Remarkable cycling durability of lithium-sulfur batteries with interconnected mesoporous hollow carbon nanospheres as high sulfur content host

Nitrogen doped hollow carbon nanospheres with interconnected mesoporous shell as ultrahigh sulfur content of Li-S batteries with ultra-long life (more than 3100 cycles). [Display omitted] •“Interpenetration twin” nano-framework of S/C ensures accessible reaction interface for sulfur species.•Interconnected open mesoporous channels in N-doped hollow carbon spheres facilitate fast transfer of Li-ion and polysulfide.•Desired micro-mesoporous volume (4.75 cm3/g) and large SBET (1875 m2/g) are conducive to the ultrahigh sulfur loading.•MHCS/S with up to a 90.4% sulfur ratio for long-life durability of 3100 cycles. To reduce capacity attenuation during cycling and improve ultrahigh-sulfur-loading of Li-S batteries, we have manufactured nitrogen doped hollow carbon nanospheres (60 nm) with interconnected mesoporous shell (MHCS) as conducting frameworks for sulfur loading. One-step dual template technique is employed to prepare nitrogen doped polymer-silica nanocomposites with “interpenetration twins” nano-architectures at the initial stage. After carbonization and etching of silica, the “interpenetration twins” nano-architectures converted into interconnected functionalized mesoporous carbon nanospheres that endow desired micro-mesoporous volume (4.75 cm3/g) and high-specific area (SBET, 1875 m2/g). To the best of our knowledge, we achieved the highest sulfur content (90.4 wt%) in the carbon-based cathodes due to the interlinked pore network between S and carbon skeleton, which is formed by occupying the space of the removed silica with sulfur. In this way sulfur element could be closely contacted with the conductive carbon skeleton. Furthermore, polyethylene oxide (PEO) and polyvinylpyrrolidone (PVP) composite polymer were adhesive on the encapsulated carbon shell to limit the leakage of lithium sulfide leading to an improved the capacity retention of Li-S batteries. Noticeably, the average of the capacity decay reached to 0.023% per cycle during 3,100 cycles, which represent optimal performance of long-period lithium-sulfur batteries heretofore. The effortless method can provide a new way to design exceptionally high pore volume with interconnected mesoporous, and maintained definite hollow nanostructure, which are critical for porous carbons and energy storage.