Interlayer-Surface Synergistic Regulation in High-Entropy O3-Type Layered Oxides Toward Structurally Robust and...

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• O3-type layered transition metal oxides are promising for sodium-ion batteries due to high energy density and Na+ storage capacity.
• However, these materials face challenges including complex phase transitions and poor air stability, limiting their practical application.

Purpose of the Study:

• To design a high-entropy layered cathode with improved structural and air stability for sodium-ion batteries.
• To investigate the effects of cation-anion co-doping and elemental tuning on material properties.

Main Methods:

• Synthesized a high-entropy layered cathode NaNi0.3Mn0.3Fe0.2Ti0.1Cu0.06Mg0.04O1.95F0.05 via cation-anion co-doping.
• Incorporated Ti and Mg to enhance lattice rigidity and alleviate strain.
• Utilized F doping to suppress Jahn-Teller distortion and regulate interlayer structure and surface chemistry.

Main Results:

• The developed cathode exhibits enhanced structural stability, mitigating multistage phase transitions.
• Improved air stability was achieved, with 88.6% capacity retained after 30 days of air exposure.
• Demonstrated high reversible capacity (130.8 mAh g-1 at 0.1 C), excellent cycling stability (85% capacity retention after 500 cycles at 2 C), and high rate capability (83 mAh g-1 at 10 C).
• A full cell achieved an energy density of 257.6 Wh kg-1 with a hard carbon anode.

Conclusions:

• The high-entropy design strategy effectively enhances the structural and air stability of O3-type layered cathodes.
• Synergistic cation and anion regulation is crucial for mitigating phase transitions and improving electrochemical performance.
• This approach offers a promising pathway for developing next-generation sodium-ion battery cathodes.