Identifying a descriptor for d-orbital delocalization in cathodes of Li batteries based on x-ray Compton scattering

Abstract

We discuss how x-ray Compton scattering spectra can be used for investigating the evolution of electronic states in cathode materials of Li batteries under the lithiation/delithiation process. In particular, our analysis of the Compton spectra taken from polycrystalline LixCoO2 samples shows that the spectra are dominated by the contribution of the O-2p redox orbital. We identify a distinct signature of d-orbital delocalization, which is tied directly to the conductivity of the material, providing a descriptor based on Compton spectra for monitoring d kinetics for lithiation range with improved conductivity an the electrochemical operation. Our study demonstrates that Compton scattering spectroscopy can provide a window for probing complex electronic mechanisms underlying the charging and discharging processes in Li-battery materials.

X‐Ray Compton Scattering Study of Liquid Sodium at Elevated Temperatures

“…[ 9,10 ] Its high applicability to a wide variety of experimental conditions and materials has also been demonstrated. [ 11–15 ]…”

High-Energy X-Ray Compton Scattering Imaging of 18650-Type Lithium-Ion Battery Cell

“…Since the Compton profile is different for various orbitals, the specific electron orbitals involved in the reduction-oxidation (redox) reaction at the electrodes can be identified by combining experimental Compton profiles with parallel first-principles simulations. In this way, the redox orbitals in LiMn 2 O 4 , LiCoO 2 , and LiFePO 4 cathode materials have been revealed and visualized [5][6][7]. In fact, by analyzing Compton line-shapes, a quantitative analysis of lithium concentration can be performed, and we developed a technique for direct imaging of the lithiation state of a commercial lithium-ion battery based on Compton scattering.…”

Dependency of the Charge–Discharge Rate on Lithium Reaction Distributions for a Commercial Lithium Coin Cell Visualized by Compton Scattering Imaging

“…Moreover, the Compton scattering technique can be applied to the materials composing the battery as well as the large-scale battery produced. In fact, we have studied the mechanism of electrode reactions in positive electrode materials, Li x Mn 2 O 4 , Li x CoO 2 , and Li x FePO 4 , using Compton profiles [9][10][11].…”