Construction of chromium-free passivation film of pomelo peel extract on the surface of lithium-ion battery copper foil and study on anti-corrosion mechanism

Abstract

Passivation treatment is the last key process to ensure the service life of copper foil for lithium-ion batteries. Although chromic anhydride commonly used in industry has an efficient passivation effect, it can threat human health and the environment. Herein, an environmentally friendly passivator is prepared from pomelo peel by a simple and economical solution extraction method, which makes copper foil have good anti-corrosion properties in air, chlorine-containing solution, and organic electrolyte. Electrochemical methods and X-ray photoelectron spectroscopy (XPS) confirm the potential of pomelo peel extractant (PP) to replace chromic anhydride as a passivating agent for copper foil. The interaction mechanism between PP and copper foil is analyzed by adsorption models, and the efficient passivation behavior of PP for copper foil is consistent with the Langmuir model. Density Functional Theory (DFT) calculations of the naringin (main component of PP) is performed to further reveal the protection mechanism of PP on copper foil. In addition, the copper foil treated by PP still has excellent electrochemical performance as lithium-ion battery current collector, indicating that the presence of PP not only protects the copper foil from corrosion, but also does not affect the conductivity of the copper foil. This research provides a new insight into the chrome-free passivation of copper foils, which is in line with the development concept of green production.