Zn anodes. Consequently, Z7M3-coated Zn electrodes achieved excellent cycling stability in both half and full cells.