Excellent Double Metal Mxenes Mowc Anode: The Different Role of Molybdenum and Tungsten Transition Metal

Abstract

Double transition metal MXenes are highly desirable as anodes in ion batteries and possess better performance than traditional single transition metal MXenes. There is much research on the overall performance of double transition metal MXenes, but few studies focus on the difference roles of the two transition metals in MXenes. This study provides a discussion of the role of W and Mo metals in MoWC, and the effect of W and Mo metals on the electrochemical properties of MoWC and MoWCO2 as anodes in sodium-ion batteries are investigated by using density functional theory calculations. The Mo layer limits the number of first adsorption Na layers. Massive electron transfer between the W side and Na leads to the stable existence of the second layer to adsorb Na atoms. Finally, the different metal layers induce Na to have low diffusion barriers (0.072 eV on the Mo layer and 0.055 eV on the W layer) in the MoWC monolayer and competitive capacities (204.10 of MoWC and 165.54 mAhg-1 of MoWCO2), exceeding the theoretical capacities of single metal MXenes Mo2C and W2C. Such study result is a great reference for future investigations of double transition metal MXenes

Keywords: two-metal MXenes, different role of metals, electronegativity, Na-ion batteries, Specific capacity, First-principles calculations