Improving molten regolith electrolysis with zirconia-based hollow anode technology

Molten regolith electrolysis is a promising in-situ resource utilization technology that targets O2 and metals production through the direct electrolysis of molten lunar regolith. However, there are still challenges associated with molten regolith electrolysis, such as bubble detachment and O2 separation and collection at the anode. A hollow anode, comprised of an oxygen-conducting yttria-stabilized zirconia shell and a platinum current collector, is designed here to address these challenges. Experimental results from an inverted hollow anode reactor successfully demonstrate that molten regolith electrolysis can be performed through a solid electrolyte. The elemental composition of both the cathodic products (primarily Fe and Si) and solidified lunar regolith simulant are reported as a function of electrolysis duration. These observations are supported by a thermochemical model built using FactSage to provide compositions of the cathodic products and solidified regolith simulant with increasing O2 removal. Finally, the behavior of yttria-stabilized zirconia in the hollow anode application is characterized, and provides guidance for the design and operation of a yttria-stabilized zirconia hollow anode to enable integration into a full-scale molten regolith electrolysis reactor.