A Rational Biphasic Tailoring Strategy Enabling High-Performance Layered Cathodes for Sodium-Ion Batteries

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Layered oxide cathodes offer tunable electrochemical performance for sodium-ion batteries due to compositional diversity.
• Complex structural chemistry in these materials impacts ion kinetics, phase transitions, and stacking preferences.

Purpose of the Study:

• To explore the stable phase diagram of P2/O3 composites using a biphasic tailoring strategy.
• To investigate the electrochemical behavior and structural evolution of a specific P2/O3 composite compared to monophasic systems.

Main Methods:

• Thermodynamic phase diagram analysis of P2/O3 composites.
• Electrochemical cycling and structural characterization of a biphasic P2/O3 cathode material.
• Comparison with monophasic P2 and O3 counterparts.

Main Results:

• A specific P2/O3 composite exhibited a highly reversible structural evolution during sodium ion cycling.
• Reduced structural strain at the phase boundary minimized phase transitions and lattice mismatch.
• The biphasic electrode achieved a large reversible capacity of 144 mAh g⁻¹ and an energy density of 514 Wh kg⁻¹.

Conclusions:

• Biphasic tailoring is an effective strategy for designing stable layered oxide cathodes for sodium-ion batteries.
• Optimized P2/O3 composites demonstrate superior electrochemical performance and structural integrity.
• This approach offers a pathway to high-energy-density sodium-ion battery systems.