Tetrafluoroborate Anion Intercalation into Graphite Electrode from Sulfolane

Electrolyte solutions of lithium tetrafluoroborate dissolved in sulfolane are applied in dual-ion batteries. A graphite positive electrode in this kind of solutions delivers a reversible anion storage capacity over 80 mAh g−1 at potentials over 4.5 V vs. Li/Li+. The structures of anion-graphite intercalation compounds are investigated in detail by the combination of in situ X-ray diffraction (XRD) and in situ Raman spectroscopic measurements. Graphite electrodes are charged to 5.5 V in 1 M LiBF4-SL. During galvanostatic charge-discharge test at 0.05 A g−1, capacity ca. 90 mAh g−1 is obtained and plateaus could be ascibed to peaks in the CV curve. The stage during charging process is determined by in situ X-ray diffraction and Raman mearsuments.