Lithium recovery through WS₂ nanofillers-promoted solar photothermal membrane crystallization of LiCl

The recovery of raw materials represents one of the greatest challenges for a circular economy. Especially, the increased demand for lithium in the last years for its critical role in Li-ion batteries implies the need for green technology for Li recovery able to address market requests. Here, we devise and implement a new technology exploiting excitons-based light-to-heat conversion promoted by WS₂ nanofillers in nanocomposite polymeric membranes for sunlight-driven photothermal membrane crystallization, applied for the efficient extraction of lithium from Li-rich brines. The activation of photothermal effects of excitonic nanofillers in the PVDF-WS₂ nanocomposite enhances the evaporative flux of water under solar irradiation by 364 %, triggering the heterogeneous nucleation and the crystallization of LiCl salt, once achieved supersaturation. This new facile, economical, and green nanotechnology-enabled platform renews the interest in functional inks based on nanosheets of van der Waals semiconductors for the fabrication of functional nanocomposites, here exploited for the first time in the field of crystallization and the recovery of economically strategic minerals in a circular-economy paradigm. Moreover, these findings open up new opportunities for large-scale, efficient, and sustainable recovery of lithium (as well as other critical raw materials) for next-generation devices for the clean energy transition.