Slight Multielement Doping-Induced Structural Order-Disorder Transition for High-Performance Layered Na-Ion Oxide...

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• O3-type layered oxides are critical for sodium-ion batteries due to their high energy density potential.
• The Ni2+/Ni4+ redox couple offers multielectron reactions but suffers from Jahn-Teller distortion, leading to structural instability and capacity fade.
• Minimizing detrimental phase transitions and structural degradation is key to achieving high-performance sodium-ion battery cathodes.

Purpose of the Study:

• To develop a multielement doping strategy for O3-type layered oxide cathodes to enhance electrochemical performance and structural stability.
• To investigate how uniform distribution of multiple dopants can alleviate structural changes and anisotropy cracks.
• To demonstrate the efficacy of this doping approach using a specific multielement-doped oxide composition.

Main Methods:

• Rational design and synthesis of a multielement-doped O3-type oxide: Na0.9Ni0.25Cu0.05Mg0.05Zn0.05Fe0.05Al0.05Mn0.40Ti0.05Sn0.05O2.
• Electrochemical characterization including cycling stability, rate capability, and voltage profiling.
• Analysis of structural changes and chemo-mechanical stability under electrochemical cycling.

Main Results:

• The multielement-doped cathode exhibits improved chemo-mechanical stability and delayed O3-P3 phase transition.
• Compared to a high Ni-content cathode, the doped material delivers a reversible capacity of 120 mAh/g (2-4.0 V).
• Achieved superior cycling stability with 90% capacity retention after 500 cycles and excellent rate capability (>70% capacity at 5.0 C).

Conclusions:

• Multielement doping is an effective strategy to enhance the performance of O3-type layered oxide cathodes for sodium-ion batteries.
• The proposed doping method successfully mitigates structural degradation and anisotropy cracks, improving cycling stability and energy density.
• This approach holds significant promise for the development of advanced sodium-ion battery materials.