Multiple Strategies to Build High-Performance Spherical Na-Ion Layered Oxide Cathodes

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Layered transition metal oxides show promise for sodium-ion batteries but suffer from poor cycle stability and complex phase transitions.
• O3-type layered oxides face challenges in practical applications.

Purpose of the Study:

• To develop a spherical high-entropy oxide (SP-HEO) material to overcome the limitations of O3-type layered oxides in sodium-ion batteries.
• To enhance electrochemical performance and air stability.

Main Methods:

• Synthesis of spherical NaNi_0.25Fe_0.15Mn_0.3Ti_0.1Sn_0.05Co_0.05Li_0.1O₂ (SP-HEO) using piling and high entropy strategies.
• Electrochemical performance testing at various rates (0.1 C and 7 C).
• Ex situ X-ray diffraction (XRD) analysis to study phase transitions.

Main Results:

• SP-HEO demonstrated a specific discharge capacity of 150.1 mA h g^-1 at 0.1 C and 100.4 mA h g^-1 at 7 C.
• Ex situ XRD confirmed that SP-HEO effectively retards complex phase transitions.
• The material exhibits enhanced electrochemical performance and air stability.

Conclusions:

• The high-entropy design provides a strategy for developing high tap density spherical storage materials.
• This work addresses industry concerns regarding the performance of sodium-ion layered oxide cathode materials.
• SP-HEO shows potential as an advanced cathode material for sodium-ion batteries.