Twisted Bilayer MXenes//MoS2 Moire Superlattices for Alkaline Metal-Ion Batteries: Insights from First-Principles Calculations

Employing first-principles calculations, we explore the impact of the formation of twisted bilayer heterostructures in terms of Ti2C//MoS2 and Ti2CO2//MoS2 Moire superlattices on their electrochemical energy storage properties as the electrode materials in alkaline metal-ion batteries (lithium-ion battery (LIB), sodium-ion battery (SIB), and potassium-ion battery (PIB)). The predicted adsorption energies and the corresponding adsorption site preferences surprisingly show a strong modulation with the twisting angle in MXenes//MoS2 Moire superlattices in which Moire spots could either attract the alkaline metal ions or repel them strongly, depending critically on the twisting angle and surface terminations of MXenes. Consequently, the obtained theoretical capacities and ion-migration energy barrier heights show the nonmonotonic relationships with the twisting angle of MXenes//MoS2 Moire superlattices. Regarding the electrochemical properties of the studied Moire superlattices, we report LIB (260-500 mAh/g), SIB (123-387 mAh/g), and PIB (100-223 mAh/g) for MXenes//MoS2 heterostructures, while the diffusion energy barrier heights are found to be 0.03-0.51, 0.02-0.37, and 0.003-0.45 eV for Li+, Na+, and K+, respectively. Overall, the electrochemical performances of Ti2C//MoS2 and Ti2CO2//MoS2 Moire superlattices for alkaline metal-ion batteries remain competitive among common two-dimensional (2D) materials with similar molar masses, especially for SIB and PIB.