Ion Bridging Enables Dual-Interface Engineering for High Capacity and Long Cycling Aqueous Zinc-Sulfur Battery

Area of Science:

• Electrochemistry
• Materials Science
• Energy Storage

Background:

• Aqueous zinc-sulfur batteries (AZSBs) offer high energy density and low cost but face challenges with sulfur cathode reversibility and zinc anode stability.
• Developing advanced electrolytes is crucial for overcoming these limitations and enabling practical AZSB applications.

Purpose of the Study:

• To develop a functionalized co-solvent electrolyte with synergistic additives to improve the electrochemical performance and interfacial stability of AZSBs.
• To investigate the mechanism of an electrolyte-derived dynamic ion bridge pathway for enhanced ion transport and charge transfer.

Main Methods:

• Incorporation of tetramethylurea (TMU) and potassium iodide (KI) as synergistic additives in a co-solvent electrolyte.
• Analysis of TMU's role in regulating Zn2+ coordination and its cooperation with iodide species.
• Investigation of the electrolyte-derived ion bridge pathway at both sulfur cathode and zinc anode interfaces.

Main Results:

• The developed TMU/KI electrolyte facilitated a dynamic ion bridge pathway, reducing kinetic barriers for Zn2+ transport and ZnS conversion.
• Homogenized Zn2+ flux at the anode, promoting uniform Zn plating/stripping and suppressing parasitic reactions.
• Achieved a high specific capacity of 759 mAh g-1 at 5 A g-1 with over 71.2% capacity retention after 1000 cycles.

Conclusions:

• The synergistic regulation via the TMU/KI electrolyte-derived ion bridge significantly enhances AZSB performance and cycle life.
• This electrolyte design strategy offers a promising route for developing high-performance and sustainable AZSBs.
• The findings contribute to advancing next-generation energy storage systems through innovative electrolyte engineering.