Designing 2D Janus MXene Zr₂CXT (X, T =O, S, Se, and Te) for Lithium-Ion Batteries using Computational Approaches

Lately, 2D MXenes have drawn significant attention owing to their potential applications in energy storage, optoelectronics, sensors, etc. Among various types of 2D MXenes, transition metal carbides with a general chemical formula of Mn_n+1X_nT_x where M represents a transition metal atom, such as Ti, V, and Zr, X represents a C or N atom, and T represents the surface termination atom including S, O, Se, and Te, have become promising materials for electrodes in Li-ion batteries (LIBs) due to its high electrical conductivity and low diffusion barrier^1,2. Through chalcogen functionalization, the MXenes with higher capacity and relatively low diffusion barrier energy can be obtained^3,4. On the other hand, by functionalizing different surface elements on the two opposite sides of a single layer MXenes, instinct materials properties can be linked together, facilitating the realization of versatile functions and the expansion of various applications. <br/> <br/>Janus Zr-based MXenes, Zr₂CXT, was recently found to possess excellent structural, elastic, electronic, and optical properties^5,6, making them promising materials in LIBs applications. It is of great interest to search for potential Janus 2D Zr₂CXT for broader applications. However, precise control of the functionalization on the MXenes surface by experimental methods is indeed very challenging. Therefore, this work aims to apply density functional theory (DFT) calculations to explore the promising Janus Zr-based MXenes for electrode materials in Li-ion batteries. Various Zr₂CXTwith surface atoms, including O, S, Se, and Te are studied. The essential properties of suitable anode materials, such as the dynamical stability, electronic properties, and diffusion barrier, are calculated. Furthermore, the adsorption energy of the Li on the Zr₂CXT surface is also calculated, as well as the capacity. It is anticipated that this work will provide insights into designing good 2D Janus MXenes for LIBs applications.<br/> <br/><b>References</b><br/>Zhan, X.; Si, C.; Zhou, J.; Sun, Z., <i>Nanoscale Horiz.</i> 2020, 5, 235-258.<br/>Salim O.; Mahmoud, K. A.; Pant, K. K.; Joshi, R. K., <i>Mater. Today Chem.</i> 2019, 14, 100191.<br/>Chen, Z.; Huang, S.; Yuan, X.; Gan, X.; Zhou, N., <i>Appl. Surf. Sci.</i> 2021, 544, 148861.<br/>Tang, C.; Wang, X.; Zhang, S., <i>Mater. Chem. Front. </i>2021, 5, 4672-4681. <br/>Jin, W.; Wu, S.; Wang, Z<i>.</i>, <i>Physica E Low Dimens. Syst. Nanostruct.</i> 2018, 103, 307-313.<br/>Wang, Y.; Tao, Y.; Zhang, Q.; Huang, R.; Gao, B.; Li, Z.; Li, G.; Hu, N.,<i> Solid State Comm.</i> 2022, 354, 114893.