High-Valence Surface-Modified LMO Cathode Materials for Lithium-Ion Batteries: Diffusion Kinetics and Operando...

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Lithium manganese oxide (LiMn2O4, LMO) is a cost-effective cathode material for lithium-ion batteries.
• LMO suffers from capacity fade, low energy density, and auto-discharge, limiting commercialization.
• Surface modification and doping are key strategies to enhance LMO performance.

Purpose of the Study:

• To synthesize and evaluate surface-modified LMO using high-valence tungsten oxide (WO3).
• To investigate the impact of WO3 surface modification on LMO's electrochemical performance and thermal stability.
• To explore the potential of WO3-modified LMO for safe, high-voltage lithium-ion batteries.

Main Methods:

• Synthesis of WO3-modified LiMn2O4 (LMO) with varying WO3 content.
• Galvanostatic charge-discharge cycling to assess rate capability.
• Cyclic voltammetry to determine ion diffusion coefficients.
• In situ Raman spectroscopy and operando accelerating rate calorimetry (ARC) for mechanism and safety analysis.

Main Results:

• 0.5%WO3-LMO demonstrated superior rate capability, retaining 51% capacity at 20C versus 34% for pristine LMO.
• WO3 modification improved ion diffusion in LMO, with coefficients of ~10^-11 cm^2·s^-1 compared to ~10^-13 cm^2·s^-1 for pristine LMO.
• Operando ARC confirmed enhanced thermal stability of the surface-modified LMO.

Conclusions:

• Surface modification with 0.5 wt% WO3 effectively enhances the electrochemical performance and cycling stability of LiMn2O4.
• The improved ion diffusion and thermal stability highlight the potential of WO3-LMO for advanced lithium-ion battery applications.
• This approach offers a promising route for developing safer, high-performance LMO cathodes for automotive applications.