Open-circuit voltage study of graphite-coated copper foil electrodes in lithium-ion battery electrolytes

The open-circuit voltage (OCV) of graphite-coated copper foil electrodes in Li-ion battery electrolytes was found to vary over time. A detailed study showed that the OCV first rapidly decreased until reaching a minimum, and then gradually increased until reaching a steady state. These results were compared with OCV studies of graphite-coated aluminum foil and copper foil without graphite coating. The influence of hydrofluoric acid and thermal treatment of the graphite coating was also studied. Combined with copper dissolution studies using atomic absorption spectroscopy, it was found that the interaction of the graphite coating with electrolyte solution was the main causative factor that resulted in the OCV variation. (C) 2002 The Electrochemical Society.