Performance Enhancement and Mechanistic Studies of Magnesium-Sulfur Cells with an Advanced Cathode Structure

Magnesium-sulfur cells based on abundant, safe Mg and S are demonstrated with a cathode containing a preactivated carbon nanofiber (CNF) electrode matrix filled with sulfur active material and a CNF-coated separator. The CNF coating on the separator serves as a polysulfide trapper and an upper current collector for facilitating high sulfur utilization and enhancing the cycle life. Mechanisms regarding the performance enhancement and the charge-discharge processes of the Mg-S cells are investigated with spectroscopic, microscopic, and electrochemical analyses.