The Corrosion Study of Al Current Collector in Phosphonium Ionic Liquid as Solvent for Lithium Ion Battery

Abstract

A room temperature ionic liquid (RTIL) based on trihexyl (tetradecyl)phosphonium bis(trifluoromethanesulfonyl) imide ([(C6H13)3P(C14H29)] [TFSI];P66614TFSI) was synthesized and analyzed to determine their characteristics and properties. The bis(trifluoromethanesulfonyl)imide (TFSI) anion is widely studied as an ionic liquid (IL) forming anion which imparts many useful properties, notably electrochemical stability. Especially its electrochemical and physical charac- teristics for solvent of lithium ion battery were investigated in detail. P66614 TFSI exhibits fairly low conductivity (0.89mS cm1) and higher viscosity (298 K: 277 cP; 343 K: 39 cP) than other ionic liquids, but it exhibits a high thermal stability (over 400oC). Especially corrosion behavior on Al current collector was tested at room temperature and further it was confirmed that thermal resistivity for Al corrosion was highly increased in 1.0 M LiTFSI/P66614-TFSI electrolyte comparing with other RTILs by linear sweep thermometry