S@C composites constructed by a graded pore-making strategy for Mg-S batteries with outstanding rate performance

Rechargeable magnesium batteries (RMBs) are low-cost energy storage devices, but they lack suitable cathode materials. Traditional sulfur (S 8 ) cathodes have attracted much attention because of their high energy density; however, their cycling stability, conductivity, and reversibility are inferior. In this work, porous carbon materials with abundant pores were obtained by graded pore-making and S@C composite materials were obtained as cathodes for magnesium-sulfur batteries after loading porous carbon materials with sulfur. The interconnected pores provide the electrode material with a wealth of electrons and ion transport channels. The hollow structure of the carbon material facilitates the electrode-electrolyte contact area ensuring ion supply at high currents. Magnesium electricity assembled using S@C for the cathode had a high initial discharge specific capacity of 728 mA h g −1 at 50 mA g −1 . When the magnification cycle reached 2000 mA g −1 , it still had a high discharge-specific capacity of 242 mA h g −1 , and the coulombic efficiency reached ∼100%, indicating excellent magnification performance. At a current density of 200 mA g −1 , the maximum discharge-specific capacity was 420 mA h g −1 . After 100 cycles, a discharge-specific capacity of ∼100 mA h g −1 remained with good cycling stability. This work provides a general strategy for the preparation of porous carbon composites and new insights for high-rate energy storage systems. A S@C composite material was successfully prepared by graded pore-making, and shows excellent electrochemical performance when used as a cathode material for magnesium-sulfur batteries.