M. Elimelech, S.K. Patel, A. Iddya, W. Pan, J. Qian
Rice University,
United States
Keywords: solid state electrolyte, lithium extraction, ion selectivity
Summary:
As the gap between lithium supply and demand continues to widen, the need to develop ion-selective technologies that can efficiently extract lithium from unconventional water sources grows increasingly crucial. In this study, we demonstrate the use of a solid-state electrolyte (SSE), typically used in battery technologies, as a membrane material for aqueous lithium extraction. We find that the transport of lithium ions through the highly ordered SSE lattice is vastly different from ion migration through the hydrated free volumes of conventional cation exchange membranes. Notably, we reveal that the SSE provides exceptional performance with respect to ion-ion selectivity, consistently demonstrating lithium ion selectivity values that are immeasurable by even the parts-per-billion detection limit of mass spectrometry. Such exceptional selectivity is shown to be the result of the characteristic size and charge exclusion mechanisms of solid-state ion transport, which may be leveraged in the design of the next generation of membrane materials for resource recovery.