2D TiB₂ monolayer as a promising anode material for high-performance magnesium-ion batteries

The design and fabrication of high-performance anode materials are pivotal in advancing the development of next-generation magnesium-ion batteries (MIBs). Herein, we conducted a comprehensive first-principles calculation to investigate the structure properties and electronic characteristics of the emerging TiB₂ monolayer, and further evaluate its potential as an anode material of MIBs. Our computational results reveal that the TiB₂ anode exhibits intrinsic metallic behavior and demonstrates a strong affinity for Mg ions with a notably low adsorption energy of -1.39 eV. Utilizing the crystal orbital Hamiltonian population analysis, it is found that the Mg-B bonds show distinct ionic bonding characteristics and dominate the interactions within Mg ion - TiB₂ anode interface. Mg ions can diffuse rapidly on the TiB₂ anode surface with a low diffusion barrier of 0.05 eV, which implies an excellent charging-discharge rate. Moreover, the efficient Mg adsorption on the two sides of TiB₂ anode leads to a high storage capacity of 3085.45 mA h/g and a low average open-circuit voltage of 0.39 V, superior to many reported 2D materials. The TiB₂ anode further demonstrates excellent thermal stability and tiny lattice change during the electrochemical cycling process, which is of paramount importance for achieving a prolonged cycle life. These exceptional properties reveal that TiB₂ monolayer is an appealing anode candidate for high-performance MIBs.