Fe2CS2 MXene: a promising electrode for Al-ion batteries

• Published in: Nanoscale Vol. 12; no. 9; pp. 5324 - 5331
• Main Authors: Lee, Sangjin, Jung, Sung Chul, Young-Kyu, Han
• Format: Journal Article
• Language: English
• Published: Cambridge Royal Society of Chemistry 07.03.2020
• Subjects: Aluminum-ion batteries; Batteries; Electrodes; Intercalation; Ions; Metals; MXenes; Performance enhancement; Potential energy; Rechargeable batteries; Sulfur; Transition metals
• DOI: 10.1039/c9nr08906c
• ISSN: 2040-3364

Aluminum-ion batteries are one of the most promising candidates for next-generation rechargeable batteries. However, the strong electrostatic interactions between highly ionic Al3+ and the electrode hinder the reversible intercalation and fast transport of Al ions. This study suggests a design strategy for a MXene electrode for realizing high-performance Al-ion batteries. Instead of early transition metals and oxygen, the metal M and surface termination T of general MXene (Mn+1XnTx), the use of late transition metals and sulfur can dramatically improve the capacity and rate capability, respectively. The capacity increases 2.2-fold, from 288 mA h g−1 (Ti2CO2) to 642 mA h g−1 (Fe2CS2), and the Al-ion diffusivity increases 104-fold, from 2.8 × 10−16 cm2 s−1 (Ti2CO2) to 6.0 × 10−12 cm2 s−1 (Fe2CS2). This remarkable performance enhancement is due to the charge redistribution in the M and T layers by the late transition metals and the shallowing of the potential energy surface for Al-ion intercalation by sulfur.