Bonding Engineering by Al/Ti Codoping for High-Rate Capability and Cycling Stability of NaNi_1/3Fe_1/3Mn_1/3O₂

Area of Science:

• Materials Science
• Electrochemistry
• Solid-State Chemistry

Background:

• O3-type NaNi_1/3Fe_1/3Mn_1/3O₂ (NFM) shows potential as a cathode for sodium-ion batteries (SIBs) due to its high capacity and low cost.
• Practical use is limited by irreversible phase transitions and slow sodium-ion (Na⁺) transport.

Purpose of the Study:

• To enhance the high-rate capability and cycling stability of NFM cathodes.
• To investigate the effects of Al/Ti codoping on the structural and electrochemical properties of NFM.

Main Methods:

• Employing a bonding engineering strategy through Al/Ti codoping.
• Synthesizing Na(Ni_1/3Fe_1/3Mn_1/3)_0.94Al_0.03Ti_0.03O₂ cathode material.
• Evaluating electrochemical performance, including rate capability and cycling stability.

Main Results:

• Al doping alleviates the Jahn-Teller effect, while Ti doping mitigates phase transition stress.
• Stronger Al-O and Ti-O bonds stabilize the framework, reduce oxygen release, and expand interlayer spacing.
• The codoped material achieved a high-rate capacity of 102.42 mAh g^-1 at 10 C with improved cycling stability.

Conclusions:

• Synergistic Al/Ti codoping effectively enhances the performance of O3-type NFM cathodes for SIBs.
• Targeted bond strengthening is crucial for developing advanced layered oxide cathode materials.
• This approach offers a promising route for high-performance sodium-ion battery development.