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 complex brines is critical for the clean energy transition.
• Conventional membranes struggle with selectivity, while solid electrolytes are brittle and not scalable.
• A need exists for robust, selective, and scalable membranes for direct lithium extraction.

Purpose of the Study:

• To develop a flexible polymer-ceramic membrane for selective lithium recovery.
• To overcome the limitations of existing membrane technologies for brine processing.
• To enable efficient and scalable direct lithium extraction from complex sources like seawater.

Main Methods:

• Fabrication of a composite membrane embedding lithium-ion conductive ceramic particles (Li$_{1.3}$Al$_{0.3}$Ti$_{1.7}$(PO$_{4}$)$_{3}$ - LATP) within a polydimethylsiloxane (PDMS) polymer matrix.
• Characterization of the membrane's hierarchical transport architecture and ion conduction properties.
• Testing the membrane's performance 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$^{-1}$.
• Exceptional Li$^{+}$/Mg$^{2+}$ selectivity of 2832 was achieved, surpassing conventional membranes.
• The membrane exhibited excellent stability, operating continuously for 480 hours during lithium extraction.

Conclusions:

• The developed flexible polymer-ceramic membrane effectively translates the high selectivity of solid electrolytes into a scalable format.
• This hierarchical architecture enables efficient and selective lithium extraction from challenging sources like seawater.
• The technology presents a promising solution for sustainable lithium sourcing for batteries and clean energy.