Heterogeneous asymmetric passable cavities within graphene oxide nanochannels for highly efficient lithium sieving

Lithium is a critical energy element that plays a pivotal role in transitions to sustainable energy. Numerous two-dimensional (2D) membranes have been developed to extract Li+ from different resources. However, their Li+ extraction efficacy is not high enough to meet industrial requirements. Here, we introduce an approach that boosts Li+ selectivity of 2D membranes by inducing asymmetricity in the morphology and chemistry of their nanochannels. Our approach provides an opportunity to manipulate cation hydration shells via a sudden change in the nanochannel size. Then, the addition of nucleophilic traps in the nanochannel intersections results in high Li+ selectivity. Our design leads to a new ion transport mechanism named “Energy Surge Baffle” (ESB) that substantially enriches Li+ in the feed by increasing the monovalent/lithium-ion selectivity up to six times that of other graphene oxide-based membranes. Our approach can be extended to other 2D materials, creating a platform for designing advanced membranes.