Solvation effect on intercalation behaviour of tetrafluoroborate into graphite electrode

Anion-intercalated graphite compounds are becoming attractive as high-potential positive electrode materials in some electric energy storage devices. The intercalation of anions from electrolyte solutions to graphite electrode generally involves the co-entrance of organic solvent molecules inside the interlayer galleries of graphite, which has a great impact on the electrochemical behaviour of the graphite electrode. In situ XRD (X-ray diffraction) and EQCM (Electrochemical quartz crystal microbalance) techniques have been corporately employed to investigate the mechanism of BF4- intercalation into graphite positive electrode from three electrolyte solutions in activated carbon/graphite capacitors. The solvation states of BF4- by different solvents inside the graphite electrode have been correlated with the performance of AC/graphite capacitors using corresponding electrolyte solutions. (C) 2014 Elsevier B.V. All rights reserved.