Interlayer-Tailored Alkyl-MXenes for Selective Electrochemical Lithium-Ion Extraction

Area of Science:

• Materials Science
• Electrochemistry
• Chemical Engineering

Background:

• Efficient lithium ion extraction from aqueous solutions is vital for resource recovery but hindered by the presence of similar alkali ions like sodium.
• Developing selective and high-capacity materials for lithium extraction remains a significant challenge in materials science and chemical engineering.

Purpose of the Study:

• To develop a two-step electrochemical strategy using tailored MXene electrodes for enhanced lithium ion extraction selectivity and rates.
• To investigate the impact of preintercalated long-chain organic molecules on MXene interlayer environments and ion transport.

Main Methods:

• Synthesized Ti3C2Tx MXene electrodes.
• Preintercalated MXene with hexadecylamine (HDA) and decyltrimethylammonium (C10).
• Evaluated lithium and sodium ion uptake and selectivity using electrochemical methods over extended cycling.

Main Results:

• HDA-intercalated MXene exhibited high Li+/Na+ selectivity, with lithium ion uptake of 2.2 mmol/L and suppressed sodium ion uptake (<0.2 mmol/L).
• Preintercalation modulated ion transport pathways, influencing structural and electrochemical stability.
• Both HDA-Ti3C2Tx and C10-Ti3C2Tx electrodes maintained nearly 100% lithium ion purity over 50 cycles.

Conclusions:

• Tailoring MXene interlayer environments with long-chain organic molecules is an effective strategy for selective lithium ion extraction.
• The developed electrochemical method offers high selectivity and stability, promising for lithium resource recovery and purification.