Restraining Lattice Distortion of LiMn<sub>2</sub>O<sub>4</sub> Facilitates Fluidic Electrochemical Lithium Extraction from Seawater.

Xu, Yongtai; Li, Yixiang; Zhao, Xiaoyu; Li, Yifan; Li, Xue Liang; Wang, Jing; Yang, Hui Ying · Nano Lett · 2025

basic_science · Level V

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Abstract

Reversible electrochemical extraction using cathode materials shows great potential for selective lithium extraction from low-concentration aqueous sources. However, ion selectivity and structural distortion challenges have limited its application to sources like seawater. Here, we synthesize Nb-modified LiMn<sub>2</sub>O<sub>4</sub> using a simple wet chemistry coating method, introducing minimal structural defects in the LiMn<sub>2</sub>O<sub>4</sub> materials and enhancing stability with a LiNbO<sub>3</sub> coating to limit lattice expansion. Additionally, operando XRD reveals reduced lattice distortion during Li<sup>+</sup> intercalation/deintercalation. Electrochemical tests show that the composite achieves high stability (over 100 cycles), fast Li<sup>+</sup> electrosorption, and robust ion selectivity. Furthermore, utilizing a fluidic electrochemical approach, we extract lithium from simulated seawater (3.5 ppm of Li<sup>+</sup>), achieving an absorption capacity of 13.8 mg g<sup>-1</sup> and an energy consumption of 9.96 Wh g<sup>-1</sup>.