An ion-selective hydrogel pump for high-throughput solar-powered lithium extraction

The growing demand for lithium has underscored the urgency of developing efficient extraction technologies from brines. Conventional methods suffer from low efficiency and high energy consumption. Inspired by the selective ion uptake and storage mechanisms of Salicornia, we designed an ion-selective hydrogel pump (ISHP) system to achieve ultra-high throughput lithium extraction. ISHP consists of a crosslinked polyvinyl alcohol (PVA) hydrogel block and an ultrathin ion-selective polyamide (PA) membrane grown in situ on its outer surface. The ultra-strong hydration capacity of the hydrogel enables the generation of an osmotic pressure of up to 47.86 bar inside it under sunlight, providing a powerful driving force for the efficient uptake of Li⁺ ions from high-salinity brine. The Li⁺ flux of ISHP reaches 1.20 g m^-2 h^-1, which is over one order of magnitude higher than the current report. A device composed of multiple integrated ISHP units connected in series is designed to enable continuous lithium extraction under natural outdoor sunlight. A comprehensive techno-economic analysis is carried out on the full process of ISHP-based Li₂CO₃ production technology. Compared with the conventional evaporation-precipitation method, this technology can shorten the production cycle by 90% and increase the annual economic benefits by eightfold.