Doping Regulation Stabilizing δ-MnO₂ Cathode for High-Performance Aqueous Aluminium-ion Batteries

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• δ-MnO₂ is a promising cathode material for aqueous aluminum-ion batteries (AAIBs) due to its layered structure.
• Structural collapse during Al³⁺ intercalation limits the performance of pristine δ-MnO₂.

Purpose of the Study:

• To enhance the structural stability and electrochemical performance of δ-MnO₂ for AAIBs.
• To investigate the effect of heterogeneous metal doping on δ-MnO₂ cathode materials.

Main Methods:

• Introduction of heterogeneous metal dopants, specifically vanadium (V), into the δ-MnO₂ framework.
• Electrochemical testing of V-doped δ-MnO₂ (V-δ-MnO₂) in AAIBs.
• Theoretical and experimental analyses of structural and electronic properties.

Main Results:

• V-δ-MnO₂ exhibits a high specific capacity of 518 mAh g^-1 at 200 mA g^-1.
• Remarkable cycling stability over 400 cycles and improved rate capabilities were achieved.
• V doping significantly enhances lattice cohesive energy, Al³⁺ interaction, and electrical conductivity.

Conclusions:

• Heterogeneous metal doping, particularly with vanadium, effectively reinforces δ-MnO₂ structure for AAIBs.
• V-δ-MnO₂ demonstrates superior performance compared to other doped materials and reported AAIB cathodes.
• This study offers a strategy for developing high-performance cathodes for advanced battery applications.