Facile Synthesis of rGO/g-C3N4/CNT Microspheres via an Ethanol-Assisted Spray-Drying Method for High-Performance Lithium–Sulfur Batteries

rGO/g-C3N4 and rGO/g-C3N4/CNT microspheres are synthesized through the simple ethanol-assisted spray-drying method. The ethanol, as the additive, changes the structure of the rGO/g-C3N4 or rGO/g-C3N4/CNT composite from sheet clusters to regular microspheres. In the microspheres, the pores formed by reduced graphene oxide (rGO), g-C3N4, and carbon nanotube (CNT) stacking provide physical confinement for lithium polysulfides (LiPSs). In addition, enriched nitrogen (N) atoms of g-C3N4 offer strong chemical adhesion to anchor LiPSs. The dual immobilization mechanism can effectively alleviate the notorious “shuttle effect” of the lithium–sulfur battery. Meanwhile, the cathode with high cyclic stability can be achieved. The rGO/g-C3N4/CNT/S cathode delivers a discharge capacity of 620 mA h g–1 after 500 cycles with a low capacity fading rate of only 0.03% per cycle at 1 C. Even, the cathode shows a retained capacity of 712 mA h g–1 over 300 cycles with a high sulfur loading (4.2 mg cm–2) at 0.2 C