Linear sweep voltammetry and electrochemical impedance spectroscopy were used to investigate the corrosion behavior of an aluminum current collector in contact with polymer solvent containing lithium bis(trifluoromethanesulfonyl) imide [LiN(CF3SO2)(2), LiTFSI] at room temperature. The electrolytes were liquid poly(ethylene glycol) dimethyl ether (Mw 250) + LiTFSI (Li:O ratio of 1:20), and composite gel electrolytes consisting of the baseline liquid electrolyte + 10 wt% fumed silica nanoparticles. Such electrolytes have potential utility in lithium-based rechargeable cells, although LiTFSI is known to affect corrosion of the commonly employed aluminum current collector. The electrochemical data indicate that aluminum corrosion is attenuated in the presence of fumed silica nanoparticles. Possible mechanisms are discussed. (C) 2004 The Electrochemical Society.