An electrochemical quartz crystal microbalance is used in an investigation of the corrosion of aluminum in electrolytes appropriate for lithium batteries. The electrolytes are solutions of LiN(CF3SO2)(2) LIC(CF3SO2)(3), LiCF3SO3, LiPF6, LiBF4, and LiClO4, singly or in a limited number of combinations, in propylene carbonate (PC) and polyethylene glycol dimethyl ether Aluminum that is scratched or abraded in an inert atmosphere (so that a protective surface film does not reform) undergoes significant corrosion in PC containing LiN(CF3SO2)(2), LiC(CF3SO2)(3), LiCF3SO3, and LiClO4, but forms a protective film in PC containing LiPF6, or LiBF4. A mechanism of corrosion of aluminum in LiN(CF3SO2)(2)/PC is proposed.