Manganese Intercalation Enabling High-Performance Aqueous Fe-VO₂ Batteries.

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Aqueous iron ion batteries (AIIBs) are promising for large-scale energy storage.
• Challenges exist with Fe2+ ion plating/stripping, necessitating improved cathode materials.

Purpose of the Study:

• To optimize tunnel-like VO2 nanosheets by intercalating Mn2+ ions for enhanced AIIB performance.
• To investigate the structural and electrochemical effects of Mn2+ intercalation in VO2 cathodes.

Main Methods:

• Synthesis of Mn2+ intercalated VO2 nanosheets (MVO).
• Electrochemical characterization of MVO as a cathode material in AIIBs.
• Density Functional Theory (DFT) calculations to understand electronic structure and ion interactions.

Main Results:

• Mn2+ intercalation stabilizes VO2 structure and introduces oxygen vacancies, creating active sites.
• DFT calculations reveal reduced band gap and electrostatic interaction between Fe2+ and VO2.
• 5% MVO electrodes achieved a capacity of 284.32 mAh g-1 at 0.1 A g-1.
• Excellent cycle life demonstrated, retaining 81.7% capacity after 600 cycles at 1.0 A g-1.

Conclusions:

• Mn2+ intercalation is an effective strategy to enhance VO2 cathode performance in AIIBs.
• The optimized MVO material offers a promising cathode choice for high-performance aqueous iron ion batteries.