title: Electronic structure of lithium battery interphase compounds: comparison between inelastic x-ray scattering measurements and theory.
abstract: In lithium ion batteries, decomposition of the electrolyte and its associated passivation of the electrode surface occurs at low potentials, resulting in an electronically insulating, but Li-ion conducting, solid electrolyte interphase (SEI). The products of the SEI and their chemical constituents/properties play an important role in the long-term stability and performance of the battery. Reactivity and the sub-keV core binding energies of lithium, carbon, oxygen, and fluorine species in the SEI present technical challenges in the spectroscopy of these compounds. Using an alternative approach, nonresonant inelastic x-ray scattering, we examine the near-edge spectra of bulk specimens of common SEI compounds, including LiF, Li(2)CO(3), LiOH, LiOH·H(2)O, and Li(2)O. By working at hard x-ray energies, we also experimentally differentiate the s- and p-symmetry components of lithium's unoccupied states using the evolution of its K edge with momentum transfer. We find good agreement with theoretical spectra calculated using a Bethe-Salpeter approach in all cases. These results provide an analytical and diagnostic foundation for better understanding of the makeup of SEIs and the mechanism of their formation.
authors.affiliation: Chemical Sciences and Engineering Division, Argonne National Laboratory, Argonne, Illinois 60439, USA. fister@anl.gov
authors.forename: Tim T
authors.initials: TT
authors.lastname: Fister
authors.forename: Moritz
authors.initials: M
authors.lastname: Schmidt
authors.forename: Paul
authors.initials: P
authors.lastname: Fenter
authors.forename: Chris S
authors.initials: CS
authors.lastname: Johnson
authors.forename: Michael D
authors.initials: MD
authors.lastname: Slater
authors.forename: Maria K Y
authors.initials: MK
authors.lastname: Chan
authors.forename: Eric L
authors.initials: EL
authors.lastname: Shirley