Air-Stable Prussian White Cathode Materials for Sodium-Ion Batteries Enabled by ZnO Surface Modification

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Iron-based Prussian white (PW) is a promising cathode material for sodium-ion batteries due to its high capacity and low cost.
• Poor air stability of PW hinders its practical application.
• Conventional metal-oxide coating methods can damage PW's structure due to sodium leaching and high-temperature decomposition.

Purpose of the Study:

• To develop a facile method for improving the air stability of iron-based Prussian white (PW) cathodes.
• To investigate the effectiveness of a ZnO surface layer in enhancing PW's stability and electrochemical performance.
• To establish a stable interface for PW cathodes through surface modification.

Main Methods:

• Constructed a ZnO surface layer on PW using ethanol as a solvent and a mild post-treatment temperature.
• Coated PW with 5 wt % ZnO (PW-5 wt % ZnO-E).
• Tested the air stability and cycling performance of coated and uncoated PW (PW-E) cathodes.

Main Results:

• The ZnO coating significantly enhanced the air stability of PW, with PW-5 wt % ZnO-E retaining 94.1% capacity after 200 cycles at 1 C, compared to 54% for PW-E.
• The ZnO layer induced the formation of a stable interface on the PW cathode.
• The facile coating method avoided structural damage associated with conventional techniques.

Conclusions:

• A ZnO surface layer effectively improves the air stability and electrochemical performance of iron-based Prussian white cathodes.
• The proposed facile coating method using ethanol and mild temperatures is suitable for sensitive electrode materials like PW.
• This work provides a foundation for the practical application of Prussian white in sodium-ion batteries.