Cycling Performances of Lithium-Air Batteries Assembled with Ionic Liquid-Based Electrolytes

Abstract

Li-air batteries have higher theoretical energy density than conventional rechargeable lithium batteries.[1,2] However, recent studies of Li-air batteries with conventional organic solvent-based electrolytes demonstrate that most of these solvents may not have long-term chemical stability in the presence of the superoxide radical.[3] Thus, improving the stability of electrolyte toward reduced oxygen species is the main key for developing the non-aqueous Li-air batteries with good capacity retention. In this work, we tried to investigate ionic liquid-based electrolytes for the Li-air batteries. They showed an oxidative stability higher than 5.3 V vs. Li/Li+, high ionic conductivity and good stability towards the superoxide radical. As a result, the Li-air batteries employing these electrolytes exhibited good cycling stability exceeding 100 cycles at a current density of 0.1 mA/cm². Good reversibility for oxygen reduction and evolution reaction was investigated by cycling voltammetry and ex-situ powder X-ray diffraction analysis.