Cooperation of Dimethyl and Diethyl Carbonates in Hexafluorophosphate Anion Intercalation into Graphite Electrode.

In dual-ion batteries, electrolyte solutions must comply with the positive electrodes of anion graphite intercalation compounds. The solutions of LiPF6 dissolved into ethylmethyl carbonate (EMC) cater to this need. In this paper, the mixtures of dimethyl carbonate (DMC) and diethyl carbonate (DEC) are employed in charge of EMC. The storage of PF6- synergistically solvated by both DMC and DEC in graphite has been identified by in/ex situ XRD measurements and conventional electrochemical tests. An optimized electrochemical performance in the solution of LiPF6-DEC/DMC is achieved if the volume ratio of DEC/DMC equals to 4. The solvation states in the LiPF6-DMC/DEC solutions are characterized by IR spectra analysis.