Corrosion study of nickel-coated copper and chromate-coated aluminum for corrosion-resistant lithium-ion battery lead-tab

The lead tab serves as a terminal that collects charges generated from each electrode inside the battery and transfers it to the outside of the battery. Among the lead tabs used in the electric vehicle industry, a corrosion of aluminum (Al), chromium-coated Al (CCAl), copper (Cu), and nickel-coated Cu(NCCu) during the cycling of lithium-ion batteries is investigated. Cyclic voltammetry (CV) analysis are performed as part of the electrochemical corrosion test during battery cycle life, scanning electron microscope (SEM) for checking lead tab surface, and X-ray photoelectron spectroscopy (XPS) depth profile for a chemical analysis. By the CV results, it was inferred that the Cr and Ni coatings form a layer on the surface, and the morphology was visually confirmed by post CV SEM analysis. Subsequent XPS results confirm the sub-reaction related to LiPF6-carbonate electrolyte. Finally, the composition and distribution of the formed passivation layer were finally confirmed by XPS depth profile analysis. These passivation layers prevent the corrosion of the lead tab and contribute to the extension of battery life by inhibiting the dissolution of Al and Cu metals and the decomposition of the electrolyte during the charge/discharge test of LIB.