N-functionalized Ti₂B MBene as high-performance anode materials for sodium-ion batteries : A DFT study

Exploring the electrode materials for rechargeable metal-ion batteries other than lithium is a key link to the design and development of the next-generation energy storage device. Herein, the structural stabilities of B, C, and N functionalized Ti₂B were systematically discussed and the potential of the stable structure Ti₂BN₂ as anode materials for Li-, Na-, K-, Mg-, Ca- and Zn-ion batteries was further studied using first-principles calculations. Specifically, phonon dispersion curves and ab-initio molecular dynamics simulations identified the dynamic and thermal stability of Ti₂BN₂. The intrinsic metallic nature and non-magnetism of Ti₂BN₂ were then revealed by the band structure and density of state. Moreover, benefiting from the light weight and energetically favorable bilayer Na adsorption, Ti₂BN₂ exhibits a high theoretical capacity of 797 mA h g⁻¹ for sodium-ion batteries (SIBs), which shows great advantage than most two-dimensional anode materials. Besides, the low diffusion barrier of 0.34 eV and suitable open circuit voltage of 0.27 V further illustrate Ti₂BN₂ is a competitive candidate for anode material of SIBs. Our work not only revealed a high-capacity electrode material of SIBs but also promoted the research of N-functionalized MBenes.