Novel lithium selective composite membranes: synthesis, characterization and validation tests in dialysis

With the general growing demand for Lithium compounds, notably for use in Lithium ion batteries, the selective extraction of this metal from various different sources is generating a lot of attention. A number of different methods have been used to recover and/or separate this element, often involving membranes technologies. In an attempt to overcome issues raised by the high rigidity of ceramic membranes and the poor selectivity performance of polymer membranes, we have tried to combine the Li selectivity of Lithium Ion Conducting Glass Ceramic (LICGC) and the flexibility of polymers. We are therefore proposing new malleable composite membranes made using a blending technique where the LICGC powder is incorporated into a flexible copolymerized anion-exchange membrane. We have attempted to demonstrate the homogeneity of the inorganic particle dispersion in the six prepared Lithium Composite Membranes (LCMs) as well as their thermal stability and mechanical properties. We have also investigated the effects of membrane composition on the physicochemical characteristics (water sorption, contact angle and conductivity) of the membranes. The selectivity of these LCMs for Li⁺ was tested under dialysis conditions using Na⁺ and K⁺ as the competitive cations, and the results were compared to those obtained with control membranes containing no LICGC particles. For the best membrane LCM5, the Li⁺/Na⁺ selectivity coefficient reaches 376 when using only Na⁺ as competitive ion. Whilst, when using both Na⁺ and K⁺, this selectivity (Li⁺/Na⁺) decrease to 278 and the Li⁺/K⁺ selectivity coefficient is found to be 364.