In situ X-ray Raman scattering spectroscopy of a graphite electrode for lithium-ion batteries

Abstract

Lithium-intercalated graphite (LIG) is the most commonly used anode material for Li-ion batteries; however, the change in the electronic structure of LIG during battery operation is not fully understood. We have developed an in situ cell and a measurement method to elucidate this change using X-ray Raman scattering (XRS) spectroscopy. A confocal-like method enables the C K-edge spectrum of LIG alone to be extracted while avoiding the spectral overlap of carbon-containing components in the cell. In situ XRS and X-ray diffraction measurements are conducted simultaneously for LiC6, LiC12, and fully delithiated graphite during the delithiation process. The results indicate that the intensity of the π* peak of the XRS spectrum increases upon delithiation, and the σ* onset shifts to higher energy, which are consistent with prior spectroscopic studies on LIG. These results demonstrate that the in situ XRS method established in this study is useful to characterize the electronic properties of LIG during the operation of batteries.