Li/Ti Dual-Doping Synergy Enabling Stable High-Voltage O3-Type Layered Oxide Sodium-Ion Batteries Cathode

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• O3-type layered oxides are crucial for high-energy-density sodium-ion batteries (SIBs).
• These materials suffer from capacity fading due to phase transitions, oxygen loss, and interface degradation at high voltages (>4.0 V).

Purpose of the Study:

• To enhance the structural stability and electrochemical performance of O3-type layered oxides for SIBs.
• To investigate the effect of Li+/Ti4+ dual doping on the properties of Na0.9Ni0.22Fe0.3Mn0.48O2 (NFM).

Main Methods:

• Synthesis of dual-doped Na0.9Ni0.22Li0.1Fe0.2Ti0.1Mn0.38O2 (NLFTM) material.
• Electrochemical characterization including cyclic voltammetry, galvanostatic intermittent titration technique (GITT), and electrochemical impedance spectroscopy (EIS).
• Ex situ X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) analyses to study structural and chemical changes.

Main Results:

• The NLFTM material delivered a reversible capacity of 180.7 mAh/g at 0.1 C and maintained 91.1 mAh/g at 10 C.
• NLFTM retained 83% of its capacity after 100 cycles at 1 C, significantly outperforming pristine NFM (56.6%).
• Dual doping improved the reversibility of O3↔P3 phase transitions, inhibited oxygen loss, and enhanced Na+ diffusion kinetics.

Conclusions:

• Li+/Ti4+ dual doping effectively stabilizes the O3-type layered oxide structure for high-voltage sodium-ion battery applications.
• The enhanced structural integrity and ion kinetics lead to superior specific capacity, rate capability, and cycling stability.
• This dual-doping strategy offers a promising approach to overcome the limitations of traditional O3-type oxides in SIBs.