Chemical Physics Seminar: The Interface of Things Correlating Molecular Orientation to Macroscopic Properties

Abstract:

The appearance of reliable, rechargeable energy storage devices, namely, lithium ion batteries, has revolutionized mobility, data accessibility, and communication. While significant achievements for portable devices are reported yearly, the shift from gasoline powered cars to electric powered vehicles has been less rapid. For example, the issue on how fast we charge an electric vehicle. Upon charging (“filling up”) a lithium-ion battery, a redox process occurs on the surface of the anode. This redox process forms an electrically insulating layer that allows lithium ion transport at a reasonable rate while hindering electrolyte decomposition on the anode surface and is termed the solid electrolyte interphase (SEI).

Can we influence the lithium-ion transport rate by structuring the SEI?

In the upcoming lecture, I will present the conclusions of my study on the composition and structure of the solid-liquid interface on Si anodes and its formation and degradation mechanisms. This study was carried out by a combination of operando sum-frequency generation (SFG) vibrational spectroscopy with ex situ surface sensitive techniques, such as: scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). In my lecture I will also address the dynamics of such an interface studied by ab-initio molecular dynamics simulations, and whether this interface structure extends into the bulk electrolyte solution based on X-ray reflectivity spectra.