Ionanofluid plasticized electrolyte with improved electrical and electrochemical properties for high‐performance lithium polymer battery

Herein, the electrochemical characteristics of Li/LiFePO4 battery, comprising a new class of poly (ethylene oxide) (PEO) hosted polymer electrolytes, are reported. The electrolytes were prepared using lithium bis(trifluoromethylsulfonyl)imide (LiTFSI) dopant salt and imidazolium ionic liquid-based nanofluid (ionanofluid) as the plasticizer. Morphological, thermophysical, electrical, and electrochemical properties of these newly developed electrolytes were studied. Using FT-IR spectroscopy, the interactions between dopant salt plasticizers and the host polymer, within the electrolytes, were evaluated. The optimized 30 wt% ionanofluid plasticized electrolyte exhibits a room temperature ionic conductivity of 6.33 × 10−3 S cm−1, wide electrochemical voltage window (~4.94 V vs Li/Li+) along with a moderately high value of lithium-ion transference number (0.47). The values are substantially higher than that of similar wt% IL plasticized electrolyte (7.85 × 10−4 S cm−1, ~4.44 V vs Li/Li+ and ~ 0.28, respectively). Finally, the Li/LiFePO4 battery, comprising optimized 30 wt% ionanofluid plasticized electrolyte, delivers 156 mAh g−1 discharge capacity at 0.1 C rate and able to retain its 92% value after 50 cycles. Such a superior battery performance as compared to the IL plasticized electrolyte cell (137 mAh g−1 and 84% after 50 cycles at the same current rate) would endow this ionanofluid a very promising plasticizer to develop electrolytes for next-generation lithium polymer battery.