First-principles prediction of Hittorf's violet phosphorene as a promising candidate of anode material for Li- and Na-ion batteries

Hittorf's violet phosphorus is the most stable phosphorus allotrope with a layered structure. The corresponding Hittorf's violet phosphorene, a more stable two-dimensional semiconducting structure than black phosphorene, is a promising two-dimensional material for electronic and optoelectronic devices. In this work, the adsorption and anisotropic diffusion process of Li and Na atoms have been studied using first-principles calculations. The adsorption energies of Li and Na atoms are calculated to be 1.65 and 1.32 eV, respectively. Based on the structural nature of Hittorf's violet phosphorene, two possible diffusion paths (in-trench diffusion and intertrench diffusion) are proposed and investigated. The results of transition state calculation indicate that intrench diffusion of metal atom has lower barrier that inter-trench diffusion, indicating the significant anisotropic diffusion of Li and Na atom on Hittorf's violet phosphorene. Our work suggests the promising application of Hittorf's violet phosphorene in ion batteries research and development.