Effect of temperature on electrochemical performance of ionic liquid based polymer electrolyte with Li/LiFePO^sub 4^ electrodes

• Published in: Solid state ionics 2017-10, Vol.309, p.192
• Main Authors: Gupta, Himani, Shalu, Balo, Liton, Singh, Varun Kumar, Singh, Shishir Kumar, Tripathi, Alok Kumar, Verma, Yogendra Lal, Singh, Rajendra Kumar
• Format: Article
• Language: English
• Subjects: Batteries; Cationic polymerization; Chemical synthesis; Conducting polymers; Conductivity; Discharge; Electrochemical analysis; Electrodes; Electrolytes; Ethylene; Ethylene oxide; Ion currents; Ionic liquids; Lithium; Polymers; Temperature; Temperature effects; Thermal stability
• ISSN: 0167-2738; 1872-7689

Poly ethylene oxide based polymer electrolytes containing salt lithium bis(trifluoromethylsulfonyl)imide and ionic liquid 1-butyl-3-methyl pyridinium bis(trifluoromethylsulfonyl)imide are synthesized. The prepared polymer electrolytes are found to be thermally stable up to 340-360 °C. Ionic conductivity is observed ~ 2.5 × 10- 5 S cm- 1 at 25 °C and 2.3 × 10- 4 S cm- 1 at 40 °C for 30% IL containing polymer electrolyte. Also, ionic transference number > 0.99 and cationic transference number ~ 0.41 with electrochemical window ~ 5.2 V at 25 °C is observed for the electrolyte containing 30% IL. The highest Li+ ion conducting polymer electrolyte is further optimised for battery application. The specific discharge capacity of the prepared cell (Li/polymer electrolyte/LiFePO4) is found to be 106 mAh g- 1 at 25 °C and 160 mAh g- 1 at 40 °C up to 25 cycles with 0.1 C current rate. The increment in discharge capacity at higher temperature may be due to the better electrode-electrolyte contact. Decrement in cell resistance is also observed at higher temperature.