[116]. Hang WS, Qu JP, Wang XD, Huang H*, Yao M*, Performance investigation of TixNx−1O2 MXene (x = 2, 3, 4) as anode materials for Na-ion batteries by first-principles calculatio, Nanotechnology, 2022, 33, 495403.

Abstract: The number of MXene layers plays a crucial role in their performance when they are used as anode materials for sodium-ion batteries. Herein, Ti-based nitride MXenes with different layers, Ti_xN_x−1O₂ MXene (x = 2, 3, 4) structures, were constructed to calculate the structural stability of their precursor, electronic properties after etching, and sodium storage behavior compared with the common Ti₂CO₂ and Ti₃C₂O₂ MXene. First-principles calculations indicate that nitride MXenes possess a better rate capability than carbide MXenes of the same thickness. Moreover, the barrier for Na diffusion on the Ti₂NO₂ MXene surface (0.114 eV) is lowest. Meanwhile, comparing the properties of three nitride MXenes with different thicknesses, Ti₂NO₂ MXene performs relatively well with a high theoretical capacity with 756 mA h g⁻¹ and a lower open circuit voltage of 1.1 V. In conclusion, the performance improvement of nitride MXene is not linear with thickness, because that of Ti₃N₂O₂ MXene is relatively weaker. This work lays the foundation for the feasibility of Ti₃N₂T_x experimental preparation and provides corresponding evidence on the choice of MXene thickness. More attention should be paid to the etching method for Ti₂NT_x MXene.