Reinforcing Particle Architectural Stability of Li-Rich Cathode With Enhanced Anionic Redox Reaction Reversibility

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Lithium-rich layered oxides (LRLOs) offer high energy density but face structural and chemical instabilities.
• Mesoscale architectural degradation, linked to precursor porosity, is a critical but overlooked challenge in LRLOs.
• Existing research on anionic redox reaction (ARR) reversibility primarily focuses on atomic-scale control.

Purpose of the Study:

• To introduce a cross-scale synergistic strategy for stabilizing LRLOs.
• To simultaneously reinforce mesoscale particle architecture and atomic-scale charge compensation.
• To address limitations hindering the commercialization of high-energy-density batteries.

Main Methods:

• Incorporation of fluorine to modulate the local electronic environment and surface energy of active facets.
• Inducing morphological transformation of primary particles from plate-like to equiaxed.
• Achieving thermodynamic reconstruction to create compact secondary particles and disrupt precursor-inherited porosity.

Main Results:

• Fluorine incorporation led to equiaxed primary particles and compact secondary particles, enhancing Li+ diffusion kinetics.
• Strengthened transition metal-oxygen (TM-O) covalency suppressed oxygen activation, improving ARR reversibility.
• The modified cathode showed a 6.8% increase in Coulombic efficiency and 88.8% capacity retention after 950 cycles.

Conclusions:

• The synergistic strategy effectively enhances both mesoscale architecture and atomic-scale chemical stability in LRLOs.
• This approach significantly improves the cycling stability and Coulombic efficiency of LRLO cathodes.
• Demonstrated exceptional long-term stability in Ah-level full cells, retaining 96.3% capacity after 1500 cycles at high voltage.