Lithium intercalation into graphite: In operando analysis of Raman signal widths
Sven Jovanovic, Peter Jakes, Steffen Merz, Rüdiger‐A. Eichel, Josef Granwehr
Abstract
Abstract The mechanism of reversible lithium intercalation in graphite anodes is still not fully understood. In operando Raman spectroscopy provides a sensitive means to monitor structural changes during the intercalation process. Analysis of the D‐band to G‐band intensity ratio (D/G ratio) is a common method to study the structure of carbon materials. However, this approach is complicated for the investigation of graphite anodes during battery cycling, as the D‐band disappears with the onset of lithium intercalation. To circumvent this issue, the D/G ratio can be replaced by using the G‐band full‐width‐at‐half‐maximum (FWHM). In this study, an investigation of the G‐band FWHM during battery cell cycling is demonstrated as an alternative to monitor the intercalation of lithium into a graphite electrode. It was observed that lithium intercalation already occurs to a small extent during solid–electrolyte interphase (SEI) formation and that the formation of staged intercalation compounds leads to a continuous deformation of the boundary graphene layer.