Difluoro(oxalato)borate's Role in the Intercalation Behavior of Mixed Anions from Sulfolane

Some previous studies have found the synergistic effect of mixed anions in dual-ion batteries (DIBs). In this work, both lithium tetrafluoroborate (LiBF4) and lithium difluoro(oxalato)borate (LiDFOB) were dissolved in sulfolane (SL) solvent, and the resultant solutions were applied for DIBs. The storage behavior of mixed anions in natural graphite positive electrodes was investigated. In-situ X-ray diffraction measurements revealed both anions could participate in the formation of graphite intercalation compounds. Their evolution followed with the decreasing tendency of discharge capacities as the content of LiDFOB increased in solutions. The exchange of anions was discussed.