Combining Experiments and Theoretical Calculations to Investigate the Intercalation Behavior of Bis(trifluoromethanesulfonimide) Anion into Graphite Electrodes from Alkyl Phosphates.

In dual-ion batteries (DIBs) utilizing organic electrolyte solutions, the combinations of electrolyte salt and solvent serve as a determiner of the electrochemical performance of graphite electrode partially because solvent participates in the anion intercalation procedure. In this case, every solvated-anion@graphite intercalation compound possesses the characteristic intercalated gallery height. However, in Li/graphite DIBs with concentrated LiTFSI (lithium bis(trifluoromethanesulfonimide))-alkyl phosphates (ca. trimethyl, triethyl, tripropyl, tributyl phosphate) solutions, solvated-TFSI-@graphite intercalation compounds have the nearly identical intercalated gallery height of about 0.803 nm, which may be mainly attributed to both the big size of TFSI- anion and the rigid PO4 framework of these alkyl phosphate solvents.