V₄C₃ MXene: a Type-II Nodal Line Semimetal with Potential as High-Performing Anode Material for Mg-Ion Battery

Area of Science:

• Materials Science
• Condensed Matter Physics
• Electrochemistry

Background:

• Magnesium-ion batteries (MIBs) are a promising next-generation energy storage technology.
• MXene materials offer unique properties for electrochemical applications.
• Exploring novel materials with enhanced topological and electrochemical characteristics is crucial for advancing battery technology.

Purpose of the Study:

• To investigate the topological properties of V4C3 and its oxide counterpart using density functional theory (DFT) simulations.
• To assess the potential of V4C3 as an anode material for Mg-ion batteries.
• To understand the impact of oxygen functionalization on the material's topological and electrochemical behavior.

Main Methods:

• Density functional theory (DFT) simulations were employed to explore electronic band structures and topological characteristics.
• Analysis of time reversal and spatial inversion symmetries to identify topological protection.
• Calculations of specific capacity, open-circuit voltage, and intercalation migration energy barriers for Mg-ion battery applications.

Main Results:

• V4C3 monolayer exhibits topological type-II nodal line semimetal properties, protected by fundamental symmetries.
• Oxygen functionalization (V4C3O2) preserves topological features while enhancing electrical conductivity.
• V4C3 demonstrates a high specific capacity (894.73 mAh/g) with minimal loss upon oxidation (789.33 mAh/g), outperforming V2C.
• Moderate open-circuit voltages and favorable intercalation energy barriers (0.29–0.63 eV) were observed.

Conclusions:

• V4C3 is a topologically robust material with excellent potential as an anode for Mg-ion batteries.
• The material's topological enhancement and stable electrochemical performance make it a strong candidate for energy storage.
• Oxygen functionalization offers a route to further tune and improve the performance of V4C3-based anodes.