1. Surface structure inhibited lithiation of crystalline silicon probed with operando neutron reflectivity
- Author
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Marcus Trapp, Robert Cubitt, Matthias Ballauff, Sébastien Cap, Arne Ronneburg, Luca Silvi, and Sebastian Risse
- Subjects
Materials science ,Silicon ,Renewable Energy, Sustainability and the Environment ,Energy Engineering and Power Technology ,chemistry.chemical_element ,02 engineering and technology ,010402 general chemistry ,021001 nanoscience & nanotechnology ,01 natural sciences ,0104 chemical sciences ,Anode ,Dielectric spectroscopy ,chemistry ,Chemical engineering ,General Materials Science ,Lithium ,Crystalline silicon ,Neutron reflectometry ,0210 nano-technology ,Dissolution ,Faraday efficiency - Abstract
Silicon is a promising anode material for lithium ion batteries due to its ten times higher specific capacity compared to commercially used graphite anodes. However, silicon anodes suffer from strong capacity fading and low Coulombic efficiency during cycling. Here we analyzed crystalline silicon anodes by operando neutron reflectometry in combination with electrochemical impedance spectroscopy. The lithiation/delithiation processes were investigated over four cycles revealing a successive growth of the lithiated zone. Moreover, the loss of Coulombic efficiency could be directly correlated to a layer formation and its dissolution on the silicon surface that suppressed the insertion of lithium ions into the silicon anode. The comparison of the currents obtained by the scattering length density profiles and the potentiostat revealed that after an initial parasitic side reaction had occurred current losses of less than 5% could be achieved. While the lithiation was hindered by side reactions the delithiation process encountered no significant problems. The results obtained by electrochemical impedance spectroscopy suggested that a layer with high charge transfer resistance was formed after each delithiation step. Hence, these operando studies provide valuable insights into the correlation of surface formation processes and the loss in Coulombic efficiency.
- Published
- 2019
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