Ultrahigh Lithium Selective Transport in Two-Dimensional Confined Ice

Area of Science:

• Materials Science
• Nanotechnology
• Electrochemistry

Background:

• Biological membrane proteins inspire artificial ion channels for selective ion transport.
• Increasing demand for lithium necessitates efficient separation technologies.
• Existing artificial channels face challenges in achieving high monovalent cation selectivity.

Purpose of the Study:

• To engineer a novel ion transport channel utilizing confined ice within two-dimensional (2D) capillaries.
• To investigate the influence of confined ice anisotropy on monovalent cation permselectivity.
• To explore the potential for efficient lithium separation using this engineered channel.

Main Methods:

• Development of an ion transport channel based on 2D confined ice within vermiculite capillaries.
• Analysis of monovalent cation permselectivity, focusing on lithium, sodium, and potassium ions.
• Investigation of the relationship between confined ice anisotropy and ion transport properties.

Main Results:

• Anomalous lithium-selective transport was observed along the (002) direction of 2D confined ice.
• Exceptional Li+/Na+ (556 ± 86) and Li+/K+ (901 ± 172) permselectivity were achieved, surpassing most existing ion-selective channels.
• Lithium permselectivity was found to be direction-dependent and tunable by adjusting interlayer spacing.

Conclusions:

• The anisotropy of 2D confined ice plays a crucial role in achieving high monovalent cation permselectivity.
• This engineered channel demonstrates significant potential for efficient lithium separation.
• The findings provide insights for designing advanced monovalent ion-selective channels.