Material Science & Engineering World Conference 2026

Abstract

The sustainable production of metallic manganese (Mn) is critical for advanced alloys, energy storage, and functional materials; however, conventional carbothermic processes are energy-intensive and generate significant CO2 emissions. Here, we report a controlled electrochemical route for Mn production from MnO in chloride molten salt at 800 °C. Thermodynamic analysis using HSC Chemistry confirms that MnO reduction occurs within the electrochemical stability window of the electrolyte. Cyclic voltammetry (CV) of the blank melt in a three-electrode system reveals a cathodic peak (vs. Pt quasi-reference electrode), associated with electrolyte decomposition, while more negative potentials result in salt species deposition on the Mo electrode. MnO pellets exhibit excellent chemical stability in the molten salt, showing negligible dissolution during prolonged exposure. To probe oxygen transport, oxide species were introduced into the melt, and X-ray photoelectron spectroscopy (XPS) confirms their dissolution, indicating effective oxygen ion accommodation and transport. The CV of MnO containing systems shows a distinct cathodic peak and anodic peak, suggesting a direct one-step reduction mechanism, further supported by square wave voltammetry. Galvanostatic electrolysis performed at 2.6-3.4 V for 2-12 h enables progressive reduction of MnO to metallic Mn. Time-dependent studies reveal a gradual transformation from the surface toward the interior. These findings establish a viable molten salt electrochemical route for producing Mn from MnO and provide mechanistic insight into oxygen ion transport and reduction behavior in chloride melts. The approach contributes to the development of lower-carbon electrometallurgical pathways for Mn and related transition metals.