Advancing Molten Salt Electrolysis for Lunar ISRU: Material Challenges, Testing, and Scalability Perspectives

Molten salt electrolysis is a method for extracting oxygen and metals from lunar regolith, contributing to sustainable long-term space exploration. Hall-Héroult electrolysis, widely used in terrestrial aluminum production, can be adapted for lunar regolith reduction. Identifying low-temperature electrolytes is crucial to reduce energy consumption. Lowering the operating temperature of the MSE cell will further aid the operation of an inert anode, enabling oxygen production. Experiments were performed using a LiF-NaF electrolyte system (melting point of 649ºC) to investigate the reduction behavior of Ca² ? ions. The focus was on calcium since it is the metal with the highest redox potential among the main constituents of the lunar regolith. The findings suggest that eutectic alkali metal mixtures, such as LiF-NaF, could be viable candidates for lunar MSE processing in which all metals, including Ca, are reduced. Experiments conducted with CaO and SiO2 mixtures show that achieving selective reduction of specific metals will require careful process optimization since the reduction reactions were not well separated. Overall, this work advances the understanding of Hall-Héroult-based molten salt electrolysis applied to lunar ISRU for scalable oxygen and metal production on the Moon.