Hybrid Molecular Sieve-Based Interfacial Layer with Physical Confinement and Desolvation Effect for Dendrite-free Zinc Metal Anodes
Jing Xu, Pingan Han, Yang Jin, Hongfei Lu, Bing Sun, Beibei Gao, Tingting He, Xiaoxue Xu, Nicola Pinna, Guoxiu Wang
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 Z 7 M 3 ) 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 Zn 2+ solvation structures by reducing the bonded water molecules, which simultaneously decrease the constraint force of solvated water molecules to Zn 2+ ions, thus promoting the penetrability and diffusion kinetics of Zn 2+ ions in Z 7 M 3 . The synergetic effects from the hybrid molecular sieves maintain a constant Zn 2+ concentration on the surface of the Zn electrode during Zn deposition, contributing to dendrite-free Zn anodes. Consequently, Z 7 M 3 -coated Zn electrodes achieved excellent cycling stability in both half and full cells.