Polystyrene Sulfonate Threaded through a Metal-Organic Framework Membrane for Fast and Selective Lithium-Ion...

Area of Science:

• Materials Science
• Chemical Engineering
• Electrochemistry

Background:

• Lithium ion extraction from salt-lake brines is crucial for producing essential lithium compounds.
• Existing methods for lithium extraction face challenges in efficiency and selectivity.
• Metal-organic frameworks (MOFs) offer potential for ion separation but require functionalization for enhanced performance.

Purpose of the Study:

• To develop a novel membrane for efficient and selective lithium ion extraction.
• To investigate the performance of a polystyrene sulfonate (PSS) threaded HKUST-1 MOF membrane.
• To enhance lithium ion conductivity and separation capabilities compared to pristine MOF membranes.

Main Methods:

• Fabrication of PSS@HKUST-1-6.7 membranes via in-situ confinement conversion.
• Characterization of membrane structure and properties.
• Measurement of Li+ conductivity, flux, and selectivity for various ions (Na+, K+, Mg2+).

Main Results:

• The PSS@HKUST-1-6.7 membrane exhibits significantly enhanced Li+ conductivity (up to 1.89×10^-3 S cm^-1 at 70°C).
• Achieved a high Li+ flux of 6.75 mol m^-2 h^-1, five orders higher than pristine HKUST-1.
• Demonstrated exceptional ideal selectivities (e.g., 10296 for Li+/Mg2+) and real binary selectivities (e.g., 1815 for Li+/Mg2+).

Conclusions:

• The PSS@HKUST-1-6.7 membrane represents a breakthrough in ionic conductors and Li+ extraction technology.
• The anchored sulfonate networks effectively enhance ion transport and selectivity.
• This approach offers a promising pathway for sustainable lithium resource recovery.