Widespread recognition of the need for detailed understanding of molecular and nanoscale processes at electrochemical interfaces is driving a growing number of in situ and operando X-ray spectroscopic investigations with both chemical and interfacial sensitivity. However, these studies may present more questions than answers and rely heavily on interpretation to make sense of the measurements. Simulation of electrified interfaces and electrolyte degrees of freedom requires large scale molecular dynamics simulations, given the natural nanoscale dimensions of the electric double layer. Furthermore, first-principles approaches are required if the chemistry at the interface is to be predicted accurately. X-ray spectra provide a convolution of spatial and temporal configurational sampling of interfacial degrees of freedom and the associated electronic structure of the species in their local environment. We make use of extensive molecular dynamics sampling and density functional-based simulations of X-ray spectra to predict or interpret insightful experiments. Our approach has been applied successfully to both aqueous and non-aqueous electrochemical contexts - canonical benchmarks and promising beyond-Li-ion materials combinations. We will present these examples and provide an outlook for future investigations involving teams with combined experimental and theoretical expertise.

First-principles interpretations of X-ray spectroscopy at electrochemical interfaces

255th National Meeting (2018)

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