Na₂VO(HPO₄)₂: an original phase solved by continuous 3D electron diffraction and powder X-ray diffraction

Area of Science:

• Materials Science
• Solid-State Chemistry
• Crystallography

Background:

• Vanadium-based phosphates are promising cathode materials for sodium-ion batteries.
• Understanding new structural phases is crucial for developing advanced energy storage solutions.

Purpose of the Study:

• To synthesize and characterize a new sodium vanadium phosphate phase.
• To determine the crystal structure of the novel material.
• To evaluate its electrochemical properties for potential energy storage applications.

Main Methods:

• Synthesis via sodium/proton ion exchange in hexanol.
• Crystal structure determination using continuous 3D Electron Diffraction and powder X-ray diffraction.
• Electrochemical performance evaluation.

Main Results:

• A new phase, Na2VO(HPO4)2, was successfully synthesized.
• The crystal structure was solved in the orthorhombic Iba2 space group with specific cell parameters.
• Electrochemical studies demonstrated the possibility of removing up to 0.66 Na per formula unit.

Conclusions:

• The novel Na2VO(HPO4)2 phase presents a new structural framework.
• The material shows potential as a cathode material for sodium-ion batteries due to its reversible sodium extraction capability.