Battery (electricity)

Engineering

Chemical physics

Lithium-ion battery

Electrochemistry

Metallurgy

Materials science

Cathode

Control engineering

Decoupling (probability)

Power (physics)

Chemical engineering

Physical chemistry

Strain (injury)

Redox

Thermodynamics

Physics

Nanotechnology

Optics

Degradation (telecommunications)

Electronic engineering

Synchrotron

Internal medicine

Medicine

Chemistry

Electrode

Anode

Meteorology

Nickel

Mesoscale meteorology

ACS Energy Letters

The degradation of nickel-rich cathode materials for lithium-ion batteries upon prolonged electrochemical cycling features a complicated interplay among electronic structure, lattice configuration, and micro-morphology. The underlying mechanism for such an entanglement of different material properties at nano- to mesoscales is fundamental to the battery performance but not well-understood yet. Here we investigate the correlation between the local redox reaction and lattice mismatch through a nano-resolution synchrotron spectro-microscopy study of LiNi0.8Co0.1Mn0.1O2 (NCM 811) cathode particles. With assistance from a machine-learning-based data classification method, we identify local regions that demonstrate a strain–redox decoupling effect, which can be attributed to different side reactions. Our results highlight the mesoscale reaction heterogeneity in the battery cathode and suggest that particle structure engineering could be a viable approach to mitigate the chemomechanical degradation of cathode materials.

Understanding the Mesoscale Degradation in Nickel-Rich Cathode Materials through Machine-Learning-Revealed Strain–Redox Decoupling