Kinetically Dormant Ni-Rich Layered Cathode During High-Voltage Operation

Area of Science:

• Materials Science
• Electrochemistry
• Battery Technology

Background:

• Nickel-rich cathodes are crucial for high-energy density batteries but degrade during high-voltage operation.
• Quantifying capacity loss contributions (thermodynamic vs. kinetic) in these cathodes is challenging.

Purpose of the Study:

• To precisely deconvolute irreversible and reversible capacity loss in a LiNi0.83Mn0.1Co0.07O2 cathode.
• To elucidate the degradation mechanisms of high-voltage cathodes during long-term cycling.

Main Methods:

• Multiscale synchrotron X-ray probes
• Electron microscopy
• Post-galvanostatic intermittent titration technique (GIT)
• Full cell configuration analysis

Main Results:

• Layered structure remains intact after 1000 cycles at 4.6 V, despite a three-order magnitude decrease in mass transfer kinetics.
• Capacity loss is largely recoverable under kinetic-free conditions, indicating kinetic dormancy.
• Degradation is linked to lattice strain evolution and structural heterogeneity (layered vs. rock-salt phases).

Conclusions:

• The structural integrity of Ni-rich cathodes is maintained at high voltage, but kinetic limitations dominate capacity fade.
• Lattice strain and phase heterogeneity are critical factors in high-voltage cathode degradation.
• These insights are vital for designing next-generation batteries with enhanced cycling stability and charging rates.