Mo2B, an MBene member with high electrical and thermal conductivities, and satisfactory performances in lithium ion batteries

Abstract

Owing to their high specific area, good flexibility and many other unique properties, two-dimensional (2D) materials have attracted extensive attention in the recent two decades. As an analogy to the well-studied MXenes, MBenes also emerged. In this work, Mo₂B, an MBene member, is predicted both in H- and T-type configurations from first-principles calculations. Structural, mechanical, electronic, and thermal properties, and performances in lithium ion batteries (LIBs) for both configurations are investigated. The H-type Mo₂B is found to be the stable structure, which can be transformed into the T-type by applying strains. The elastic constants c₁₁ in the H- and T-type Mo₂B are respectively calculated to be 187.5 and 157.6 N m⁻¹, which are higher than that in the previously reported Mo₂C. The electronic thermal conductivity and electrical conductivity are investigated based on the semiclassical Boltzmann transport theory. The electrical conductivities for both structures are of the order of 10⁶ Ω⁻¹ m⁻¹. Because of the large phonon contributions, the thermal conductivities in the H- and T-type Mo₂B are much higher than that of the synthesized Mo₂C. Based on a 5 μm flake length, the phonon thermal conductivities at room temperature are calculated to be 146 and 141 W m⁻¹ K⁻¹ respectively for the H- and T-type configurations. The T-type Mo₂B shows promising performances in LIBs. The theoretical volumetric capacity is as high as 2424 mA h cm⁻³, and the migration energy barrier is as low as 0.0372 eV. These data imply that Mo₂B has widespread applications, such as in conductive films and anode materials.