Interplay among Hexafluorophosphate, Difluoro(oxalato)borate Anions and Ethylene Carbonate during Their Insertion into a Graphite Electrode.

Ethylene carbonate solutions dissolving mixed lithium salts composed of both difluoro(oxalato)borate (DFOB - ) and hexafluorophosphate (PF 6 - ) anions are introduced into Li/graphite cells. The anions' intercalation procedures into the graphite positive electrode from these solutions are explored by charge/discharge, cyclic voltammetry, and impedance spectroscopic tests in combination with electrochemical in situ characterization including X-ray diffraction (XRD) and Raman spectroscopy. Furthermore, these solutions are characterized by ionic conductivity together with nuclear magnetic resonance measurements. The properties of the solutions are linked to the capacity values delivered by Li/graphite cells.