Data-Driven Site Occupancy Statistics in Cubic Prussian Blue

Area of Science:

• Materials Science
• Electrochemistry
• Computational Chemistry

Background:

• Sodium-ion batteries are a sustainable alternative to lithium-ion technology.
• Prussian blue compounds are promising cathode materials due to structural stability and ion diffusion.
• Atomistic details of Prussian blue structural changes during cycling are not fully understood.

Purpose of the Study:

• To determine stable sodium configurations in Prussian blue.
• To derive reliable site occupancy statistics for sodium ions.
• To explore the complete configurational space of cubic Prussian blue.

Main Methods:

• Periodic density functional theory (DFT) calculations.
• Construction of the complete convex hull for the cubic Prussian blue system.
• Exploration of all 24d sites within the structure.

Main Results:

• Identification of a new, more stable sodium arrangement in fully sodiated cubic Prussian blue.
• Discovery of a single stable intermediate sodium concentration (x=1) via convex hull analysis.
• Comparative analysis showing consistency between cubic and rhombohedral phases during transitions.

Conclusions:

• The identified sodium configurations are essential for accurate atomistic modeling of Prussian blue.
• Prussian blue compounds exhibit significant potential as cathode materials for sodium-ion batteries.
• The study provides critical insights into the complex sodium ordering within Prussian blue structures.