Chemical Analysis of Graphite/Electrolyte Interface Formed in LiBOB-Based Electrolytes

To understand the source of thermal stability of LiBOB-based electrolyte in lithium-ion cells as well as its unique ability to stabilize graphitic anodes even in the strongly exfoliating solvent propylene carbonate (PC), the solid electrolyte interface on graphite formed by LiBOB-based electrolyte was investigated by X-ray photoelectron spectroscopy. Preliminary results show that, due to the BOB anion presence, the content of semicarbonate-like components in the graphite/electrolyte interface increases significantly, as indicated by the conspicuous peak located at 289 eV. These components, believed to originate from the oxalato moiety of the anion, are mainly responsible for the protection of graphitic anodes, either at elevated temperatures or in the presence of PC.