High Configurational Entropy Engineered Hollow Microspheres Layered Mn-Based Cathode Enabling Stress Self-Dissipation...

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• High-voltage P2-type Mn-based layered oxides are promising for sodium-ion batteries (SIBs).
• Practical application is hindered by irreversible oxygen redox reactions, Jahn-Teller distortion, and microcracking.

Purpose of the Study:

• To develop a novel cathode material for SIBs that overcomes limitations of current Mn-based oxides.
• To enhance the stability and performance of SIBs across a wide temperature range.

Main Methods:

• Fabrication of high configurational entropy engineered hollow microspheres (HEHM-NMO) with a specific composition (Na0.67Li0.18Co0.08Mn0.71Mg0.13Cu0.08O2).
• Investigation of the material's structural, electronic, and electrochemical properties using advanced characterization techniques.
• Evaluation of cycling stability, Coulombic efficiency, and wide-temperature performance (-10-60 °C).

Main Results:

• HEHM-NMO exhibits enhanced electronic structure disorder and optimized orbital hybridization, enabling reversible oxygen redox (O2-/On-).
• The hollow microsphere structure facilitates spontaneous stress dissipation during cycling.
• Achieved ultrahigh initial charge capacity (171.7 mAh g-1 at 1.5-4.5 V) with high initial Coulombic efficiency (92.9%).
• Demonstrated excellent cycling stability (85.8% retention after 300 cycles at 2C) and wide-temperature workability (152.0 mAh g-1 at -10 °C, 192.7 mAh g-1 at 60 °C).

Conclusions:

• High configurational entropy and hollow microsphere engineering are effective strategies for developing stable and high-performance cathode materials for SIBs.
• The HEHM-NMO material shows significant potential for practical SIB applications due to its reversible oxygen redox and wide-temperature operability.
• This study provides insights into entropy-dominant regulation for activating reversible oxygen redox in layered oxide cathodes.