Effect of Ionic Liquids as Additives on Lithium Electrolytes: Conductivity, Electrochemical Stability, and Aluminum Corrosion

We investigated the influence that eight ionic liquids (ILs) as additives have on the conductivity and electrochemical stability of lithium salt-based electrolytes. The investigated salts were the well-known lithium hexafluorophosphate (LiPF 6 ), which is the preferred salt for lithium ion batteries (LIBs), and the new salt lithium difluoro(oxalato)borate (LiDFOB). Conductivity studies performed over the temperature range (238.15 to 333.15) K showed a temperature-dependent increase in conductivity caused by several IL additives. The electrochemical stabilities of the solutions were determined at platinum and aluminum electrodes. At the Pt electrode, LiPF 6 is the more stable salt, whereas at the aluminum electrode, LiDFOB exhibits a 0.5 V higher potential window in comparison with LiPF 6 -based solutions. An investigation of the influence of added ILs on the corrosion of aluminum, the current collector material for cathodes of LIBs, did not reveal any adverse effects.