Hexafluorophosphate Intercalation into the Graphite Electrode from Mixed Cyclic Carbonates

The storage of anions in the graphite electrode depends upon the composition of electrolyte solutions. LiPF6 and cyclic carbonates are the most common components of nonaqueous electrolyte solutions. In this paper, we investigated the performance and solvation states of the graphite cathode in 1 M LiPF6 solutions dissolved in traditional cyclic carbonates including EC, PC, BC, and their mixtures. The storage behavior of PF6– in the graphite electrode was elucidated by several electrochemical experiments combined with ex situ and in situ XRD measurements. The intercalation of the anion co-solvated by more than two carbonates into graphite has been discovered. It was also found that the storage performance of PF6– in the graphite electrode was closely related to the composition of electrolyte solution. This study provides a simple method for tailoring the solvation states of anions within graphite electrodes.