Brine pre-treatment and lithium concentration using percolating graphene oxide assemblies

Conventional methods for lithium extraction via evaporation pools or hardrock mining have both local and global environmental consequences that limit lithium supply. To meet the demand for mineral components for lithium batteries while lessening the environmental impact, new technologies for 'direct' lithium extraction aim to selectively capture lithium from aqueous solution among a melange of competing ionic species (for example, sodium and magnesium). In this work, we present a new concept for direct lithium extraction based on far-from-equilibrium transport of lithium through colloidal graphene oxide (GO) percolating networks formed with alternating current electric fields. Our goal is to use these active textures to selectively and actively transport lithium without requiring extensive pre-treatment. We demonstrate that lithium transport far-from-equilibrium can be enhanced relative to competing cations due to its weaker specific interactions with the percolating GO network, leading to high mobility. This finding runs counter to many conventional approaches to lithium extraction, which rely on high lithium selectivity but are implicitly limited by low binding/exchange turnover rates. We propose that enhancing lithium transport, rather than binding selectivity, may be key to high-rate direct lithium extraction from brine sources and show that active colloids are one potential medium in which this paradigm can be realized.