Unveiling the Potential of Boron-Rich Two-Dimensional TiB₆ Monolayer as a High-Performance Anode Material for Sodium-Ion Batteries: Insights into Correlation Mechanisms for Multi-Ion Migration

Boron-rich materials have emerged as a promising class of anode materials, because of their unique structural and electrochemical properties. In this study, we investigate the potential of a boron-rich two-dimensional (2D) TiB6 monolayer as an anode material for SIBs using first-principles calculations and crystal structure predictions. Our findings reveal that the TiB6 monolayer, with its unique B-rich structure, can not only accommodate larger Na ions but also shield metal cations, thereby weakening the repulsion between Na ions and metal cations and increasing the capacity of the anode. We demonstrate that the TiB6 fully sodiumated phase is TiB6Na4, which exhibits an extremely high theoretical capacity of 951.23 mAh g–1. Moreover, our simulations show that the TiB6 monolayer has a lower diffusion barrier and average open circuit voltage, compared with other anode materials. Additionally, our systematic calculations of ion diffusion reveal that the migration of multiple Na ions on the TiB6 monolayer is mainly governed by a correlation mechanism, where the diffusing Na ions can push others to migrate, resulting in an extremely low diffusion energy barrier. These findings highlight the potential of the boron-rich 2D TiB6 monolayer as a high-performance anode material for SIBs and shed light on the importance of boron-rich materials in the search for next-generation battery materials.