Artificial Cation–Chloride Co‐Transporters for Chloride‐Facilitated Lithium/Magnesium Separation
Yushuang Hou, Chenguang Zhu, Haozhe Sun, Yongye Zhao, Shangfa Pan, Shengtao Ma, Qianqian Fu, Xin Sui, Xueli Liu, Lei Jiang, Jun Gao
Abstract
Abstract Inspired by nature, many artificial ion sieving materials have been developed, shedding light on the next‐generation ion, e.g., Li + , extraction applications. Artificial co‐transporters remain difficult to construct since they have a much more complex ion‐sieving property. For example, the cation–chloride co‐transporters have both alkaline ion and chloride ion selectivity but no alkaline ion/chloride ion selectivity. We here demonstrate a method to construct artificial co‐transporters, using a porous organic framework membrane which has a relatively disordered stacking structure and rich quaternary ammonium groups paired with counter‐ions. This imparts the membrane with extremely narrow pores (∼0.3 nm) and almost no surface charge, enabling size‐based high alkaline ion selectivity against other cations, high Cl − selectivity against other anions, but almost no alkaline ion/Cl − selectivity. Such synchronized sieving property allows us to enhance the extraction of high‐value cations (Li + ) by simply feeding excessive low‐value anions (Cl − ). As a demonstration, we realized high‐flux (0.44 mol m −2 h −1 ) and highly selective (selectivity: 185) Li + /Mg 2+ separation by reversing the current industrial brine‐based lithium extraction process, i.e., sieving Li + before removing NaCl.