Site-Selective Yttrium Substitution in Ti3AlC2 Enables Interlayer Engineering and Li Transport in Ti3C2Tx cathodes for High-Power Energy Storage
Abstract
In this work, we introduce a precursor-level strategy by substitutionally doping the Ti3AlC2 MAX precursor with a small amount of Yttrium during top-down MAX preparation. This allows permanent structural changes that are retained in the resulting Ti3C2Tx MXene. Density functional theory (DFT) calculations identify the outer Ti(4f) site, facing the Al layer, as the preferred incorporation site for Y under the Al-excess synthesis conditions used here, rather than the inner Ti(2a) or Al(2b) sites. This site-specific substitution is consistent with the experimentally observed lattice expansion and carbide-like Y bonding and provides a microscopic basis for the structural changes retained in the resulting Ti3C2Tx MXene. Y incorporation expands the MXene interlayer spacing due to an increase in the amount of hydroxyl surface terminations, creating more favorable pathways for lithium-ion transport. Comprehensive structural characterization (including XRD, XPS and TEM) confirms these modifications. As a result, the Y-doped Ti3C2Tx cathode shows diffusion-controlled charge storage with a Li diffusion coefficient of 10-9-10-11 cm2/s. It delivers a reversible capacity of about 130 mAh/g at 0.2 C and retains 74 mAh/g after 1000 cycles at 2 C with nearly 100% Coulombic efficiency. The electrode also achieves a high power density of up to 3970 W/kg, outperforming the undoped MXene and previously reported multilayered MXene cathodes. These results show that substitutional doping of the MAX precursor is a promising strategy for controlling the interlayer structure of MXenes and improving ion transport, providing a new route for the development of high-power energy-storage electrodes.
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BibTeX
@misc{boichuk2026siteselective,
title = {{Site-Selective Yttrium Substitution in Ti3AlC2 Enables Interlayer Engineering and Li Transport in Ti3C2Tx cathodes for High-Power Energy Storage}},
author = {Tetiana Boichuk and Andrii Boichuk and Mahesh Eledath Changarath and Joao Fonseca and Said Agouram and Marie Finas and Alejandro Molina-Sanchez and Juan F. Sanchez-Royo},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.32707},
eprint = {2609.32707},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.32707},
}
RIS
TY - UNPB
TI - Site-Selective Yttrium Substitution in Ti3AlC2 Enables Interlayer Engineering and Li Transport in Ti3C2Tx cathodes for High-Power Energy Storage
AU - Tetiana Boichuk
AU - Andrii Boichuk
AU - Mahesh Eledath Changarath
AU - Joao Fonseca
AU - Said Agouram
AU - Marie Finas
AU - Alejandro Molina-Sanchez
AU - Juan F. Sanchez-Royo
PY - 2026
DA - 2026/09/26
PB - arXiv
DO - 10.48550/arxiv.2609.32707
UR - https://arxiv.org/abs/2609.32707
AB - In this work, we introduce a precursor-level strategy by substitutionally doping the Ti3AlC2 MAX precursor with a small amount of Yttrium during top-down MAX preparation. This allows permanent structural changes that are retained in the resulting Ti3C2Tx MXene. Density functional theory (DFT) calculations identify the outer Ti(4f) site, facing the Al layer, as the preferred incorporation site for Y under the Al-excess synthesis conditions used here, rather than the inner Ti(2a) or Al(2b) sites. This site-specific substitution is consistent with the experimentally observed lattice expansion and carbide-like Y bonding and provides a microscopic basis for the structural changes retained in the resulting Ti3C2Tx MXene. Y incorporation expands the MXene interlayer spacing due to an increase in the amount of hydroxyl surface terminations, creating more favorable pathways for lithium-ion transport. Comprehensive structural characterization (including XRD, XPS and TEM) confirms these modifications. As a result, the Y-doped Ti3C2Tx cathode shows diffusion-controlled charge storage with a Li diffusion coefficient of 10-9-10-11 cm2/s. It delivers a reversible capacity of about 130 mAh/g at 0.2 C and retains 74 mAh/g after 1000 cycles at 2 C with nearly 100% Coulombic efficiency. The electrode also achieves a high power density of up to 3970 W/kg, outperforming the undoped MXene and previously reported multilayered MXene cathodes. These results show that substitutional doping of the MAX precursor is a promising strategy for controlling the interlayer structure of MXenes and improving ion transport, providing a new route for the development of high-power energy-storage electrodes.
ER -