Suppression of aluminum corrosion by using high concentration LiTFSI electrolyte

Although lithium bis(trifluoromethanesulfonyl imide) (LiTFSI) has a high thermal stability and fine tolerance to water and is an outstanding candidate as an electrolyte, there is an urgent need to control aluminum corrosion. Here, we explain how we suppressed aluminum corrosion by controlling the LiTFSI concentration. SEM observations and XPS depth profiles of the electrode at high LiTFSI electrolyte concentrations showed that stable passivation film composed of LiF was formed on an aluminum electrode, which prevented the continuous decomposition reaction of the LiTFSI electrolyte. As a result, a lithium-ion battery with LiTFSI demonstrated excellent properties for several cycles without aluminum corrosion, which should accelerate progress in its applications to industry.

► In higher LiTFSI concentration, aluminum corrosion was remarkably suppressed.
► From XPS depth profile, Li and F are mainly detected unlike normal concentration.
► We found a film composed of LiF played a role to prevent from aluminum corrosion.
► As results, a battery with high LiTFSI concentration could work without degradation.