Novel bis(fluorosulfonyl)imide-based and ether-functionalized ionic liquids for lithium batteries with improved cycling properties
Novel ionic liquids (ILs), which were functionalized with ether oxygens to suppress crystallization and with bis(fluorosulfonyl)imide (FSI) anions to improve ionic conductivity, were synthesized and compared. Electrolyte mixtures were prepared by adding LiFSI to N-ethoxyethyl-N-methylpiperidinium FSI ([P 1,2O2 ][FSI]) and N-ethoxyethyl-N-methylmorpholinium FSI ([M 1,2O2 ][FSI]) in ratio of 1:9 (mol/mol). The electrolyte mixtures were found to exhibit a glass transition temperature between −71 and −93 °C and a decomposition temperature higher than 266 °C.