Selective Interfacial Regulation of LiMn₂O₄ for Flow Electrochemical Lithium Extraction

Gas-produced water (GPW) is increasingly recognized as an important low-quality aqueous lithium resource. Electrochemical lithium extraction using LiMn₂O₄ (LMO) offers a promising strategy for lithium extraction from aqueous resources. However, its application to GPW is hindered by competing-ion co-intercalation and Mn dissolution, which compromise extraction selectivity and stability. Inspired by selective ion transport in biological ion pumps, a Li_0.33La_0.56TiO₃ (LLTO)-engineered LMO interface is developed to integrate Li⁺-sieving nanochannels with interfacial stabilization. Experimental and mechanistic analyses demonstrate that the LLTO-engineered interface promotes local Li⁺ enrichment, while its Li⁺-sieving nanochannels restrict competing-cation access, thereby accelerating selective Li⁺ transport and optimizing Li⁺ storage. Concurrently, the LLTO suppresses Mn dissolution, thereby preserving interfacial stability during repeated Li⁺ extraction and release. Furthermore, the cyclic flow 3LLTO-LMO//3LLTO-λ-MnO₂ system delivers 16.6 mg·g^-1 lithium release capacity after 10 cycles and achieves an 87.5% Li⁺ recovery rate while retaining 60.7% Li⁺ purity from simulated GPW after 20 cycles, and further demonstrates applicability to real GPW. This work establishes a Li⁺-selective interfacial regulation strategy for efficient and stable lithium extraction and provides a material-to-process framework for sustainable lithium extraction from low-quality aqueous lithium resources.