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LiMn2O4 is of great potential for selectively extracting Li+ from brines and seawater, yet its application is hindered by its poor cycle stability and conductivity. Herein a two‐step strategy to fabricate highly conductive and stable CNT‐strung LiMn2O4 (CNT‐s‐LMO) is reported, by first stringing Mn3O4 particles with multiwalled carbon nanotube (CNT), then converting the hybrids into CNT‐s‐LMO through hydrothermal lithiation. The as‐synthesized CNT‐s‐LMO materials have a net‐like structure with CNTs threading through LMO particles. This unique structure has endowed the CNT‐s‐LMO electrode with excellent conductivity, high specific capacitance, and enhanced rate performance. Because of this, the CNT‐s‐LMO electrode in the hybrid capacitive deionization cell (HCDI) can deliver a high Li+ extraction percentage (≈84%) in brine and an outstanding lithium selectivity with a separation factor of ≈181 at the Mg2+/Li+ molar ratio of 60. Significantly, the CNT‐s‐LMO‐based HCDI cell has a high stability, evidenced by 90% capacity retention and negligible Mn loss in 100 cycles. This method has paved a new way to fabricate carbon‐enabled LMO‐based absorbents with tuned structure and superior capacity for electrochemical lithium extraction with high Li+ selectivity and exceptional cycling stability, which may help to tackle the shortage in supply of Li‐ion batteries in industry in the future.

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Activated carbon (AC) is one of the most typical carbon materials used for capacitive deionization (CDI) due to its large specific surface area and porous structure. However, the poor water wettability of AC remains a major challenge for CDI application in aqueous solutions. Here, polydopamine (PDA) is facilely modified on AC surface (PDA/AC) via self-polymerization of dopamine to improve its wettability, while the PDA thickness can be conveniently tuned by varying the soak time. X-ray photoelectron spectroscopy (XPS), Energy dispersive spectroscopy (EDS), Fourier transform infrared spectroscopy (FTIR), N2 adsorption and contact angle measurements are taken to characterize the properties of PDA/AC. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) analysis indicate that PDA/AC electrodes exhibit an ideal electrochemical double layer capacitive behavior. The salt removal amount of 12 mg/g on PDA/AC with 4 h soaking is achieved during the desalination process, compared to 4.5 mg/g of AC electrode. The PDA/AC electrode is a very promising material for capacitive deionization.