Corrosion of aluminum electrodes in aqueous slurries for lithium-ion batteries

Current manufacturing methods for lithium ion batteries use a non-aqueous solvent for producing slurries of cathode active materials and applying them to the aluminum current collectors. Transition to a water-based process may be desirable to reduce volatile organic compound emissions and costs, and increase processing efficiency. This transition may lead to additional complexities such as corrosion that could impact the performance of cells in service. The current work shows that the use of aqueous-based slurries for manufacturing lithium ion batteries can lead to general and pitting corrosion of the aluminum alloy foils used as current collectors with contact times as short as 100 s. Pitting corrosion initiates due to localized galvanic cells between cathodic intermetallic particles present in the aluminum alloy and the locally anodic aluminum matrix. The extent of pitting and amount of general corrosion product formed differs when using slurries of different active material compositions and increases with slurries of higher inherent pH. The presence of the intermetallic particles in the aluminum alloy is expected based on the chemical composition of the material. While elimination of the intermetallics from the aluminum is possible by increasing the purity of the material, it is unlikely that this mitigation strategy would be implemented due to economic considerations.