Aluminum current collectors for cathodes in 61 life-tested lithium-ion batteries were microscopically examined for evidence of corrosion. In addition, galvanostatic anodic polarization tests were conducted in LiPF6-containing battery electrolytes on samples of bare aluminum, of aluminum coated with a LiFePO4 cathode, and of aluminum affixed with polyethylene crevices. The results indicate that aluminum current collectors are susceptible to corrosion, which most likely occurs as underdeposit corrosion at pores in the cathode. (c) 2005 The Electrochemical Society.