Surface Reconstruction-Integrated Bulk Defect Engineering Beyond Conventional Chemical Modulation for Na-Layered...

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Layered oxides are promising cathode materials for sodium-ion batteries (SIBs).
• However, they face challenges like phase transitions, oxygen loss, and interfacial degradation during cycling.
• Existing modification strategies often fall short in addressing these multifaceted issues simultaneously.

Purpose of the Study:

• To develop an integrated modification strategy for O3-NaNi1/3Fe1/3Mn1/3O2 layered oxide cathodes.
• To simultaneously improve bulk, surface, and interfacial properties for enhanced SIB performance.
• To establish a novel approach for advancing high-performance sodium-ion battery cathodes.

Main Methods:

• Surface reconstruction to create a Y-enriched NaYO2 (NYO) coating.
• Inducing local oxygen vacancy (OV) defects via charge balancing.
• Utilizing theoretical calculations and advanced synchrotron characterization.
• Investigating synergistic effects between Y-O-TM bonds and OV charge buffering.

Main Results:

• The NYO coating facilitates site-selective bulk substitution and induces beneficial OV defects.
• Synergistic interactions modulate electronic band structure, preventing detrimental oxygen oxidation and dimer formation.
• The perovskite NYO surface acts as a fast Na+ conductor and a mechanical barrier, suppressing side reactions and metal dissolution.
• Anion redox reversibility and local chemical environment stability are significantly enhanced.

Conclusions:

• The integrated modification strategy effectively addresses bulk, surface, and interfacial degradation in layered oxide cathodes.
• This approach leads to improved electrochemical kinetics and charge transfer efficiency in SIBs.
• The study presents a new paradigm for designing high-performance sodium-ion battery cathode materials.