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

Lithium recovery from complex brines is a key challenge for the clean energy transition. Conventional polymer membranes lack selectivity, while highly selective ceramic solid electrolytes are brittle and difficult to scale. Here we address this gap by creating a flexible polymer-ceramic membrane that embeds Li_1.3Al_0.3Ti_1.7(PO₄)₃ (LATP) ceramic particles into a processable PDMS polymer matrix. This hierarchical transport architecture creates an ion 'superhighway', providing selective Li⁺ conduction through LATP while the PDMS phase imposes an additional interfacial penalty on competing ions. In lithium-selective electrodialysis, the membrane achieves a Li⁺ flux of 968 mmol m^{- 2} h^{- 1} and an exceptional Li⁺/Mg²⁺ selectivity of 2832 and remains stable for 480 h of continuous lithium extraction from real seawater brine. This strategy translates the selectivity of solid electrolytes into a scalable membrane, enabling efficient direct lithium extraction.