MnB2 nanosheet and nanotube: stability, electronic structures, novel functionalization and application for Li-ion batteries

Abstract

In this paper, two kinds of two-dimensional manganese boride monolayers, h-MnB₂ and t-MnB₂, are predicted to be stable metallic nanosheets, which exhibit favorable mechanical and thermal properties. The Young's moduli of h-MnB₂ and t-MnB₂ are 77.73 N m⁻¹ and 59.59 N m⁻¹, respectively. Ab initio molecular dynamics results show that h-MnB₂ and t-MnB₂ can sustain up to 500 K and 1000 K, respectively. The magnetic property of h-MnB₂ is frustrated antiferromagnetic with a Néel temperature of about 25 K, and the magnetic property of t-MnB₂ is collinear antiferromagnetic with a Néel temperature of about 317 K. In addition, the electronic structure of the h-MnB₂ monolayer can be tuned by passivation to exhibit Dirac states. h-MnB₂ can also self-assemble to form nanotubes, and is thus very promising for application as the anode for Li-ion batteries because of its high capacity (about 875 mA h g⁻¹), low diffusion barrier (about 0.03 eV) and strong stability.