LiMn₂O₄ Nanoparticles In Situ Embedded in Carbon Networks for Lithium Extraction from Brine via Hybrid Capacitive Deionization

Highly selective and efficient extraction of lithium from brine is considered a promising strategy to alleviate the imbalance between supply and demand of lithium resources. However, it is still challenging for lithium ions (Li⁺) recovery from brine. In this work, LiMn₂O₄ nanoparticles embedded in situ in carbon networks (LMO-C) derived from metal-organic frameworks by incomplete calcination have been developed for lithium extraction from brine via the hybrid capacitive deionization (HCDI) process. The adsorption capacity of the obtained LMO-C for Li⁺ is 3.5 mmol g^-1, while the separation factor reaches 24.5 at a high Mg:Li ratio of 20. The extraction and insertion of Li atoms in the LiMn₂O₄ lattice were visually confirmed. In addition, it is found that the synergistic effect between the LMO and the carbon networks is retained in the surface of LMO-C, and the above effect effectively promotes the migration of Li⁺ and the sustainability of the HCDI process. This work is believed to provide a guidance for the design and synthesis of high-performance HCDI materials for the practical lithium extraction from brine.