Suppressing Electric-Field-Induced Cathodic Salt Crystallization for Stable Zinc-Ion Batteries

Area of Science:

• Electrochemistry
• Materials Science
• Energy Storage

Background:

• Aqueous zinc-ion batteries (AZIBs) offer sustainable energy storage but face challenges with capacity decay, especially at low temperatures.
• Interfacial instability, including salt crystallization, is a major contributor to AZIB degradation, hindering their practical application.

Purpose of the Study:

• To identify and elucidate the mechanism of electric-field-induced catastrophic interfacial salt crystallization (CISC) in AZIBs.
• To develop an electrolyte engineering strategy to suppress CISC and enhance the stability of AZIBs, particularly under subzero conditions.

Main Methods:

• Investigated interfacial failure pathways using mechanistic studies and molecular dynamics simulations.
• Employed experimental observations to validate simulation findings and assess the impact of sulfolane (TS) as an electrolyte additive.
• Evaluated battery performance through cycling tests at room temperature and -20°C.

Main Results:

• Unveiled CISC, driven by solvent depletion and anion enrichment in the electric double layer, as a critical degradation pathway.
• Demonstrated that sulfolane effectively disrupts interfacial ion ordering and elevates the crystallization barrier, suppressing CISC.
• Achieved remarkable stability in V₂O₅||Zn batteries, retaining 378.9 mAh g^-1 after 300 cycles at room temperature and over 20,000 cycles at -20°C.

Conclusions:

• Interfacial salt crystallization is a key failure mechanism limiting AZIB performance, especially at low temperatures.
• Electrolyte engineering with sulfolane provides a viable molecular-level strategy to enhance AZIB stability and cycle life.
• The findings pave the way for developing robust AZIBs for diverse energy storage applications.