Binder‐Free LiMn2O4 Nanosheets on Carbon Cloth for Selective Lithium Extraction from Brine via Capacitive Deionization

Abstract In this study, a three‐step strategy including electrochemical cathode deposition, self‐oxidation, and hydrothermal reaction is applied to prepare the LiMn 2 O 4 nanosheets on carbon cloth (LMOns@CC) as a binder‐free cathode in a hybrid capacitive deionization (CDI) cell for selectively extracting lithium from salt‐lake brine. The binder‐free LMOns@CC electrodes are constructed from dozens of 2D LiMn 2 O 4 nanosheets on carbon cloth substrates, resulting in a uniform 2D array of highly ordered nanosheets with hierarchical nanostructure. The charge/discharge process of the LMOns@CC electrode demonstrates that visible redox peaks and high pseudocapacitive contribution rates endow the LMOns@CC cathode with a maximum Li + ion electrosorption capacity of 4.71 mmol g −1 at 1.2 V. Moreover, the LMOns@CC electrode performs outstanding cycling stability with a high‐capacity retention rate of 97.4% and a manganese mass dissolution rate of 0.35% over ten absorption–desorption cycles. The density functional theory (DFT) theoretical calculations verify that the Li + selectivity of the LMOns@CC electrode is attributed to the greater adsorption energy of Li + ions than other ions. Finally, the selective extraction performance of Li + ions in natural Tibet salt lake brine reveals that the LMOns@CC has selectivity ( = 7.48) and excellent cycling stability (100 cycles), which would make it a candidate electrode for lithium extraction from salt lakes.