Enhanced Oxygen Redox Activity and Structure Stability of P2-Type Manganese-Based Cathodes Through Medium-Entropy...

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Oxygen redox reactions in manganese-based oxides offer high energy density but suffer from poor stability due to structural transitions.
• Entropy stabilization, using elemental synergy, is a promising approach to enhance structural robustness.

Purpose of the Study:

• To integrate ionic potential into medium-entropy design for element selection in manganese-based oxides.
• To enhance and stabilize high-voltage oxygen redox reactions for improved battery performance.

Main Methods:

• Developed a medium-entropy design strategy guided by ionic potential.
• Synthesized and characterized a P2-type oxide, Na0.8Li0.1Ni0.1Cu0.1Ti0.1Mn0.6O2, with dopants of low ionic potential.
• Evaluated electrochemical performance, including capacity, energy density, and cycling stability.

Main Results:

• The medium-entropy oxide achieved a high reversible capacity of 223.7 mAh g-1 and energy density of 616.3 Wh kg-1.
• Demonstrated 87% capacity retention over 200 cycles, indicating excellent long-term stability.
• Suppressed detrimental structural transitions, transition metal layer gliding, and Jahn-Teller distortions, preserving Mn redox activity and suppressing voltage decay.

Conclusions:

• The ionic potential-guided medium-entropy design strategy effectively enhances both reversible capacity and phase stabilization.
• This approach offers a practical route for developing next-generation, high-capacity, and durable sodium-ion batteries.
• The study highlights the potential of entropy stabilization for overcoming stability limitations in advanced battery materials.