Investigation of the anodic behavior of Al current collector in room temperature ionic liquid electrolytes

We have investigated the anodic behaviors of aluminum as a cathodic current collector for lithium ion batteries in several kinds of room temperature ionic liquids (RTILs) and EC + DMC solutions containing LiN(CF3SO2)2 by cyclic voltammetry (CV), chronoamperometry (CA), scanning electron microscopy (SEM), energy dispersive X-ray (EDX) spectroscopy and X-ray photoelectron spectroscopy (XPS). Cyclic voltammetry and chronoamperometry data showed that the current density for aluminum foil with the RTIL electrolytes was less than that of aluminum foil in the EC + DMC solutions. Besides, much corrosion pits appeared on the aluminum foil surface after the electrochemical measurement in the EC + DMC solutions, while they were not observed on the aluminum foil with the RTIL electrolytes, suggesting that aluminum current collector was stable in the RTIL electrolytes. Further research by EDX and XPS analysis revealed that a good passivating film composed mainly of the products from the oxidation between aluminum and the anions of the RTIL electrolytes on the aluminum foil surface after the anodic polarization which suppressed the aluminum corrosion.