Electrochemical analysis for highly efficient manganese dioxide electrolysis

In this work, the electrochemical oxidation behavior of Mn²⁺ ions in sulfuric acid solutions was systematically studied via cyclic voltammetry, linear voltammetry, electrochemical impedance spectroscopy, and electrolytic experiments. The results show that a passivation phenomenon is present in the electro-oxidation process of Mn²⁺ to MnO₂, suggesting that the applied current should be reasonably controlled to reduce the side reactions caused by polarization. To achieve high-efficient MnO₂ electrolysis, the anodic potential should be controlled within an appropriate range to avoid oxygen evolution and the generation of MnO₄^- ions. Increasing the electrolytic temperature can significantly relieve the passivation on the interface during the electrolysis of MnO₂, and combined with reasonable anodic current control, a higher current efficiency can be obtained. The optimum current efficiency of 96.6% for MnO₂ electrolysis is achieved when the anodic current is 6 mA/cm² and at 80 ℃ in 50 g/L H₂SO₄ solution containing 25 g/L Mn²⁺.