A two-dimensional VO₂/VS₂ heterostructure as a promising cathode material for rechargeable Mg batteries: a first...

Area of Science:

• Materials Science
• Electrochemistry
• Computational Chemistry

Background:

• Rechargeable magnesium batteries (RMBs) are promising energy storage systems.
• Development is hindered by cathode materials lacking fast Mg2+ diffusion and high energy density.

Purpose of the Study:

• To propose and investigate a 2D VO2/VS2 heterostructure as a cathode material for RMBs.
• To enhance discharge voltage, specific capacity, and Mg2+ diffusion kinetics.

Main Methods:

• First-principle calculations were employed.
• Systematic study of geometric structures, electronic characteristics, Mg2+ adsorption, and diffusion behaviors in VO2/VS2.

Main Results:

• VO2/VS2 exhibits metallic properties and a low Mg2+ diffusion barrier (0.6 eV).
• Average discharge platform increased to 1.7 V (vs. 1.25 V for VS2).
• Theoretical capacity increased to 301 mA h g-1 (vs. 233 mA h g-1 for VS2).
• Theoretical energy density reached 511.7 W h kg-1 (vs. 291.3 W h kg-1 for VS2).

Conclusions:

• The VO2/VS2 heterostructure demonstrates potential for high-rate performance in RMBs.
• This material significantly surpasses VS2 in energy density.
• Provides guidance for designing high-energy, high-rate 2D heterostructure cathodes for multivalent ion batteries.