Qian et al, ACS Energy Lett. 2021 - EXAFS Data

Understanding the mesoscale degradation in nickel-rich cathode materials through machine-learning-revealed strain-redox decouplingThe 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 meso- scales 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 result highlights the mesoscale reaction heterogeneity in the battery cathode and suggests that the particle structure engineering could be a viable approach to mitigate the chemomechanical degradation of cathode materials.