Hollow Layered Iron-Based Prussian Blue Cathode with Reduced Defects for High-Performance Sodium-Ion Batteries.

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Iron-based Prussian blue (Fe-PB) analogues are promising cathode materials for sodium-ion batteries due to their low cost and high capacity.
• Practical application is limited by [Fe(CN)6] defects, which reduce capacity and cycle stability.
• Existing hydrothermal synthesis methods often suffer from low product yield.

Purpose of the Study:

• To develop a defect-minimized, hollow layered Fe-PB composite material for enhanced sodium-ion battery performance.
• To improve the synthesis yield of Fe-PB using a hydrothermal method.
• To investigate the impact of a hollow layered structure on sodium ion diffusion and electrochemical stability.

Main Methods:

• Hydrothermal synthesis of hollow layered Fe-PB using 1,3,5-benzenetricarboxylic acid (BTA) as a chelating and etching agent.
• Characterization of the material's structure, defects, and electrochemical properties.
• Fabrication and testing of sodium-ion battery cells using the synthesized Fe-PB as a cathode.

Main Results:

• The BTA-assisted method significantly reduced defects and increased Fe-PB yield compared to benzoic acid.
• The hollow layered structure facilitated faster sodium ion diffusion and mitigated volume changes during cycling.
• The Fe-PB cathode demonstrated an initial capacity of 95.9 mAh g-1 at 1 A g-1, retaining 73.1 mAh g-1 after 500 cycles with a low decay rate (0.048%).
• A full cell achieved an energy density of 312.2 Wh kg-1 at a power density of 291.0 W kg-1.

Conclusions:

• The hollow layered Fe-PB synthesized using BTA offers superior sodium storage performance and stability.
• This approach effectively addresses the defect and yield limitations of traditional Fe-PB synthesis.
• The findings provide valuable insights for developing high-performance Prussian blue cathode materials for sodium-ion batteries.