Effect of aqueous-based cathode slurry pH and immersion time on corrosion of aluminum current collector in lithium-ion batteries

Corrosion of aluminum can occur during the manufacturing of lithium-ion batteries when using aqueous-based cathode slurries. In exposure tests, the alkaline pH value of aqueous-based cathode slurries and immersing time were revealed as the principle factors that control the corrosion of aluminum during the cathode manufacturing process. The nickel manganese cobalt oxide active material used in the slurry does not have a direct impact on corrosion of the aluminum current collector. The initiation and evolution of localized corrosion on aluminum are closely related to the formation of galvanic cells between aluminum matrix and intermetallic particles. X-ray photoelectron spectroscopy results confirmed that the pH of cathode slurry was the only factor that alters aluminum surface composition, during which the oxide passive film was gradually degraded into hydroxide. Electrochemical characterizations showed that aluminum electrodes gave remarkably different response to the different pH of test solutions. The time-pH-variant electrochemical response was ascribed to the change of passive film and electric double layer properties.