Lithium Metal Recovery from Sea Water by a Flexible and Scalable Membrane with Lithium‐Ion Exclusive Channels

Sea water is abundant in lithium reserves, and extracting lithium metal from it holds the potential to not only mitigate the shortage of lithium in light of the fast-growing electric vehicle industry, but also serve as an anode electrode to provide electricity. The task, however, is challenging due to the harsh reactions and low lithium concentration in sea water. Here, we present a single-channel strategy based on a flexible and scalable lithium ion-sieve membrane for efficient lithium extraction. Our composite membrane exhibits high separation factor β_Li/Na of more than 2.87×10⁷ with an ionic conductivity of 6.2×10^-5 S cm^-1. Lithium metal was electrolytically extracted from sea water through a hybrid-electrolyte system, which yielded a high Coulombic efficiency of 98.04 % and a low energy consumption of 17.4 kWh kg_Li ^-1 at an optimized extracting current of 200 μA cm^-2. The extracted lithium metal can be directly integrated into a lithium-sulfur battery, delivering an energy output of 395 Wh kg^-1. To demonstrate its industrial viability, we also fabricate a pouch cell with Li metal anode extracted by an amplified extraction prototype. This study has the potential to dispel concerns of lithium depletion and facilitate the sustainable development of lithium-based energy storage systems.