@misc{SchmeisserSchmidtSeiboldetal., author = {Schmeißer, Dieter and Schmidt, Stephan and Seibold, G{\"o}tz and Cherkashinin, Gennady and Jaegermann, Wolfram}, title = {Localized Gap States in LiCoO2 and their Influence on the Transport Properties in Li-Ion Batteries}, series = {ECS Transactions}, volume = {25}, journal = {ECS Transactions}, number = {35}, issn = {1938-5862}, pages = {37 -- 45}, language = {en} } @misc{SchmidtSchmeisser, author = {Schmidt, Stephan and Schmeißer, Dieter}, title = {Electronic structure of cobalt-nickel mixed oxides}, series = {Solid State Ionics}, journal = {Solid State Ionics}, number = {225}, issn = {1872-7689}, doi = {10.1016/j.ssi.2012.06.009}, pages = {737 -- 741}, abstract = {We investigate the electronic structure of cobalt-nickel mixed oxides by means of SR-based electron spectroscopy. We vary the Co-Ni content systematically and find that the most significant changes in the spectroscopic data occur at a mixing ratio of 30/70. We analyze the electronic structure of this material in detail and we are able to distinguish between pure covalent contributions, which cause a band gap of about 6 eV and empty defect states, whichfill the band gap almost completely. These defects are associated with the formation of 3d7L charge transfer states. These are correlated defect states and are identified by resonant photo-emission spectroscopy.}, language = {en} } @inproceedings{SchmidtSchmeisser, author = {Schmidt, Stephan and Schmeißer, Dieter}, title = {Cobalt/nickel mixed oxides - cathode materials for Li-Ion-Batteries}, series = {Verhandlungen der Deutschen Physikalischen Gesellschaft, Reihe 6, Bd. 45}, booktitle = {Verhandlungen der Deutschen Physikalischen Gesellschaft, Reihe 6, Bd. 45}, publisher = {Deutsche Physikalische Gesellschaft}, address = {Bad Honnef}, issn = {0420-0195}, pages = {S. 596}, abstract = {Replacing Co by large amounts of Ni is considered to reduce costs in Li-Ion-Batteries while maintaining their performance. We are interested in whether this replacement causes changes in the valence band (VB) and conduction band (CB) states or not. Samples were prepared as thin films from nitrate solutions on metal substrates and annealed in air and UHV. The Co to Ni ratio was varied from 50/50 over 40/60 and 30/70 up to 20/80. The results are compared to the pure Co-oxide. Experiments were carried out at the U49/2 beamline at BESSYII, Berlin. XPS of the TM2p states reveals the existence of charge transfer ground states and different oxidation states. NEXAS at the Co2p, Ni2p and O1s edges projects the density of unoccupied states while resonant PES at these edges provides the related partial density of states (pDOS) and thus can be used to distinguish between the different contributions of TM3d and O2p states in the valence band region. We find systematic variation of the VB structure, the valence band maximum and a shift at the O1s absorption edge while the TM2p XPS and absorption spectra do not seem to be affected by the mixing.}, language = {en} }