Design of Next-Generation Dendrite-Free Eco-Electrolytes for High-Voltage Aqueous Zn-Metal Batteries

As a sustainable alternative to lithium-ion batteries, aqueous zinc-ion batteries (AZIBs) are promising for grid-scale and portable energy storage due to their inherent safety, low cost, and environmental friendliness. However, their widespread practical application is hindered by dendrite formation and side reactions caused by free water molecules in the electrolyte. These issues lead to poor cycling stability, reduced coulombic efficiency, and limited lifespan. In this study, we present an environmentally-friendly alternative - lithium acetate (LiAc) with additives - that improve its hydrophilicity, widen the electrochemical stability window, and promote the formation of a uniform solid electrolyte interphase (SEI) on the zinc anode. We systematically compare the effect of LiAc, lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) and potassium hydroxide (KOH) in Zn-based electrolytes. Through various characterization techniques, including cyclic chargedischarge tests, linear sweep voltammetry (LSV), X-ray diffraction (XRD), scanning electron microscopy (SEM), Raman spectroscopy, viscosity, and contact angle measurements, we found that the optimized Zn:Li molar ratio of 1:4, particularly with LiAc-based systems, exhibits enhanced cycle stability, minimize dendrite formation, and enhanced capacity retention, overall improving the long-term cycling performance. This work provides valuable insights into electrolyte design for high-performance, sustainable AZIBs.