Biomimetic artificial ion channels for recovering critical minerals

Abstract

The sustainable development in lithium extraction and recycling techniques is critical for securing a stable global supply to meet the increasing energy storage demands. Current direct lithium extraction methods rely on organic solvents and harmful chemicals to extract lithium from ores selectively and efficiently but suffer from low output, high energy consumption, and potential to cause environmental damage. Biomimetic ion transport systems offer a promising alternative for selective and energy-efficient lithium recovery from naturally occurring ores and brines Herein, we report a class of bioinspired pillar[5]arene based membrane channels exhibiting high lithium selectivity over monovalent (Li⁺/M⁺ ≈ 100, M⁺ = K⁺, Na⁺) and divalent ions (Li⁺/Mg²⁺ ≈ 500, Li⁺/Ca²⁺ ≈ 230) in electrochemically driven transport assays. These artificial channels, based on pillar[5]arene cores functionalized with diphenyl phosphine oxide (DPP) ligands, achieved a single-channel conductance of 13.35 pS, transporting ~1.34 × 10⁷ Li⁺ ions per second. Molecular dynamics simulations revealed that ion dehydration barriers and size-selective exclusion drive this remarkable selectivity. To advance practical applications, we designed and developed a scalable artificial tissue platform for selective lithium transport. The first-generation channel proved incompatible with the tissue matrix, prompting the development of second-generation peptide-functionalized channels. Among them, phenylalanine appended pillar[5]arene based channel successfully integrated into the artificial tissue membrane, maintaining high lithium selectivity under applied potential gradient across the membrane These findings establish supramolecular ion channels as next-generation lithium separation platforms, that could be a sustainable, efficient, and environmentally friendly alternative for lithium purification and recovery.