Theoretical Prediction of a Novel Phase Ti2B2 Monolayer as an Outstanding Electrode Material for Lithium/Sodium-Ion Batteries

Transition metal borides (MBenes) have provoked widespread interest in the field of power storage due to their excellent electrochemical performance. Using structural prediction software and first-principles calculations, a two-dimensional Ti₂B₂ phase has been predicted; it possesses favorable structural stability and metal-like electronic characteristics. The Ti₂B₂ monolayer is suitable as an electrode material for lithium/sodium storage due to its excellent ion migration ability, moderate open circuit voltage, and high storage capacity. Especially, the theoretical capacity broke the upper limit of the Li (double-layer) and Na (single-layer) storage of MBenes with transition metals as surfaces, and the diffusion barrier of the Li atom is 1 order of magnitude lower than those of other MBenes. Besides, the adsorbed ions maintain a complete and orderly layered arrangement at 500 K, which ensures excellent cycling performance. This work provides a novel orientation for designing electrode materials of secondary batteries in fields such as portable electronics and electric vehicles.