Insight into the Mechanism of MXene Electrodes in Alkali Metal Batteries

TL;DR

This paper explores how different alkali metal ions interact with MXene electrodes in batteries, revealing how ion size affects performance and stability.

Contribution

The study provides a direct comparison of MXene electrode mechanisms with Li+, Na+, and K+ ions under identical conditions.

Findings

Li+ shows intercalation plateau, Na+ intermediate behavior, and K+ surface-dominated adsorption.

Larger ionic radius correlates with lower electrochemical reversibility and capacity retention over 300 cycles.

MXene surface chemistry and vibrational modes change with delamination and cycling.

Abstract

The future growth of alkali metal-based batteries requires an understanding of how ion size affects the exchange mechanisms. In this work, we present a direct, comparative electrochemical study of MXene-based electrodes mechanism vs. lithium (Li+), sodium (Na+), and potassium (K+) ions using the same electrochemical conditions. This controlled method enables an extensive investigation of the size-dependent interactions between the MXene structure and alkali metal ions. X-ray photoelectron spectroscopy and Raman analysis of TMAOH-treated Ti3C2Tx MXene electrodes show that delamination and cycling alter vibrational modes and the surface chemistry. Voltage profile study reveals diverse storage behaviors: Li+ has a prominent intercalation plateau, Na+ shows intermediate properties, and K+ displays sloping profiles, indicating surface-dominated adsorption. The significant correlation between ionic radius and electrochemical reversibility is shown by long-term cycling data over 300 cycles, which show greater capacity retention and stability for Li+ and progressively lower performance for Na+ and K+. These findings provide new mechanistic insights into MXene–ion interactions and build the foundation for developing MXene-based materials for specific alkali-ion chemistries in next-generation energy storage devices.

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