Temperature-Decoupling Solar Lithium Enrichment System with Closed-loop Energy Cycle via Superhydrophilic transparent coatings

Abstract

With the depletion of fossil energy, the demand for Lithium (Li) has globally surged and the extraction of Li must be environmentally and socially responsible for a sustainable future. Solar pool-based Li extraction shows promise but is limited by climate-dependent evaporation rates and long production cycles. While closed systems for steam energy recovery offer improvements, accumulated condensation often reduces light transmittance and efficiency. In this study, we report a super hydrophilic hydrogel coating (DOH coating) that can be coated on the top of a closed system showing broad application prospects in salt lake Li extraction. The DOH coating, featuring abundant hydrogen-bond functional groups and synergistic supramolecular interactions, exhibited unique properties, including superhydrophilicity (WCA < 5°), high light transmittance (91.515%), and low haze (0.735%). Furthermore, a brine concentration and collection device (the closed DOH system) was constructed, which achieved 81.6% heat recovery efficiency and an evaporation rate 5.4 times that of open systems even at 0 °C. It majestically advanced the concentration efficiency of brine by 12 times and realized the synchronization of Li concentration and clean freshwater collection from salt lake.