Porous alumina-supported lithium aluminum titanium phosphate membrane for lithium extraction using the electrodialysis process

Inorganic membranes that possess lithium ionic conductivity exhibit considerable potential as a viable option for the targeted extraction of lithium from brine sources. However, the practical implementation of ceramic anisotropic thin film membranes for lithium-ion extraction presents ongoing challenges due to the scarcity of suitable membrane materials and complex fabrication techniques. This research proposes an innovative approach to address this issue by employing a battery material, a lithium-ion conducting electrolyte, to produce a membrane that selectively permits the passage of lithium ions. A scalable approach was employed to fabricate an asymmetric lithium aluminum titanium phosphate (LATP) membrane by utilizing a citric acid-assisted sol–gel coating method on a porous alumina substrate and subsequent sintering. A continuous and compact LATP membrane with an approximate thickness of 14.32 ± 1.36 μm was successfully deposited onto the porous support through the dip coating technique. The lithium-ion permeation was checked using the electrodialysis system from a feed solution containing Li⁺ coexisting with Na⁺ and Mg^2+. A high lithium flux of 215 mmol/h/m² with a Li⁺/Mg²⁺ selectivity of 33 was produced when 2 V of voltage was applied to the 1.65 cm2 ionic conductor anisotropic membrane containing a mixed alkaline solution containing lithium chloride, sodium chloride, and magnesium chloride at the feed solution. These findings underscore the potential for producing lithium-selective membranes using electrolyte materials.