Dual Role of Niobium(V) for Stabilizing High-Nickel Cathode Active Materials: Microstructural Control and Doping

Area of Science:

• Materials Science
• Electrochemistry
• Battery Technology

Background:

• High-nickel layered oxides are promising cathode materials for lithium-ion batteries (LIBs) due to their high energy density.
• Limited cycling stability hinders the commercial adoption of these advanced LIB cathodes.
• Niobium (Nb) doping is a known strategy to improve cathode stability, but current methods are difficult to scale.

Purpose of the Study:

• To develop a scalable, dry process for homogeneous niobium doping in high-nickel layered oxide cathodes.
• To investigate the impact of ultrafine niobium oxide nanoparticles on cathode microstructure and electrochemical performance.
• To elucidate the mechanisms by which niobium doping enhances cycling stability and rate capability.

Main Methods:

• Synthesis of ultrafine niobium pentoxide (Nb2O5) nanoparticles via flame spray pyrolysis.
• Development of a dry process to dope Li1Ni0.83Mn0.05Co0.12O2 precursor with Nb2O5 nanoparticles.
• Electrochemical testing (half-cell and full-cell cycling) and multiscale structural/chemical analysis.

Main Results:

• Achieved homogeneous Nb5+ doping into Li1Ni0.83Mn0.05Co0.12O2 using only 0.5 mol.% Nb5+.
• Demonstrated significantly improved electrochemical performance: high capacity (211 mAh g-1), excellent capacity retention (97% after 100 cycles in half-cell), and enhanced long-term cyclability (83% over 500 cycles in full-cell).
• Identified that Nb5+ addition modifies grain morphology, mitigating intergranular cracking and suppressing surface reconstruction for stable grain boundaries.

Conclusions:

• The dry process using ultrafine Nb2O5 nanoparticles is an effective and scalable method for homogeneous niobium doping.
• Homogeneous Nb5+ doping significantly enhances the structural integrity and electrochemical stability of high-nickel layered oxide cathodes.
• This approach provides a promising strategy for developing next-generation LIBs with improved cycle life and performance.