Berlin 2018 – scientific programme
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MM: Fachverband Metall- und Materialphysik
MM 2: Battery Materials
MM 2.4: Talk
Monday, March 12, 2018, 11:00–11:15, H 0106
Electrochemical Lithiation of crystalline Si investigated by operando NR and EIS — •Arne Ronneburg1,2, Marcus Trapp1, Robert Cubitt3, Luca Silvi1, Sebastian Risse1, and Matthias Ballauff1, 2 — 1Helmholtz-Zentrum Berlin, Institute of Soft Matter and Functional Materials, Hahn-Meitner Platz 1, 14109 Berlin, Ger-many — 2Humboldt-University Berlin, Institute of Physics, Zum Großen Windkanal 6, 12489 Berlin, Germany — 3Institute Laue Langevin (ILL), 71 avenue des Martyrs - CS 20156, 38042 Cedex 9 Grenoble, France
Silicon is a promising material for Li-Ion batteries due to its eleven times higher specific capacity compared to graphene. However, Si-anodes suffer from strong capacity fading. Therefore more fundamental understanding of the degradation is needed for further improvement. Neutron scattering is ideally suited for the investigation of the Li/Si system due to the high contrast between the scattering length densities. Si anodes were investigated with operando neutron reflectometry in parallel with electrochemical impedance spectroscopy to elucidate the solid electrolyte interface(SEI) layer growth and decomposition during (de-)lithiation. The lithiation kinetics were investigated over four cycles revealing a successive growth of the lithiated zone and the formation of a SEI-layer within delithiation and its decomposition during lithiation. The correlation of the integrated electric current with the Li fraction in the Si electrode discloses the amount of charge that is needed to dissolve the SEI-layer during lithiation. This necessary investment of charge is a reason for a low coulombic efficiency.