Chloride-Bridged Compact Interfacial Shielding for Practical Seawater Zinc Batteries

Area of Science:

• Electrochemistry
• Materials Science
• Energy Storage

Background:

• Aqueous zinc-ion batteries offer a cost-effective energy storage solution.
• Natural seawater as an electrolyte reduces manufacturing costs but introduces severe zinc anode corrosion due to chloride ions and water.
• Developing protective strategies for zinc anodes in natural seawater electrolytes is crucial for practical applications.

Purpose of the Study:

• To design a novel electrolyte system using natural seawater for zinc-ion batteries.
• To mitigate the corrosion of zinc anodes in natural seawater electrolytes.
• To enhance the cycling stability and performance of zinc anodes and full cells.

Main Methods:

• Formulation of a natural seawater electrolyte with a host-guest complex additive (2-mercaptobenzothiazole guest and cyclodextrin host).
• Investigation of the sustained release behavior of the additive in the electrolyte.
• Analysis of the protective mechanism of the additive on the zinc anode interface using bridging effects of chloride ions.
• Electrochemical testing of Zn||Zn symmetric cells and Zn||NaV3O8·1.5H2O full cells.
• Performance evaluation of an Ah-level pouch cell.

Main Results:

• The host-guest additive creates a compact shield on the zinc anode, forming a chloride/water-poor microenvironment.
• The zinc anode achieved an extended cycling life of 400 hours in a symmetric cell at 42.7% depth of discharge.
• The Zn||NaV3O8·1.5H2O full cell demonstrated 99% capacity retention after 600 cycles at 0.5 A g⁻¹.
• An Ah-level pouch cell maintained stable cycling for 50 cycles with an initial discharge capacity of 1.21 Ah.

Conclusions:

• The designed natural seawater electrolyte with a host-guest additive effectively suppresses zinc anode corrosion.
• This approach significantly enhances the cycle life and stability of aqueous zinc-ion batteries.
• The findings pave the way for low-cost, high-performance zinc-ion batteries utilizing natural seawater electrolytes.