Lithium salt assisted enhanced performance of supercapacitor based on quasi solid-state electrolyte

Abstract

The role of lithium salt [LiTFSI] in ionic liquid [EMIMTFSI] based quasi solid-state electrolyte (QS-SE) on the performance of supercapacitor has been investigated. TGA results show that the synthesized QS-SE has good thermal stability (∼340 °C; onset temperature). The ionic conductivity of QS-SE increases with increasing the temperature and attains a value of ∼1.93 × 10−3 S.cm−1 at 30 °C and 4.91 × 10−3 S.cm−1 at 70 °C. The supercapacitor is fabricated using two carbon electrodes and can operate up to 3 V. The prepared supercapacitor has improved specific capacitance of 90 F.g−1 at 1 mA.cm−2 discharging rate (∼specific current 0.625 A.g−1). The cyclic tests indicate the stable performance of the supercapacitor cell with only 17% of initial fading in specific capacitance and high Coulombic efficiency (between 98 and 99%) after more than 2000 charge–discharge cycles.