Sodium (Na) and magnesium (Mg) are becoming important for making energy-storage batteries and structural materials. Herein, we develop a liquid-metal-electrode-assisted electrolysis route to producing Na and Mg with low-carbon emissions and no chlorine gas evolution. The clean production stems from the choice of a molten NaCl-NaCO electrolyte to prevent chlorine gas evolution, an inert nickel-based anode to produce oxygen, and a liquid metal cathode to make the cathodic product sit at the bottom of the electrolytic cell. We achieve a current efficiency of >90% for the electrolytic production of liquid Na-Sn alloy. Later, Mg-Sn alloy is prepared using the obtained Na-Sn alloy to displace Mg from molten NaCl-MgCl with a displacement efficiency of >96%. Further, Na and Mg are separated from the electrolytic Na-Sn and displaced Mg-Sn alloys by vacuum distillation with a recovery rate of >92% and Sn can be reused. Using this electrolysis-displacement-distillation (EDD) approach, we prepare Mg from seawater. The CO emission of the EDD approach is ∼20.6 kg CO per kg Mg, which is less than that of the Australian Magnesium (AM) electrolysis process (∼25.0 kg CO per kg Mg) and less than half that of the Pidgeon process (∼45.2 kg CO per kg Mg).

中文翻译：

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液态金属电极辅助电解生产钠和镁

钠 (Na) 和镁 (Mg) 对于制造储能电池和结构材料变得越来越重要。在此，我们开发了一种液态金属电极辅助电解路线，以低碳排放且无氯气逸出的方式生产钠和镁。清洁生产源自于选择熔融的 NaCl-Na2CO 电解质来防止氯气逸出、惰性镍基阳极来产生氧气以及液态金属阴极来使阴极产物位于电解池的底部。我们在电解生产液态 Na-Sn 合金时实现了 >90% 的电流效率。随后，利用所得的Na-Sn合金从熔融的NaCl-MgCl中置换Mg，制备了Mg-Sn合金，置换效率>96%。此外，通过真空蒸馏从电解Na-Sn和置换Mg-Sn合金中分离出Na和Mg，回收率>92%，并且Sn可以重复使用。使用这种电解-置换-蒸馏 (EDD) 方法，我们从海水中制备镁。EDD方法的CO排放量为~20.6 kg CO/kg Mg，低于澳大利亚镁（AM）电解工艺（~25.0 kg CO/kg Mg），不到皮江工艺的一半（~每千克镁 45.2 千克二氧化碳）。