Passivation of zinc in alkaline solution effected by chromates and CrO3–graphite system

Electrochemical properties of porous zinc electrode in alkaline solution have been modified by the additive of chromium compounds such as chromates and CrO3–graphite system. Insertion of chromates inside the zinc electrode caused the limited solubility of the anodic dissolution products and their retention in the electrode interior. Different behaviour of the passivated zinc electrode was observed depending on cation of the used chromate. The improvement of cyclic performance of zinc has also been noted after the electrode is admixed with CrO3–graphite system containing intercalated/incorporated oxide. Electrochemical properties of zinc electrode strongly depend on the way of chromium insertion to active material of anode. Anodic and cathodic charges have been measured during potentiodynamic cycles for the observation of passivating effect.