title: Wet Nanoindentation of the Solid Electrolyte Interphase on Thin Film Si Electrodes.
abstract: The solid electrolyte interphase (SEI) film formed at the surface of negative electrodes strongly affects the performance of a Li-ion battery. The mechanical properties of the SEI are of special importance for Si electrodes due to the large volumetric changes of Si upon (de)insertion of Li ions. This manuscript reports the careful determination of the Young's modulus of the SEI formed on a sputtered Si electrode using wet atomic force microscopy (AFM)-nanoindentation. Several key parameters in the determination of the Young's modulus are considered and discussed, e.g., wetness and roughness-thickness ratio of the film and the shape of a nanoindenter. The values of the Young's modulus were determined to be 0.5-10 MPa under the investigated conditions which are in the lower range of those previously reported, i.e., 1 MPa to 10 GPa, pointing out the importance of the conditions of its determination. After multiple electrochemical cycles, the polymeric deposits formed on the surface of the SEI are revealed, by force-volume mapping in liquid using colloidal probes, to extend up to 300 nm into bulk solution.
authors.affiliation: Analytical Chemistry - Center for Electrochemical Sciences (CES), Ruhr-University Bochum , Universitätsstraße 150, 44780 Bochum, Germany.
authors.forename: Volodymyr
authors.initials: V
authors.lastname: Kuznetsov
authors.affiliation: Institute for Materials, Ruhr-University Bochum , Universitätsstraße 150, 44801 Bochum, Germany.
authors.forename: Arndt-Hendrik
authors.initials: AH
authors.lastname: Zinn
authors.affiliation: Analytical Chemistry - Center for Electrochemical Sciences (CES), Ruhr-University Bochum , Universitätsstraße 150, 44780 Bochum, Germany.|Semiconductor & Energy Conversion - Center for Electrochemical Sciences (CES), Ruhr-Universität Bochum , 44780 Bochum, Germany.
authors.forename: Giorgia
authors.initials: G
authors.lastname: Zampardi
authors.affiliation: Institute for Materials, Ruhr-University Bochum , Universitätsstraße 150, 44801 Bochum, Germany.
authors.forename: Sara
authors.initials: S
authors.lastname: Borhani-Haghighi
authors.affiliation: Semiconductor & Energy Conversion - Center for Electrochemical Sciences (CES), Ruhr-Universität Bochum , 44780 Bochum, Germany.|Energiespeicher- und Energiewandlersysteme, Universität Bremen , Wiener Str. 12, 28359 Bremen, Germany.
authors.forename: Fabio
authors.initials: F
authors.lastname: La Mantia
authors.affiliation: Institute for Materials, Ruhr-University Bochum , Universitätsstraße 150, 44801 Bochum, Germany.|Materials Research Department, Ruhr-Universität Bochum , Universitätsstr.150, 44780 Bochum, Germany.
authors.forename: Alfred
authors.initials: A
authors.lastname: Ludwig
authors.affiliation: Analytical Chemistry - Center for Electrochemical Sciences (CES), Ruhr-University Bochum , Universitätsstraße 150, 44780 Bochum, Germany.|Materials Research Department, Ruhr-Universität Bochum , Universitätsstr.150, 44780 Bochum, Germany.
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Schuhmann
authors.affiliation: Analytical Chemistry - Center for Electrochemical Sciences (CES), Ruhr-University Bochum , Universitätsstraße 150, 44780 Bochum, Germany.
authors.forename: Edgar
authors.initials: E
authors.lastname: Ventosa
keywords: Li-ion battery; Young’s modulus; atomic force microscopy (AFM); colloidal probe force microscopy; mechanical properties; nanoindentation; silicon electrode; solid electrolyte interphase (SEI)