Exploring the potentials of Ti3N2 and Ti3N2X2 (X = O, F, OH) monolayers as anodes for Li or non-Li ion batteries from first-principles calculations

Abstract

The electronic properties and different metal ion (Li, Na, Mg) storage capabilities of the two-dimensional (2D) Ti₃N₂ monolayer and its Ti₃N₂X₂ derivatives (X = O, F, and OH) as anode materials in rechargeable batteries have been systematically investigated by density functional theory (DFT) computations. Results show that the bare Ti₃N₂ and terminated monolayers in their most stable configurations are all metallic before and after metal ion adsorption. The relatively low diffusion barriers on the bare Ti₃N₂ monolayer were also confirmed, which implies faster charge and discharge rates. With respect to storage capacity, a high theoretical capacity of 1874 mA h g⁻¹ can be provided by the Ti₃N₂ monolayer for Mg due to its multilayer adsorption and two-electron reaction. The existence of functional groups is proven to be unfavorable to metal ion migration and will decrease the corresponding storage capacities, which should be avoided in experiments as much as possible. These excellent performances suggest that the bare Ti₃N₂ is a promising anode material for Li-ion or non-Li-ion batteries.