High-Performance B-Doped Na_0.44MnO₂ Cathode Materials for Sodium-Ion Batteries

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Sodium-ion batteries (SIBs) are a promising alternative to lithium-ion batteries.
• Na0.44MnO2 (NMO) exhibits a unique tunnel structure suitable for sodium storage.
• Improving the stability and performance of SIB cathode materials is crucial for their commercialization.

Purpose of the Study:

• To investigate the effect of boron (B) doping on the electrochemical properties and stability of Na0.44MnO2.
• To synthesize and characterize the boron-doped cathode material Na0.44Mn0.98B0.02O2 (NMOB0.02).
• To evaluate the potential of NMOB0.02 as an improved cathode for sodium-ion batteries.

Main Methods:

• Synthesis of boron-doped Na0.44MnO2.
• Electrochemical performance testing including capacity retention and cycling stability at various rates and temperatures.
• Electrochemical impedance spectra (EIS) and Galvanostatic Intermittent Titration Technique (GITT) for analyzing ion diffusion.
• In situ X-ray diffraction (XRD) to study structural reversibility during cycling.

Main Results:

• Boron doping significantly enhances the electrochemical stability and air stability of the NMO cathode.
• The NMOB0.02 material delivers an initial reversible specific capacity of 100.5 mAh g-1 at 0.2 C.
• Capacity retention improved from 69.8% to 86.8% after 350 cycles at 1 C (room temperature) and from 63.6% to 88.9% after 100 cycles at 1 C (50 °C).
• Boron doping promotes Na+ diffusion and maintains structural integrity during charge/discharge cycles.

Conclusions:

• Optimal boron doping is an effective strategy to enhance the performance and stability of Na0.44MnO2 cathodes for SIBs.
• NMOB0.02 demonstrates excellent cycling stability and improved sodium-ion kinetics.
• This research offers valuable insights for designing high-performance, thermally stable cathode materials for next-generation sodium-ion batteries.