An Ion-Selective Li1.3al0.3ti1.7(Po4)3 Membrane for Electrolytic Lithium Extraction from Brine

Abstract

The rapid commercialization of electric vehicles and portable electronic devices has significantly increased the demand for lithium resources. Extracting lithium from brine has become a critical pathway to address future lithium production challenges. However, the lithium extraction efficiency of conventional technologies is limited by the low concentration of Li+ and the high Mg2+/Li+ ratio in brine. A one-step electrolysis method based on a solid-state electrolyte has been reported to directly extract metallic lithium with high efficiency. Due to low-cost, good stability, and high ionic conductivity, Li1.3Al0.3Ti1.7(PO4)3 (LATP) is regarded as a highly promising selective membrane for large-scale lithium extraction from brine sources. Herein, LATP electrolytes were synthesized by optimizing the conditions of the solid-state reaction method. The resulting the LATP pellets exhibited a high relative density of 98.29% and an impressive ionic conductivity of 3.93 × 10-4 S cm-1. The lithium extraction device utilizing LATP as a selective membrane achieved a remarkable current efficiency of 97.4%. After lithium extraction process, the LATP pellets retained the ionic conductivity of 2.69 × 10-4 S cm-1 and preserved the sodium super ion conductors (NASICON) crystal structure. This work demonstrates an effective and practical lithium-ion selective membrane for directly lithium extraction from natural brine.

Keywords: Lithium extraction, Lithium-ion selective membrane, Brine, LATP