3D analysis of a LiCoO_2-Li(Ni_(1/3)Mn_(1/3)Co_(1/3))O_2 Li-ion battery positive electrode using x-ray nano-tomography

A full-field high-resolution x-ray nano-tomography technique, transmission x-ray microscopy (TXM), was used to reveal the 3D morphology of the lithium ion battery composite positive electrode: LiCoO_2 (LCO)-Li(Ni_(1/3)Mn_(1/3)Co_(1/3))O_2 (NMC). The TXM method allowed the unambiguous chemical identification of oxide particles by tuning the x-ray energy relative to the transition-metal absorption edges. The NMC particles have a much rougher surface compared to the LCO particles. Cracks due to processing exist in both LCO and NMC particles but the NMC particles exhibit more severe cracking and also tend to have internal pores in addition to radial cracks. Further, the carbon-based phases including the binder and the conductive carbon were identified using Zernike phase contrast imaging.