A Molecular-Sieve Electrolyte Membrane enables Separator-Free Zinc Batteries with Ultralong Cycle Life.

Abstract

The poor stability of the zinc-metal anode is a main bottleneck for practical application of aqueous zinc-ion batteries. Herein, a series of molecular sieves with various channel sizes are investigated as an electrolyte host to regulate the ionic environment of Zn²⁺ on the surface of the zinc anode and to realize separator-free batteries. Based on the ZSM-5 molecular sieve, a solid-liquid mixed electrolyte membrane is constructed to uniformize the transport of zinc ions and foster dendrite-free Zn deposition. Side reactions can also be suppressed through tailoring the solvation sheath and restraining the activity of water molecules in electrolyte. A V₂ O₅ ||ZSM-5||Zn full cell shows significantly enhanced performance compared to cells using glass fiber separator. Specifically, it exhibits a high specific capacity of 300 mAh g^-1 , and a capacity retention of 98.67% after 1000 cycles and 82.67% after 3000 cycles at 1 A g^-1 . It is attested that zeolites (ZSM-5, H-β, and Bate) with channel sizes of 5-7 Å result in best cycle stability. Given the low cost and recyclability of the ZSM and its potent function, this work may further lower the cost and boost the industrial application of AZIBs.