%0 Journal Article
%A Jakes, Peter
%A Kröll, Leonard
%A Ozarowski, Andrew
%A Tol, Johan van
%A Mikhailova, Daria
%A Ehrenberg, Helmut
%A Eichel, Rüdiger-A.
%T Coordination of the Mn$^{4+}$-Center in Layered Li[Co$_{0.98}$Mn$_{0.02}$]O$_{2}$ Cathode Materials for Lithium-Ion Batteries
%J Zeitschrift für physikalische Chemie
%V 231
%N 4
%@ 2196-7156
%C Berlin
%I De Gruyter
%M FZJ-2017-02879
%P 905-922
%D 2017
%X The local coordination of the manganese in Li[Co0.98Mn0.02]O2 cathode materials for lithium-ion batteries has been investigated by means of a joint XRD and multi-frequency electron paramagnetic resonance (EPR) characterization approach. EPR showed the manganese being in a tetravalent high-spin Mn4+-oxidation state with S=32. The set of spin-Hamiltonian parameters obtained from the multi-frequency EPR analysis with Larmor frequencies ranging between 9.4 and 406 GHz is transformed into structural information by means of the recently introduced Monte-Carlo Newman-superposition modeling. Based on this analysis, the Mn4+ are shown being incorporated for the Co3+-sites, i.e. acting as donor-type functional centers Mn∙Co. In that respect, for Mn4+ the negative sign of the axial second-order fine-structure interaction parameter B02 is indicative of an elongated oxygen octahedron in its first coordination sphere, whereas B02>0 rather points to a compressed octahedron coordinated about the Mn4+-centers. Furthermore, the results obtained here suggest that the oxygen octahedron about the Mn4+-ion is slightly distorted as compared to the CoO6 octahedron. Concerning the coordination to next-nearest neighbor ions, part of the manganese resides in manganese-rich domains, whereas the for the remaining centers the Co3+-site is randomly occupied with Co/Mn according to the effective stoichiometry of the compound. Finally, a structural stability range emerges from the Newman-modeling that supports the discussed ability of manganese to act as an structure-stabilizing element in layered oxides.
%F PUB:(DE-HGF)16
%9 Journal Article
%U <Go to ISI:>//WOS:000394164200013
%R 10.1515/zpch-2016-0909
%U https://juser.fz-juelich.de/record/829066