Ion Superhighways in a Hierarchical Polymer-Ceramic Membrane Enable Rapid and Selective Lithium Extraction

Area of Science:

• Materials Science
• Chemical Engineering
• Electrochemistry

Background:

• Lithium recovery from brines is vital for the clean energy transition but faces challenges with conventional membranes.
• Polymer membranes lack selectivity, while ceramic electrolytes are brittle and difficult to scale.

Purpose of the Study:

• To develop a flexible, scalable membrane for selective lithium extraction from complex brines.
• To overcome the limitations of existing technologies for direct lithium extraction.

Main Methods:

• Fabrication of a composite membrane embedding Lithium aluminum titanium phosphate (Li_1.3Al_0.3Ti_1.7(PO₄)₃ - LATP) ceramic particles within a polydimethylsiloxane (PDMS) polymer matrix.
• Utilizing a hierarchical transport architecture for selective ion conduction.
• Testing the membrane in lithium-selective electrodialysis using real seawater brine.

Main Results:

• The polymer-ceramic membrane demonstrated a high Li⁺ flux of 968 mmol m^-2 h^-1.
• Achieved exceptional Li⁺/Mg²⁺ selectivity of 2832.
• Maintained stability for 480 hours of continuous operation in seawater brine.

Conclusions:

• The developed flexible membrane successfully translates the high selectivity of solid electrolytes into a scalable format.
• This approach enables efficient and stable direct lithium extraction, addressing a key challenge in clean energy.
• The hierarchical architecture provides an ion 'superhighway' for selective lithium transport.