Interfacial solar evaporation-driven lithium extraction from saltlake brines for battery-grade Li 2 CO 3 production

Abstract

The rising demand for lithium, essential for energy storage, has heightened the need for efficient extraction methods from salt-lake brines, as current techniques are inefficient and energy-intensive. Here we present a facile, durable and energyefficient approach for lithium extraction using a solar evaporation-driven ion pump. The evaporation system, composed of a porous hydrogel matrix embedded with lithium-ion sieves and featuring directional salt crystallization function, effectively separates lithium ion from other cations and accelerates lithium diffusion toward adsorption sites. Consequently, lithium adsorption kinetics (saturation time decreased from 8 h to 5 h), selectivity (from 65 to 413) and capacity (from 10.7 to 24.7 mg g -1 in salt-lake brine) are all significantly enhanced. Additionally, the designed evaporator enables zero-liquid discharge brine evaporation, ensuring long-term stable performance for freshwater production, which is used for subsequent lithium elution and battery grade Li 2 CO 3 production. Thus, a closed-loop system is achieved, enabling sustainable cycles of lithium extraction, freshwater generation, lithium elution, absorbent regeneration, and water reuse.