Multiscale morphological characterization of process induced heterogeneities in blended positive electrodes for lithium–ion batteries

The 3D morphology of LiNi1/3Mn1/3Co1/3O2 (NMC), LiFePO4 (LFP), and blended NMC/LFP electrodes envisioned for electric vehicles Li–ion batteries is characterized by both synchrotron X-ray tomography and FIB/SEM tomography. The size distribution of the active materials, the carbon phase and the pores, the specific surface area of the different solid phases, the concentration variations of the various phases through the total electrode thickness (X-ray tomography) or in smaller volumes (FIB/SEM tomography) are quantified. Results are assessed in relationship with the electrode composition and with their typical slurry rheological properties. Several heterogeneities are evidenced as the fingerprint of phenomena associated with the different processing steps of the electrodes.