The Effect of the SEI Layer Mechanical Deformation on the Passivity of a Si Anode in Organic Carbonate Electrolytes

Journal Article · 26 March 2023 · ACS Nano

DOI: https://doi.org/10.1021/acsnano.3c00724 · OSTI ID:2325982

Yoon, Insun  ^[1]; Larson, Jonathan M.  ^[1]; Kostecki, Robert  ^[1]

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1. Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)

The solid electrolyte interphase (SEI) on a Si negative electrode in carbonate-based organic electrolytes shows intrinsically poor passivating behavior, giving rise to unsatisfactory calendar life of Li-ion batteries. Moreover, mechanical strains induced in the SEI due to large volume changes of Si during charge-discharge cycling could contribute to its mechanical instability and poor passivating behavior. This study elucidates the influence that static mechanical deformation of the SEI has on the rate of unwanted parasitic reactions at the Si/electrolyte interface as a function of electrode potential. Further, the experimental approach involves the utilization of Si thin-film electrodes on substrates with disparate elastic moduli, which either permit or suppress the SEI deformation in response to Si volume changes upon charging-discharging. We find that static mechanical stretching and deformation of the SEI results in an increased parasitic electrolyte reduction current on Si. Furthermore, attenuated total reflection and near-field Fourier-transform infrared nanospectroscopy reveal that the static mechanical stretching and deformation of the SEI fosters a selective transport of linear carbonate solvent through, and nanoconfinement within, the SEI. These, in turn, promote selective solvent reduction and continuous electrolyte decomposition on Si electrodes, reducing the calendar life of Si anode-based Li-ion batteries. Finally, possible correlations between the structure and chemical composition of the SEI layer and its mechanical and chemical resilience under prolonged mechanical deformation are discussed in detail.

• Research Organization: Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)
• Sponsoring Organization: USDOE Office of Energy Efficiency and Renewable Energy (EERE), Office of Sustainable Transportation. Vehicle Technologies Office (VTO)
• Grant/Contract Number: AC02-05CH11231
• OSTI ID: 2325982
• Journal Information: ACS Nano, Journal Name: ACS Nano Journal Issue: 7 Vol. 17; ISSN 1936-0851
• Publisher: American Chemical Society (ACS)Copyright Statement
• Country of Publication: United States
• Language: English