Solid Oxide Membrane Electrolysis Process for Aluminum Production: Experiment and Modeling

This paper reports a solid oxide membrane (SOM) electrolysis process using an LSM (La 0.8 Sr 0.2 MnO 3- δ )-Inconel inert anode current collector and liquid silver anode for production of aluminum and oxygen from aluminum oxide dissolved in a pre-selected molten oxy-fluoride flux containing Ca, Mg, Al and Y at 1473K (1200°C). The electrochemical behavior of the SOM cell was characterized by various electrochemical techniques including electrochemical impedance spectroscopy, potentiodynamic scan and potentiostatic electrolysis. Based on the electrochemical measurement results, an equivalent circuit model of the SOM electrolysis process is presented. A polarization model for aluminum and oxygen production was developed and the polarization losses in the cell were analyzed according to the equivalent circuit. Based on the polarization model analysis, potential approaches to improve the cell performance are also discussed. The aluminum produced and the yttria stabilized zirconia (YSZ) membrane were characterized with scanning electron microscope and energy-dispersive X-ray spectroscopy after the electrolysis.