Cycling Performances of Lithium-Air Cells Assembled with Mixed Electrolytes of Ionic Liquid and Diethylene Glycol Diethyl Ether

Abstract

Ionic liquid-based electrolytes composed of diethylene glycol diethyl ether (DEGDEE) and 1-butyl-1-methyl pyrrolidinium bis(trifluoromethane) sulfonyl imide (BMP-TFSI) were prepared and evaluated for non-aqueous lithium-air cell applications. Adding an appropriate amount of BMP-TFSI to the electrolyte solution improved ionic conductivity, oxidative stability and interfacial stability, and reduced flammability and volatility. When BMP-TFSI was mixed with DEGDEE under optimal condition, the cycle performance was remarkably improved as compared with either the organic electrolyte or ionic liquid electrolyte alone. The Li-air cell assembled with an optimized ionic liquid-based mixed electrolyte initially delivered a high discharge capacity of 10,620 mAh g(-1) and exhibited good cycling stability exceeding 150 cycles at a current density of 0.1 mA cm(-2) by limiting depth of discharge to 500 mAh g(-1).