Janus Cellular Design Drives Solar‐Powered Spatial Lithium Extraction and Water Co‐Generation from Salt‐Lake Brines

Lithium plays a vital role in energy storage technologies, with global demand rapidly increasing. Current adsorption-based direct lithium extraction from salt-lake brines holds promise but suffers from low ion extraction efficiency due to sluggish intercalation kinetics and poor selectivity, necessitating repeated cycles that increase water and energy consumption. Here, a Janus cellular-structured solar-powered platform (JCSP) is developed for energy-efficient lithium extraction and sustainable water harvesting. The cellular platform features a symmetrical, multi-branched cantilever geometry with distinct upper and lower lattice architectures, where the lower lattice is functionalized with titanium-based porous adsorbents. This rational lattice design and functionalized adsorption interfaces enhance light absorption, sustain evaporative flow, and create an ion diffusion gradient for selective lithium extraction. Its cantilever configuration enables a self-flipping mechanism, preventing salt crystallization and ensuring long-term stability in high-salinity environments. This design boosts water evaporation efficiency to 3.85 kg m^-2 h^-1, increases lithium adsorption capacity to 43.5 mg g^-1, and enhances Li⁺/Na⁺ and Li⁺/Mg²⁺ selectivity to 112 and 268, respectively, when treating multi-ionic hypersaline environment (20 wt% total dissolved salt). The JCSP system demonstrates stable long-term performance in water evaporation and lithium recovery under extreme conditions, providing a sustainable solution to global water scarcity and rising lithium demand.