Uncovering the unusual anodic current during tetrafluoroborate anion deintercalation from a graphite cathode in ethylene carbonate.

During the deintercalation of ethylene carbonate (EC)-solvated tetrafluoroborate anions (BF) from a graphite cathode, an unusual anodic counter current was observed. The generation of counter-current is revealed to stem from the interaction between EC and BF, which provides new clues to the often-overlooked C-H⋯anion weak interactions in dual-ion battery (DIB) or other battery electrolyte research.