MXene/Borophene Heterostructures: Mechanistic Insights into Cathode Stability and Capacity in Aluminum-Ion Batteries

The development of Aluminum dual-ion batteries (ADIBs) is hindered by the structural instability and limited capacity of cathode caused by AlCl₄ intercalation. A deeper understanding of cathode-anion interactions and the fundamental reaction mechanisms is necessary to address these challenges. Herein, MXene-borophene, V₂CT_x/B heterostructures are proposed as high-performance cathodes for ADIBs, which combines the high electronic conductivity and tunable surfaces of MXenes with the mechanical strength and effective charge transport properties of borophene. First-principles calculations show that AlCl₄ adsorption in V₂CT_x/B heterostructures is significantly stronger than in pristine V₂CT_x and B monolayers and the low diffusion barrier of V₂CO₂/B (0.31 eV) allows rapid charge/discharge kinetics. With a large storage capacity of 232 mAh g^-1, voltage profile exhibits an average working voltage of 1.73 V therefore emphasizing their applicability. Moreover, Ab initio molecular dynamics (AIMD) simulations verify the thermodynamic stability of the heterostructure under operating conditions. These results highlight the V₂CO₂/B heterostructure as a potential cathode that provides significant understanding of AlCl₄ intercalation mechanisms and helps the systematic development of next-generation aluminum-based energy storage devices.