A High-Entropy Engineering on Sustainable Anionic Redox Mn-Based Cathode with Retardant Stress for High-Rate...

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Manganese-based layered oxides are promising cathode materials for sodium-ion batteries (SIBs) due to their high energy density and cost-effectiveness.
• However, SIBs using these cathodes face challenges like irreversible oxygen redox reactions, phase transitions, and microcracking, leading to performance degradation.
• Developing strategies to enhance structural integrity and electrochemical stability is crucial for advancing SIB technology.

Purpose of the Study:

• To introduce a high-entropy engineering strategy for P2-type Mn-based layered oxide cathodes (HE-NMCO).
• To investigate the impact of this strategy on lattice framework stability, oxygen redox activity, and sodium-ion transport kinetics.
• To evaluate the electrochemical performance, particularly cycling stability and rate capability, of the engineered HE-NMCO cathodes.

Main Methods:

• High-entropy engineering applied to P2-type Mn-based layered oxide cathodes.
• Multimodal characterization techniques to analyze structural integrity, elemental interactions, and redox behavior.
• Electrochemical testing including deep (de)sodiation cycling and rate capability measurements.

Main Results:

• The high-entropy strategy (HE-NMCO) created a robust lattice framework with optimized elemental interactions, mitigating stress and preventing fractures.
• HE-NMCO demonstrated sustainable reversible oxygen activity and accelerated Na+ transport kinetics.
• Remarkable cycling stability was achieved, retaining 93.5% capacity after 100 cycles, with an enhanced rate capability of 134.1 mAh g-1 at 5C.
• Comparative studies confirmed superior reversibility of oxygen anion redox (OAR) reactions in HE-NMCO compared to conventional NMCO.

Conclusions:

• High-entropy engineering is an effective strategy for stabilizing Mn-based layered oxide cathodes in SIBs.
• This approach enhances structural integrity, promotes reversible oxygen redox reactions, and improves Na+ kinetics.
• The developed HE-NMCO cathodes show significant potential for high energy and power density applications in next-generation SIBs.