Electrochemical Property-Structure Correlation for Ni-Based Layered Na-Ion Cathodes

Area of Science:

• Materials Science
• Electrochemistry
• Solid-State Chemistry

Background:

• Nickel-based layered oxides are promising cathode materials for sodium-ion batteries.
• Tuning the crystal structure and phase composition is crucial for optimizing electrochemical performance.

Purpose of the Study:

• To synthesize and characterize Ni-based layered NaₓNi₀.₅Mn₀.₃Co₀.₂O₂ oxide composites.
• To investigate the effect of Na content and annealing temperature on phase formation.
• To evaluate the electrochemical performance and structural stability of different phases.

Main Methods:

• Solid-state synthesis process.
• Structural and chemical characterization (e.g., XRD, elemental analysis).
• Electrochemical testing (specific capacity, rate capability, cycling stability).

Main Results:

• Mixed P-, O-, and P-/O-type phases were obtained by controlling synthesis parameters.
• A triphase P2/P'3/O'3 composite demonstrated superior electrochemical properties.
• The triphase composite delivered 126 mA h g⁻¹ capacity, high rate capability (72% at 5 C), and good cycling stability (100 cycles at 0.5 C).

Conclusions:

• The phase composition significantly influences the electrochemical performance of Ni-rich layered oxides.
• The triphase P2/P'3/O'3 composite represents a promising cathode material for sodium-ion batteries.
• Understanding structural transitions is key to designing high-performance materials.