An Aqueous Electrolyte Regulator for Highly Stable Zinc Anode Under-35 to 65 °C

The reversibility and long-term cycling stability of aqueous zinc-ion batteries (AZIBs) in a wide temperature range have rarely been explored. Herein, diethylene glycol monoethyl ether (DG) is introduced as an electrolyte additive to enhance Zn performance within a wide temperature range of -35 to 65 degrees C. Operando synchrotron Fourier transform infrared spectroscopy analysis combined with molecular dynamics simulations reveal that the introduction of DG disrupts the initial hydrogen bonding network of the aqueous electrolyte, restructuring the solvation structure surrounding Zn2+ ions and mitigating water-induced parasitic reactions. Adding DG reduces the freezing point of the aqueous electrolyte without compromising its incombustibility. Moreover, operando electrochemical quartz crystal microbalance with dissipation monitoring (EQCM-D) and X-ray photoelectron spectroscopy demonstrated that the coordinated DG and OTF- undergo reductive decomposition, forming a self-healing solid electrolyte interphase comprising an inorganic/organic ZnF2-ZnS, which can effectively suppress the notorious side reactions and guide the uniform Zn deposition. Consequently, the symmetric Zn/Zn cells demonstrate excellent cycling stability for 3500 h under 1 mA cm(-2) at 25 degrees C, and for 1000 h under 1 mA cm(-2) at both -35 and 65 degrees C. Full batteries with a DG-containing electrolyte exhibit a long lifespan of 5000 cycles at 2 A g(-1).

Automated summary

In this study, diethylene glycol monoethyl ether (DG) was introduced as an electrolyte additive to enhance the reversibility and long-term cycling stability of aqueous zinc-ion batteries (AZIBs) in a wide temperature range. The addition of DG disrupted the hydrogen bonding network of the electrolyte, mitigated water-induced parasitic reactions, and formed a self-healing solid electrolyte interphase, leading to improved battery performance.