Two-dimensional AlB₄/Al₂B₂: high-performance Dirac anode materials for sodium-ion batteries

Area of Science:

• Materials Science
• Electrochemistry
• Computational Chemistry

Background:

• Sodium-ion batteries (SIBs) are gaining attention due to the abundance and low cost of sodium.
• Two-dimensional (2D) Dirac materials are promising anode candidates for SIBs owing to their superior electronic conductivity.

Purpose of the Study:

• To investigate the potential of AlB4 (Al2B2) monolayers and bilayers as anode materials for SIBs.
• To evaluate their electrochemical performance, including storage capacity, ion diffusion barriers, and voltage profiles.

Main Methods:

• First-principles calculations were employed to study the properties of AlB4 (Al2B2) materials.
• The theoretical storage capacity, diffusion barriers, open-circuit voltage, and lattice expansion upon sodiation were calculated.

Main Results:

• AlB4 (Al2B2) monolayer demonstrates a high theoretical capacity of 954.15 (709.17) mA h g-1 and a low diffusion barrier of 0.36 (0.03) eV.
• The calculated average open-circuit voltage (0.68/0.18 V) is within the acceptable range for anode materials (0.1–1.0 V).
• The AlB4 (Al2B2) monolayer exhibits minimal lattice expansion (0.9%/2.4%) upon full sodiation, indicating good reversibility. Bilayers show stronger Na binding on the outer surface.

Conclusions:

• AlB4 (Al2B2) monolayers and bilayers are identified as promising high-performance anode materials for SIBs.
• The study provides valuable insights into the electrochemical behavior of these 2D materials for next-generation energy storage.