Isosorbide dimethyl ether enables interfacial regulation to boost the aqueous zinc–sulfur battery performance

Abstract

Aqueous zinc–sulfur batteries (AZSBs) offer high theoretical capacity, intrinsic safety, and low cost, but suffer from unstable interfaces, hydrogen evolution, and sluggish sulfur kinetics due to parasitic water activity and a poor solvation structure. In this work, air stable isosorbide dimethyl ether (ID) is introduced as a multifunctional co-solvent into a 2M Zn(OTf)₂ aqueous electrolyte (IDW). ID restructures the Zn²⁺ solvation shell and interacts with the Zn anode via its ether groups, forming an interface that reduces interfacial water activity, suppresses hydrogen evolution and enables uniform Zn deposition. Simultaneously, ID's electron-donating ability enhances interaction with iodine, promoting the formation of soluble I₃⁻ species and establishing efficient I₃⁻/I⁻ redox mediation that accelerates sulfur conversion and mitigates active material loss. As a result, Zn∥Zn cells with IDW exhibit over eightfold longer lifespan (∼1300 h) compared to the baseline aqueous electrolyte at 1 mA cm⁻² and 1 mAh cm⁻². The full AZSB delivers high capacity, excellent rate performance, and maintains 70% capacity retention after 200 cycles. This work demonstrates a dual-interfacial regulation strategy through rational electrolyte design and provides a promising pathway toward high-performance, long-cycle-life AZSBs.