Ionic liquid-based electrolytes for lithium-ion batteries: review of performances of various electrode systems

Lithium-ion cells based on Graphite/LiFePO4 (Cgr/LFP), Li4Ti5O12/LiFePO4 (LTO/LFP) and Li4Ti5O12/LiNi1/3Mn1/3Co1/3O2 (LTO/NMC), using [C1C n Im][NTf2]- and [C1C1C n Im][NTf2] (n = 4 and 6)-based electrolytes with different lithium salts such as Li[N(SO2CF3)2] (LiNTf2), Li[N(SO2F)2] (LiFSI) and LiPF6 were tested at 333 K and compared to a commercial carbonate-based electrolyte [EC:DEC][LiPF6]. The impact of different factors such as length of side-alkyl chain on imidazolium ring or its C2-H substitution with CH3 group was studied, and the influence of the presence of organic additives as well as the value of the nominal voltage of the systems, was also reported. Finally, common trends for all these IL-based electrolyte systems were discussed.