Lithium insertion in graphite from ternary ionic liquid–lithium salt electrolytes: II. Evaluation of specific capacity and cycling efficiency and stability at room temperature

In this paper we report the results about the use of ternary room temperature ionic liquid–lithium salt mixtures as electrolytes for lithium-ion battery systems. Mixtures of N-methyl-N-propyl pyrrolidinium bis(fluorosulfonyl) imide, PYR13FSI, and N-butyl-N-methylpyrrolidinium bis(trifluoromethansulfonyl) imide, PYR14TFSI, with lithium hexafluorophosphate, LiPF6 and lithium bis(trifluoromethansulfonyl) imide, LiTFSI, containing 5 wt.% of vinylene carbonate (VC) as additive, have been used in combination with a commercial graphite, KS6 TIMCAL. The performance of the graphite electrodes has been considered in term of specific capacity, cycling efficiency and cycling stability. The results clearly show the advantage of the use of ternary mixtures on the performance of the graphite electrode.