New insights into aging in LiNiO₂ cathodes from high resolution paramagnetic NMR spectroscopy

Area of Science:

• Materials Science
• Electrochemistry
• Solid-State Chemistry

Background:

• Lithium nickel oxide (LiNiO2) is a key cathode material for high-energy density batteries.
• Understanding degradation mechanisms is crucial for improving battery performance and lifespan.
• Bulk degradation processes in LiNiO2 cathodes remain incompletely understood.

Purpose of the Study:

• To investigate the bulk degradation processes in LiNiO2 cathodes.
• To correlate capacity decay with the emergence of bulk heterogeneity.
• To elucidate the nature of coexisting structural domains in the charged state.

Main Methods:

• High-resolution solid-state Nuclear Magnetic Resonance (NMR) spectroscopy.
• Magnetometry.
• X-ray Diffraction (XRD).

Main Results:

• Capacity decay in LiNiO2 cathodes is directly correlated with bulk heterogeneity.
• Multiple distinct structural domains coexist within the cathode material in the charged state.
• The lithium (Li) content and electrochemical activity of these individual domains were successfully unraveled.

Conclusions:

• Bulk heterogeneity, characterized by coexisting structural domains, is a primary driver of degradation in LiNiO2 cathodes.
• This study provides the first detailed characterization of the Li content and electrochemical activity within these domains.
• These findings offer critical insights for designing more stable and durable LiNiO2-based cathode materials.