Optimizing the Sulfur Loading in Microporous Carbon Aerogel Host for High‐Performance Lithium/Sulfur Battery Cathode

The insulating nature and complex redox reaction of elemental sulfur mandate their encapsulation inside an electronic conductor such as carbon. Herein, a sulfur/microporous carbon aerogel (S/CA) composite as an efficient, low‐cost, high‐performance cathode for rechargeable lithium‐sulfur (Li/S) battery is discussed. The S/CA cathode with varying ratios of sulfur:CA is prepared using pressure‐induced melt diffusion technique. Of the four different ratios, (sulfur:CA = 70:30) exhibits the best performance. The Li/S cell with (sulfur:CA = 70:30) cathode shows a first discharge capacity of 1308 mAhg −1 at a current rate C/10, and the cell is stable up to 300 cycles with a discharge capacity ≈750 mAhg −1 . This composition also exhibits good rate capability over the current density range (0.1–2)C. Post cycling UV–visible absorbance spectroscopy is carried out to ascertain the dissolution of lithium polysulfides in various S/CA cathodes. UV–visible results confirm that among the various sulfur:CA compositions, the one with the (sulfur:CA = 70:30) has the optimum retention of polysulfides leading to a superior Li/S battery performance.