Investigation of two-dimensional hf-based MXenes as the anode materials for li/na-ion batteries: A DFT study

Density functional theory calculations are performed to investigate electronic properties and Li/Na storage capability of Hf3C2 and its derivatives (uniform passivated: Hf3C2T2 [T = F, O, OH] and hybrid passivated: Hf3C2FxO2-x and Hf3C2Ox(OH)(2-x) [x = 1.0, 1.5]). For Hf3C2 monolayer, it has excellent performance, such as good conductivity, low diffusion energy barrier, low open circuit voltage, and high storage capacities (Li(1034.70 mAh g(-1)), Na(444.90 mAh g(-1))), providing the most prospective as anode material. However, due to the unsaturated dangling bonds of surface Hf, so it is easily passivated. For the uniform passivated ones, Hf3C2T2, show higher diffusion barriers and lower storage capacities than bare monolayer Hf3C2. Nevertheless, compared with uniform passivated ones, the hybrid passivated derivative, Hf3C2F1.5O0.5 and Hf3C2OOH possess a lower energy barrier and a better storage capacity. Therefore, Hf3C2F1.5O0.5 and Hf3C2OOH are deemed to be a suitable candidate as anode electrode material for Li-ion batteries. (c) 2019 Wiley Periodicals, Inc.