A Bioinspired Membrane with Ultrahigh Li + /Na + and Li + /K + Separations Enables Direct Lithium Extraction from Brine.

Membranes with precise Li ⁺ /Na ⁺ and Li ⁺ /K ⁺ separations are imperative for lithium extraction from brine to address the lithium supply shortage. However, achieving this goal remains a daunting challenge due to the similar valence, chemical properties, and subtle atomic-scale distinctions among these monovalent cations. Herein, inspired by the strict size-sieving effect of biological ion channels, a membrane is presented based on nonporous crystalline materials featuring structurally rigid, dimensionally confined, and long-range ordered ion channels that exclusively permeate naked Li ⁺ but block Na ⁺ and K ⁺ . This naked-Li ⁺ -sieving behavior not only enables unprecedented Li ⁺ /Na ⁺ and Li ⁺ /K ⁺ selectivities up to 2707.4 and 5109.8, respectively, even surpassing the state-of-the-art membranes by at least two orders of magnitude, but also demonstrates impressive Li ⁺ /Mg ²⁺ and Li ⁺ /Ca ²⁺ separation capabilities. Moreover, this bioinspired membrane has to be utilized for creating a one-step lithium extraction strategy from natural brines rich in Na ⁺ , K ⁺ , and Mg ²⁺ without utilizing chemicals or creating solid waste, and it simultaneously produces hydrogen. This research has proposed a new type of ion-sieving membrane and also provides an envisioning of the design paradigm and development of advanced membranes, ion separation, and lithium extraction.
(© 2024 The Author(s). Advanced Science published by Wiley‐VCH GmbH.)