Efficient and Selective Lithium Extraction from Brine Water Via a Photothermal Sandwich Sieve Structure

Abstract Lithium is being recognized as a strategic resource on a global scale, mainly because of its growing importance in the production of lithium‐ion batteries for electric vehicles and energy storage systems. Due to its uneven geographical distribution and limited availability on Earth, extracting lithium from brines and seawater presents a sustainable supply pathway. However, conventional lithium extraction techniques are still challenging, necessitating significant costs and energy consumption. This study primarily employs a solar‐utilizing selective extraction strategy for efficient lithium harvesting by designing a solar‐thermal sandwich sieve structure. Herein, a portable solar‐driven lithium extraction device has been developed based on HKUST‐1 and LIG. Due to the sub‐nano channels provided by HKUST‐1, the hydrated Li⁺ can selectively pass through the MOF layer. The excellent solar heating of the layer enables the device an accelerate vapor escaping, it then facilitates the delivery of Li⁺, resulting in lithium accumulation at the interface for convenient collection. The maximum lithium extraction capacity in one cycle is 1467 mg m⁻², demonstrating good Li⁺ selectivity absorption with a high Mg²⁺/Li⁺ ratio under 1 solar illumination. Moreover, the device shows excellent cycle stability. This work offers an integrated solar utilization for scalable and sustainable lithium extraction from brine water.