Rapid Lithium Extraction via Solar Thermal Interfacial Evaporation with Zero Liquid Discharge

Abstract

Global lithium demand has surged by over 150% in the past three years, intensifying the need for sustainable extraction methods beyond traditional ore mining. Extraction from salt-lake brines offers an abundant alternative, yet existing processes are slow, energy-intensive, and environmentally damaging. Here, we introduce an energy-efficient and self-sustaining solar thermal interfacial evaporator with simultaneous extraction of lithium (STEEL) without brine discharge by integrating a lithium-ion sieve (LIS) technology. STEEL is made of a multi-functional superwicking black metal (SWBM) panel that can pull a thin water film uphill across its surface and absorb nearly all solar radiation for interfacial evaporation. To enable on-site selective lithium-ion extractions, we embed HTO nanoparticles (NPs) in the micro-capillaries of SWBM. HTO NPs efficiently extract lithium in the solution while reject other common ions. Additionally, the thin film evaporation on STEEL’s passive region induces a evaporation peak at the water boundary, allowing surface self-cleaning even when treating Mg2+ containing saltwater, which is unattainable by most solar evaporators. STEEL demonstrates stable performance under one sun illumination, achieving an average evaporation rate of 1.07±0.01 kgm-2h-1, salt harvesting rate of 106.01±2.09 gm-2h-1, and lithium-ion mining rate of 0.21±0.02 gm-2day-1, corresponding to nearly 100% total mineral recovery and 50% lithium extraction efficiency. The resulting eluate from Great Salt Lake water exhibits a significant increase in lithium composition, rising from 0.09% in salt-lake water to 70.12%, making it an ideal feedstock for subsequent refining. This self-powered and zero-waste approach offers a scalable pathway for sustainable lithium production from natural brine.