Hierarchical Surface-to-Bulk Architecture for High-Performance O3-Type Sodium Cathodes

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• O3-type layered oxide cathodes face challenges with surface instability and slow sodium-ion (Na+) transport.
• These issues are worsened by humid air and fast charging, causing degradation and capacity loss.

Purpose of the Study:

• To develop a strategy for improving the stability and Na+ transport in O3-type layered oxide cathodes.
• To enhance the fast-charging performance and cycle life of sodium-ion batteries.

Main Methods:

• A mild ethylene-glycol-assisted treatment was used to modify NaNi1/3Fe1/3Mn1/3O2 (NFM) particles.
• This treatment created a hierarchical surface-to-bulk architecture with a rock-salt layer and Na-vacancy gradient.

Main Results:

• The modified NFM exhibited a stable surface and improved Na+ percolation pathways.
• The material showed enhanced fast-charging capability (107.6 mAh g-1 at 5C) and 81.6% capacity retention after 400 cycles.

Conclusions:

• Gradient interphase engineering and Na-vacancy control are effective for high-performance layered oxide cathodes.
• This approach offers a promising route for developing advanced sodium-ion batteries.