Ionic liquid electrolytes for high-voltage, lithium-ion batteries

Ionic liquid electrolytes based on imidazolium and tetra-alkyl-ammonium cations, coupled with bis(perfluroalkylsulfonyl)imide anions, are specifically tailored for lithium battery systems operating up to almost 5 V. Their ion transport properties and the electrochemical stability are herein reported and compared. Specifically, the effect of temperature and lithium salt incorporation as well as the nature of the main cation side group are discussed. Preliminary battery cycling tests of the selected ionic liquid electrolytes employing high-voltage, lithium-rich layered oxide positive electrodes, (i.e., Li1.2Ni0.2Mn0.6O2) are also reported. Also, potential anodic dissolution phenomena of the aluminum current collector, due to the presence of the ionic liquid electrolytes, were preliminarily investigated.