Scalable lithium selective composite membrane with high LATP loading for efficient direct lithium extraction

Efficient lithium extraction is crucial for the rapid development of the new energy industry. While solid-state electrolyte membranes offer high lithium selectivity, their inherent brittleness limits large-scale deployment. Here, we propose blending solid-state electrolyte Li 1.3 Al 0.3 Ti 1.7 (PO 4 ) 3 (LATP) with a positively charged polymer and utilizing a coating method to fabricate flexible lithium-selective membranes suitable for large-scale production. LATP provides lithium transport pathways, while a semi-interpenetrating network formed by poly(vinylidene fluoride) (PVDF) and quaternized polyepichlorohydrin (qPECH) serves as a flexible backbone that inhibits the leakage of impurity cations through Donnan exclusion. Increasing LATP content to 90 wt% expands lithium transport channels to boost flux. In simulated Yiliping brine, the LATP/PVDF/qPECH membrane achieves a Li + flux of 2.32 × 10 −9 mol cm −2 s −1 , which is 7.7 times higher than that of commercial CIMS membrane, along with high lithium selectivity (Li + /Mg 2+ of 570 and Li + /Na + of 690). This work advances the large-scale fabrication and application of high-performance lithium-selective membranes.