Electrochemical desulfurization of galena-stibnite in molten salts to prepare liquid Sb-Pb alloy for liquid metal battery

摘要

A green, straightforward and inexpensive sulfide metallurgy approach is of great importance to reduce the Sulfur oxides gas emissions caused by the conventional extraction methods. Herein, liquid antimonial lead alloy (Sb3Pb7) can be directly extracted from the mixture of antimony sulfide and lead sulfide (Sb2S3-PbS) at the cathode in eutectic sodium chloride-potassium chloride (NaCl-KCl) melt at 730 degrees C, and sulfur gas evolves at the graphite inert anode. The reduction mechanism of Sb2S3-PbS involves two stages: the insertion of sodium ion (Na+) into liquid sulfides and then the removal of divalent sulfide ion (S2- ) to generate uniform Sb-Pb alloy. The electrolytically generated Sb-Pb alloy as the positive electrode for Li||Sb-Pb liquid metal battery (LMB) can be nearly fully discharged to xLi = 0.45 (lithium mole fraction, Li/(Li + SbPb)) at 50 mA cm-2 and 500 degrees C. During the discharge process, Li2Sb and Li3Sb formed as the intermetallic layer because of the high melting point and low solubility of the intermetallic in the liquid Pb. The present study provides an environmentally benign way to electrochemically convert sulfide minerals to value-added Sb-Pb alloys not only for the large-scale energystorage system but also for metal production.