Exploring the potentials of Ti(3)N(2) and Ti(3)N(2)X(2) (X = O, F, OH) monolayers as anodes for Li or non-Li ion batteries from first-principles calculations

The electronic properties and different metal ion (Li, Na, Mg) storage capabilities of the two-dimensional (2D) Ti(3)N(2) monolayer and its Ti(3)N(2)X(2) 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 Ti(3)N(2) 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 Ti(3)N(2) 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 Ti(3)N(2) 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 Ti(3)N(2) is a promising anode material for Li-ion or non-Li-ion batteries.