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 LiMn2O4 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 LiMn2O4 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.

Layered Double Oxide as a Cl− Selective Anode for High-Performance Electrochemical Lithium Extraction

“…The development of an efficient and environmentally friendly technology for lithium extraction from brines is extremely essential. Electrochemical lithium extraction is regarded as a promising method for lithium extraction from brines due to its environmental friendliness and easy deintercalation (regeneration of electrodes). , The electrochemical lithium extraction process was driven by the electric field, where the anions (Cl − ) and cations (Li + ) were captured by the anode and cathode, respectively. , The cathode is commonly a battery-type material for Li + intercalation/deintercalation including LiMn 2 O 4 (LMO) , and LiFePO 4 (LFP), − owing to the high Li + intercalation capacity and selectivity . Many modifications in the cathode material have been performed in recent years to enhance the extraction performance.…”