Surface analytical approaches to reliably characterize lithium ion battery electrodes

Active Li-ion battery materials are typically characterized using X-ray photoelectron spectroscopy when regarding chemical state elucidation. This work presents a multiplet-splitting approach comprising in minimum 3 third-row transition metals, namely, Mn, Co, and Ni, to improve the results in comparison to peak barycenter or single symmetric Voigt profile approaches. The achieved X-ray photoelectron spectroscopy 2p templates in particular address the complex peak structures consisting of significant photoelectron multiplet splitting, shake-up and plasmon loss features, and additional Auger and photoelectron overlaps, inevitable also for a reliable quantification. To separate from topography effects and contributions of the electrode's binder and conductive carbon in powder electrodes, the developed procedure in a first attempt was successfully transferred to novel radio frequency magnetron sputtered Li-Ni-Co-Mn-O thin films, designed for all-solid-state Li-ion batteries. In all cases, special care was taken with respect to air sensitivity, contamination during sample handling, and probable method induced sample decomposition.