Study of a Novel W–Si Passivation Process for Lithium Copper Foils: Rational Utilization of the Polyhydroxy Structure Based on Sodium Gluconate

Abstract

The traditional chromate passivation process for lithium copper foils is hazardous and does not meet the requirements of green development. Therefore, in this study, utilizing the characteristics of gluconate coordinated with Cu²⁺, gluconate is adsorbed on the surface of copper foil, providing an anchor point for the action of JH-M902. Its rich hydroxyl structure (C–OH) and the Si–OH produced by the hydrolysis of JH-M902 dehydrate and condense to form Si–O–C. Then, WO₄²⁺ and Cu²⁺ formed by CuWO₄ fill in the film layer. These three passivators synergistically construct a W–Si passivation film with excellent corrosion resistance. Electrochemical tests show that the corrosion inhibition rate of the passivated film is as high as 98.08%, which is much higher than that of the existing chromate passivation process. The process proposed in this study can promote the development of chrome-free passivation of lithium copper foil and provides new ideas for the protection of other metal materials.