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 for sodium-ion batteries (SIBs) but face challenges like phase transitions and interfacial degradation.
• Existing chemical modulation methods have limitations in addressing these issues comprehensively.

Purpose of the Study:

• To develop an integrated modification strategy for layered oxide cathodes to improve bulk, surface, and interfacial properties.
• To enhance the electrochemical performance and cycling stability of O3-NaNi1/3Fe1/3Mn1/3O2 cathodes for SIBs.

Main Methods:

• Surface reconstruction to create a Y-enriched NaYO2 (NYO) coating on O3-NaNi1/3Fe1/3Mn1/3O2.
• Inducing local oxygen vacancies (O_V) through charge balancing.
• Investigating synergistic effects of Y-O-TM bonds and O_V charge buffering.
• Utilizing theoretical calculations and advanced synchrotron characterization.

Main Results:

• The NYO coating facilitates site-selective bulk substitution and induces beneficial O_V defects.
• Synergistic interactions stabilize the electronic band structure, preventing detrimental oxygen oxidation and dimer formation.
• The perovskite NYO surface enhances Na+ transport and acts as a mechanical barrier, suppressing side reactions and metal dissolution.
• Anion redox reversibility and local chemical environment stability were significantly improved.

Conclusions:

• The integrated modification strategy offers a novel paradigm for advancing high-performance sodium-layered oxide cathodes.
• This approach simultaneously addresses bulk, surface, and interfacial degradation, leading to superior electrochemical kinetics and charge transfer efficiency.
• The study demonstrates a promising pathway for developing next-generation sodium-ion batteries.