title: The Role of Reduced Graphite Oxide in Transition Metal Oxide Nanocomposites Used as Li Anode Material: An Operando Study on CoFe2O4/rGO.
abstract: A composite consisting of CoFe2O4spinel nanoparticles and reduced graphite oxide (rGO) is studied as an anode material during Li uptake and release by applying synchrotron operando X-ray diffraction (XRD) and operando X-ray absorption spectroscopy (XAS), yielding a comprehensive picture of the reaction mechanisms. In the early stages of Li uptake, a monoxide is formed as an intermediate phase containing Fe2+and Co2+ions; this observation is in contrast to reaction pathways proposed in the literature. In the fully discharged state, metallic Co and Fe nanoparticles are embedded in an amorphous Li2O matrix. During charge, metallic Co and Fe are oxidized simultaneously to Co2+and Fe3+, respectively, thus enabling a high and stable capacity to be achieved. Here, evidence is presented that the rGO acts as a support for the nanoparticles and prevents the particles from contact loss. The operando investigations are complemented by TEM, Raman spectroscopy, galvanostatic cycling, and cyclic voltammetry.
authors.affiliation: Institute of Inorganic Chemistry, University of Kiel, Max-Eyth-Strasse 2, 24118, Kiel, Germany.
authors.forename: Stefan
authors.initials: S
authors.lastname: Permien
authors.affiliation: Institute for Applied Materials - Energy Storage Systems, Karlsruhe Institute of Technology, P.O. Box 3640, 76021, Karlsruhe, Germany.
authors.forename: Sylvio
authors.initials: S
authors.lastname: Indris
authors.affiliation: Institute for Materials Science, University of Kiel, Kaiserstrasse 2, 24143, Kiel, Germany.
authors.forename: Gero
authors.initials: G
authors.lastname: Neubüser
authors.affiliation: Institute for Applied Materials - Energy Storage Systems, Karlsruhe Institute of Technology, P.O. Box 3640, 76021, Karlsruhe, Germany.
authors.forename: Andy
authors.initials: A
authors.lastname: Fiedler
authors.affiliation: Institute for Materials Science, University of Kiel, Kaiserstrasse 2, 24143, Kiel, Germany.
authors.forename: Lorenz
authors.initials: L
authors.lastname: Kienle
authors.affiliation: Helmholtz-Zentrum Berlin, Helmholtz-Zentrum Berlin für Materialien und Energie, Hahn-Meitner-Platz 1, 14109, Berlin, Germany.
authors.forename: Stefan
authors.initials: S
authors.lastname: Zander
authors.affiliation: ANKA Synchrotron Radiation Facility, Karlsruhe Institute of Technology, P.O. Box 3640, 76021, Karlsruhe, Germany.
authors.forename: Stephen
authors.initials: S
authors.lastname: Doyle
authors.affiliation: Institute of Inorganic Chemistry, University of Kiel, Max-Eyth-Strasse 2, 24118, Kiel, Germany.
authors.forename: Björn
authors.initials: B
authors.lastname: Richter
authors.affiliation: Institute of Inorganic Chemistry, University of Kiel, Max-Eyth-Strasse 2, 24118, Kiel, Germany.
authors.forename: Wolfgang
authors.identifier: http://orcid.org/0000-0002-3111-580X
authors.initials: W
authors.lastname: Bensch
keywords: CoFe2O4/rGO; anode; lithium ion batteries; nanoparticles; operando