The aluminum corrosion behavior of lithium bis(oxalato)borate (LiBOB) in composite polymer electrolyte (CPE) was investigated and compared to LiPF6 through various electrochemical methods. The open-circuit voltage of the Li/CPE/Al 2032 button cells with LiBOB is 0.4-0.5 V higher than that with LiPF6. The polarization current density is effectively suppressed in LiBOB electrolyte. The electrical impedance spectroscopy results revealed that aluminum is electrochemically stable with LiBOB at 5.0 V (vs Li/Li+) or even higher. At 70 degrees C, the aluminum also remains rather stable at 5.0 V with LiBOB, while in LiPF6, it suffers severe corrosion. (c) 2007 The Electrochemical Society.