The Role of Li-Rich Disordered Domain in Li-Rich Cathodes

Area of Science:

• Materials Science
• Electrochemistry
• Battery Technology

Background:

• Li-rich cathodes exhibit electrochemical degradation due to phase incompatibility.
• This instability arises from structural differences between Li-rich and LiTMO2-like phases.

Purpose of the Study:

• Identify and characterize the transitional Li-rich disordered (LRD) domain.
• Investigate the role of the LRD domain in electrochemical degradation.
• Develop strategies to mitigate degradation by controlling the LRD domain.

Main Methods:

• Advanced structural analyses to characterize the LRD domain.
• Synthesis tailoring to constrict the LRD domain.
• In situ high-temperature X-ray diffraction (XRD) to track domain formation.

Main Results:

• Identified the LRD domain as a bridge between Li-rich and LiTMO2-like phases.
• Observed transition metals (Ni) occupying Li sites within the LRD domain.
• Demonstrated that constricting the LRD domain mitigates structural evolution and strain.

Conclusions:

• The constricted LRD domain acts as a buffer, suppressing oxygen loss and enhancing structural integrity.
• Engineered cathodes show significant improvements in specific capacity and cycling stability.
• Controlling the LRD domain is crucial for stabilizing anionic redox in Li-rich cathodes.