An electrolysis–displacement–distillation approach for the production of Li, Mg, Ca, Sr, and Ba metals

Abstract

Green metal-electrode batteries call for the clean production of s-block metals. Herein, we developed an electrolysis–displacement–distillation (EDD) approach for producing s-block metals with low-carbon emissions and no chlorine gas evolution. The clean production stems from the choice of a molten NaCl–Na₂CO₃ electrolyte to prevent chlorine gas evolution, an inert nickel-based anode to produce oxygen, and a liquid metal cathode to make the cathodic product (e.g., Na–Sn) sit at the bottom of the electrolytic cell. Later, M–Sn (M = Li, Mg, Ca, Sr, and Ba) alloys were successfully prepared by a displacement reaction between the Na–Sn alloy and molten NaCl–LiCl, NaCl–MgCl₂, NaCl–CaCl₂, NaCl–SrCl₂, or NaCl–BaCl₂ with a displacement efficiency of >96.0%. Furthermore, Li, Mg, Ca, Sr, and Ba metals were separated from M–Sn alloys using vacuum distillation with a separation rate of >95.0%. We achieved a current efficiency of 81.0% for the electrolytic production of 100 kg of a liquid Na–Sn alloy, which holds promise to produce s-block metals at a large scale.