Hexagonal Ti2B2 monolayer: A Promising Anode Material Offering High Rate Capability for Li-Ion and Na-Ion Batteries

TL;DR

This study uses first-principles calculations to identify hexagonal Ti2B2 monolayer as a highly promising anode material for Li-ion and Na-ion batteries due to its high capacity, excellent ion diffusivity, and structural stability.

Contribution

It introduces a new 2D Ti2B2 monolayer with superior electrochemical properties for battery applications, supported by comprehensive stability and performance analyses.

Findings

High theoretical capacities for Li and Na (456 and 1027 mAh/g)

Ultralow ion diffusion energy barriers (0.017/0.008 eV)

Good electronic conductivity and structural robustness during lithiation

Abstract

Combining first-principles density functional method and crystal structure prediction techniques, we report a series of hexagonal two-dimensional (2D) transition metal borides (TMBs) including Sc2B2, Ti2B2, V2B2, Cr2B2, Y2B2, Zr2B2, and Mo2B2. Their dynamic and thermal stabilities are testified by phonon and molecular dynamics simulations. We investigate the potential of 2D Ti2B2 monolayer as the anode material for Li-ion batteries (LIBs) and Na-ion batteries (NIBs). The Ti2B2 monolayer possesses high theoretical specific capacities of 456 and 1027 mAhg-1 for Li and Na, respectively. The very high Li/Na diffusivity with ultralow energy barrier of 0.017/0.008 eV indicates an excellent charge-discharge capability. In addition, the good electronic conductivity during the whole lithiation process is found by electronic structure calculations. The very small change in volume after the adsorption of one, two, and three layers of Li and Na ions indicates that the Ti2B2 monolayer is robust. These results highlight the suitability of Ti2B2 monolayer as well as the other 2D TMBs as excellent anode materials for both LIBs and NIBs.