Hydrophilic Nanoisland Interface Engineering for Conquering Activity–Stability Trade-Off in High-Efficiency Salt Lake Lithium Extraction

Abstract

The adsorption-based lithium extraction technology from ultralow-grade salt lake brine is severely restricted by the inherent activity–stability trade-off of traditional granular Li/Al-LDHs adsorbents (GLDHs). Herein, a nanoisland encapsulation strategy integrated with hydrophilic interface engineering is developed to fabricate Li/Al-LDHs composite granules with tailored hydrophilic interfaces (HILDHs), breaking the long-standing bottleneck of conventional aluminum-based lithium adsorbents used in the salt lake industry. Systematic experiments and multiscale simulations reveal that the strong water affinity of polyacrylonitrile cyano groups (−C≡N) creates a highly hydrated microenvironment for rapid Li+ transport, while the nanoisland-confined structure anchors Li/Al-LDHs nanosheets to preserve the layered framework under harsh deep desorption conditions, thus enabling excellent cycling stability. The optimized HILDHs deliver a 3.02-fold higher working adsorption capacity (7.25 mg g–1 vs 2.40 mg g–1 for GLDHs) in actual Qarhan old brine within 60 min, along with a 13.36-fold increase in adsorption rate constant, 40% lower rinsing water consumption, and excellent cycle stability. It is calculated the nanoisland encapsulation strategy can achieve a nearly 5-fold increase for the annual Li2CO3 production capacity from salt lake lithium industrial lines.