Application of a Sulfur Cathode in Nucleophilic Electrolytes for Magnesium/Sulfur Batteries

We report the potential feasibility of a high-capacity and low-cost sulfur cathode that is compatible with nucleophilic electrolytes for Mg/S batteries. The electrochemical performance of sulfur in an easily prepared (PhMgCl)2-AlCl3/THF nucleophilic electrolyte depends on cathode current collectors. A sulfur cathode that uses Cu as a current collector, which is electrochemically stable in the range of operating voltage, exhibits an initial discharge capacity approximately corresponding to 659 mAh g−1, and maintains a reversible capacity of 113 mAh g−1 after 20 cycles at a current density of 10 mA g−1. It is different from the sulfur cathode with few capacities that uses stainless-steel as a current collector. Copper sulfides formed when sulfur is coated on a Cu current collector at 50°C provide a strong chemical interaction between Cu and sulfur, which protects sulfur and increases its compatibility with the electrolyte. A metal-stabilized sulfur cathode provides an effective approach to improve the electrochemical performance of Mg/S batteries in nucleophilic electrolytes.