\textit{In situ} nonresonant inelastic x-ray scattering spectra of LiCoO$_{2}$ battery electrodes

The rational design of improved battery electrodes for Li-ion batteries faces many barriers, not the least of which is a correct, fundamental understanding of the changes in local electronic structure that accompany insertion and removal of lithium. We present nonresonant inelastic x-ray scattering (NIXS) spectra from the 2$p$, 3$s$, and 3$p$ initial states in Co and the 1$s$ initial state in O from LiCoO$_{2}$ cathodes from working electrochemical cells. These spectra were measured using the lower energy resolution inelastic x-ray scattering (LERIX) spectrometer at the Advanced Photon Source. NIXS at $\sim $1 eV energy resolution provides a bulk-sensitive alternative to x-ray absorption spectroscopy for studies of low-energy ($<$1.5 keV) electronic transitions. Furthermore, at sufficiently high momentum transfers NIXS is sensitive to dipole-forbidden transitions, providing additional information about electronic structure.