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

TL;DR

Researchers developed a method using modified MXene materials to selectively extract lithium ions from water, outperforming other similar ions.

Contribution

A two-step electrochemical strategy using preintercalated MXene electrodes to enhance lithium ion selectivity and extraction rates.

Findings

HDA-intercalated MXene achieved high Li+/Na+ selectivity with 2.2 mmol/L lithium uptake and <0.2 mmol/L sodium uptake.

Both HDA and C10 intercalants maintained nearly 100% lithium purity over 50 electrochemical cycles.

Molecular preintercalation modulates ion transport and improves structural and electrochemical stability.

Abstract

The efficient and selective extraction of lithium ions
from aqueous
media is crucial for resource recovery, yet remains challenging due
to the chemical similarity of coexisting alkali ions, such as sodium.
In this study, we report a two-step electrochemical strategy that
utilizes tailored MXene electrodes for lithium ion extraction with
enhanced selectivity and extraction rates. By preintercalating hexadecylamine
(HDA) and decyltrimethylammonium (C10), which are long-chain organic
molecules, into the Ti3C2T
x
MXene structure, we tailored the interlayer environment to
favor lithium ions over sodium ions. The HDA-intercalated MXene demonstrated
high Li+/Na+ selectivity with a lithium ion
uptake of 2.2 mmol/L and a suppressed sodium ion uptake (<0.2 mmol/L).
Extended cycling revealed that molecular preintercalation modulates
ion transport pathways and influences structural and electrochemical
stability. Both HDA-Ti3C2T
x
and C10-Ti3C2T
x
maintained a lithium ion purity of nearly 100% over 50 cycles.

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