Element doping-driven band regulation toward stable 4.5 V sodium-ion layered oxides

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• P2-type layered oxides are promising for sodium-ion batteries (SIBs) due to high capacity and stability.
• High operating voltages in SIBs are limited by phase transitions and oxygen release.
• Developing stable, high-voltage cathodes is crucial for advanced SIB technology.

Purpose of the Study:

• To investigate a simple, cost-efficient single-element doping strategy for P2-type layered oxide cathodes.
• To enhance the electronic and structural properties of cathode materials for high-voltage SIBs.
• To elucidate the doping mechanism and structure-activity relationship for optimized cathode design.

Main Methods:

• Single-element doping was employed to modify cathode material properties.
• Characterization techniques were used to analyze electronic structure, bonding, and structural stability.
• Electrochemical cycling was performed to evaluate performance and capacity retention.

Main Results:

• Doping shifted the oxygen p-band center and modified transition metal coordination.
• Enhanced TM-O bonding and stabilized octahedral framework suppressed Jahn-Teller distortions.
• Capacity retention improved significantly from 23.4% to 69.3% after 300 cycles at high voltage.

Conclusions:

• Single-element doping is an effective strategy to stabilize high-voltage P2-type layered oxide cathodes.
• The doping mechanism enhances structural integrity and reversibility of anionic redox reactions.
• This research provides insights for designing advanced sodium-ion battery cathodes.