On the possibility of using ionic liquids as electrolyte solutions for rechargeable 5 V Li ion batteries

We report herein on the reversible cycling of LiNi0.5Mn1.5O4 spinel electrodes with their reversible lithium intercalation potential of about 4.7–4.8 V vs. Li/Li+, in electrolytes based on 1-methyl-3-methylimidazolium tetrafluoroborate (EMIBF4) and 1-butyl-3-methylimidazolium tetrafluoroborate (BMIBF4). In this application, one of the main advantages of room temperature ionic liquids, their high anodic stability, is well exploited.