Electrosprayed multiscale porous carbon microspheres as sulfur hosts for long-life lithium-sulfur batteries

Highly conductive carbon microspheres (CMSs) with a hierarchical porous structure are prepared by electrospraying polystyrene/polyvinylpyrrolidine (PS/PVP) solution containing Ketjen carbon black (KB) nanoparticles. The branched KB particles serve as the structural skeleton to support CMSs while the hybrid polymer precursor forms multiscale pores upon pyrolysis. The CMSs possessing an extremely large pore volume of 2.08 cm³ g⁻¹ and a large specific surface area of 756 m² g⁻¹ are melt-infiltrated with sulfur to form sulfur/CMS composite cathode for lithium-sulfur batteries. The cathode delivers a remarkable initial capacity of 1006 mAh g⁻¹ at 1 C with high retention of 67.5% after 1000 cycles, and an initial capacity of 728 mAh g⁻¹ at 2 C with high retention of 68.5% after 2000 cycles. The excellent electrochemical performance is attributed to the distinct functional and structural features of CMS framework: namely, microscale grain size, closely packed KB particles, large pore volume and hierarchical pore size, as well as superior conductive framework, which in turn suppress the shuttling of dissoluble polysulfides and boost the utilization of encapsulated sulfur. The above findings may offer insights into designing new carbon frameworks for other types of high performance rechargeable batteries.