  A new class of high-performance pyrrolidinium cation based ionanofluid
electrolytes with higher lithium salt concentration are developed. The
electrolytes are formed by dispersing imidazolium ionic liquid functionalized
TiO2 nanoparticles in low conducting, 0.6 M lithium salt doped
N-alkyl-N-butylpyrrolidinium bis(trifluoromethylsulfonyl)imide (Pyr14TFSI)
ionic liquid (IL) hosted electrolyte. Viscosity, ionic conductivity and thermal
properties of these electrolytes are compared with well studied 0.2 M salt
doped Pyr14TFSI IL-based electrolyte. The highly crystalline 0.6 M lithium salt
dissolved IL-based electrolytes gradually become amorphous with the increasing
dispersion of surface functionalized nanoparticles within it. The ionic
conductivity of the electrolytes shows unusual viscosity decoupled
characteristics and at the 5.0 wt% nanoparticle dispersion it attains a maximum
value, higher than that of pure IL host. As compared to pure IL-based
electrolytes, the ionanofluid electrolyte also possesses a significantly higher
value of lithium ion transference number. The Li/LiMn2O4 cell with the best
conducting ionanofluid electrolyte delivers a discharge capacity of about 131
mAh g-1 at 25 degree C at a current density of 24 mA g-1, much higher than that
obtained in 0.2 M Li salt dissociated Pyr14TFSI electrolyte (87 mAh g-1).
Superior interfacial compatibility between ionanofluid electrolyte and
electrodes as indicated by the excellent rate performance with outstanding
capacity retention of the cell as compared to pure IL-based analogue, further
establish great application potentiality of this optimized newly developed
electrolyte for safer LMBs.
