Quasi in situ XPS investigations on intercalation mechanisms in Li-ion battery materials

New concepts for Li-ion batteries are of growing interest for high-performance applications. One aim is the search for new electrode materials with superior properties and their detailed characterization. We demonstrate the application of X-ray photoelectron spectroscopy (XPS) to investigate electrode materials (LiCoO(2), LiCrMnO(4)) during electrochemical cycling. The optimization of a quasi in situ analysis, by transferring the samples with a transport chamber from the glove box to the XPS chamber, and the reliability of the experiments performed are shown. The behavior of characteristic chemical species at the electrodes and the changes in oxidation states of LiCrMnO(4) during cycling is discussed. The formation of Cr(6+) is suspected as a possible reason for irreversible capacity loss during charging up to complete Li deintercalation (approximately 5.2 V).