Two-dimensional Mo4/3B2−xTz boridene cathodes for Al-ion batteries

Rechargeable aluminum-ion batteries (AIBs) represent a highly promising solution for large-scale energy storage systems, owing to their exceptional safety, low cost, and high volumetric energy density. However, key challenges in this emerging technology include the development of suitable cathode materials capable of efficient intercalation/deintercalation of Al-complex ions and a deeper understanding of the underlying electrochemical reaction mechanisms. Here we show Boridene (MBene), a two-dimensional (2D) transition metal boride (Mo4/3B2-xTz, (where Tz is fluorine, oxygen, or hydroxide surface terminations), as a cathode material for AIBs. Using density functional theory simulations, we calculated the adsorption energies of [AlCl4]− on MBene cathodes with varying termination concentrations, revealing that adsorption strength increases with decreasing termination density. Our findings demonstrate that the 2D Mo4/3B2-xTz cathode, with its moderate adsorption energy for Al-complex ions, enables superior electrochemical performance. These results not only provide a new strategy for designing high-performance AIB cathodes but also highlight the potential of 2D MBenes in next-generation energy storage systems. Rechargeable aluminum-ion batteries offer a promising avenue for largescale energy storage, yet challenges remain in developing efficient cathode materials. Here, boridene is demonstrated as a cathode in aluminum-ion batteries and shows high reversible capacity of 212 mAh g s−1 and maintains <95% Coulombic efficiency.