Holey Graphyne as a Promising Cathode Material for Aluminum-Ion Batteries: A First-Principles Study

Aluminum-ion batteries are among the most efficient battery technologies owing to the abundance of aluminum and its trivalent redox properties. However, their practical application remains limited by the poor longevity of cathode materials. In this study, we investigate the potential of the two-dimensional porous carbon allotrope holey graphyne (HGY) as a cathode material for aluminum-ion batteries. Density functional theory calculations are employed to systematically examine the interaction of AlCl₄ species with HGY and assess its potential for AlCl₄ storage. The results indicate that AlCl₄ on the HGY surface has an adsorption energy of -1.59 eV, suggesting significant energetic stability of the adsorbate system. The monolayer HGY provides a specific capacity of 372 mAh g^-1, substantially higher than that of graphite (70 mAh g^-1) and graphene (155 mAh g^-1). Furthermore, the calculated average open-circuit voltage of the HGY cathode is approximately 2.25 V, higher than that of graphite (2.00 V). Additionally, the low diffusion barrier of 0.04 eV indicates high mobility of AlCl₄ on the HGY surface, suggesting rapid ion transport and favorable fast-charging capability. These findings highlight the significant potential of HGY as an effective cathode material for aluminum-ion batteries.